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Search Results: 1 - 10 of 3202 matches for " Ralf;Kubota "
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Calibra??o do "simplified simple biosphere model - SSiB" para áreas de pastagem e floresta na Amaz?nia com dados do LBA
Correia, Francis Wagner Silva;Alvalá, Regina Célia dos Santos;Manzi, Ant?nio Ocimar;Gielow, Ralf;Kubota, Paulo Yoshio;
Acta Amazonica , 2005, DOI: 10.1590/S0044-59672005000200017
Abstract: the parameters of the simplified simple biosphere model - ssib were validated and subsequently calibrated for the fazenda nossa senhora aparecida (62o22'w; 10o45's) pasture site and the reserva biológica do jaru (62o22'w; 10o45's) forest site, both located in the state of rond?nia. micrometeorological and hydrological data collected during the dry period of 2001, as part of the large-scale biosphere-atmosphere experiment in amazonia - lba, were used. the results showed that the model simulated well the net radiation, both at the pasture and at the forest. the latent heat flux was super-estimated in both sites. the model sub-estimated the sensible heat flux at the pasture and at the forest, mainly during the night period; notwithstanding, the values for the forest were nearer to the observed ones. with the calibrated parameters, the model generated better estimations of the latent and the sensible heat fluxes, thus better representing the energy partition both at the forest and at the pasture.
Gender differences and laterality in maximal handgrip strength and controlled force exertion in young adults  [PDF]
Hiroshi Kubota, Shinichi Demura
Health (Health) , 2011, DOI: 10.4236/health.2011.311115
Abstract: This study examines gender differences and laterality in maximal handgrip strength and controlled force exertion (CFE) in young adults. The subjects were 75 healthy young males (mean age 19.6 ± 1.6 yrs.) and 50 healthy young females (mean age 20.9 ± 1.9 yrs.). Maximal handgrip strength was measured twice. The subjects performed the CFE test three times after one practice trial. They matched their handgrip strengths to the demand values, which constantly changed and ranged from 5 to 25% of maximal handgrip strength. The difference between the demand value and the grip exertion value was used as an estimate of CFE. Maximal handgrip strength was significantly larger in males than in females in both the dominant and non-dominant hands, and was significantly larger in the dominant hand in both males and females. Insignificant gender differences were found in CFE of both hands. CFE was significantly superior in the dominant hand in both genders. In conclusions, gender differences are present in maximal handgrip strength of the dominant and non-dominant hands in young adults, but not in CFE of both hands. Laterality exists in maximal handgrip strength and in CFE for both genders.
Role on Moment of Inertia and Vortex Dynamics for a Thin Rotating Plate  [PDF]
Yoshihiro Kubota, Osamu Mochizuki
World Journal of Mechanics (WJM) , 2013, DOI: 10.4236/wjm.2013.36028
Abstract:

In this study, we focused on the lift generation with a thin rotating plate. The objective of this study is to understand the appropriate shape and the role of vortex for rotating thin plate. We determined the shape of the plate through free-flight tests of paper strips and investigated the aerodynamic characteristics of the rotating plate with the selected shape. The rectangular plate with an aspect ratio 7 was relevant from moment of inertia and bending stress. An endplate on a wing tip increased the stability on the lateral vortex structure behind the rotating plate. Velocity field measurement by Particle Image Velocimetry (PIV) showed that the lift force was generated twice in a rotating cycle.

Numerical Investigation of Aerodynamic Characteristics by a Rotating Thin Plate  [PDF]
Yoshihiro Kubota, Osamu Mochizuki
World Journal of Mechanics (WJM) , 2015, DOI: 10.4236/wjm.2015.53005
Abstract: In this study, we use a thin rotating plate to generate propulsion and lift for a paper plate. And the thin plate rotates along the spanwise axis. We numerically determine the influence on aerodynamic characteristics with a rotational velocity of the thin plate. The rotational velocity is obtained with spin parameter which is the ratio of the peripheral speed of the plate to the main flow velocity. And the numerical simulations based on the discrete vortex method show that the autorotation mode of the plate in a uniform flow appears naturally when the spin parameter is unity. Vortex formed from the backward-rotating edge is weaker than those generated from the forward-rotating edge of thin plate. The maximum lift generated at S = 0.75 if S < 1. The negative moment becomes negative for the nondimensional rotating speed S ≤ 1.75. The most negative moment appears when S = 1; at that time, autorotation occurs naturally.
Splash Formation Due to a Frog Diving into Water  [PDF]
Yoshihiro Kubota, Osamu Mochizuki
World Journal of Mechanics (WJM) , 2015, DOI: 10.4236/wjm.2015.57014
Abstract: Herein, we present the results of our experimental investigation of splashes formed by a frog diving into water from the ground or from a leaf and the accompanying sound generated by the impact of the frog on the water. The experiments are performed by visualizing the flow with a high-speed camera. In addition, we used physical models comprising hydrophilic bodies made from hydrogel or acrylic resin to experimentally study how hydrophilicity affects the splash. In these experiments, we use the degree of swelling to define the hydrophilicity degree. The results show that different splashes are caused by the increase in water-film velocity upon an increase in hydrophilicity. For a body with strong hydrophilicity, at a relatively high film velocity, the water film forms when the body impacts the water surface separates from the body surface. In addition, an aircavity forms when the film separates from the body. We empirically examine the relation between the hydrophilicity degree and film velocity. The results indicate that increased hydrophilicity does not reduce the splash. Therefore, we conclude that reducing of the formation of water from the biomimetic point of view is related to the shape of body.
