bluuebunny/crossref_metadata_2025 huggingface dataset:
Dietary patterns during pregnancy and the risk of postpartum depression: the mother–child ‘Rhea’ cohort in Crete, Greece
Authors: Chatzi Leda , Melaki Vasiliki , Sarri Katerina , Apostolaki Ioanna , Roumeliotaki Theano , Georgiou Vaggelis , Vassilaki Maria , Koutis Antonis , Bitsios Panos , Kogevinas Manolis
Published: August 2011

Objective

To identify and describe dietary patterns in a cohort of pregnant women, and investigate whether dietary patterns during pregnancy are related to postpartum depression (PPD).

Design

The study uses data from the prospective mother–child cohort ‘Rhea’ study. Pregnant women completed an FFQ in mid-pregnancy and the Edinburg Postpartum Depression Scale (EPDS) at 8–10 weeks postpartum. Dietary patterns during pregnancy (‘health conscious’, ‘Western’) were identified using principal component analysis. Associations between dietary patterns categorized in tertiles and PPD symptoms were investigated by multivariable regression models after adjusting for confounders.

Setting

Heraklion, Crete, Greece, 2007–2010.

Subjects

A total of 529 women, participating in the ‘Rhea’ cohort.

Results

High adherence to a ‘health conscious’ diet, characterized by vegetables, fruit, pulses, nuts, dairy products, fish and olive oil, was associated with lower EPDS scores (highest v. lowest tertile: β-coefficient = −1·75, P = 0·02). Women in the second (relative risk (RR) = 0·52, 95 % CI 0·30, 0·92) or third tertile (RR = 0·51, 95 % CI 0·25, 1·05) of the ‘health conscious’ dietary pattern were about 50 % less likely to have high levels of PPD symptoms (EPDS ≥ 13) compared with those in the lowest tertile.

Conclusions

This is the first prospective study showing that a healthy diet during pregnancy is associated with reduced risk for PPD. Additional longitudinal studies and trials are needed to confirm these findings.
Human tonsil
B
-
cell lymphoma 6
(
BCL6
)-expressing CD4
+
T-cell subset specialized for B-cell help outside germinal centers
Authors: Bentebibel Salah-Eddine , Schmitt Nathalie , Banchereau Jacques , Ueno Hideki
Published: August 2011

T follicular helper (Tfh) cells represent a Th subset engaged in the help of B-cell responses in germinal centers (GCs). Tfh cells abundantly express the transcription repressor B-cell lymphoma 6 (Bcl6), a factor that is necessary and sufficient for their development in vivo. Whether Tfh or Tfh-committed cells are involved in the help of B cells outside GCs remains unclear, particularly in humans. In this study, we identified a previously undefined
BCL6
-expressing CD4
+
T-cell subset in human tonsils. This subset expressed IL-7 receptor and chemokine receptor 5 (CXCR5) and inducible costimulator (ICOS) at low levels (CXCR5
lo
ICOS
lo
), and it was found exclusively outside GCs. CXCR5
lo
ICOS
lo
CD4
+
T cells secreted larger amounts of IL-21 and IL-10 than CXCR5
hi
ICOS
hi
GC-Tfh cells upon activation, and they induced proliferation and differentiation of naïve B cells into Ig-producing cells more efficiently than GC-Tfh cells. However, this subset lacked the capacity to help GC-B cells because of the induction of apoptosis of GC-B cells through the FAS/FAS–ligand interaction. CXCR5
lo
ICOS
lo
CD4
+
T cells expressed equivalent amounts of
BCL6
transcript with CXCR5
hi
ICOS
hi
GC-Tfh cells, but they expressed less Bcl6 protein. Collectively, our study indicates that CXCR5
lo
ICOS
lo
CD4
+
T cells in human tonsils represent Tfh lineage-committed cells that provide help to naïve and memory B cells outside GCs.
Integrated logic circuits using single-atom transistors
Authors: Mol J. A. , Verduijn J. , Levine R. D. , Remacle F. , Rogge S.
Published: August 2011

Scaling down the size of computing circuits is about to reach the limitations imposed by the discrete atomic structure of matter. Reducing the power requirements and thereby dissipation of integrated circuits is also essential. New paradigms are needed to sustain the rate of progress that society has become used to. Single-atom transistors, SATs, cascaded in a circuit are proposed as a promising route that is compatible with existing technology. We demonstrate the use of quantum degrees of freedom to perform logic operations in a complementary-metal–oxide–semiconductor device. Each SAT performs multilevel logic by electrically addressing the electronic states of a dopant atom. A single electron transistor decodes the physical multivalued output into the conventional binary output. A robust scalable circuit of two concatenated full adders is reported, where by utilizing charge and quantum degrees of freedom, the functionality of the transistor is pushed far beyond that of a simple switch.
Optimizing the laser absorption technique for quantification of caesium densities in negative hydrogen ion sources
Authors: Fantz U , Wimmer C
Published: August 2011

