The effect of bilateral thoracoplasty on lung development in fetal sheep

The relationship of breathing movements to lung development in the ovine fetus was investigated by partially removing ribs on each side of the chest and closing the deficiencies with silicone membranes at 114 days of gestation; the increase in compliance of the chest wall that resulted caused blunting of the amplitude of phasic negative pressures recorded in the trachea to less than 10 torr. Compared to sham operated controls (n = 5), the lungs of the thoracoplasty group (n = 5) at term weighed significantly (P less than 0.05) less, both wet (1.5 +/- 0.2 v. 2.3 +/- 0.1% of body weight) and dry (0.14 +/- 0.01 v. 0.18 +/- 0.01% of body weight. In addition, DNA content of the thoracoplasty group was less than that of the control group (0.47 +/- 0.05 mg v. 0.72 +/- 0.20 mg). Distensibility of the left lung with air at 40 cmH20 was less than in the thoracoplasty group than in controls (10.0 +/- 2.0 v. 18.9 +/- 3.0 ml.kg-1 body weight) but no differences were found in the concentrations of saturated phosphatidylcholine in lung tissue and lavage fluid, in DNA concentrations or in the amount of lung water (as % of wet weight of lung). It is concluded that phasic negative pressures of normal intensity are necessary for normal development of the fetal lungs.     

Phyto-oestrogens: where are we now?

Phyto-oestrogens have emerged from their esoteric role in animal husbandry following the hypothesis that the human Western diet is relatively deficient in these substances compared with societies where large amounts of plant foods and legumes are eaten. Evidence is beginning to accrue that they may begin to offer protection against a wide range of human conditions, including breast, bowel, prostate and other cancers, cardiovascular disease, brain function, alcohol abuse, osteoporosis and menopausal symptoms. Of the two main classes of these weak oestrogens, the isoflavones are under intensive investigation due to their high levels in soyabean. Like the 'anti-oestrogen' Tamoxifen, these seem to have oestrogenic effects in human subjects in the cardiovascular system and bone. Although previously only available from food, isoflavones are now being marketed in health-food supplements or drinks, and tablets may soon be available over the counter as 'natural' hormone-replacement therapy. In cancer, anti-oestrogenic effects are thought to be important, although genistein especially has been shown to induce wide-ranging anti-cancer effects in cell lines independent of any hormone-related influence. There are few indications of harmful effects at present, although possible proliferative effects have been reported. In infants, the effects of high levels in soya milk formulas are uncertain. The second group, lignans, have been less investigated despite their known antioestrogenic effects and more widespread occurrence in foods. Investigation of the possible benefits of phyto-oestrogens is hampered by lack of analytical standards and, hence, inadequate methods for the measurement of low levels in most foods. This problem may prove to be a major dilemma for regulatory authorities, clinicians and others wishing to advise the general public on whether these compounds really do have the health benefits attributed to them.     

Active markers in operative motion analysis

Surgical correction of spinal deformities is a complex mechanical process that may involve the insertion of screws, hooks, and curved rods. Visualizing the correction of the spine during the surgical procedure is difficult because the size of the incision and exposure of the spine are minimized to reduce trauma and scarring to the patient. The issue of visualization is compounded by the three-dimensional (3-D) nature of typical deformities and the applied instrumentation further obscuring the view of the spine. The amount of correction on the spine relies on a subjective feeling from the orthopedic surgeons. To provide an objective measurement of correction, an innovative marker system has been developed to track the position of the spine in real time. For this system, the errors in a patient-less operating room during a simulated surgical correction procedure in 3-D translation and rotation measurements were found to be 60/spl plusmn/4 /spl mu/m and 0.05/spl plusmn/0.23/spl deg/, respectively. This system will potentially help orthopedic surgeons deliver better treatment to patients and assess immediate treatment effects in real time.     

A quantitative assessment of orthoses for stabilization of the anterior cruciate ligament deficient knee.

Knee braces are used to restore functional stability to joints which have become unstable as a result of the traumatic disruption of the anterior cruciate ligament. A number of quite different designs of knee brace have evolved and are used clinically in the management of these injuries although to the authors' knowledge little quantitative data are available on their relative mechanical characteristics. This paper reports the results of static testing carried out to determine the stiffness characteristics of 24 commonly used braces. The data obtained indicated clear differences between different brace designs with the stiffest having values closely approaching that achieved physiologically in uninjured joints, and the least effective having minimal stiffnesses. It was found that the mechanical performance of any individual brace was determined by three factors: the mechanical characteristics of the individual components from which it was constructed, the structural integrity of its design, and the interaction of the brace with the limb during loading.     

