Prominent Edges Research Articles

Surgical release of iliopsoas tendon for groin pain after total hip arthroplasty

After total hip arthroplasty (THA), some patients continue to have groin pain. Conditions that can cause groin pain include infection or tumor, aseptic loosening of the components, and soft tissue inflammation. Occasionally the soft tissue inflammation is tendinitis of the iliopsoas tendon. This condition commonly occurs because the anterior metal wall of the cup protrudes above the anterior bony acetabular wall [1], such as would occur with a lateralized cup, especially if capsulectomy has been done (Fig. 1). This also could occur if the cup is placed in a retroverted position, for which revision has been required [1]. This pain can be relieved by surgical release of the iliopsoas tendon. Over 6 years, we have treated 5 patients who had persistent groin pain after THA without evidence of infection or loosening of the cup. Cup position was measured as satisfactory in each hip [2]. All of these patients complained of groin pain that occurred with activities that required use of the iliopsoas muscle, including straight-leg raising and active flexion of the hip, such as ascending stairs, lifting the operative leg into bed, and lifting the leg to get into and out of a car. Occasionally, there would be some pain radiation to the anterior thigh, which also was more pronounced with these activities. Level walking did not cause symptoms because the iliopsoas muscle is not active during walking on level ground. The pain-specific activities of active flexion of the hip helped to differentiate iliopsoas tendinitis from septic or aseptic loosening, which causes pain with any weight bearing. Little has been written about iliopsoas tendinitis. Mostly this condition has been described in sports medicine and radiology literature [3–5]. There is only 1 report of iliopsoas tendinitis after THA; it described 2 hips in which the acetabular component was placed in retroversion, which caused fraying and inflammation of the tendon as it passed over the edge of the shell and required revision surgery of the cup [1]. One of our patients had a prominent anterior edge of the cup as a cause (Fig. 2). The patient had a previous operation because of anterior dislocation of the hip and groin pain. That operation was done through an anterior incision that exposed the cup, and a new liner was placed with the hood anteriorly. The dislocations stopped, but the groin pain with flexion activities continued until the tendon was released by us. An increase of the hip offset or hip length of 1 cm also could cause this tendon irritation. One of the 5 patients operated by us had an increased offset of 1.8 cm, and 2 of 5 patients had increased hip lengths of 2.1 cm and 1 cm. When the groin pain is caused by iliopsoas tendinitis, it can be eradicated by surgical release of the tendon from the lesser trochanter. Pain relief occurred in all 5 of our patients.

An integrated approach to the elicitation of customer requirements for engineering design using picture sorts and fuzzy evaluation

Product definition is widely accepted as one of the key factors to be considered in the early stage of product design and development. It has a direct impact on the success of a new product in the marketplace. Frequently, product definition is solicited through the voice of the customer (VoC). As such, an organization will obtain a prominent competitive edge over its competitors if it is able to effectively capture the genuine VoC or the requirements of a customer. Sorting techniques provide a means to elicit customer requirements. Although a number of sorting techniques were developed, few of them are able to handle the uncertainty and imprecision inherited from the VoC and subjective judgment because of their crisp decision making. An integrated approach is described, which is based on repeated single-criterion sorts and fuzzy evaluation, for the elicitation of customer requirements. The details of the integrated approach are presented. The approach is validated using a case study on the design of a wooden golf-club head. The details of the validation are discussed.

The First High‐Resolution X‐Ray Spectrum of Cygnus X‐1: Soft X‐Ray Ionization and Absorption