The performance of negative hydrogen ion sources, which rely on the formation of negative hydrogen ions on a surface with low work function, depends strongly on the caesium dynamics in the source. A quantitative measurement of the amount of caesium in the source during plasma-on and plasma-off (vacuum phase) is highly desirable. The laser absorption technique is optimized for the diagnostics of neutral caesium densities close to the extraction surface on which the negative hydrogen ions are generated. The setup is simplified as much as possible utilizing also an automatic data evaluation for online measurements at high power rf sources. The setup is tested and calibrated in a small scale laboratory experiment. The system and the analysis of the D2 caesium line at 852.1 nm are described in detail, including effects of line saturation and density depletion. The system is sensitive in the density range 1013–1017 m−3 (path length of about 15 cm), allowing also for a temporal resolution of 40 ms. First very promising results from the negative hydrogen ion source are presented, such as the increase in the caesium density due to the caesium evaporation and time traces before, during, and after the discharge indicating a strong caesium redistribution.
Evaluation of length-scale effects for mechanical behaviour of micro- and nanocantilevers: I. Experimental determination of length-scale factors
Authors: Tang Chenzhi , Alici Gursel
Published: August 2011

When the thickness of micro- and nanocantilevers, which are the building blocks of micro- and nanoelectromechanical systems, are below 10 µm, the natural frequency and quasi-static deflection of the cantilevers cannot be estimated accurately using the conventional natural frequency and quasi-static-deflection models. The effect of the thickness is summed into what is known as the length-scale factor, which is incorporated into the models in order to improve the accuracy of the models. With this in mind, this paper, which is the first of two parts, reports on the experimental determination of length-scale factors for micro- and nano-sized silicon cantilevers, the micro- and nano-sized length-scale factors are estimated using experimental data collected from nanoindentation and microindentation experiments. The same experimental data are used to cross-validate the empirical length-scale factors in the literature. The experimentally estimated length-scale factors are then incorporated into the natural frequency and static-deflection models. The experimental results presented suggest that the length-scale factors have a great influence on the natural frequency and quasi-static deflection of micro- and nano-sized silicon cantilevers, compared with the natural frequency and deflection calculated using the conventional models not incorporating the length-scale factor.
Toward physical cosmology: focus on inhomogeneous geometry and its non-perturbative effects
Authors: Buchert Thomas
Published: August 2011

We outline the key steps toward the construction of a physical, fully relativistic cosmology. The influence of inhomogeneities on the effective evolution history of the Universe is encoded in backreaction terms and expressed through spatially averaged geometrical invariants. These are absent and potential candidates for the missing dark sources in the standard model. Since they can be interpreted as energies of an emerging scalar field (the morphon), we are in a position to propose a strategy of how phenomenological scalar field models for dark energy, dark matter and inflation, that are usually added as fundamental sources to a homogeneous-geometry (FLRW) cosmology, can be potentially traced back to the inhomogeneous geometrical properties of space and its embedding into spacetime. We lay down a line of arguments that is—thus far only qualitatively—conclusive, and we address open problems of quantitative nature, related to the interpretation of observations. We discuss within a covariant framework (i) the foliation problem and invariant definitions of backreaction effects; (ii) the background problem and the notion of an effective cosmology; (iii) generalizations of the cosmological principle and generalizations of the cosmological equations; (iv) dark energies as energies of an effective scalar field; (v) the global gravitational instability of the standard model and basins of attraction for effective states; (vi) multiscale cosmological models and volume acceleration; (vii) effective metrics and strategies for effective distance measurements on the light cone, including observational predictions; (viii) examples of non-perturbative models, including explicit backreaction models for the LTB solution, extrapolations of the relativistic Lagrangian perturbation theory and scalar metric inhomogeneities. The role of scalar metric perturbations is critically examined and embedded into the non-perturbative framework.
Myocardial damage in patients with sarcoidosis and preserved left ventricular systolic function: an observational study
Authors: Patel Amit R. , Klein Michael R. , Chandra Sonal , Spencer Kirk T. , DeCara Jeanne M. , Lang Roberto M. , Burke Martin C. , Garrity Edward R. , Hogarth D. Kyle , Archer Stephen L. , Sweiss Nadera J. , Beshai John F.
Published: August 2011

Aims

Late gadolinium enhanced cardiovascular magnetic resonance (LGE‐CMR) is a valuable test to detect myocardial damage in patients with sarcoidosis; however, the clinical significance of LGE in sarcoidosis patients with preserved left ventricular ejection fraction (LVEF) is not defined. We aim to characterize the prevalence of LGE, its associated cardiac findings, and its clinical implications in sarcoidosis patients with preserved LVEF.

Methods and results

One hundred and fifty‐two patients with biopsy proven extra‐cardiac sarcoidosis, no known cardiac sarcoidosis, and LVEF ≥50% referred for LGE‐CMR were included in this observational study. The presence of LGE in the left ventricular myocardium was considered diagnostic for cardiac sarcoidosis. The cohort was divided into two groups based on the presence or absence of LGE. Twenty‐nine patients (19%) had LGE involving 11 ± 9% of the left ventricle. The modified Japanese Ministry of Health and Welfare (JMHW) criteria for diagnosing cardiac sarcoidosis only had a sensitivity of 52% and specificity of 83% for identifying myocardial LGE in these patients. Compared with those patients without LGE, those with LGE had a higher heart rate (84 ± 19 vs. 76 ± 18 b.p.m., P= 0.002), greater prevalence of an abnormal electrocardiogram (76 vs. 31%, P< 0.001), diastolic dysfunction (67 vs. 33%, P= 0.05), reduced right ventricular ejection fraction (49 ± 8 vs. 55 ± 6%, P= 0.012), and evidence of non‐sustained ventricular tachycardia (33 vs. 6%).

