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Over 450 cores were extracted from roadways throughout Mississippi to provide a realistic picture of mechanical properties in later-age chemically stabilized soil. Cores ranged from 10 to 54 years old and were stabilized with either lime-fly ash, cement, or lime. Indirect tensile strength (IDT), unconfined compressive strength (UCS), and elastic modulus (E) tests were used to quantify mechanical properties. Generally speaking, IDT, UCS, and E values tended not to exceed 250, 1500, and 1,500,000 psi (1724 kPa, 10,342 kPa, and 10,342 MPa), respectively, in pavements over 10 years old. Cores were also compared to mechanical property relationships found in the 1993 AASHTO design guide and the Mechanistic-Empirical Pavement Design Guide (MEPDG) and the literature to determine their applicability to later-age pavement properties. Relationships from the literature comparing IDT to UCS were generally good predictors of later-age property relationships; however, relationships between E and UCS were not good predictors of later-age strength as most equations did not account for the decrease in E development over time when compared to UCS. [ABSTRACT FROM AUTHOR]

We give a necessary and sufficient condition on $\beta $ of the natural extension of a $\beta $ -shift, so that any equilibrium measure for a function of bounded total oscillations is a weak Gibbs measure. [ABSTRACT FROM AUTHOR]

This paper develops a two-stage method for the justification of investment in modern material handling systems. The underlying approach places heavy emphasis on the use of cost avoidance data quantified by activity-based costing systems. The first stage collects the life-cycle costs and benefits resulting from the reconfiguration of material handling systems in manufacturing facilities. A recently developed software package for process modelling and management is employed to capture the characteristics of material handling activities and to derive accurate applied cost rates for each activity and material handling system combination. These activity-related cost data as well as various opportunity costs are incorporated in a case-specific, investment decision model that constitutes the second stage of the method. The model performs an Economic Value Analysis for each material handling alternative. In doing so, it offers a sound basis for economic comparison of different systems. A case study illustrates the merit of our two-stage method in decision making by placing an accurate and reliable economic value on the transition from manual to automated material handling in a manufacturing facility. The use of activity-based costs reverses the decision of sustaining the 'status quo' supported by a traditional investment justification approach restricted to solely labour cost reductions [ABSTRACT FROM AUTHOR]

Necrotizing fasciitis is a highly morbid soft tissue infection that rarely involves the upper torso. An extremely unusual case of necrotizing fasciitis of the chest wall is reported, including the method by which an open thoracic cage was managed. This represents the second reported case of a patient surviving necrotizing fasciitis of the chest wall requiring rib resection and chest wall reconstruction.

The purpose of this article is twofold: (1) to investigate the histomorphology of cartilaginous proliferation using three different otoplasty techniques and (2) to determine whether recurrence is related either to the method of otoplasty or the duration of suture fixation. Eighteen 6-week-old New Zealand white rabbits were divided into three equal groups. In each animal, a skin pocket was developed on the posterior surface of both ears; the perichondrium of the left ear was stripped off, whereas the perichondrium of the right ear was left undisturbed. Otoplasties were performed by inserting permanent mattress sutures with (Converse-Wood-Smith) or without (Mustardé) cartilaginous incisions or by scoring of the anterior cartilaginous surface of the antihelix (Stenstrom). In each group, sutures were cut at 1, 2, 4, and 6 weeks and the animals killed 1 week later. Histomorphometric analysis was performed. Perichondrial stripping stimulated cartilaginous proliferation in all groups. The antihelical fold maintained its shape best in group 3, in which the anterior perichondrium was rasped; a fibrocartilaginous cap formed over the rasped convex surface of the antihelical fold, reinforcing and stabilizing the newly created fold. Groups 1 and 2, in contrast, demonstrated significantly less anterior cartilaginous proliferation than did group 3, and cap formation was not observed. No significant differences were apparent between groups 1 and 2 in either the quantity or quality of cartilaginous proliferation in any of the time periods. Cutting the sutures at 1 week resulted in loss of shape or "flattening" of the fold in all groups; however, increased cartilaginous proliferation between 2 and 6 weeks stabilized the fold, minimizing deformability.(ABSTRACT TRUNCATED AT 250 WORDS)

