Detail Of Interest Research Articles

Estimation of Tissue Permeability in MRI Images by Empirical Mode Decomposition Method.

The precise evaluation of tissue permeability using the Magnetic Resonance Imaging (MRI) method requires high-quality images. Due to noisy acquired dynamic MRI images, some methods of processing are required to obtain the imaging detail of interest. This study aimed to implement Empirical Mode Decomposition (EMD) to the Lock-Locker (LL) images to improve the permeability of the normal tissue and tumor region, evaluated by the Quantitative Autoradiography (QAR) method. In this experimental and analytical study, the EMD method was used to improve the tissue permeability from the LL- MRI images of the rat brain. The EMD components were extracted from LL images, and the resulting components were combined using different weighting factors. The tissue permeability was derived by extracting the information of each pixel from the LL image series and fitting curves to the data. The optimum weighted combination factors images were 0.7 for the middle and low-frequency components and 1 for the high-frequency component. The calculated tissue permeability was between 0.0023-0.0043 (ml.min-1.g-1) for abnormal tissue. The estimation of the permeability of tumors in the rat brain with the LL images and the processed LL images by the EMD method shows that the EMD method and the weighted combination of frequency components can improve the permeability calculation in the LL images for the rat brain. The results of permeability estimation by EMD due to noise reduction of LL images are closer to the values obtained from the Quantitative Autoradiography (QAR).

The Correspondence of G. H. Lewes and Charles Darwin

The Correspondence of G. H. Lewes and Charles Darwin

Automated Reinforcement Learning (AutoRL): A Survey and Open Problems

The combination of Reinforcement Learning (RL) with deep learning has led to a series of impressive feats, with many believing (deep) RL provides a path towards generally capable agents. However, the success of RL agents is often highly sensitive to design choices in the training process, which may require tedious and error-prone manual tuning. This makes it challenging to use RL for new problems and also limits its full potential. In many other areas of machine learning, AutoML has shown that it is possible to automate such design choices, and AutoML has also yielded promising initial results when applied to RL. However, Automated Reinforcement Learning (AutoRL) involves not only standard applications of AutoML but also includes additional challenges unique to RL, that naturally produce a different set of methods. As such, AutoRL has been emerging as an important area of research in RL, providing promise in a variety of applications from RNA design to playing games, such as Go. Given the diversity of methods and environments considered in RL, much of the research has been conducted in distinct subfields, ranging from meta-learning to evolution. In this survey, we seek to unify the field of AutoRL, provide a common taxonomy, discuss each area in detail and pose open problems of interest to researchers going forward.