Conclusions

In patients with sarcoidosis and preserved systolic function, myocardial damage is commonly present and may increase the risk of ventricular tachy‐arrhythmias. The JMHW Criteria were neither sensitive nor specific for predicting the presence of myocardial LGE.
The effect of nanofibre surface amine density and conjugate structure on the adhesion and proliferation of human haematopoietic progenitor cells
Authors: Jiang Xuesong , Christopherson Gregory T. , Mao Hai-Quan
Published: August 2011

Previous studies have shown that substrate surface chemistry and topography exhibit significant impact on haematopoietic progenitor cell adhesion, proliferation and differentiation. In the present study, the effect of surface amine density and structure of grafted polymer chains on the adhesion and expansion of haematopoietic progenitor cells was investigated. Cryopreserved human umbilical cord blood CD133
+
cells were expanded in cytokine-supplemented medium on ethylenediamine (EDA)- or 2-aminoethyl methacrylate hydrochloride (AEMA)-grafted polyethersulphone (PES) nanofibre scaffolds for 10 days. Although the percentage of CD34
+
cells among the expanded cells increased with the surface amine density, the maximum fold expansion of CD34
+
cells was obtained at a moderate amine density of 20–80 nmol cm
−2
. When comparing nanofibre matrices with similar amine densities, but prepared with two different methods, cells cultured on the AEMA-grafted PES nanofibre matrix showed lower fold expansion in terms of total cell number (300 ± 84 fold) and CD34
+
cell number (68 ± 19-fold) in comparison with those cultured on EDA-grafted nanofibres (787 ± 84-fold and 185 ± 84-fold, respectively). These results indicate that the surface amine density and the conjugate structure are important determinants for the preservation of CD34 surface marker and expansion efficiency of CD34
+
cells.
Micro-pixel accuracy centroid displacement estimation and detector calibration
Authors: Zhai Chengxing , Shao Mike , Goullioud Renaud , Nemati Bijan
Published: August 2011

Conventional centroid estimation fits a template point spread function (PSF) to image data. Because the PSF is typically not known to high accuracy, systematic errors exist. Here, we present an accurate centroid displacement estimation algorithm by reconstructing the PSF from Nyquist-sampled images. In absence of inter-pixel response variations, this method can estimate centroid displacement between two 32×32 images to sub-micropixel accuracy. Inter-pixel response variations can be calibrated in Fourier space by using laser metrology. The inter-pixel variations of Fourier transforms of the pixel response functions can be conveniently expressed in terms of powers of spatial wavenumbers. Calibrating up to the third-order terms in the expansion, the displacement estimation is accurate to a few micro-pixels. This algorithm is applicable to a new mission concept of performing mirco-arcsecond level relative astrometry using a 1 m telescope for detecting terrestrial exoplanets and high-precision photometry missions.
Computing a ranking network with confidence bounds from a graph-based Beta random field
Authors: Fushing Hsieh , McAssey Michael P. , McCowan Brenda
Published: August 2011

We address two largely overlooked, fundamental issues in computing a ranking hierarchy within a society: which information in the network is relevant, and what effect chance has on the hierarchy. To properly account for uncertainty from limited data, we construct a random field in a matrix form having entry-wise posterior Beta distributions based on a graph of pairwise conflict outcomes. To evaluate relevant network information using information transitivity, another random matrix of synthesized transitive dominance odds is computed collectively along observed dominance paths. These two matrices are coupled together to fuse both direct and indirect dominance information. An ensemble of realizations of this fused random matrix facilitates an ensemble of optimal ranking networks by means of simulated annealing. Conditional statistical inferences regarding network features are derived, manifesting the effect of uncertainty. Our computational approach is suitable for large graphs of pairwise conflict outcomes, and can accommodate tremendous data heterogeneity—a typical feature in such studies. We also demonstrate the infeasibility of the classical maximum-likelihood approach, and expose the mechanistic flaws that stem from completely ignoring relevant information residing in the graph. We analyse two real datasets of decisive conflict outcomes, the first involving college football teams, and the second involving an adult rhesus macaque society in captivity.
Stem cells as a therapeutic tool for the blind: biology and future prospects
Authors: Singh Mandeep S. , MacLaren Robert E.
Published: August 2011

Retinal degeneration due to genetic, diabetic and age-related disease is the most common cause of blindness in the developed world. Blindness occurs through the loss of the light-sensing photoreceptors; to restore vision, it would be necessary to introduce alternative photosensitive components into the eye. The recent development of an electronic prosthesis placed beneath the severely diseased retina has shown that subretinal stimulation may restore some visual function in blind patients. This proves that residual retinal circuits can be reawakened after photoreceptor loss and defines a goal for stem-cell-based therapy to replace photoreceptors. Advances in reprogramming adult cells have shown how it may be possible to generate autologous stem cells for transplantation without the need for an embryo donor. The recent success in culturing a whole optic cupin vitrohas shown how large numbers of photoreceptors might be generated from embryonic stem cells. Taken together, these threads of discovery provide the basis for optimism for the development of a stem-cell-based strategy for the treatment of retinal blindness.
Prognostic model for total mortality in patients with haemodialysis from the Assessments of Survival and Cardiovascular Events (AURORA) study
Authors: Holme I. , Fellström B. C. , Jardin A. G. , Schmieder R. E. , Zannad F. , Holdaas H.
Published: August 2011