We studied fibroblast activity during tendon healing with an in vitro tendon culture model. Tendons were embedded in a translucent collagen gel matrix whose porous nature permitted free nutrient diffusion, fibroblast migration out of the tendon, and microphotographic documentation of fibroblast activity. Experiments were performed using one or more tendons cultured in the same collagen gel. We identified three zones of fibroblast activity in the gel. Zone I was an area of randomly dispersed cells directly adjacent to the tendon where collagen synthesis and remodeling were probably taking place. In zone II, spindle-shaped fibroblasts were aligned pointing away from the cut tendon end forming a sunburst-like aggregate of cells. Zone II fibroblasts were responsible for formation of migration trails by exerting a mechanical force on the collagen matrix, which was evident as a local gel contraction. Zone III was the leading edge of the sunburst populated by the fastest moving fibroblasts, which responded to guidance by other cut tendon ends. We speculate that the collagen gel used in the culture system may help maintain a chemotactic concentration gradient that allows fibroblasts to locate other distal cut tendon surfaces also embedded in the collagen gel.

Severity of lacerative skin injury depends on the applied load and the resistance of the tissue. At low (static) rates of loading there is a high degree of correlation between skin tensile strength and the degree of collagen crosslinking, with little added strength due to collagen interactions with the glycosaminoglycan matrix. We examined the effects of high (ballistic) rates of loading in order to determine the contributions to strength made by both the degree of collagen crosslinking and the collagen-matrix interaction. Tensile failure experiments were conducted using the dorsal skin of rats 1.5-6 months of age. Test specimen orientations were cut parallel and transverse to the body axis at cephalad and caudad locations on the dorsum. Tensile strength was measured at nominal strain rates of 30%/sec (low speed) and 6000%/sec (high speed) using both control and lathyrogen fed rats. Biochemical analyses were conducted to determine the amount of total and crosslinked (insoluble) collagen. In low-speed tests, there was a significant correlation (r > or = 0.900) between collagen content and skin tensile strength measured both transverse and parallel to the spine. The degree of correlation was higher with insoluble (r = 0.973) collagen content than with total (r = 0.901) collagen. The effect of a lathyrogen diet produced a significant (P < 0.001) reduction (two- to threefold) in tensile strength compared to control. In both high- and low-speed groups, tensile strength was greatest in the transverse samples with a significant correlation to collagen content (r > or = 0.858).(ABSTRACT TRUNCATED AT 250 WORDS)

Full-thickness cranial (membranous) and split-thickness iliac crest (endochondral) onlay bone grafts were placed subperiosteally without fixation onto the snout (membranous) and tibia (endochondral) in 30 rats. The animals had been divided into three equal groups in which the bone grafts had been demineralized, autoclaved, or used fresh. Recipient sites were harvested at 7 and 14 days at the snout and 14 days at the tibia, and revascularization was studied utilizing silicone rubber injection and a gridcounting technique. Endochondral grafts were found to have quantitatively greater revascularization than membranous grafts in all three groups at both sites (p less than 0.005). There was generally no statistically significant difference in revascularization between fresh and demineralized grafts, but vessel ingrowth was significantly decreased in autoclaved implants as compared with fresh grafts. Differences in graft architecture are theorized to account for the disparity in revascularization in endochondral and membranous grafts. Angiogenic and chemotactic factors are thought to play a role in the similarities and differences in revascularization among fresh, demineralized, and autoclaved bone.

Of 457 patients with facial fractures admitted by the plastic surgery service from 1986 to 1988 at Wayne State University, there were seven displaced orbital roof fractures in five patients. All presented with supraorbital rim fractures, inferior dystopia, limitation of supraduction, upper eyelid ptosis, and diplopia. Proptosis was present in four orbits in three patients. One of these patients had an orbital floor fracture. However, enophthalmos was present in three orbits in two patients with associated zygoma and floor fractures. Two patients had intracranial neurologic injuries, but no ocular injuries were seen. Patients underwent frontal craniotomy and removal of the supraorbital rim for exposure. The orbital roof was reconstructed with outer-table cranial bone grafts. Associated fractures were repaired. Mean follow-up was 21.4 months. In all patients, the inferior dystopia, proptosis or enophthalmos, limitation of supraduction, and diplopia were corrected. In one patient, residual mild eyelid ptosis was seen. No residual neurologic or ocular injury was seen.