The Antiquary: John Aubrey's Historical Scholarship by Kelsey Jackson Williams

Reviewed by: The Antiquary: John Aubrey's Historical Scholarship by Kelsey Jackson Williams Andrea Walkden (bio) Kelsey Jackson Williams. The Antiquary: John Aubrey's Historical Scholarship. Oxford UP, 2016, 224 pp. ISBN 978-0198784296, $100.00. The Antiquary opens with a story: in a freezing cold January in 1649, as England prepared to execute its imprisoned monarch, the twenty-two-year-old John Aubrey left the bedside of his dying father to join a friend on a hunt through the Wiltshire countryside. The trail led across the chalkland downs, a landscape strewn with sarsen stones, crystalline sandstone boulders that put [End Page 461] Aubrey in mind of the stone missiles once hurled by earthborn giants against the Olympian gods. The hunt rode through Avebury, a small village partly enclosed by a great stone circle, sixteen times larger than the circle at Stonehenge some nineteen miles away that Aubrey had known since boyhood. "Wonderfully surprized," he dismounted and left his companions for a while, amusing himself with this "more delightfull indagation" (2). Derived from the Latin verb indāgāre, to trace or track as hounds track their quarry, Aubrey's "indagation" presents itself as an alternative form of hunting, the pursuit not of a fleeing fox but of a receding prehistoric past. It was this first encounter with the Avebury landscape, or so Kelsey Jackson Williams proposes in his impressively learned and thoughtful study, that launched Aubrey's career as an antiquary: a person "studious to know ancient things" (6), according to one mid-seventeenth-century dictionary, or, in the more lyrically expansive words of Francis Bacon, one of those "industrious persons" who, "by an exact and scrupulous diligence and observation … do save and recover somewhat from the deluge of time" (Bacon 66). Williams divides his monograph into two parts. Part one deals with "artefacts and sites" (18): chapter one focuses on Aubrey's investigative fieldwork at Stonehenge, while chapter two addresses his broader site-based study of the ancient landscape of Britain. Chapter three turns to Aubrey's study of medieval architecture and, especially, his pioneering method of dating buildings by the shape and style of their windows—"guessing by Windowes" in Aubrey's own, disarmingly modest phrase (81). Bridging the modern disciplines of archeology and architectural history, these various projects were collected into the Monumenta Britannica, a massive work Aubrey assembled over several decades that he was never quite able to bring to publication. His efforts to do so conclude the first half of Williams's book. The three chapters in part two turn from physical remains to words and texts. Chapter four reconsiders Aubrey's most famous work, his book of lives, commonly known as his Brief Lives, in the context of his lifelong antiquarian endeavors. Chapters five and six, by contrast, recover some of the least well-known and neglected aspects of Aubrey's sprawling oeuvre: his exploration of English folklore and folk practices, on the one hand, and his linguistic study of Welsh and English toponyms, on the other. For readers of Biography, the chapter devoted to the Brief Lives has the most immediate claim to their attention. In a clever reversal, Williams here imagines Aubrey engaged in a practice he describes as "a sort of preventative or anticipatory antiquarianism" (104), painstakingly recording every conceivable detail of interest so that some unborn antiquary, centuries hence, might reconstruct from this archive of biographical evidence a fuller understanding [End Page 462] of the muddled realities of seventeenth-century life. Without Aubrey, we wouldn't know that the poet John Milton pronounced the letter R very hard like the snarl of a dog (Aubrey 663). Without Aubrey, we wouldn't know that the political philosopher Thomas Hobbes continued to play tennis until his seventy-fifth year (105), or that Walter Raleigh's beard turned up naturally at its tip (Aubrey 230). Williams does not communicate the deep playfulness of Aubrey's lives, but he mounts a forceful case for their motivation, showing how, by a supreme act of the antiquarian imagination, Aubrey projected the republic of letters into the future, preserving as much as he could. While the chapter on the Brief Lives is of most direct relevance...

Active Vision: Dynamic Reformatting of Visual Information by the Saccade-Drift Cycle

Visual processing depends on rapid parsing of global features followed by analysis of fine detail. A new study suggests that this transformation is enabled by a cycle of saccades and fixational drifts, which reformat visual input to match the spatiotemporal sensitivity of fast and slow neuronal pathways.

On the compatibility of polarisable and non-polarisable models for liquid water

The properties of water at physiological conditions can be modelled at different levels of resolution: (1) sub-atomic models that take into account electronic degrees of freedom, (2) atomic models that only account for atomic degrees of freedom and (3) supra-molecular models that only involve some supra-molecular degrees of freedom. To enhance the computational efficiency of molecular simulation, models at different levels of resolution should be simultaneously usable for different parts of a system for which the level of detail of interest is different. This requires these different types of models to be compatible with each other. In the present study, the compatibility of two polarisable models for liquid water, COS/G2 and COS/D, with a non-polarisable model for liquid water, SPC, is investigated. It is shown that these models are compatible. The polarisable models can thus be used to solvate biomolecules described by a biomolecular force field that is compatible with the SPC water model.

Fatigue Crack Propagation Behavior of the Welded Steel of a Railway Bridge

In the context of a R&D project concerning the new Alcácer do Sal composite railway bridge, a study of the fatigue crack growth on samples of its base material and weldments was performed. For this purpose, tests were carried out on CT specimens designed according to ASTM E647 standard, using the approximate thickness (B) of a structural detail of interest, B=32mm. The choice of B led to a relatively large specimen and was justified by the desire to better simulate service conditions, which would not be possible with smaller specimens, particularly in the case of weldments. The test matrix used included three values of R ratio (maximum/minimum load), 0.1, 0.4 and 0.7, and three material conditions, namely base material (BM), heat affected zone (HAZ) and weld metal (WM). When the nominal range of the stress intensity factor (DK) is used, the measured data displays a strong effect of the weldments on the FCG rates, with the base material presenting higher da/dN values. An evaluation of opening load behaviour was carried out, and it showed extensive closure caused by residual stresses in the HAZ and WM specimens. The investigation included the full field measurement of the residual stress perpendicular to the crack plane, using the contour technique. When the opening load effect was taken into consideration it was found that the da/dN vs. ∆K of the BM, HAZ and WM specimens is approximately identical. Furthermore if loading effects are considered, no significant difference is found for the three R values used, even if, as expected, higher R corresponds to higher da/dN values.