We observed the black hole candidate Cyg X-1 for 15 ks with the High-Energy Transmission Grating Spectrometer aboard the Chandra X-Ray Observatory. The source was observed during a period of intense flaring activity, so it was about a factor of 2.5 brighter than usual, with a 0.5-10 keV (1-24 ?) luminosity of 1.6 ? 1037 ergs s-1 (at a distance of 2.5 kpc). The spectrum of the source shows prominent absorption edges, some of which have a complicated substructure. We use the most recent results from laboratory measurements and calculations to model the observed substructure of the edges. From the model, we derive a total absorption column of (6.21 ? 0.22) ? 1021 cm-2. Furthermore, the results indicate that there are ~ 10%-25% abundance variations relative to solar values for neon, oxygen, and iron. The X-ray continuum is well described by a two-component model that is often adopted for black hole candidates: a soft multicolor disk component (with kT = 203 eV) and a hard power-law component (with a photon index of ~2). Comparing the fit results to those of the hard and soft states, we conclude that the source was in a transitional state. Finally, the spectrum also shows the presence of faint emission lines, which could be attributed to highly ionized species.

Spectral Evolution of Circinus X‐1 along Its Orbit

We report on the spectral analysis of Circinus X-1 observed by the ASCA satellite in 1998 March along one orbital period. The luminosity of the source (in the 0.1-100 keV band) ranges from 2.5 × 1038 ergs s-1 at the periastron (orbital phase 0.01) to 1.5 × 1038 ergs s-1 at orbital phase 0.3. From the spectral analysis and the light curve, we argue that Cir X-1 shows three states along the orbital evolution. The first state is at the orbital phase interval 0.97-0.3: the luminosity becomes super-Eddington, and a strong flaring activity is present. In this state a shock could form in the inner region of the system because of the super-Eddington accretion rate, producing an outflow of ionized matter whose observational signature could be the prominent absorption edge at ~8.7 keV observed in the energy spectrum at these phases. In the second state, corresponding to the orbital phase interval between 0.3 and 0.7, the accretion rate is sub-Eddington, and we observe a weaker outflow, with a smaller hydrogen column: the absorption edge is now at ~8.3 keV with an optical depth a factor of 2.5-6 smaller. The third state corresponds to the orbital phase interval 0.78-0.97. In this state the best-fit model to the spectrum requires the presence of a partial covering component, indicating that the emission from the compact object is partially absorbed by neutral matter, probably the atmosphere of the companion star and/or the accreting matter from the companion.

A Moving Cold Front in the Intergalactic Medium of A3667

We present results from a Chandra observation of the central region of the galaxy cluster A3667 with emphasis on the prominent sharp X-ray brightness edge spanning 0.5 Mpc near the cluster core. Our temperature map shows large-scale nonuniformities characteristic of the ongoing merger, in agreement with earlier ASCA results. The brightness edge turns out to be a boundary of a large cool gas cloud moving through the hot ambient gas, very similar to the fronts discovered by Chandra in A2142. The higher quality of the A3667 data allows the direct determination of the cloud velocity. At the leading edge of the cloud, the gas density abruptly increases by a factor of 3.9 ± 0.8, while the temperature decreases by a factor of 1.9 ± 0.2 (from 7.7 to 4.1 keV). The ratio of the gas pressures inside and outside the front shows that the cloud moves through the ambient gas at near-sonic velocity, M = 1 ± 0.2 or v = 1400 ± 300 km s-1. In front of the cloud, we observe the compression of the ambient gas with an amplitude expected for such a velocity. A smaller surface brightness discontinuity is observed further ahead, ~350 kpc in front of the cloud. We suggest that it corresponds to a weak bow shock, implying that the cloud velocity may be slightly supersonic. Given all the evidence, the cold front appears to delineate the remnant of a cool subcluster that recently has merged with A3667. The cold front is remarkably sharp. The upper limit on its width, 35 or 5 kpc, is several times smaller than the Coulomb mean free path. This is a direct observation of suppression of the transport processes in the intergalactic medium, most likely by magnetic fields.