Abstract.  Holme I, Fellström BC, Jardin AG, Schmieder RE, Zannad F, Holdaas H (Oslo University Hospital, Ullevål, Oslo, Norway; British Heart Foundation Glasgow Cardiovascular Research Centre, Glasgow, UK; University Hospital, Erlangen, Germany; Centre d`Investigation Clinique; Centre Hospitalier Universitaire, and Nancy Université, Nancy, France; and Oslo University Hospital, Oslo, Norway). Prognostic model for total mortality in patients with haemodialysis from the Assessments of Survival and Cardiovascular Events (AURORA) study. J Intern Med 2012; 271: 463–471.

Objectives.  Risk factors of mortality in patients with haemodialysis (HD) have been identified in several studies, but few prognostic models have been developed with assessments of calibration and discrimination abilities. We used the database of the Assessment of Survival and Cardiovascular Events study to develop a prognostic model of mortality over 3–4 years.

Methods.  Five factors (age, albumin, C‐reactive protein, history of cardiovascular disease and diabetes) were selected from experience and forced into the regression equation. In a 67% random try‐out sample of patients, no further factors amongst 24 candidates added significance (P < 0.01) to mortality outcome as assessed by Cox regression modelling, and individual probabilities of death were estimated in the try‐out and test samples. Calibration was explored by calculating the prognostic index with regression coefficients from the try‐out sample to patients in the 33% test sample. Discrimination was assessed by receiver operating characteristic (ROC) areas.

Results.  The strongest prognostic factor in the try‐out sample was age, with small differences between the other four factors. Calibration in the test sample was good when the calculated number of deaths was multiplied by a constant of 1.33. The five‐factor model discriminated reasonably well between deceased and surviving patients in both the try‐out and test samples with an ROC area of about 0.73.

Conclusions.  A model consisting of five factors can be used to estimate and stratify the probability of death for individuals The model is most useful for long‐term prognosis in an HD population with survival prospects of more than 1 year.
Investigation of staining, polarization and fluorescence‐microscopic properties of myoendothelial cells
Authors: Puchtler Holde , Sweat Faye , Terry Mary S. , Conner H. M.
Published: August 2011

Electron microscopists have described in vascular endothelial cells filaments which resemble myofibrils. These fibrils cannot be demonstrated with conventional staining techniques. On the basis of previous investigations of relations between dye structure and affinity for muscle fibres, a staining method for demonstration of myoendothelial cells by direct, polarization and fluorescence microscopy has been developed. Carnoy‐fixed paraffin sections were treated consecutively with Kernechtrot, tannic and phosphomolybdic acid and counter‐stained with Levanol fast cyanine 5RN. This procedure stained myoendothelial cells and muscle fibres deep blue, connective tissues yellow and nuclei pink. For polarization and fluorescence‐microscopic studies thiazine red R was substituted for Levanol fast cyanine 5RN and Kernechtrot was replaced by Mayer's acid hæmalum. The light‐microscopic characteristics of fibrils in endothelial cells and in smooth muscle cells were identical.

Correlation of light‐microscopic observations with electron‐microscopic data supported the conclusion that the staining procedure indeed demonstrates myofilaments in endothelial cells. Formation of multiple layers of myoendothelial cells was observed in areas of thickening of the intima, while the cells in the deeper layers became indistinguishable from smooth muscle cells. These findings support earlier concepts of the transformation of endothelial cells into intimal muscle cells.
Fourier images in electron microscopy and their possible misinterpretation
Authors: Rogers G. L.
Published: August 2011

Conditions for the formation of Fourier images in the electron microscope are explored in terms of Ewald's sphere of reflection. An optical analogue experiment shows that false images can be obtained in systems with very low spherical aberration.
Ultra‐thin sectioning artifacts resembling plasmodesmata
Authors: Cox G. C.
Published: August 2011

Sections of plant tissue cut for the electron microscope sometimes show localized wrinkles running across the cell wall. These resemble plasmodesmata under low‐power magnification, and appear identical to the ‘densely stained plasmodesmata’ described in some early papers.
Analysis of polarized light with two quarter‐wave plates
Authors: Goldstein D. J.
Published: August 2011

The following method is proposed for the analysis of the elliptically polarized light leaving a transparent, birefringent and dichroic specimen (in which the direction of maximum absorption coincides with either of the principal axes of refractive index), oriented with its optic axis at ± 45° relative to the transmission azimuth of the polarizer.

