There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The analysis of medical images has been woven into the fabric of the pattern analysis and machine intelligence (PAMI) community since the earliest days of these Transactions. Initially, the efforts in this area were seen as applying pattern analysis and computer vision techniques to another interesting dataset. However, over the last two to three decades, the unique nature of the problems presented within this area of study have led to the development of a new discipline in its own right. Examples of these include: the types of image information that are acquired, the fully three-dimensional image data, the nonrigid nature of object motion and deformation, and the statistical variation of both the underlying normal and abnormal ground truth. In this paper, we look at progress in the field over the last 20 years and suggest some of the challenges that remain for the years to come.

https://hal.inria.fr/inria-00615100/document

Medical image analysis: progress over two decades and the challenges ahead

The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm

https://www.lfb.lv/files/ESVS-AAA-guidelines.pdf

Management of abdominal aortic aneurysms clinical practice guidelines of the European society for vascular surgery.

Magnetic resonance elastography: Non-invasive mapping of tissue elasticity

Bibliographic Databases in Tribology

Wear resistance has been found to improve for Al–Si alloyswith increasing silicon content up to the eutectic compo-sition (12.6 at.% Si), after which it deteriorates [1–3].Wear in Al–Si alloys has been characterized into mild andsevere wear regimes. Mild wear occurs under conditions oflow normal loads, and an oxide layer that forms on thewear surface usually slows down the wear process. Severewear occurs under high normal loads and is often charac-terized by inclusions of the worn counterface, along withoxides, in the mechanically mixed surface tribolayers [4,5]. The results of Razavizadeh and Eyre [6] suggest thatthere is generally insufﬁcient frictional heating on the wearsurface for general oxide formation. Instead, a mechanismof oxidation of asperities followed by fracture and com-paction of these oxidized asperities into the valleys on themetal wear surface has been suggested [7, 8]. During mildwear of Al–Si alloys, a smooth surface is generallyobserved with interspaced wear scar areas [1]. The pres-ence of material from the worn counterface embedded inthe wear pin has been observed on both smooth and scarredareas [7, 9, 10].Lower wear rates may be observed when harder coun-terfaces, such as diamond-like carbon (DLC) or yttria-stabilized zirconia, are used instead of the hardened steelsurfaces traditionally employed in wear tests, particularly ifthe hard counterface has a smooth surface [11]. Also, argontest environments have shown reduced wear rates ascompared to tests performed in air, with the wear ratesunder argon being as much as ten times lower in somecases [11, 12]. The increase in wear rates in atmosphereswith higher oxygen content has been attributed to thepresence of abrasive wear debris on the surface [12].In a recent paper [12], we studied the wear of as-casteutectic Al–Si against a yttria-stabilized zirconia counter-face using pin-on-disk tribotests in two different environ-ments, air and dry argon. The wear rate of the pins tested inair was more than twice that of those tested under argon.Similarly, the zirconia counterface showed much morewear for tests conducted in air. There was substantialsubsurface cracking in the pins during wear testing in air,but none was observed in pins tested under argon. Scanningtransmission electron microscope (STEM) examination ofthe near-surface region of the pins that had been worn in airshowed mechanically mixed regions with considerableamounts of both aluminum oxide and zirconium oxide—the aluminum oxide particles had evidently acted as abra-sive particles to remove material from the zirconia coun-terface. In contrast, the pins tested in argon showed littlezirconium oxide in the near-surface regions.In that study [12], it was unclear whether the moisturepresent in air made a signiﬁcant contribution to the wearrate. Thus, the objective of the present study was to clarifythe inﬂuence of moisture in the wear environment and itseffects on the proposed wear mechanism of crack forma-tion and debris accumulation on wear surfaces. To that end,pin-on-disc wear tests were performed in a ﬂowing dryoxygen environment using the same materials and condi-tions as in our previous study, and the resulting wear sur-faces were characterized in the same fashion [12]. Theresults, described below, are compared with those fromprevious tests conducted in air and in dry argon. It ispossible that the size of the Si particles may affect the wear

Effect of sliding environment on dry sliding wear of as-cast eutectic Al–Si

The objective of this work is to quantify the effect of shear rate on the viscosity of multigrade lubricants. The study is based on the assumption that multigrade lubricants are two phase systems with the phases responding more-or-less independently to external mechanical actions. The assumption generates two questions: 1) Are there rules of behavior respected by all members of a given family of blends (same additive in different concentrations and the same class of base oils with different viscosities)? and 2) To what extent do the nature of the additive and the base oil affect these rules? This paper deals with the first question. It analyzes the flow behavior of the Mineral Oil-Hydrogenated Styrene Butadiene (MO-HSB) system, a popular family of multigrade lubricants. It was found that certain rules exist which control the effect of shear rate on viscosity at constant temperature. Experimental results obtained with a Couette-type viscometer showed that viscous torque varies with shear rate in the same p...

The Effect of Shear Rate on Viscosity of the Mineral Oil-HSB System

: A microscopic examination, an analytical study, and an experimental study were carried out to determine why and how thermocracking occurs in the mating ring of a mechanical face seal. Microscopic examination of the cobalt-based superalloy mating ring of a marine propeller shaft seal yielded a better understanding of the initiation and propagation of thermocracks in the seal ring and of the role played by second phase particles in thermocracking. An analysis of surface temperatures and stresses in the seal, using finite element techniques, showed that the dominant stresses in the seal components are thermal stresses. A thermocracking mechanism is proposed, based on the analytical study, which agrees well with all microscopic features. The analytical model assumed that thermoelastic instabilities cause concentrated contact patches to form at the seal interface prior to the onset of thermocracking. The presence of these contact patches was confirmed by use of a novel contact probe in the experimental study. Suggestions are made of steps that could be taken to alleviate the thermocracking problem and guidance is offered for the choice of future seal materials.

Factors Influencing Thermomechanical Failure of Face Seals. III.

Compensation for intraoperative tissue motion in the registration of preoperative image volumes with the OR is important for improving the utility of image guidance in the neurosurgery setting. Model-based strategies for neuroimage compensation are appealing because they offer the prospect of retaining the high-resolution preoperative information without the expense and complexity associated with full volume intraoperative scanning. Further, they present opportunities to integrate incomplete or sparse, partial volume sampling of the surgical field as a guide for full volume estimation and subsequent compensation of the preoperative images. While potentially promising, there are a number of unresolved difficulties associated with deploying computational models for this purpose. For example, to date they have only been successful in representing the tissue motion that occurs during the earliest stages of neurosurgical intervention and have not addressed the later more complex events of tissue retraction and resection. IN this paper, we develop a mathematical framework for implementing retraction and resection within the context of finite element modeling of brain deformation using the equations of linear consolidation. Specifically, we discuss the critical boundary conditions applied at the new tissue surfaces created by these respective interventions and demonstrate the ability to model compound events where updated image volumes are generated in succession to represent the significant occurrences of tissue deformation which take place during the course of surgery. In this regard, we show image compensation for an actual OR case involving the implantation of a subdural electrode array for recording neural activity.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Francis E. Kennedy

Papers

Bibliographic Databases in Tribology

Effect of sliding environment on dry sliding wear of as-cast eutectic Al–Si

The Effect of Shear Rate on Viscosity of the Mineral Oil-HSB System

Factors Influencing Thermomechanical Failure of Face Seals. III.

Finite element modeling of tissue retraction and resection for preoperative neuroimage compensation concurrent with surgery