Sulfur K-edge XANES study of local electronic structure in ternary monosulfide solid solution [(Fe, Co, Ni) 0.923 S

Synchrotron radiation S K-edge XANES spectra and unit-cell parameters are used to investigate the local electronic structure of non-stoichiometric binary and ternary Fe-Co-Ni monosulfide solid solution (mss; M0.923S, M = Fe, Co, Ni) quenched from 800 °C and low pressure. The prominent absorption edge feature of the XANES spectra represents transition of S 1s core level electrons to unoccupied S 3p σ* antibonding orbitals hybridized with empty metal 3d(eg) orbitals. There is a progressive increase in area of the edge peak from Fe0.923S to Ni0.923S and Co0.923S, which correlates with progressive decrease in c and a parameters for the NiAs-type subcell and increase in metallic character, and reflects increase in the number and availability of empty eg β orbitals and covalence of metal-S bonds. More generally, the area of the edge peak exhibits an inverse linear correlation with a, c and unit-cell volume of binary and ternary mss. This inverse linear correlation is attributed to progressive increase in covalence and M-S-M bonding interaction in the c-axis direction, through metal-S [M 3d(eg) - S 3p (or 3d)] π bonding. However, the area of the edge peak does not correlate very well with the average number of 3d electrons per metal atom in these solid solutions, showing that the absorption of synchrotron radiation reflects the local electronic structure of individual absorber atoms (i.e. the SM6 cluster), and is not a group (crystal energy band) effect.

Iron in hibonite: a spectroscopic study

A combined polarized optical absorption and 57Fe Mossbauer spectroscopy study of inhomogeneous, Fe and Ti-bearing terrestrial hibonite (Madagascar) has been carried out. Mossbauer data were also obtained on synthetic material prepared under different fo2 inconditions. A strong band at 5400 cm-1 in the near-infrared spectra is attributed to spin-allowed d-d transitions of Fe2+ occupying tetrahedral sites within the spinel blocks of the hibonite crystal structure. There is agreement with the Mossbauer results, showing that ferrous iron orders onto a single, low-coordinated crystallographic site. Ferric iron is distributed over several positions, but shows strongest preference for the large bipyramidal site located outside the spinel blocks. The colour and pleochroism of hibonite in thin section is related to a prominent UV absorption edge, and several broad absorption bands in the visible spectrum ascribed to charge-transfer transitions involving Fe2+, Fe3+ and Ti4+.

1300 km long late Pleistocene-Holocene shelf edge barrier reef system along the western continental shelf of India: occurrence and significance

A detailed analysis of echosounding and side-scan sonar data collected from the western continental margin of India has revealed the presence of prominent shelf edge reefs, concentrated mostly on the central and the southern parts. Their depth of occurrence varies between 85 and 136 m. The reefs are 1–12 m high and 0.1–2.6 km wide (av. 700 m). Morphologically, they may be classified into (1) simple and (2) complex types. The former are single and broad or narrow (av. width 350 m), while the latter are generally massive (av. width 950 m) with several superimposed peaks. Sub-bottom profiles indicate the presence of paleolagoons. This reef system, more than 1000 km long, trends NNW-SSE i.e., parallel to subparallel to the present-day shoreline. It is surmised that coral/algal reef growth commenced with the advent of the Holocene transgression and favorable antecedent topography, and continued until early Holocene. Subsequently, rapid sea level rise drowned the reefs. The shelf edge reefs, therefore, are part of “relict, submerged” barrier reef system and reflect late Pleistocene/early Holocene shoreline.

Estimation of perceived image blur using edge features

Sharpness (or its complement, perceived blur or unsharpness) is an important attribute of image quality, and the spread of the physical blurring kernel is the predominant parameter determining that attribute. In this article we present an algorithm to estimate an objective measure for sharpness, called the blur index. The algorithm first estimates the physical parameter of blur spread from the blurred image and subsequently uses that estimate to compute the blur index. A global estimate of blur spread for the entire image is obtained by the weighted averaging of the local estimates of blur spread at prominent edge locations in the image. These local estimates at edges are obtained by nonlinearly combining local derivatives. The edge prominence is based on the edge height and the edge-contour length. The blur index is computed from the estimated blur spread by taking the sensitivity of the visual system to changes in the blur spread into account. The results of a psychophysical experiment in which subjects judged the unsharpness of natural images are also reported. By correlating the estimates of the blur index, as obtained from the algorithm, with the results obtained in the psychophysical experiment, we show that the blur index correlates well with the perceived unsharpness, and hence can be considered a psychometric measure of sharpness. © 1996 John Wiley & Sons, Inc.

