Submersion injuries in children and adults

Drowning and near drowning remain a common cause of childhood death and disability. Toddlers aged one through four drown in private swimming pools. Submersions greater than 10 minutes and lack of CPR at the scene or the need for greater than 20 minutes of resuscitation portends a poor prognosis. Management of respiratory failure without neurologic impairment has the most successful outcome. Prevention of drowning morbidity is dependent on constant parental supervision, and immediate and expert CPR.     

Magnetic resonance compatibility of multichannel silicon microelectrode systems for neural recording and stimulation: design criteria, tests, and recommendations

Magnetic resonance (MR) compatibility of biomedical implants and devices represents a challenge for designers and potential risks for users. This paper addresses these problems and presents the first MR-compatible multichannel silicon chronic microelectrode system, used for recording and electrical stimulation of the central nervous system for animal models. A standard chronic assembly, from the Center for Neural Communication Technology at the University of Michigan, was tested on a 2 Tesla magnet to detect forces, heating, and image distortions, and modified to minimize or eliminate susceptibility artifacts, tissue damage, and electrode displacement, maintaining good image quality and safety to the animals. Multiple commercial connectors were tested for MR compatibility and several options for the reference electrode were also tested to minimize image artifacts and provide a stable biocompatible reference for shortand long-term neural recordings. Different holding screws were tested to anchor the microelectrode assembly on the top of the skull. The final selection of this part was based on MR-compatibility, biocompatibility, durability, and mechanical and chemical stability. The required adaptor to interconnect the MR-compatible microelectrode with standard data acquisition systems was also designed and fabricated. The final design is fully MR-compatible and has been successfully tested on guinea pigs.     

Depth defined optoelectronic modulation spectroscopy

It is shown that if the gate depletion region of a MESFET is maintained with a constant width, channel current optoelectronic modulation spectroscopy reveals a spectrum of responses arising predominantly from charge variations in the depletion region at the interface between the active layer and the substrate. Optically induced charge variations as small as 2 × 10⁹ electrons/cm²/eV have been detected. A refinement of the basic method is described which should allow the responses of electron states in a region of selected depth within the active layer states to be seen. The method will be of particular value in observing states that have a role in back-gating.     

Fatigue Resistance of HPS-485 W (70 W) Welded Butt-Splice Connections Using Narrow Gap Improved Electroslag Welding

The writers investigated the performance of narrow gap improved electroslag weld (NGI-ESW) procedures in welded butt splices using high-performance steel grade HPS-485 W (70 W) through comparison against similar specimens fabricated using submerged arc welding (SAW). Five NGI-ESW and five SAW specimens were tested in fatigue at very high stress ranges, and all achieved run-out at or above 2 million cycles. Two each of the specimens created using SAW and NGI-ESW were tested an additional 3 million cycles; the NGI-ESW specimens did not experience fracture, whereas one SAW specimen failed in the base metal and another completed the additional cycles without failure. All intact specimens were statically tested to failure and results were compared. All 10 specimens performed considerably better than predicted by the AASHTO (2007) fatigue life equation. The NGI-ESW specimens performed at least as well as the SAW specimens under fatigue and static testing, suggesting that inclusion of the NGI-ESW process in AWS D1.5 may be appropriate when used with HPS-485 W (70 W). Additionally, testing supports extension of current code provisions to the use of NGI-ESW in fracture-critical applications.     

A patient-specific computational model of hypoxia-modulated radiation resistance in glioblastoma using 18F-FMISO-PET

Glioblastoma multiforme (GBM) is a highly invasive primary brain tumour that has poor prognosis despite aggressive treatment. A hallmark of these tumours is diffuse invasion into the surrounding brain, necessitating a multi-modal treatment approach, including surgery, radiation and chemotherapy. We have previously demonstrated the ability of our model to predict radiographic response immediately following radiation therapy in individual GBM patients using a simplified geometry of the brain and theoretical radiation dose. Using only two pre-treatment magnetic resonance imaging scans, we calculate net rates of proliferation and invasion as well as radiation sensitivity for a patient''s disease. Here, we present the application of our clinically targeted modelling approach to a single glioblastoma patient as a demonstration of our method. We apply our model in the full three-dimensional architecture of the brain to quantify the effects of regional resistance to radiation owing to hypoxia in vivo determined by [¹⁸F]-fluoromisonidazole positron emission tomography (FMISO-PET) and the patient-specific three-dimensional radiation treatment plan. Incorporation of hypoxia into our model with FMISO-PET increases the model–data agreement by an order of magnitude. This improvement was robust to our definition of hypoxia or the degree of radiation resistance quantified with the FMISO-PET image and our computational model, respectively. This work demonstrates a useful application of patient-specific modelling in personalized medicine and how mathematical modelling has the potential to unify multi-modality imaging and radiation treatment planning.     

Coherent lidar airborne wind sensor II: flight-test results at 2 and 10 νm

The use of airborne laser radar (lidar) to measure wind velocities and to detect turbulence in front of an aircraft in real time can significantly increase fuel efficiency, flight safety, and terminal area capacity. We describe the flight-test results for two coherent lidar airborne shear sensor (CLASS) systems and discuss their agreement with our theoretical simulations. The 10.6-μm CO(2) system (CLASS-10) is a flying brassboard; the 2.02-μm Tm:YAG solid-state system (CLASS-2) is configured in a rugged, light-weight, high-performance package. Both lidars have shown a wind measurement accuracy of better than 1 m/s.     

Chromatic contrast sensitivity: the role of absolute threshold and gain constant in differences between the fovea and the periphery

A model of foveal achromatic and chromatic sensitivity [Vision Res. 36, 1597 (1996)] was extended to the peripheral visual field. Threshold-versus-illuminance functions were analyzed to determine effects of eccentricity on absolute thresholds and gain constants of chromatic and luminance mechanisms. The resulting peripheral model successfully predicted peripheral contrast sensitivity as a function of wavelength, for both white and 500-nm backgrounds. We conclude that the short-wavelength-sensitive cone opponent mechanism may mediate thresholds in Sloan's notch in the normal periphery and that interpretation of reduced chromatic sensitivity in the periphery requires an explicit model of how eccentricity affects both the gain constant and the absolute threshold.     

Flexural behavior of prestressed FRP tubular bridge deck

An experimental and analytical study was undertaken to assess the flexural behavior of a new fiber reinforced polymer (FRP) deck system. The deck consists of a series of pultruted FRP tubes, post-tensioned in between each two stringers. Seven pure compression tests and eleven flexural tests were carried out to investigate the effect of tube size, bonding condition, post-tensioning, and supporting conditions. Finite element modeling of compression and flexural specimens was carried out to determine the effect of tube interface friction, bond and geometry restraints. The study showed feasibility of the new deck system for bridges with closely spaced stringers, where lack of two-way panel action is not a primary concern. Failure modes were also identified for these types of deck systems. Longer span decks generally failed in bending, whereas shorter span decks suffered from local shear failure at the corner of the tubes. Prestressing provided redundancy and reserved strength to the deck system.