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Solute transport through the extracellular matrix (ECM) is crucial to chondrocyte metabolism. Cartilage injury affects solute transport in cartilage due to alterations in ECM structure and solute-matrix interactions. Therefore, cartilage injury may be detected by using contrast agent-based clinical imaging. In the present study, effects of mechanical injury on transport of negatively charged contrast agents in cartilage were characterized. Using cartilage plugs injured by mechanical compression protocol, effective partition coefficients and diffusion fluxes of iodine- and gadolinium-based contrast agents were measured using high resolution microCT imaging. For all contrast agents studied, effective diffusion fluxes increased significantly, particularly at early times during the diffusion process (38 and 33% increase after 4 min, P

Before effective remedial treatments can be implemented at hazardous intersections, it is often necessary to identify the causal factors affecting accident frequency. However, a problem often encountered in safety studies is the underreporting of accidents. This biased reporting may affect the selection of the parsimonious model. This study analyzes the factors affecting road accident frequency at three-legged signalized intersection approaches in Singapore, with special emphasis to underreporting. The annual accidents at 104 three-legged signalized intersections are modeled as the sum of observed Poisson outcome of accident reports. The reporting mechanism is introduced as a probit equation. The model shows that several geometric, traffic, and traffic control factors significantly affected the accident occurrence. The total approach volumes, left-turn volumes, existence of unprotected left-turn slip roads, number of signal phases per cycle, use of permissive right-turning phase, and sites with sight distances less than 100 m or greater than 300 m appear to increase accident occurrence. However, the presence of right-turn channelization, provision of an acceleration section for left turning, existence of a surveillance camera, availability of median railings, and presence of an approach gradient greater than +5% may reduce the occurrence of intersection approach accidents. Moreover, the study shows that the reporting rate may drop because current law enforcement requires that only injury accidents and accidents at intersections in a residential area be reported.

A compact design for a single-feed cavity-backed slot antenna is presented for operating at GSM (900 MHz) and DCS (1800 MHz). With the use of a carefully designed power distribution network, a single-feed design is realized for a dual- and wideband slot antenna with high gain and good radiation patterns. Measured results show that the antenna has a wide bandwidth at both frequency bands and it exhibits high gain and good radiation patterns, which is desirable for many dualband applications.© 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1570–1572, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22549

Summary Cuming's barb (Puntius cumingii Gunther) is an endangered endemic species of fish in Sri Lanka. A study was carried out on the reproductive biology and breeding of this species in captivity. At maturity, males and females measured 32.6 and 33.1 mm, respectively. In the ovaries, the egg-diameter distribution pattern indicated the presence of large and small yolked eggs in two groups. Large mature eggs ranging from 0.45 to 0.80 mm in diameter were shed during spawning. Small eggs measurin 0.20–0.45 mm took 7–10 weeks to reach mature size, then were shed at the next spawning. The number of eggs shed per sawning cycle and total fecundity raned from 256 to 976 and from 383 to 1829, respectively. Hatckng rate varied from 5.3 to 97.1 %, with a mean value of 68.3 %. A majority (55 %) of the females completed spawning within 1 day. This investiation indicated that P. cumingii could be successfully reared and bred in captivity; the results would be useful in the development of breeding programmes for this species.

An in vitro total hip-arthroplasty model was evaluated to determine if centrifugation of bone cement results in greater static strength and low-cycle fatigue strength than hand-mixing. The static-failure test of the stem, cement, and simulated bone composite demonstrated that the centrifuged cement had significantly greater static strength than the hand-mixed cement. However, under low-cycle fatigue tests on the same composite models, the centrifuged and hand-mixed specimens were not significantly different.

Singapore can be considered as one of the few Asian cities to be successful in urban transport planning and management. It has introduced several far-reaching vehicle- restraint policies, such as the vehicle quota system, the electronic road pricing scheme and a high vehicle tax structure, all of which have been effective in relieving traffic congestion on the roads. Recognizing that these restraint policies must be complemented by a good public transport and transportation management system, the Singapore Government has, in the past two decades, embarked on several ambitious programs to introduce intelligent systems into its transportation operations as well as to develop an efficient urban rail network. These decisions are in line with Singapore's long-term transportation plan to integrate land use and transportation planning, to develop a comprehensive road network, to manage car population and road usage, and to provide quality public transport for its people. This chapter discusses the issues related to urban transportation planning in Singapore, with the intention of drawing out the lessons learned from its experience.