Preparation of Recipient Areas When Skin Grafting for Camouflage of Static Localised Vitiligo

SummaryA prospective randomized study was undertaken in 50 patients with static localised vitiligo to determine the optimum thickness of the excision of patches of vitiligo prior to grafting with normally pigmented very thin split-thickness skin grafts.Recipient areas (diseased skin) were prepared in 1 of 5 different ways (n = 10 per group): Group 1, dermabrasion of epidermis alone; Group 2, shaving of thin partial-thickness skin; Group 3, shaving of medium partial-thickness skin; Group 4, excision of full-thickness skin alone and Group 5, excision of full-thickness skin with subcutaneous fat.After a minimum follow up of 6 months, results showed that in Groups 1 and 2, the skin grafts desquamated by the re-growth of epidermis from the recipient bed. In the Group 3, grafts were unsightly because of retention cysts and a prominent edge. In Group 5, grafts became hyper-pigmented and the grafted area was scalloped. Optimum results were obtained in Group 4 with best aesthetic appearance. Vitiligo patches are best treated by excision of full-thickness skin when resurfacing with normally pigmented thin split-thickness skin grafts.

Shrink-Resistant Properties and Surface Characteristics of Wool Fibers Treated with Multifunctional Epoxides

Shrink-resistant properties and surface characteristics were investigated for wool fibers treated with hydrophilic multifunctional epoxides (glycerol polyglycidyl ether—GPE). Two different reaction conditions were used for the treatment, one in a saturated NaCl aqueous solution (S sample ) and the other in the absence of NaCl (W sample). Add- on percentages of both samples were almost the same. On the other hand, both shrink- resistant properties and surface characteristics were different for these two samples, showing that the reaction medium strongly affected the reaction mode of GPE. The degree of shrink-resistance of the W sample did not improve, while that of the S sample was much improved and almost equal to Cl/Hercostt (commercially) treated wool fibers. FTIR analyses showed that the surface concentration of GPE in the S sample was lower than that in the W sample, reflecting that the hydrophobic nature of the scale surface was maintained for the S sample and not the W sample. SEM observation results revealed prominent scale edges for the W sample but not for the S sample. These results explain the differences in shrink-resistant properties for the two samples.

Sequence stratigraphy of the Middle Miocene-Pliocene southern offshore Sandakan Basin, East Sabah

A sequence stratigraphic study was performed in the southern offshore Sandakan Basin with the aim of deriving a workable chronostratigraphic scheme and identifying plays, including stratigraphic traps. The data set includes 1800 km of high quality 1990 seismic and 8 wells. The study area can be divided into a structurally complex landward northern province and a relatively undisturbed basinward southern province. Three chronostratigraphic units were identified, each bounded by Type 1 third-order sequence boundaries. Each unit consists ofthird to fourth-order sequences which can be correlated from landward coastal plain facies to basinward bathyal facies. Unit 1 (Middle Miocene-early Upper Miocene) is characterised by moderate progradation, moderate aggradation; Unit 2 (middle Upper Miocene) by high progradation, low aggradation; and Unit 3 Oate Upper Miocene-Pliocene) by high aggradation, low progradation. . The positions of the prominent shelf edges in Unit 1, Unit 2 and lower Unit 3 indicate a southeastward progradation from Middle to Upper Miocene. Pliocene progradation was probably eastwards as suggested by N-S growth faults in the northeastern part of the study area, and is interpreted to have occurred within a ramp setting, as prominent shelf edges are lacking. The study led to the recognition of two play-types in the southern province, both associated with lowstand systems tract sediments. The fIrst is a slope fan play in Unit 1. The second is a basin floor fan play in Unit 2. Comparison of the locally derived onlap chart and the global onlap chart of Haq et al. (1987) highlighted some differences. The main difference is major Upper Miocene progradation in the study area versus Upper Miocene aggradation in the global chart, testifying to the importance of the interplay of local tectonics and sedimentation in the Sandakan Basin.

