Urban Form and Household Activity‐Travel Behavior

ABSTRACT Cities and metropolitan regions face several challenges including urban sprawl, auto dependence and congestion, and related environmental and human health effects. Examining the spatial characteristics of daily household activity‐travel behavior holds important implications for understanding and addressing urban transportation issues. Research of this sort can inform development of urban land use policy that encourages the use of local opportunities, potentially leading to reduced motorized travel. This article examines the potential household activity‐travel response to a planned metropolitan polycentric hierarchy of activity centers. Behavioral observations have been drawn from an activity‐travel survey conducted in the Portland, Oregon, metropolitan area during the mid‐1990s. Evidence presented from exploratory analysis indicates an urban/suburban differential, with less daily travel and smaller activity spaces for urban households. Investigation of the travel reduction potential of the proposed land‐use strategy suggests that location effects could be offset by adjustments to household sociodemographic and mobility characteristics.     

Surgical Stabilization of the Equine Cervical Spine

The Cloward technique for intervertebral fusion was utilized on 12 horses ranging from 3 months to 2 years of age. Of the 12 horses, 9 had been diagnosed as having equine cervical vertebral malformation (CVM) or "wobbles," and 3 were normal controls. A large hole was drilled from the ventral border of the vertebral bodies spanning the intervertebral disc and the vertebral end plates of the 2 articulating vertebrae. Frozen homologous bone dowels of slightly larger diameter from equine cadaver ilia were inserted in the holes. No adverse postoperative complication arose. Clinical improvement was seen in all horses with CVM. Three months postoperatively, partial or complete fusion was evident radiographically in 11 of the 12 horses. Necropsies were performed 3–6 months postoperatively to evaluate the quality of the fusion. Cadaver manipulation demonstrated reduced intervertebral movement at the operative site in all cases. The articulations of the equine cervical spine can be operatively fused by the Cloward technique, and surgically induced trauma is minimal. This technique can be used for stabilizing subluxations and may be applicable for treating fractures and osteolytic processes that have weakened vertebrae.     

In Vitro Biomechanical Evaluation and Comparison of FiberWire,FiberTape, OrthoFiber,and Nylon Leader Line for Potential Use During Extraarticular Stabilization Of Canine Cruciate Deficient Stifles

Objective— To compare biomechanical properties of 3 new generation polyethylene sutures (FiberTape [FT], FiberWire [FW], and OrthoFiber [OF]) with nylon leader line (NL) for use during extraarticular fixation of cranial cruciate deficient stifles. Study Design— In vitro biomechanical testing of suture loops under monotonic tensile and cyclical loading until failure. Sample Population— Constructs of FT, FW, OF, and NL. Methods— Twenty loops of each of 12 combinations of fixation and suture had monotonic tensile and cyclical loading. Two knotting techniques (square knot [SQ], slip knot [SL]) and a crimp clamp (CR) system were evaluated. Elongation, stiffness, and strength of constructs was tested. The main effects of group, loop material, and their interaction were evaluated. Results— Knotted FT, FW, and OF had less elongation than knotted NL under monotonic tensile and cyclical loading. Under monotonic tensile loading, knotted FT and OF were stiffer than knotted NL. CR FT, CR FW, and CR OF were stiffer than CR NL and CR FT, CR FW, and CR OF were stiffer than knotted FT, FW, and OF. FW and OF knotted loops were weaker than knotted NL. CR FT was stronger than CR NL. CR FT and CR OF were weaker than knotted FT and OF. Conclusions— Polyethylene sutures are stronger, stiffer and elongate less than nylon leader. Crimping suture alters the biomechanical properties of the loop. Clinical Relevance— FW, FT, and OF may perform better in reconstructive procedures, where increased strength and stiffness are considered to be beneficial.     