The incorporation of autogeneic bone graft into a porous coated segmental endoprosthesis after high-dose irradiation was studied in dogs. A mid-diaphyseal defect was surgically created and then reconstructed with a porous-coated segmental endoprosthesis in 16 dogs. Autogeneic bone grafts were placed over the porous-coated regions of the endoprosthesis and at the endoprosthesis-bone junctions to achieve extracortical fixation. In eight dogs, the reconstructed femora were treated with a time-equivalent dose of 5500 cGy, delivered over a five-week period, beginning three weeks after surgery. In eight dogs, which served as the control group, the reconstructed femora were not irradiated. Dogs were killed 12 weeks after surgery, and the reconstructed femora were evaluated clinically, roentgenographically, mechanically, and histologically. Extracortical bone formation and bone ingrowth into the porous-coated segmental endoprosthesis were significantly inhibited by high-dose irradiation. Nonirradiated reconstructed femora had higher maximum torque at the implant-bone junction than irradiated femora. Nonirradiated femora had significantly greater bone ingrowth within the porous space than irradiated femora. Intracortically, irradiated femora had greater unlabeled bone and less porosity as well as more new bone than nonirradiated femora at 12 weeks postsurgery. Extracortically, irradiated femora had greater original cortical bone and less porosity as well as more new bone than nonirradiated femora at 12 weeks postsurgery. Mineral apposition was less in the irradiated femora from the initiation of radiotherapy to the time of killing five weeks after cessation of irradiation.

Roentgenographic analysis showed that centrifugation significantly reduced the gross and regional porosity of the cement compared with hand-mixed controls in a simulated total hip arthroplasty model. Static failure test of the prosthetic system demonstrated that the centrifuged cement had significantly greater strength than the hand-mixed cement. Under low-cycle fatigue tests of the same composite models, there was a trend for the centrifuged cement to be stronger than the hand-mixed specimens, although statistically it was not significant. Thus, centrifugation can reduce porosity and significantly improve the static strength of cement in a simulated in vitro total hip replacement model. When cement is used, any possible improvement in the physical properties of bone cement should be considered.

An in vitro total hip-arthroplasty model was evaluated to determine if centrifugation of bone cement results in greater static strength and low-cycle fatigue strength than hand-mixing. The static-failure test of the stem, cement, and simulated bone composite demonstrated that the centrifuged cement had significantly greater static strength than the hand-mixed cement. However, under low-cycle fatigue tests on the same composite models, the centrifuged and hand-mixed specimens were not significantly different.

The stochastic collection process of a large drop capturing a spectrum of randomly positioned small droplets is investigated by Monte Carlo simulation, and sample growth statistics from 32 independent trials are analyzed and compared to the values obtained from integrating the growth equation. It is found that the sample mean drop mass is compatible with that predicted by the growth equation. However, the sample mean radius is significantly less than the value resulting from continuous growth at the end of 1000 sec. The large-drop growth rate in a polydisperse cloud with an empirical spectrum is compared with that in a monodisperse cloud with the same liquid water content and the same mean volume radius. The growth rate is shown to be considerably smaller in the monodisperse cloud even though it is represented by droplets with a size that is larger than three-fourths of the droplets in the polydisperse spectrum. The problem of cloud spectrum evolution is investigated using the kinetic equation wi...

The surgical treatment of extensive metastatic diaphyseal lesions of the humerus with pathologic fractures is difficult. Patients with failed internal fixation often have large segments of bone loss. Rigid fixation often is not possible in these cases. Four patients were treated with a titanium segmental defect (SD) prosthesis with good clinical results. A comparative in vitro analysis of fixation with the SD prosthesis, a Rush rod, and a dynamic compression plate (DCP) augmented with methylmethacrylate was performed. The SD prosthesis performed better than the Rush rod and DCP in both the nondestructive four-point bending test and the destructive torsional test. The reconstructed humeri using the SD prosthesis had a torsional strength approaching that of an intact specimen. Hence, the SD prosthesis is a useful adjunct device in treating patients with extensive destructive lesions of the humerus secondary to metastatic disease and hematologic malignancies and in patients with malignant diseases who have had failed attempts at internal fixation.