Hypothesizing Structures in Edge-Focused Cerebral Magnetic Resonance Images Using Graph-Theoretic Cycle Enumeration

We present a novel method for the automatic generation of structure hypotheses (that is, educated guesses) suitable for recognition in medical images. The notion is that computer-based image analysis cannot be accomplished in a purely bottom-up fashion; the system should first organize the image structure into promising hypotheses, each of which is then compared to elements of the system modelbase for recognition or rejection. In this work, we tackle the hypothesis generation problem, for which computational efficiency is a major concern. We base our approach on segment-based edge-focusing to delineate significant boundaries precisely, and graph-theoretic cycle enumeration to produce natural closures and, therefore, plausible tissue structures of interest from incomplete boundary information. An efficient edge focusing algorithm selects significant fine scale boundaries as those natural descendants (in scale space) of prominent coarse scale edges. The fine scale representation provides the localization precision necessary, while the focusing ensures that only significant contours surviving over a range of scales are considered and so eliminates much of the "clutter" associated with a fine scale edge map. The spatial relationships among the edge segments are stored in the form of a directed graph. Possible extensions (closures) of broken edge segments are searched using time- and space-efficient voting methods. Cycle enumeration techniques for directed graphs then generate the structure hypotheses. The overall paradigm is fairly general and can be used in other problem domains, certainly for images of other parts of the anatomy. We demonstrate the effectiveness of the method with extensive experimental results on various magnetic resonance images of the human brain.

Co-occurrence matrices for image analysis

This paper presents a range of techniques for image segmentation and edge detection based on co-occurrence matrices. Co-occurrence matrices are described and transforms are defined which adapt to global image characteristics and emphasise the differences between typical and atypical image features using co-occurrence matrices as look-up tables. The techniques are extended by analysing the matrices and labelling them, with the result that a labelled matrix can be used to segment the regions of an image and to simultaneously detect prominent edges. Examples are given for a variety of images: synthetic, infrared, multispectral and temporal. It is also shown that the techniques presented can be integrated easily with a variety of postprocessing techniques such as hysteresis and relaxation labelling for enhanced performance.

Automobile headlamp alignment by visual aim: Photometric correlates of the visual cutoff and aim variability

An automobile headlamp projects a beam pattern that exhibits a relatively abrupt drop off in intensity near the lamp's horizontal axis. This apparent edge is used as a reference line in visual alignment of the headlamp. This laboratory experiment was conducted to identify the photometric parameter that best represents the location of this visual edge; the relationship between edge sharpness and variability of beam pattern alignment was also investigated. Subjects in the experiment vertically aligned each of 14 illumination patterns so that the most salient visual edge of the pattern overlaid a horizontal line on the projection screen. On average, the vertical position chosen as the most prominent edge was closest to the point of largest intensity contrast. The variability in aiming performance was closely related to the peak intensity contrast value of the beam pattern.

Detecting texture edges from images

Edge detection takes an important place in image processing and pattern recognition. Its objective is to locate prominent edges in an image, and so to separate the components of an image into subsets that may correspond to the physical objects in the scene. In general, this can be achieved by generating an edge map using, for example, edge detection operators or some threshold techniques. In most cases, these methods assume that at the edge the grey level intensity changes in a discontinuous way (usually as a step function). If we need to segment a textural scene by finding the texture boundaries, traditional methods of edge detection are usually not successful since they cannot distinguish between the micro-edges within each texture and the boundaries between different textures. One reason for their failure is their inability to properly characterize a texture. This problem can be solved by combining the traditional edge detection techniques with some efficient textural measures. That is, in the intensity based edge detection operators, grey levels are replaced by textural features. Recently, the texture spectrum method has been proposed for texture characterization. This paper presents an example of the application of the texture spectrum to edge detection. Promising results are obtained when locating texture boundaries of some of Brodatz's natural images.