Between the specimen and the rotatable analyser are two λ/4 plates; that nearer the specimen is fixed with its slow axis at ± 90° to the polarizer, while that nearer the analyser is rotatable. If the amplitude ratio of the components of light leaving the specimen is tan Y (Y being less than 45°), and their relative retardation is Δ°, at compensation the azimuth of the rotatable λ/4 plate will be Δ/2 (relative to its initial position orthogonal to the polarizer) and that of the analyser will be (45° ‐ Y), relative to the new azimuth of the rotatable λ/4 plate.

Apart from involving minimal calculations, the method is capable of high precision with suitable equipment, since all critical settings can be made with the aid of a Nakamura half‐shade plate. Although so far used only in transmission polarization microscopy, the method is quite general and could be applied in any work involving polarized light.
A new method for the detection of tissue‐bound polysaccharides
Authors: Pritchard Hayden N. , Argot Jeanne E. , Perry Mary H.
Published: August 2011

An alternative cytochemical procedure is described for the periodic acid‐Schiff reaction (PAS) for adjacent glycol groups. This method appears to be as reliable as the PAS in its specificity and reproducibility, is simple to perform and its fully developed colour is more intense than the PAS reaction, although it fades after a few hours.
Light‐microscopic demonstration of myoid fibrils in renal epithelial, mesangial and interstitial cells
Authors: Harper J. T. , Puchtler Holde , Meloan Susan N. , Terry Mary S.
Published: August 2011

In kidney sections treated with the tannic acid‐phosphomolybdic acid‐Levanol fast cyanine 5RN procedure, myoid fibrils were observed in tubular and glomerular cells. The myoid fibrils in tubular epithelial cells were delicate in normal kidneys, but became conspicuous under pathological conditions. Under certain conditions myoid fibrils were found in capsular epithelium and mesangial cells of glomeruli; in some cases podocytes also contained prominent myoid fibrils. There seemed to be a continuous system of myoid fibrils from the media of the afferent arteriole into the mesangium and through the capsular into the tubular epithelium. These myoid fibrils could not be identified with certainty in sections treated with conventional staining methods.

Correlations of light‐microscopic observations with electron‐microscopic data indicate that the myoid fibrils in renal epithelial cells visualized by the TP‐Levanol fast cyanine 5RN stain correspond to the myofilamentous system described in electron‐microscopic studies by Pease (1968a). The myoid fibrils in tubular and capsular epithelial cells resembled the long forgotten ‘Basalreifen’ described around the turn of the century. A review of the literature shows that structures corresponding to the basal myoid fibrils were known to early histologists and that contractile functions had been suggested.
Estimation of the size distribution of triaxial ellipsoidal particles from the distribution of linear intercepts
Authors: Dehoff R. T. , Bousquet P.
Published: August 2011

Methods for estimating particle‐size distributions in metallurgical structures from the distribution of linear intercepts observed on a metallographic section are extended to include systems in which the particle shape may be modelled by triaxial ellipsoids. Procedures are developed for oriented, partially oriented and randomly oriented systems of particles. Methods for determining the axial ratios appropriate to a given system are outlined for these cases.
The wear of diamond in cutting aluminium‐silicon alloy*
Authors: Keen D.
Published: August 2011

Because of the large variation found in the life of single‐point diamond tools used to machine aluminium‐silicon‐alloy piston skirts, a study of the wear of this type of tool has been carried out. Brief details of the machining process are given, followed by a description of some of the relevant properties of diamond and the theories which have already been proposed for its mechanism of wear. The procedure for the study of both special test tools and tools used in piston production is outlined. Microscopical and other techniques used for tool‐wear examination are described in detail. Different aspects of wear, such as fracture and grooving, are reported, together with suggested explanations for some of the wear phenomena observed. The influence of crystallographic orientation on the shape of the wear region is commented upon and the effect of swarf erosion of sintered metal tool shanks is dealt with. The main part of the study is completed by a description of some of the wear microstructures observed using replica transmission electron microscopy. In the final discussion it is suggested that better inspection of tools by the manufacturers, using optical microscopy techniques, could improve tool life by improvement in the initial quality of tools. It is also suggested that sintered metal shanks should be improved by increasing their resistance to abrasion by swarf. Although crystallographic orientation of the diamond affects the shape of wear, it is thought unlikely that a possible optimum orientation would justify the increased cost to produce it within the close tolerance which would be required. No confirmation of any particular wear mechanism for diamond is made but, if the general process of wear is mechanical, it is thought that the fragments of diamond removed will be of sub‐micro size.
Studies on haemoglobin from the Indian toad, Bufo melanostictus, by electron microscopy
Authors: Misra D. N.
Published: August 2011

Hæmoglobin from an amphibian, Bufo melanostictus, was studied by electron microscopy after metal shadowing and after negative staining with uranyl acetate. The effect of the electron stain on the protein was investigated by spectrophotometry. The sample was also characterized by alkali denaturation and sedimentation analysis. The results were compared to those of adult human hæmoglobin.

Spectrophotometry of the sample showed characteristics similar to those of normal oxyhæmoglobin. The protein, like human adult hæmoglobin, was found to be completely alkali‐labile. Ultracentrifugation of a freshly prepared sample showed a single symmetrical peak, an indication for the presence of a homogeneous component. The S020,W value (5.1) was found to be markedly higher than that of adult human hæmoglobin. With storage, however, the peak became asymmetrical suggesting the formation of a limited amount of a heavier component.