Cloaked Near-Field Scanning Optical Microscope Tip for Noninvasive Near-Field Imaging

Near-field imaging is a well-established technique in biomedical measurements, since closer to the detail of interest it is possible to resolve subwavelength details otherwise unresolved by regular lenses. A near-field scanning optical microscope (NSOM) tip may indeed overcome the resolution limits of far-field optics, but its proximity inherently perturbs the measurement. Here, we apply the recent concept of a "cloaked sensor" to an NSOM device in collection mode, showing theoretically how a proper plasmonic cover applied to an NSOM tip may drastically improve its overall measurement capabilities.

Application of low-angle polishing for rapid assessment of the texture and morphology of thick film Y1Ba2Cu3O7 superconducting tapes

Metallographic polishing was used for the rapid assessment of the texture quality of 2μm thick YBa2Cu3O7 (YBCO) layers deposited on oxide buffered RABiTS™ metal substrates. The YBCO films were grown using the barium fluoride ex situ process. The method is based on partial removal of the YBCO layer by mechanical polishing, resulting in the formation of a 200–300μm wide wedge of YBCO material with an approximately linear thickness profile. Due to the linearity of the thickness profile of the wedge, the depth below the film surface, of any visible structural detail in the wedge area, can be determined by simply measuring the lateral distance from the detail of interest to the film surface/wedge intersection. In this study the wedge area was inspected by optical microscopy for changes in morphology, twin plane pattern, and YBCO grain size. It is demonstrated how X-ray diffraction, combined with low-angle polishing can help establish the origins of YBCO texture degradation in the sub-surface layers of thick YBCO films. It is concluded that homogeneous nucleation is responsible for the appearance of random texture in sub-surface YBCO layers.

IS MELD-SCORE ENOUGH TO PREDICT NOT ONLY DEATH ON WAITING LIST BUT ALTHOUGH POST TRANSPLANT SURVIVAL? CONSIDERATIONS BASED ON 622 PATIENTS.

O163* Aims: Model for End-stage Liver Disease (MELD) score has emerged as a useful tool in predicting mortality in patients awaiting liver transplantation, although it was originally designed to assess short-term prognosis in patients undergoing transjugular intrahepatic portosystemic shunt. Methods: From Jan 1997 to Nov 2003 662 adult patients with End Stage Liver Disease were put on the Waiting List for orthotopic liver transplantation (OLT). 388 patients were transplanted, 131 died on list, 55 were removed from the waiting list due to tumor progression (n=11), poor condition (n=6), non compliance (n=7), clinical improvement (n=28) or technical reasons (n=3). 48 patients are still awaiting OLT. All patients were categorized according to the MELD Score. Results: The difference in the MELD Score at listing versus MELD Score off listing (died on list, transplanted or removed) is shown on table below. Patients died on list showed a significant increase during waiting time as well as a significant higher MELD score at listing compared to patients who were transplanted or removed (p<0,001).FigureTable 1 Multivariate analysis (Cox Model) identified meld score at listing (p=0,002; RR 9,3), ascites (p=0,002; RR=9,7) and encephalopathy (p=0,007; RR=7,2) as independent risk factors for death on the waiting list. Patient survival estimated by Kaplan Meier method was similar at 3, 6 and 12 months after transplantation regardless of the MELD Score. However, patients with a MELD Score >=25 showed a remarkable trend towards a lower survival at 3 years (62% versus 80%, p=0.08). This trend is confirmed in a multivariate analysis evaluating MELD Score as a pre-transplant risk factor for long term survival after OLT (p=0,02; RR=5,6). A further detail of interest in this analysis is the fact that patients with MELD Score < 11 showed a higher risk for death after OLT (89% survival) than on waiting list (98% survival) at three months. Conclusions: Our study demonstrated that MELD Score is a strong predictor for death on the waiting list and should also be considered as a pre-transplant risk factor for long term post-transplant survival.