Canine teeth of bats (Microchiroptera): size, shape and role in crack propagation

Upper canines in microchiropteran bats show a variety of cross-sectional shapes. A consistent feature of all species studied here is that the tooth is edged and not simply round or oval. Prominent sharp edges are positioned in several directions but particularly antero-medially toward the incisors and posteriorly toward the premolars. These edges appear to direct the cracks made in food items to the incisors or to the premolars. A continuous cutting edge is apparent in the occlusal view of the palate running from tip of canine to the ectoloph of the molars. Size and shape analysis indicates that larger bats have slender, rather than stouter, canines for their height, a condition that may be attributable to the nature of the prey. Most bats take prey that have little hard substance imbedded within. The compromises in tooth shape may vary between that of a terrestrial predator with short, conical canines for processing endoskeletal prey to that of a small flying predator with long, slender, edged canines for capturing and processing exoskeletal prey. Unicuspid teeth and how they might function in food break-up have been overlooked to the literature; such a study could lead to an understanding of how more complex teeth function.

Non-BCS behaviour of the superconducting order parameter in YBa 2Cu 3O 7 studied with infrared spectroscopy

We report on detailed measurements of the temperature dependence of the infrared reflectivity spectra of YBa 2Cu 3O 7. It is shown that the prominent edge 1 at 8k B T c shows practically no energy shift as a function of temperature, whereas the oscillator strength of this feature depends strongly on temperature with a marked critical behavior at the superconducting transition temperature. This behavior coincides with the temperature dependence of the superfluid fraction, which was determined from the spectra using two different methods. A precursor at the same energy position persists at temperatures above T c. If the edge can be interpreted as the characteristic energy required to break up to a pair, we arrive at the conclusion that the gap itself can not be considered as an order parameter in this case. The superfluid density on the other hand changes approximately as 1 − ( T/T c ) 4. We point out that a remarkable analogy exists to the situation in itinerant magnetism, where short range order persists above the Curie temperature resulting in an exchange splitting that does not vanish 2 at T c.

Détection des contours de texture d'images numériques

Abstract Edge detection takes an important place in image processing and segmentation of remotely sensed data. Its objective is to locate prominent edges in an image, and so to separate the components of an image into subsets that may correspond to the physical objects in the scene. In general, this can be achieved by generating an edge map using, for example, edge detection operators or some threshold techniques. In most cases, these methods assume that at the edge the grey level intensity changes in a discontinuous way (usually as a step function). If we need to segment a textural scene by finding the texture boundaries, traditional methods of edge detection are usually not successful, since they cannot distinguish between the micro-edges within each texture and the boundaries between different textures. One reason for their failure is their inability to characterize properly a texture. This problem can be solved by combining the traditional edge detection techniques with some efficient textural measure...

Failure Mechanisms of Metal-Backed Patellar Components

A specific type of failure of a metal-backed patella occurred, consisting of a separation of the polyethylene from the metal backing. This dissociation is followed by wearing of the metal backing against the femoral component. This produces clinical signs and symptoms that usually require revision. This failure occurred in 16 knees of 14 patients. Average time to failure was 14 months. Failure was associated with patellar implant design, surgical technique, patient characteristics, and femoral component design. The plastic of the metal-backed patellae was thin at the periphery. The metal plate did not extend to the edge of the plastic and acted like a sharp edge that cut the thin plastic. The plastic dome was not bonded to the plate and became separated from the plate once the plastic tore. The plate became deformed. Failure was more likely with a subluxated, tilted, or excessively thick patella or flexed femoral component. The typical patient was a large, active male who had achieved more than 115 degrees of flexion. A prominent edge on the lateral intercondylar ridge of the femoral component resulted in a concentrated load being applied to the plastic dome and favored rapid wear of the patella. Until a greater understanding of patello-femoral loading is acquired, caution in the use of metal-backed patellae is recommended.