The electron micrographs of the shadowed preparations revealed a characteristic shape and ultrastructure of the protein molecules and their average height was found to be 5.5 nm. The micrographs of the negatively stained samples showed many particles with a substructure similar to that of the shadowed molecules and a mean dimension of 6.1 nm, a number of dimers of average length 6.0 nm and overall width 3.6 nm, and many globules of average diameter 3.6 nm. These were interpreted as whole, half and quarter hæmoglobin molecules, respectively. Both techniques revealed at the most four subunits in a molecule. The structure of the subunits and their arrangement in the molecule were found to be essentially similar to those of normal human adult hæmoglobin, and could be interpreted in terms of the Perutz model. Spectrophotometry of the mixture of the protein and uranyl acetate showed that the protein becomes denatured with time and that the denaturation is due to the low pH (4.3) of the stain. Nevertheless, this study showed that by keeping the staining time very short, it is possible to obtain acceptable electron micrographs of small multi‐unit protein molecules such as haemoglobin.
Frozen‐fractured viruses; a study of virus structure using freeze‐etching
Authors: Willison J. H. M. , Cocking E. C.
Published: August 2011

Tobacco mosaic virus (TMV), tobacco rattle virus (TRV), Tipula iridescent virus (TIV), turnip yellow mosaic virus (TYMV), T2 phage and Lambda phage were examined by freeze‐etching water/glycerol suspensions. It was found that the virus particles usually fracture internally.

TMV rarely fractures at its surface. Careful consideration of the fracture planes within TMV indicates not only that the TMV subunits do not fracture but also that there are no ‘preferred planes’ of fracture. An unexpected channel appears at the position of the RNA in TMV on one side of the capsid only. It is proposed that this indicates that the fracture of RNA is out of step with that of the subunit. By deep‐etching, a 5 nm repeat can sometimes be seen at the capsid surface of TMV (vulgare).

TRV sometimes fractures to reveal its surface. It is proposed that this indicates that the surface of this rod‐shaped virus is smoother than that of the similar TMV.

The large icosahedral virus, TIV, fractures between core and coat protein. The core which appears to consist of globular subunits is icosahedral and fits closely into its enclosing coat. The coat thickness is 10–12 nm. Numerous collapsible fibrous projections (probably up to 150 nm long) project from the surface of the coat.

T2 phage sometimes fractures to reveal the surface of the enclosed DNA which is smooth and very compact.

Fracture by the freeze‐etch technique is shown to be a valuable adjunct to other techniques for the study of virus structure. It can reveal otherwise hidden internal structures. It may also disclose planes of minimum chemical bond energies represented by recurring regular fracture planes.

The technique appears to be unsuitable, however, for the smaller viruses TYMV and Lambda phage.
Random sets theory and its applications to stereology
Authors: Matheron G.
Published: August 2011

In order to study objects forming a sub‐set A of euclidean space, mathematical morphology uses structuring figures B and notes the frequency of events such as ‘B hits A’, ‘B is included into A’ etc. Thus, a probabilistic formalism is associated with this experimental technique and facilitates its interpretation. If A is considered as a closed set, we obtain a random closed‐sets theory, closely connected with integral geometry. The functionals T defined by T(K) = P(A ∩ K ≠ Ø) for K compact are characterized as alternating capacities of infinite order. Interesting classes of functionals T are obtained if A is indefinitely divisible or semi‐markovian. At last, the mathematical notion of granulometry (size distribution) is studied by using an axiomatic method.
Experimental determination of the topological properties of three‐dimensional microstructures
Authors: DeHoff R. T. , Aigeltinger E. H. , Craig K. R.
Published: August 2011

Procedures have been developed whereby the topological properties of single‐phase cell structures, and two‐phase structures, may be estimated from a series of closely spaced microsections. In both cases, the analysis is straightforward but tedious. However, because the topological properties abstract a description of the basic skeleton or framework of the structure from details of shape and size, their quantitative knowledge provides insights into microstructural behaviour that may be obtained in no other way. These combined factors make it likely that the application of these procedures will be limited to very select problems, but that where they are applied the results will significantly affect the thinking in the field.
The use of geometrical models as a stereological aid exemplified by the solidification geometry of ferrous metals
Authors: Wlodawer Robert
Published: August 2011

In the present paper, model geometry is used to describe the three‐dimensional nature of some structural constituents of ferrous metals, such as cells, grains, dendrites, networks etc. in the course of their solidification process.

Based on micrographs of eutectic cells, highly magnified model structures were built. By cutting the models, all the features found in real micrographs (cell boundaries, groupings, phosphide figures etc.) could be simulated.

Using the known geometrical properties of the models, parameters such as the porosity due to phosphides, can be calculated; this allowed precautionary casting techniques to be derived. Further, conclusions could be drawn about processes occurring during structure formation, i.e. during cooling and solidification of the metal. A geometrical derivation of various equations for internal surfaces, hydraulic diameters during the last moments of crystallization etc., and the technological applications of this knowledge are possible.