Residual Stress Effect on Fatigue Strength of Non-Load-Carrying Cruciform Welded Joints of SM570Q Steel for Welded Structures

It is common to evaluate the tatigue strength of welded joints by testing simple specimens incorporating the weld detail of interest, usually at R = 0. However, such specimens do not usually contain significant residual stress, whereas yield-magnitude tensile residual stresses generally exist in real welded structures. As a result, the effective maximum stress in the fatigue loading is equal to yield, giving more severe loading than R = 0. Thus, unsafe estimates of fatigue lives may be obtained from small-scale specimens at R = 0. In this study, the technique of applying fatigue loading that cycles down from yield to simulate the effect of high tensile residual stress (σmax = σy testing) was applied to non-load-carrying cruciform welded joints in 20 mm thick SM570Q steel. Comparative tests were performed on narrow specimens under σmax = σy loading and wider specimens, fabricated to ensure that they did contain high tensile residual stress, under R = 0. The results were in good agreement, confirming that the fatigue performance of large-scale welded structures can be reproduced using the σmax = σy test technique.

In-Situ Ion Milling in the Transmission Electron Microscope (TEM) Outlook to a New Preparation Technique

Abstract Recent developments in transmission electron microscopy put high demands on specimen preparation. in general the imaging quality is not limited by the performance of the microscope but by the quality of the specimen. in order to achieve a spatial resolution of 0.1 nm in HRTEM undamaged samples with a thickness below 10 nm are required. in energy filtering analytical electron microscopy (EFTEM), a constant specimen thickness over large areas and very low contamination is needed. Conventional ion-milling techniques for TEM specimen preparation are essentially blind. Thus, it is left to chance whether the specimen detail of interest is suitable for TEM-imaging (many specimen areas are too thick). Another problem is the reaction of the specimen with the atmosphere during the transfer from the preparation stage to the microscope, which makes it very difficult to obtain the clean specimen surfaces that are needed in analytical EFTEM. Especially in high-resolution electron microscopy and electron holography the formation of amorphous oxidation and contamination layers on otherwise crystalline materials may seriously reduce the quality of high resolution images of the crystal structure.

Demand-driven image transmission with levels of detail and regions of interest

In this paper, we introduce a formal model which describes consistently levels of detail and regions of interest for the progressive transmission of raster images. This model serves as the foundation of a wavelet-based image communication framework which supports the progressive, redundancy-free transmission of multiple, possibly overlapping regions of interest in an image. To support demand-driven transmission, we introduce a method for interleaving control commands with the embedded bit stream. Since the dyadic wavelet decomposition allows the image resolutions in x and y direction to differ at most by a factor of two, we propose a new wavelet decomposition scheme which raises this number to a power of two for increased flexibility. We discuss some applications including the rectangular fish eye view, a focus and context display technique for raster images which efficiently uses this transmission method and saves screen real-estate.

The Application of S-N Curves Considering Mismatch of Stress Concentration Between Test Specimen and Structure

This paper presents a procedure for the adjustment of S-N diagrams for noncontinuous welded joints in the fatigue analysis of structural details. The adjustment takes into account the effects of differences in geometry between the test specimen underlying the S-N curve and the hull structural detail it is applied to, considering the inelastic response of material at the anticipated crack origin, multiple modes of loading, and their statistical correlation. The basis of the approach is a comparison of relative fatigue lives for the structural detail of interest and the corresponding baseline specimen, using the local strain approach to fatigue, with extensions to the high-cycle regime. An S-N diagram so corrected is used in the conventional manner to predict fatigue damage or to establish related allowable stresses. The procedure developed is thus entirely compatible with present fatigue life assessment methods. The developed procedure is illustrated through numerical examples.

Discussion of the Fatigue Crack Model Used as Decision Basis for Probabilistic Inspection Planning

Abstract Marine structures are often highly utilized structures and are operating in an environment dominated by dynamic loading. The fatigue limit state is of main concern and is governing the structural dimensions and the amount of resources utilized in inspection of several members and joints. There is a considerable uncertainty related to the parameters determining the fatigue life, and probabilistic analyses have therefore been used extensively in fatigue analysis. The models used both on describing the fatigue driving mechanisms and the deterioration mechanism, however, are always compromises between ability to describe nature and computational applicapability. In a state-of-the-art probabilistic fatigue analysis, major assumptions are made when establishing the crack growth model, such as: 1) the relation between membrane and bending stresses is assumed to be constant for all stress ranges, and one common stress component for the total stress is used to calculate fatigue crack growth. 2) The crack growth is assumed to follow a pattern with a constant relation between crack depth and crack length. This paper investigates the foregoing fundamental assumptions for the fatigue driving mechanism and shows the effect on time to the first inspection based on state-of-the-art probabilistic crack growth analysis for the detail of interest, for a simple but realistic jacket structure.