Demonstration of spectral and spatial interferometry at THz frequencies

A laboratory prototype spectral-spatial interferometer has been constructed to demonstrate the feasibility of the double-Fourier technique at far infrared (FIR) wavelengths (0.15-1 THz). It is planned to use this demonstrator to investigate and validate important design features and data-processing methods for future astronomical FIR interferometer instruments. In building this prototype, we have had to address several key technologies to provide an end-end system demonstration of this double-Fourier interferometer. We report on the first results taken when viewing single-slit and double-slit sources at the focus of a large collimator used to simulate real sources at infinity. The performance of the prototype instrument for these specific field geometries is analyzed to compare with the observed interferometric fringes and to demonstrate image reconstruction capabilities.     

Distributed fusion architectures and algorithms for target tracking

Modern surveillance systems often utilize multiple physically distributed sensors of different types to provide complementary and overlapping coverage on targets. In order to generate target tracks and estimates, the sensor data need to be fused. While a centralized processing approach is theoretically optimal, there are significant advantages in distributing the fusion operations over multiple processing nodes. This paper discusses architectures for distributed fusion, whereby each node processes the data from its own set of sensors and communicates with other nodes to improve on the estimates, The information graph is introduced as a way of modeling information flow in distributed fusion systems and for developing algorithms. Fusion for target tracking involves two main operations: estimation and association. Distributed estimation algorithms based on the information graph are presented for arbitrary fusion architectures and related to linear and nonlinear distributed estimation results. The distributed data association problem is discussed in terms of track-to-track association likelihoods. Distributed versions of two popular tracking approaches (joint probabilistic data association and multiple hypothesis tracking) are then presented, and examples of applications are given.     

Sealing Fuji Prescale pressure sensitive film for protection against fluid damage: the effect on its response

Fuji Prescale pressure sensitive film will record pressures as a characteristic pink stain; the optical density response of these stains can be calibrated to allow subsequent conversion into full field pressure data. Due to its ease of use, Fujifilm has been employed extensively within animal joints. For this application, the potential disruption to the stain producing mechanism posed by the presence of joint fluids has led to the widespread use of fluid proof materials, within which the Fujifilm is protected; however, little data have been presented on the effect of protective materials on the subsequent stain response. This paper presents a quantitative assessment of the mean optical density responses of both protected film and a control group of unprotected film; the first group consisted of Fujifilm sealed between two layers of a readily available self-adhesive material, forming sealed packets. The results indicated significant differences between groups (p<0.05); however, the effect of these differences is dependent on the method used to produce pressure data. Qualitative observations indicated that sealing reduced stain uniformity; preliminary qualitative observations regarding data manipulation methods to overcome this phenomenon are presented. Consequently, this work indicates the importance of validating methods for protecting Fuji film from fluid damage and their associated methods of data manipulation.     

A new support structure for high field magnets

Pre-stress of superconducting magnets can be applied directly through the magnet yoke structure. We have replaced the collar functionality in our 14 Tesla R&D Nb/sub 3/Sn dipole magnets with an assembly procedure based on an aluminum shell and bladders. Bladders, placed between the coil pack and surrounding yoke inside the shell, are pressurized up to 10 ksi [70 MPa] to create an interference gap. Keys placed into the interference gap replace the bladder functionality. Following the assembly, the bladders are deflated and removed. Strain gauges mounted directly on the shell are used to monitor the stress of the entire magnet structure, thereby providing a high degree of pre-stress control without the need for high tolerances. During assembly, a force of 8.2 /spl times/ 10/sup 5/ lbs/ft [12 MN/m] is generated by the bladders and the stress in the 1.57" [40 mm] aluminum shell reaches 20.3 ksi [140 MPa]. During cool-down the thermal expansion difference between shell and yoke generates an additional compressive force of 6.85 /spl times/ 10/sup 5/ lbs/ft [10 MN/m], corresponding to a final stress in the shell of 39.2 ksi [270 MPa]. Pre-stress conditions are sufficient for 16 T before the coils separate at the bore. Bladders have now been used in the assembly and disassembly of two 14 T magnets. This paper describes the magnet structure, assembly procedure and test results.