As structural constituents of metals are sometimes complicated bodies, our more intuitive geometrical approach using models often provides more reliable information about their appearance than very elegant but abstract arithmetical methods.
The study of the three‐dimensional structural relationships in connective tissues by high voltage electron microscopy
Authors: Glauert Audrey M. , Mayo C. R.
Published: August 2011

An examination of stereo‐electron micrographs taken at 1 MV in an AEI EM7 high voltage electron microscope of sections 0.5–1.0 μm thick has provided three‐dimensional information of the structural relationships in connective tissues. Sufficient contrast is obtained after block staining with uranyl acetate and with prolonged staining of the sections with lead citrate. Selective staining was observed when either the uranyl acetate or lead staining was omitted. Preliminary results indicate that there may be regions of fusion of the cisternae of the rough endoplasmic reticulum and the plasma membrane in chondrocytes that are secreting collagen. The observations also suggest that matrix vesicles in regions of calcification are formed from long cytoplasmic processes of osteoblasts by a ‘pinching off’ mechanism and that bone crystallites form within the vesicles only after the vesicles have completely separated from the surrounding cells. It is concluded that the high voltage electron microscope is capable of making a significant contribution to the understanding of the three‐dimensional structural relationships associated with specific biochemical events.
Quantitative measurement of human articular surface topography in vitro by profile recorder and stereo‐microscopy techniques
Authors: Clarke Ian C.
Published: August 2011

The degree of irregularity presented by the 20–40 μm diameter depressions in adult human articular surfaces was measured in vitro, using the scanning electron microscope (SEM), replication, stereo‐microscopy and profile recording techniques.

Using stereo‐microscopy, the measured articular surface depressions varied from 0.9 to 15 μm in depth and the corresponding humps on the replicas varied from 0.3 to 8.9 μm in height. The heights of the replicated contours measured by the profile recording device varied from 0.2 to 5 μm. It was emphasized that, while these values give some indication as to the possible degree of surface irregularity in vivo, the actual contours in a living, load‐bearing joint may be quite different.
The Polanret variable densiphase microscope
Authors: Richards Oscar W.
Published: August 2011

Continuously variable contrast, phase microscopy is obtained with the Polanret microscope by adjusting one control for phase retardation and another for the two kinds each of bright and dark contrast. The B + type dark contrast is available in a commercial instrument. The Polanret unit fits on recent, AO‐Spencer microscopes and accepts standard trinocular to monocular bodies and cameras. Densiphase detail (absorption, optical path and combinations of them) can be made visible optimally and selectively with the complete range and four kinds of contrast provided within the Polanret system. Illustrations show the need for and advantage of variable contrast, over fixed‐phase objectives. Applications include: unstained cells and tissues, biopsy tissues, transparent industrial materials, isotropic minerals, moderately absorbing materials, pigmented tissues, thin sections (nm range and thicker), and refractive index measurement of transparent and opaque materials.
The preparation of flexible thin sections of rocks and coals
Authors: Zeidler W.
Published: August 2011

A method for the preparation of flexible thin sections is described, which allows their use for macro‐ and micro‐examinations.
The determination of the geometry and nature of small Frank loops using the weak‐beam method
Authors: Jenkins M. L. , Cockayne D. J. H. , Whelan M. J.
Published: August 2011

Theoretical and experimental investigations have been carried out to determine under which conditions weak‐beam images can give useful information on the geometry, size and nature of small Frank loops. Suitable experimental conditions for obtaining such information were deduced from computed weak‐beam images of Frank loops under various selected loop and foil orientations and diffraction vectors. Experiments to check these deductions were performed in silicon damaged by irradiation with phosphorus ions. It was found that the geometry and size of loops of diameter 8 nm (80 Å) viewed normal to their habit plane was well defined by weak‐beam images taken in {220} reflections lying in the loop plane for which g.b = 0 and g.b × u ≠ 0. By imaging in reflections with g vectors not in the loop plane the enclosed stacking faults were imaged (thus confirming the loops to be Frank loops) and the sense of the Burgers vector (i.e. the loop nature) was determined.
Observations of lattice defects using the weak‐beam technique
Authors: Guyot P.
Published: August 2011

The advantages of the weak‐beam technique of electron microscopy for the study of small defects and dislocations are illustrated by micrographs taken of small loops in aluminium and Al–Ag alloys, GP zones and θ″ precipitates in Al + 4% Cu, and dislocation networks in Cu + 20% Zn. An estimate of 19·5 mJ m−2 (erg cm∼2) is made for the stacking‐fault energy of Cu–20% Zn from the size of extended nodes and the width of the dissociated dislocations imaged under weak‐beam conditions.
High resolution dark‐field electron microscopy
Authors: Dubochet Jacques
Published: August 2011

In the last few years some promising images of biological specimens have been obtained using the high contrast and resolution of dark‐field electron microscopy. However, important problems of image interpretation and difficulties in specimen preparation limit at the present time, the usefulness of this mode of image formation. The destruction of the sample by the electron beam, is of utmost importance. Some possibilities of partly overcoming it are discussed.
A low cost, one‐piece nitrogen burst processing rack for 3¼× 4 inches and 4×5 inches TEM and SEM negatives
Authors: Thurston E. Laurence , Scott James R. , Schroeter Gilbert L.
Published: August 2011

