311 research outputs found
Application of parallel distributed processing to space based systems
The concept of using Parallel Distributed Processing (PDP) to enhance automated experiment monitoring and control is explored. Recent very large scale integration (VLSI) advances have made such applications an achievable goal. The PDP machine has demonstrated the ability to automatically organize stored information, handle unfamiliar and contradictory input data and perform the actions necessary. The PDP machine has demonstrated that it can perform inference and knowledge operations with greater speed and flexibility and at lower cost than traditional architectures. In applications where the rule set governing an expert system's decisions is difficult to formulate, PDP can be used to extract rules by associating the information an expert receives with the actions taken
Montezuma Quail Management in Arizona
The Montezuma quail (Cyrtonyx montezumae meamsi) has substantially different habitat requirements than other quails found in the U.S. They inhabit evergreen oak woodlands of mountain ranges in the Southwest and feed primarily on underground bulbs and tubers. Populations respond to summer precipitation because the vegetation which provides food and cover for Montezuma quail flourishes after the summer rains. Moderate to heavy grazing increases availability of Montezuma quail food plants, but resultant lack of cover precludes use of such sites. Montezuma quail avoid areas with greater than 50% forage utilization by ungulates. As with other Arizona quail species, hunting has been shown to have limited or no impact on the population level during the following years. Birds may be depleted in localized areas temporarily, but available habitat is re-occupied when pre-nesting dispersal occurs. Annual pre- and posthunt flush counts were conducted 1988-1996 by the Arizona Game & Fish Department, United States Forest Service, volunteers, and local quail hunters. Average covey size decreased during the hunting season, but the magnitude of the decrease was similar in unhunted populations. Montezuma quail populations fluctuate in response to habitat and weather conditions. A state-wide hunter questionnaire program estimated total harvest trends for Arizona. In addition, wing collection barrels had been placed in heavily hunted areas from 1981 to 1996 to obtain hunter-effort information and sex/age characteristics of the harvest. Data from these wings indicate average percentage of juveniles in the harvest was higher for Montezuma quail (x = 74.4%, range = 55.9-84.9%) than other Arizona quail species, such as Gambel\u27s (x = 65.6%, range = 23-77%). Hunters harvested an average of 2.2 Montezuma quail per day. In 3,107 hunter-days during this period, only 13 (0.4%) resulted in a limit of birds. Three of these limits occurred in 1996 when the bag limit was reduced from 15 to 8 Montezuma quail
Use of the Anterolateral Thigh in Cranio-Orbitofacial Reconstruction
Objective. To detail the clinical outcomes of a series of patients having undergone free flap reconstruction of the orbit and periorbita and highlight the anterolateral thigh (ALT) as a workhorse for addressing defects in this region. Methods. A review of 47 patients who underwent free flap reconstruction for orbital or periorbital defects between September 2006 and May 2011 was performed. Data reviewed included demographics, defect characteristics, free flap used, additional reconstructive techniques employed, length of stay, complications, and follow-up. The ALT subset of the case series was the focus of the data reviewed for this paper. Selected cases were described to highlight some of the advantages of employing the ALT for cranio-orbitofacial reconstruction. Results. 51 free flaps in 47 patients were reviewed. 38 cases required orbital exenteration. The ALT was used in 33 patients. Complications included 1 hematoma, 2 wound infections, 3 CSF leaks, and 3 flap failures. Conclusions. Free tissue transfer allows for the safe and effective reconstruction of complex defects of the orbit and periorbital structures. Reconstructive choice is dependent upon the extent of soft tissue loss, midfacial bone loss, and skullbase involvement. The ALT provides a versatile option to reconstruct the many cranio-orbitofacial defects encountered
Novel Irradiated Axial Rotational Flap Model in the Rodent
Abstract
Objectives: To design an easily reproducible rodent rotational skin flap and to evaluate the effects of radiation on flap viability.
Methods: Ten rats received 40 Gy irradiation to the abdominal wall. Following a recovery period of one month, a 3 X 8 cm fasciocutaneous flap based axially on the inferior epigastric vessel, was raised and rotated 60 degrees into a contralateral deficit. Five non-irradiated rats underwent the identical procedure as a control. Animals were sacrificed seven days postoperatively, areas of flap necrosis were documented, and histological specimens were taken to compare flap viability and vessel density.
Results: 60% of the rats in the irradiated group had necrosis of the distal flap ranging from 1 to 6 cm from the distal edge, whereas none of the animals (0%) in the control group exhibited necrosis (p\u3c0.001). Histology revealed collagen and vascular changes in the irradiated skin. Vascular density analysis revealed a significant difference between radiated and non-radiated flaps; p = 0.004, 0.029 and 0.014 in the distal, middle and proximal segments of the flap respectively.
Conclusion: This novel rat axial rotational flap model demonstrates increases flap necrosis and a decrease in vascular density due to the effects of radiation. Using a linear electron accelerator a dose of 40 gy can be delivered to the skin without resulting in devastating gastrointestinal side effects
A Preliminary Report of Percutaneous Craniofacial Osteoplasty in a Rat Calvarium
Objective: To evaluate the potential for injectable, permanent bone augmentation by assessing the biocompatibility and bioactivity of subperiosteal hydroxylapatite (Radiesse) deposition in a rat model.
Methods: Fourteen adult Sprague Dawley rats were injected in the parietal skull with hydroxylapatite (n=10) or a carrier gel control (n=4), using a subperiosteal injection technique on the right and a subcutaneous injection technique on the left. At 1, 3, and 6 months, 3 rats (1 negative control, 2 variables) were sacrificed. At 12 months, the remaining 5 rats were sacrificed. After each harvest, the calvaria were examined under both light and polarized microscopy.
Results: The inflammatory response was limited in all specimens. Injectables were still present 12 months after the injection. New bone formation was only seen when the injection was located deep to a disrupted periosteum The odd of new bone formation was 48.949 times higher (95% CI (2.637, 3759.961), p = 0.002) with subperiosteal hydroxylapatite injections compared to all other combinations of injection plane and injectable.
Conclusion: This preliminary report of subperiosteal hydroxylapatite (Radiesse) injection in a rat model has verified the biocompatibility of injectable hydroxylapatite at the bony interface and suggests the potential for new bone formation
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