Vascular changes in the rat brain during chronic hypoxia in the presence and absence of hypercapnia.

Changes in brain vascularity in adult rats during adaptation to chronic normobaric hypoxia with or without elevated CO(2) were morphometrically investigated. Immunohistochemistry with anti-rat endothelial cell antigen (RECA-1) antibody was carried out for the vascular analysis. After the rats were subjected to hypoxia for 2 to 8 weeks (wks)(10 percent O(2) in N(2)), the total area of blood vessels was measured in 6 brain regions. After 2 wks of hypoxia, the blood vessel area was found to be significantly increased in the frontal cortex, striatum, hippocampus, thalamus, cerebellum, and medulla oblongata, by 44% , 96% , 65% , 50% , 102% and 97% , respectively. The ratio of large vessels with an area &#62; 500 micro m(2) was also increased in all brain regions. Hypoxic adaptation in brain vascularity did not change during 8 wks of hypoxia, and the hypoxia-induced levels measured in the vasculature returned to control levels 2 wks after the termination of hypoxia in areas of the brain other than the cortex and thalamus. In addition, hypoxia-induced changes in terms of the total vascular area and vessel size distribution were significantly inhibited by the elevation in CO(2), whereas chronic hypercapnia without hypoxia had no effect on brain vascularity. These findings suggested that adaptations in brain vascularity in response to hypoxia are rapidly induced, and there are regional differences in the reversibility of such vascular changes. Carbon dioxide is a potent suppressor of hypoxia-induced vascular changes, and may play an important role in vascular remodeling during the process of adaptation to chronic hypoxia.</p

Application of optimal control in Vertical Weight Stabilizer (VWS) system for actual ship

Improvement of stability has been going for decades. Anti-rolling system like bilge keel, anti-rolling tank, and weight stabilizer, those basic ideas were first proposed by researchers in the period of latter half of 19th century. While on the other hand, fin stabilizer was invented around 1920`s. Some of the ideas remain undeveloped for years while others turned out to be a successful system in years to come. Among those system there is weight stabilizer which offers wide concept of anti-rolling system. As the horizontal type has been treated as common, researchers now have pay high interest to vertical type weight stabilizer. Vertical type can change both the height of the center of gravity and the moment of inertia of the system or in other word change the radius of gyration (gyradius). By using movable weight, gyradius will change as the weight position is moved upward or downward. VWS system mass only take few percent of total ship displacement and is positioned at the back upper deck of the ship. The development of VWS is actually the key to doubts and problems from previous research. From anti-rolling tank, the result has shown that the system demands large space for the installation while from the Air Fin Stabilizer(AS) research, we found out that system has 0% efficiency in immobile state. VWS has been improved to overcome these problems and meet the requirements of more promising system. With new ideas and skills, VWS works even when the ship is at rest condition. Moreover, the space used is minimal and loads can be adjust based on ship`s condition. As the device is installed above draught level, water friction also can be reduced. VWS is controlled by PID control system which analyses GAIN`s value needed for weight’s movement. The optimization of the control system will be further discussed and confirmed by carrying out numerical and physical simulation

Longitudinal stability augmentation of seaplanes in planing

The towing tank experiments conducted at Yokohama National University from November 30 to December 9 in 2005 suggested a new way of suppressing a dangerous coupled motion between heave and pitch called porpoising. The research in this paper was developed on the observations made in the experiments and conducted numerical simulations to further investigate the parametric design space. Two linear-time-invariant models were developed: rigid-body planing craft (conventional float planes or flying boats), and flexibly supported planing craft. The latter could simulate the new method found in the experiments for suppressing porpoising. In this study, the stability of the oscillatory motions was analyzed to see the effect of design variables on the inception of porpoising. The parametric study of flexibly supported float planes in the context of porpoising was a new contribution in the conceptual design of seaplanes

Administration of Bone Marrow-Derived Mononuclear Cells Contributed to the Reduction of Hypoxic-Ischemic Brain Injury in Neonatal Rats