不同光照条件对槲蕨组织培养外植体褐化的影响

采用组织培养方法,探讨了黑暗、1 000 lx、2 000 lx和3 000 lx等4种不同光照条件对槲蕨外植体褐变程度的影响.结果表明:随着光照时间的延长,槲蕨外植体的PPO、POD和总酚含量均表现为先增加后减少的趋势:在相同培养时间下,随着光照强度的增加,槲蕨外植体的PPO和POD活性也同时增加,其中光照强度1 000 lx处理的PPO和POD的活性均低于其他光照强度处理;光照对槲蕨外植体的总酚含量在相同培养时间下影响并不直接,但1 000 lx处理下的槲蕨外植体的总酚含量积累较少,说明1 000 lx是槲蕨的组织培养较为适宜的光照条件.     

The Supply of Private Acreage for Public Recreational Use in Southern and Central Appalachia

Public lands in Southern and Central Appalachia (SCA) available for outdoor recreational pursuits are limited relative to the rest of the country. This study identifies factors that encourage private landowners to permit public access to their land for recreational purposes and determines how much acreage would be offered in the SCA region. The Tobit and Heckman's sample selection models suggest that the probability of offering land to the public is correlated with the number of acres offered. Having acreage suited for recreation is a positive determinant of acres leased, but attributes developed by the landowner act as a disincentive. Type of recreational activity has no effect on the landowner's decision, and the supply of recreational acreage is inelastic with respect to price.     

Lateral Thoracic Artery Axial Pattern Flap in Cats

Objective— To describe the location of the lateral thoracic artery (LTA), determine dimensions of an axial pattern flap based on this artery, and report use of this flap in 2 cats.
Study Design— Ex vivo study and case reports.
Animals— Cat cadavers (n=8); cats (n=2) with thoracic limb skin defects.
Methods— Dissection of the LTA was carried out on 1 side of each cadaver and the contralateral side was used for injection studies. In 4 specimens, the LTA was cannulated and injected with positive contrast material and the flap was raised and radiographed. In 4 specimens, the flap was injected with methylene blue. Adequacy of flap injection was subjectively evaluated and leakage of methylene blue from the cut edge was noted.
Results— The cutaneous location of the LTA caudal to the triceps muscle was confirmed. Mean flap size was 8.7 cm × 15.5 cm for a mature, averaged-sized cat. Perfusion of the entire flap was demonstrated and viability of the flap was confirmed in 2 clinical cases.
Conclusion— The LTA flap is useful for repair of skin defects of the brachium and antebrachium in cats.
Clinical Relevance— The LTA flap is an alternative technique for repair of skin defects involving the thoracic limb of cats.     

Changes in the chemistry of soil solution and acetic-acid extractable P following different types of freeze/thaw episodes

Freezing significantly influences the amount and chemical form of extractable soil phosphorus and, therefore, has important consequences regarding plant nutrient availability. Much of the current evidence relies on field-based observations and tends to be rather contradictory. The present work reports the specific effects various freezing episodes have on phosphorus availability. Experimental treatments included the freezing rate and the time soil remained frozen together with the number of freeze/thaw cycles. These laboratory incubations used two soils, an iron humus podzol and a peaty podzol, sub-samples of which were equilibrated at three different soil-moisture contents. Concentrations of phosphorus in soil solutions and acetic acid extracts (Ac-P) were measured. Freezing had the greatest effect on the organic (Op) horizon of the peaty podzol, where the amounts of total dissolved phosphorus (TDP) and Ac-P increased from 0.58 to 3.21 and from 11.8 to 19.3 mg P kg^?1, respectively. TDP in soil solution was subdivided into three broad categories, dissolved (molybdate) reactive (MRP), organic (DOP) and condensed (DCP). The rather variable effect that freeze/thaw episodes had on these fractions highlighted the problems associated with attributing the ‘freezing effect’ to any single process.     