A processing rack designed with a built‐in nitrogen burst plenum to accommodate 3¼ × 4 in. and 4 × 5 in. negative can be inexpensively constructed from plexiglass.
A new type of storage container for freeze‐etch specimens
Authors: Krah Stephanie , Staehelin L. Andrew , Nettesheim Eugene
Published: August 2011

A new storage container for freeze‐etch specimens is described which (1) dramatically reduces the loss of liquid nitrogen from the storage dewar, (2) which always sits on the bottom of the dewar and can be quickly identified and retrieved therefrom, (3) which cannot open accidentally during long term storage and (4) which can withstand continual exposure to temperature extremes. Using such containers over 300 different kinds of specimens can be readily stored in a 30 1 liquid nitrogen dewar.
High resolution microanalysis of aluminium solid solution alloys using combined electron microscopy and energy analysis
Authors: Edigton J. W. , Hibbert G.
Published: August 2011

The technique of combined electron microscopy and energy analysis is described, together with the main energy loss process that is used to analyse composition. It is shown that the spatial resolution of the technique is ∼ 14 nm which is ten times better than any other technique available at present. The composition resolution in aluminium alloys is < 1 at.%, the exact value depends upon which alloy system is used.

Applications of the technique to the measurement of fine scale concentration gradients are described for Al‐Cu, Al‐Mg and Al‐Zn‐Mg alloys.
Examination of cell suspensions prepared by cryobiological techniques*
Authors: Werner Gerhard , Neumann Klaus , Morgenstern Eberhard
Published: August 2011

Ultrathin frozen sections have been obtained from single cells both in the fixed and native state. For fixed material a rapid method is described which yields excellent structural preservation. The preparation is based on brief treatment with glutaraldehyde, polyvinylpyrrolidone and ‘encapsulation’ in gelatin. Ultra‐thin frozen sections prepared after this technique seem to be especially suitable for cytochemical work. Unfixed testis has been also cut with a dry knife. The contrast in this completely untreated section is sufficient to discern the different parts of spermatozoa.
A system for simultaneous stimulation and film‐marking during cinemicrography
Authors: Klipple Kenneth , Bagby Roland M.
Published: August 2011

In this report a stimulation slide is described which is simple to manufacture and which may be used with all microscope objectives, including oil immersion types. The event‐marking system described herein gives a distinct spot visible during projection, and the apparatus is highly dependable despite the inexpensive components used.
Modern techniques in reflectance measurements
Authors: Piller Horst
Published: August 2011

In the field of quantitative investigation of microscopic images reflectance measurements with the aid of photoelectric equipment play an important role. Reflectances can be used for the identification of various components in a polished specimen, for chemical analysis and for the determination of the refractive index of a specimen as well as for a determination of the various absorption parameters of reflecting solid material.

The parameters involved are: reflectances at given wavelengths, spectral reflectance curves in the visible, UV‐, and near IR‐spectral range, reflectances of optically anisotropic surfaces at varying orientations of the vibration plane of linearly polarized light, reflectances in air and in an immersion liquid (mainly in standard immersion oil). From spectral curves, quantitative expressions of colour can be derived. Due to improvements in reflectance standard materials and technical design of apparatus the measurements and calculations can be carried out very conveniently, quickly and precisely.
FIM analysis of dislocation core structure
Authors: Brandon D. G. , Melmed A. J.
Published: August 2011

A direct colour superposition technique has been used to study two dislocations in W, using He field‐ion imaging at 77°K. Limitations due to instrumentation and field‐ion microscopy are discussed. A single spiral and a double spiral on (112) W were each dissected, by field evaporation, through three successive atom layers, and apparent core shapes and dimensions were determined. The shapes were irregular with diameters of at most 0.5–2 nm for the single spiral and 0.5–1.7 nm for the double spiral. Observed displacements in the positions of the core regions may be associated with dislocation movement induced by the high electric field needed for the observations.
Ultraviolet microscopy at wavelengths below 240 nm
Authors: Wood J. R. , Goring D. A. I.
Published: August 2011

Modification of the techniques used for ultraviolet microscopy have allowed extension of the usable wavelength range down to about 220 nm. The 150 W xenon lamp in a Leitz ultraviolet microscope was replaced with a 1000 W xenon‐mercury lamp. A special low gelatin content film was employed and a new epoxy embedding medium of low UV absorbance was formulated.
A simple ultraviolet microbeam apparatus
Authors: Starling D.
Published: August 2011

The construction of a simple device for the micro‐irradiation of parts of cellular organelles is described. A few examples of its use on widely differing specimens are given. Suggestions are made for simple modifications to further widen the range of experiments to which the instrument is applicable.
Classification of crystalline interfaces by means of the O‐lattice method
Authors: Bollmann W.
Published: August 2011

The different kinds of crystalline interfaces can be classified by means of the O‐lattice method. Two groups of parameters have to be known for the description of an interface. The first group concerns the structures and the relative orientation of the adjoining crystals and the second group deals with the position and orientation of the interface. The O‐lattice method allows one to deal with the two groups of parameters independently. This method gives a description of the interface in terms of dislocations, and hence of the possible relaxation in the boundary. Different kinds of interface will be discussed and illustrated by electron micrographs.