Background/Objective: Perinatal hypoxic-ischemia (HI) causes neonatal death and permanent neurological deficits. Cell therapy using various cell sources has been recently identified as a novel therapy for perinatal HI. Among the available types of cell sources, bone marrow-derived mononuclear cells (BMMNCs) have unique features for clinical application. For example, stem cells can be collected after admission, thus enabling us to perform autologous transplantation. This study aimed to investigate whether the administration of BMMNCs ameliorated HI brain injury in a neonatal rat model.Methods: Seven-day-old rats underwent left carotid artery ligation and were exposed to 8% oxygen for 60 min. BMMNCs were collected from the femurs and tibias of juvenile rats using the Ficoll–Hypaque technique and injected intravenously 24 h after the insult (1 × 105 cells). Active caspase-3, as an apoptosis marker, and ED1, as an activated microglia/macrophage marker, were evaluated immunohistochemically 48 h after the insult (vehicle, n = 9; BMMNC, n = 10). Behavioral assessments using the rotarod treadmill, gait analysis, and active avoidance tests were initiated 3 weeks after the insult (sham, n = 9, vehicle, n = 8; BMMNC, n = 8). After these behavioral tests (6 weeks after the insult), we evaluated the volumes of their hippocampi, cortices, thalami, striata, and globus pallidus.Results: The mean cell densities of the sum of four parts that were positive for active caspase-3 significantly decreased in the BMMNC group (p &lt; 0.05), whereas in the hippocampi, cortices, thalami, and striata cell densities decreased by 42, 60, 56, and 47%, respectively, although statistical significance was not attained. The number of ED1 positive cells for the sum of the four parts also significantly decreased in the BMMNC group compared to the vehicle group (p &lt; 0.05), whereas in each of the four parts the decrease was 35, 39, 47, and 36%, respectively, although statistical significance was not attained. In gait analysis, the BMMNC normalized the contact area of the affected hind paw widened by HI. The volumes of the affected striata and globus pallidus were significantly larger in the BMMNC group than in the control group.Conclusion: These results indicated that the injection of BMMNCs ameliorated HI brain injury in a neonatal rat model

Tsunami run-up heights of the 2003 Tokachi-oki earthquake

Tsunami height survey was conducted immediately after the 2003 Tokachi-oki earthquake. Results of the survey show that the largest tsunami height was 4 m to the east of Cape Erimo, around Bansei-onsen, and locally at Mabiro. The results also show that the tsunami height distribution of the 2003 Tokachi-oki earthquake is clearly different from that of the 1952 Tokachi-oki earthquake, suggesting the different source areas of the 1952 and 2003 Tokachioki earthquakes. Numerical simulation of tsunami is carried out using the slip distribution estimated by Yamanaka and Kikuchi (2003). The overall pattern of the observed tsunami height distribution along the coast is explained by the computed ones although the observed tsunami heights are slightly smaller. Large later phase observed at the tide gauge in Urakawa is the edge wave propagating from Cape Erimo along the west coast of the Hidaka area.The 2003 Tokachi-oki earthquak

Evaluation of resistance increase and speed loss of a ship in wind and waves

Given the indication of the IMO’s intent to the application of the EEDI and EEOI, the complete and precise total resistance of a ship and induced speed loss in wind and wave is primarily required. This paper proposed a practicable method to evaluate the total resistance in seaway. Besides the still water resistance, the added resistance due to waves is computed using panel method and the wind resistance is obtained using CFD with the verification of an open wind test and statistical formula. The speed loss is acquired in consideration of the matching of the hull, engine and propeller. A hull optimization method is consequently presented based on the proper resistance evaluation approach. The approach is validated available and the total resistance of a ship could be reduced after hull optimization

Effectiveness of a Head Movement Interface for Steering a Vehicle in a Virtual Reality Driving Simulation

Recently, virtual reality (VR) has become popular for a variety of applications, such as manufacturing and entertainment. In this study, considering that a driver&rsquo;s head moves according to the motion of turning the steering wheel, we explored the effectiveness of head movement as a means for steering a vehicle in a virtual reality driving simulation. First, we analyzed the motion axes that are effective for control and found that the x (horizontal) direction, yaw rotation, and roll rotation are potential candidates. Through the implementation of a simulator, which allows participants to steer the vehicle by means of head movement, it was found that the x-axis movement was the most reliable as it reduced VR sickness while guaranteeing better usability and realistic motion. Human&ndash;machine interaction can become conceived of as symmetrical in the sense that if a machine is truly easy for humans to handle, it means that they can get the best out of it