Flexible External Fixation for Craniodorsal Coxofemoral Luxations in Dogs

An external fixator consisting of two Ellis pins connected by a flexible band was developed and evaluated as a treatment for craniodorsal coxofemoral luxations in dogs. The technique for closed application of the fixator without injury to the coxofemoral joint or sciatic nerve was developed in six dog cadavers. The coxofemoral joints were then surgically destabilized and the limbs were manipulated through a full range of motion to assess the efficacy of the fixator in maintaining joint reduction. The fixator maintained joint reduction and stability after a surgically created craniodorsal luxation except when the femur was externally rotated 90d?. A flexible external fixator was then applied unilaterally in four healthy dogs. The dogs tolerated the fixator well and were bearing weight on the limb within 2 days after surgery; the range of motion was not limited by the fixator. The efficacy of a flexible external fixator in maintaining joint reduction after craniodorsal coxofemoral luxation was then evaluated in eight large dogs. The right coxofemoral joint in each dog was luxated surgically by removal of the dorsal joint capsule and transection of the ligament of the head of the femur and deep gluteal muscle. The joint was reduced and the fixator pins were applied in a closed fashion. In four dogs, a flexible external band was applied to the pins. Luxation did not reccur in these four dogs. The bands were not applied initially in four control dogs. Luxation occurred in three of the four control dogs within 24 hours of surgery. The joints that luxated were reduced and the flexible bands applied. Luxation did not recur after the bands were in place. The dogs tolerated the external fixators well, were bearing weight within 2 days of surgery, and walking with only minimal lameness 5 days after surgery. Luxation of the coxofemoral joints did not occur during the 2-week period in which the fixators were in place. The joints remained stable 1 week after removal of the fixators, at which time the dogs were euthanatized. Necropsy evaluation identified inflammation surrounding the pins and fibrous thickening of the dorsal joint capsule. The flexible external fixators were applied closed, maintained reduction of the coxofemoral joint after replacement of a craniodorsal luxation, and allowed weight bearing and limb usage soon after surgery. The flexible external fixator has several advantages over other methods of treating craniodorsal coxofemoral luxations. Complications noted in this study included pin tract drainage, pin loosening, and disruption of the flexible bands.     

Force Plate Analysis of Triple Pelvic Osteotomy for the Treatment of Canine Hip Dysplasia

Triple pelvic osteotomy was performed in 15 dogs with bilateral hip dysplasia. Ten dogs were treated bilaterally and five dogs were treated unilaterally. Ten untreated dogs with normal hips served as controls. Force plate analysis, lameness evaluation, and radiography were performed before surgery and at weeks 5, 10, 15, and 28. Three dogs treated unilaterally were euthanatized and the hips were examined grossly and microscopically. Force plate data indicated that young dysplastic dogs transmitted significantly less vertical force through the hip joints than normal dogs. The force transmitted through treated hips reached or approached control levels by week 28 and was significantly greater than the force transmitted through untreated hips. Clinical lameness resolved in 92% of limbs and progression of radiographically detectable degenerative joint disease was minimal. Gross and microscopic degenerative changes in the articular cartilage were similar in the treated and untreated hips. The synovial membrane was less reactive in treated hips.     

Colopexy as a Treatment for Rectal Prolapse in Dogs and Cats: A Retrospective Study of 14 Cases

Colopexy was evaluated as a treatment for recurrent rectal prolapse in eight dogs and six cats. Cases included in the study were from two institutions; the University of Pennsylvania School of Veterinary Medicine and the University of Tennessee College of Veterinary Medicine. Two different colopexy techniques were used: A simple suture technique was used in two cats and four dogs (University of Pennsylvania), and an incisional technique was used in four cats and four dogs (University of Tennessee). Rectal prolapse had not recurred in any of the 14 animals at the time of follow-up. Incisional dehiscence occurred in two animals and in one instance may have been related to the colopexy procedure. Infection at the colopexy site, secondary to suture penetration of the colonic lumen, is a potential complication of this procedure. Colopexy, using either surgical technique described here, was effective in preventing recurrent rectal prolapse.