It is widely held that neonates are obligatory nasal breathers. Although cleft lip repair may compromise the nasal airway, respiratory distress following such a procedure is rarely reported. A review of the literature reveals that only a minority of neonates are obligatory nasal breathers. When the nasal airway is compromised in these patients, however, respiratory distress may result. Two patients with this complication are presented, and their successful treatment with a nasopharyngeal airway is described.

The application of craniofacial techniques has led to a greater variety of methods for operative exposure. In the orbital region, the inferior marginotomy of Tessier is a valuable adjunct in the reconstruction of severe orbital floor fractures and their sequelae. This concept has been extended to the superior, lateral, and medial orbital rims to improve the exposure of the respective orbital wall. These marginotomies have been used for a variety of problems. There have been no complications related to the inclusion of a periorbital marginotomy, and its use in appropriate patients is strongly recommended.

Review of 1,008 admissions over the past two years to the Detroit Medical Center Burn Unit revealed 227 patients with facial or scalp burns. Of these, 12 patients sustained burns directly as a result of accidentally igniting a hair activator product called "Jheri-Curl." Eleven patients sustained superficial partial-thickness burns and were adequately treated with Dermaide. One had deeper burns requiring split-thickness skin grafting.

The following report reviews 851 applications of Biobrane on partial skin thickness burn wounds awaiting epithelialization. After the patients had been evaluated and resuscitated as needed, the burn wounds were cleansed and debrided. Those evaluated as shallow were treated with Biobrane application. Joint surfaces were splinted for immobilization. The wound was inspected at 24 and 48 h and if any fluid had accumulated it was aspirated and the wound was redressed. When the Biobrane was adherent, the wound was covered with a light dressing and joint immobilization was discontinued. Treatment with Biobrane dressing provided certain advantages over other topical wound care. As the dressing changes were performed less frequently outpatient care was possible, with a resultant decrease in both the length of hospital stay and the ultimate cost of burn care. Wound desiccation is prevented and pain is decreased. Accurate diagnosis of wound depth is crucial if Biobrane is to be used. Very deep wounds will not allow Biobrane adherence, neither will it occur if the wound has a high bacterial count. If joint surfaces are not splinted, the Biobrane will shear and not adhere to the wound. Convex and concave surfaces can be treated with Biobrane, which may need to be meshed.

In 37 cadavers of average age 75.5 years, the calvarium was studied. In all, the diploe and outer and inner tables were found to be definite layers. Although the parietal bone thickness did decrease with age in this study, there was no correlation between age and the outer table or diploe thickness. No significant change with age occurred in the occipital bone. Although this study supports the use of split calvarial grafts in older patients without the necessity for a craniotomy, the relative brittleness of this bone in this population should be considered.

A 43-year-old woman experienced the sudden onset of unexplained bilateral blindness 42 days after a 55 per cent total body surface area burn. Possible causes are examined, and a comparison with cases previously reported in the literature is made.

Metastatic tumors to the stomach are distinctly unusual. Rarer still is renal cell carcinoma metastatic to the stomach following radical excision of the primary tumor several years previously. During evaluation for an upper gastrointestinal hemorrhage, a patient was found to have a large antral mass. Endoscopic biopsy revealed renal cell carcinoma. At celiotomy the tumor was found to have penetrated through to the liver capsule. An antrectomy and wedge resection of the left lobe of the liver was performed. There was no evidence of further metastatic disease. This is the first report of such a patient resected for cure, and emphasizes the unique biology of this tumor in its potential for late, solitary metastasis and surgical resectability.

This review emphasizes two of the difficult problems associated with electrical injury to the hand and forearm. Early wound closure to preserve important vascular, nerve, and tendon structures in the hand must be considered, recognizing the tendency for continued necrosis of tissue in this type of injury. Tissue fibrosis, even in areas of the hand not grossly injured, may develop, progressively compromising function. Five patients are presented to illustrate the early care and rehabilitation of these patients.