Budgeting in Historical and Comparative Perspective

The researcher who wishes to say something meaningful about budgeting must avoid the twin pitfalls of assuming that budget functions may be prescribed in identical and unchanging terms whatever the context, or of losing himself or herself in a morass of bewildering and idiosyncratic detail of scant interest beyond the moment. Aaron Wildavsky steered between these two traps by generating theories relating budgeting to time and place—from ideas, politics, economics, and social milieus. The Politics of the Budgetary Process appeared in 1964, and its appeal lay in its transformation from a restricted, somewhat technical study into a much broader inquiry into the reality of how budgeting was actually conducted. He expanded the conventional boundaries of discussion of public budgeting by expanding the functions of the budget. As an all-encompassing general theory, which would enable comparisons across time and space, Budgeting failed to measure up.

The external PIXE setup for the analysis of manuscripts at the Florence University

The external beam PIXE setup of the 3 MV Van de Graaff accelerator in Florence is extensively used for the analysis of parchments, rulings, inks and miniature temperas of Medieval and Renaissance manuscripts. The beam is collimated to about 200 μm and exits from the vacuum environment through a 8 μm Kapton window. Beam currents from 200 to 500 pA are used; they have been found to produce no visible damage to the examined materials. Two Si(Li) detectors are simultaneously used with different geometries in order to cover the widest possible Z-range of the detected elements: even Na is detected with good sensitivity. A robust and versatile support has been constructed for safe and easy handling of the manuscripts. A laser alignment system allows accurate aiming at the detail of interest. A rotating chopper samples the beam at a frequency of the order of 1 Hz; X-rays produced on a Ni layer evaporated on the graphite vane of the chopper are used for charge normalization, since the weak current pulses would be unreliably measured in air due, in particular, to space-charge effects. An application is shortly presented, concerning the materials used for the “colour” rulings which are found, starting from the 11th century, to delimit the writing field for the copyist.

SNR and noise measurements for medical imaging: I. A practical approach based on statistical decision theory

A method of measuring the image quality of medical imaging equipment is considered within the framework of statistical decision theory. In this approach, images are regarded as random vectors and image quality is defined in the context of the image information available for performing a specified detection or discrimination task. The approach provides a means of measuring image quality, as related to the detection of an image detail of interest, without reference to the actual physical mechanisms involved in image formation and without separate measurements of signal transfer characteristics or image noise. The measurement does not, however, consider deterministic errors in the image; they need a separate evaluation for imaging modalities where they are of concern. The detectability of an image detail can be expressed in terms of the ideal observer's signal-to-noise ratio (SNR) at the decision level.

Evaluation of X-ray beam quality and film-screen combinations for detection of small low-contrast objects

The detection of small low-contrast objects in transmission radiography has been simulated by phantom experiments for specific anatomical regions (phantom thicknesses). Improvement of image quality in combination with a low patient dose is addressed to a complicated optimization problem. It has been shown that in the low-contrast case, the image resolution is largely determined by the low-frequency part of the noise spectrum and by the absorption contrast between detail of interest and surrounding medium. Improvement of image resolution is performed more efficiently via beam quality (by enhancement of absorption contrast). This is also true in the case of photoelectrically recorded photons (DLR). Conversely, the detector MTF (modulation transfer function) is of minor importance for the low-contrast case. The role of X-ray scattering in the phantom as well as light propagation in the phosphor is outlined. Numerous commercially available film-screen combinations of different speed and phosphors have been tested. In summary, fast screens of Gd2O2S phosphors are most appropriate for detection of low-contrast objects.

Hearing and Deafness

The first edition appeared in 1947. The passage of time has necessitated a changed emphasis in some sections of the field of audiology, resulting in extensive rewriting of some chapters. Others remain virtually unchanged. Thus, though the original organization has been retained, there has been expansion of the parts on hearing and hearing loss, with much more detail of interest to the otologist. Equally useful is the expansion of the former chapter on tests of hearing to 3 chapters, on audiometry, special auditory tests, and medicolegal considerations. The chapter on hearing aids has been brought up to date. The value of this introductory textbook in audiology has been enhanced by this revision, and it is strongly recommended.