Trends of Abundance of Salton Sea Fish: A Reversible Collapse or a Permanent Condition?  [PDF]
Ralf Riedel
Natural Resources (NR) , 2016, DOI: 10.4236/nr.2016.710045
Abstract: The Salton Sea is a closed-basin, 980 km2 salt lake in the Sonoran Desert of southern California. Three marine species, bairdiella (Bairdiella icistia), orangemouth corvina (Cynoscion xanthulus), and sargo (Anisotremus davidsoni), established from introductions of over 34 species beginning in 1929. During the late 1960s and early 1970s, a hybrid tilapia (Oreochromis mossambicus × O. urolepis hornorum) invaded the Salton Sea and became dominant by number and weight. Recent surveys show a precipitous decline of all four species above starting sometime between 2001 and 2002. Declines were more evident in nearshore than in estuarine habitats. Corvina has probably declined the soonest, followed by Gulf croaker. Tilapia declines were followed by more recent increases in population numbers. The tilapia rebound observed are probably only sustainable if a curb in Salton Sea salinity levels is realized. The marine species will likely need restocking to reach historic levels, if the salinity of the lake is managed at 40 gL1 or below. Restoration alternatives for the Salton Sea must take into consideration estuarine areas as essential fish habitats and fish refuge against high salinities.
Recent advances and limitations of surgical treatment for pancreatic cancer
Keiichi Kubota
World Journal of Clinical Oncology , 2011, DOI: 10.5306/wjco.v2.i5.225
Abstract: Recent advances in surgical treatment for pancreatic cancer have been remarkable. Pancreatoduodenectomy is a standard surgical procedure for cancer of the pancreatic head, and is now indicated even for elderly patients over 80 years of age. Pancreatoduodenectomy with combined resection of the peripancreatic vessels has improved survival, but extended resection including lymph nodes is considered to have no extra survival benefit. Furthermore, laparoscopic resection procedures including pancreatoduodenectomy, distal pancreatectomy, enucleation and central pancreatectomy can now be performed safely. Neoadjuvant or adjuvant chemotherapy using gemcitabine may further improve the surgical outcome. An understanding of the oncological aspects of pancreatic cancer and the development of surgical techniques and chemotherapy may further contribute to improving the outcome of surgery for pancreatic cancer.
Designs of Second-Order Associated Memory Networks with Threshold Logics: Winner-Take-All and Selective Voting
Toshiro Kubota
Journal of Computers , 2009, DOI: 10.4304/jcp.4.10.962-974
Abstract: The capacity of an order-d associative memory model is O(Nd/logN) where N is the memory size in bit. In contrast, the capacity of the Hopfield network is limited to O(N/logN). Among higher order associative memory models (d > 1), the second order memory (d = 2) has attractive properties: a relatively small implementation cost of O(N2), a small number of spurious states, and the presence of a diagonalization form. Due to these properties, it is of both practical and scientific interests to investigate efficient computational mechanisms of such network. One disadvantage of higher order associative memory is that it cannot be implemented with simple threshold neurons or McCulloch-Pitts neurons, thus a direct implementation of its computational mechanism on a biological substrate is questionable and its silicon implementation is expensive. In this paper, we propose two approximation models of a second order associative memory using threshold logics. Both are two-layered and employ eigenvalue decomposition of the correlation tensor. The first model uses a winner-takeall mechanism and the second uses a weighted voting by those with significant responses. Architectural-level designs of these memory models are presented. Extensive numerical simulations demonstrate effectiveness of the proposed models in retrieving contents with noisy probe vectors.
Associative Learning for Cognitive Development of Partner Robot through Interaction with People
Naoyuki Kubota
Journal of Systemics, Cybernetics and Informatics , 2009,
Abstract: This paper discusses associative learning of a partner robots through interaction with people. Human interaction based on gestures is very important to realize the natural communication. The meaning of gestures can be understood through the actual interaction with a human and the imitation of a human. Therefore, we propose a method for associative learning based on imitation and conversation to realize the natural communication. Steady-state genetic algorithms are applied for detecting human face and objects in image processing. Spiking neural networks are applied for memorizing spatio-temporal patterns of human hand motions, and relationship among perceptual information. Furthermore, we conduct several experiments of the partner robot on the interaction based on imitation and conversation with people. The experimental results show that the proposed method can refine the relationship among the perceptual information, and can reflect the updated relationship to the natural communication with a human.
Innate IFN-γ-Producing Cells in the Spleen of Mice Early after Listeria monocytogenes Infection: Importance of Microenvironment of the Cells Involved in the Production of Innate IFN-γ
Koichi Kubota
Frontiers in Immunology , 2011, DOI: 10.3389/fimmu.2011.00026
Abstract: Production of innate interferon-γ (IFN-γ) is a crucial step in immunological defense against bacteria. However, there is little information regarding cellular mechanisms underlying IFN-γ production in vivo early after bacterial infection. Here we analyze innate IFN-γ production in the spleen of mice early after Listeria monocytogenes (LM) infection ex vivo by flow-cytometry and in situ by immunohistochemistry, and compare them with the IFN-γ-producing cells reported previously in our in vitro coculture system in which cell-cell interaction between lymphocytes and dying bacterial-infected macrophages is required for the production of IFN-γ. In the spleen at 20 h after LM infection, natural killer (NK) cells, a subset of αβ T cells, and subsets of NKT and γδ T cells produced IFN-γ with features similar to the IFN-γ-producing cells in our in vitro coculture system. Immunohistochemistry revealed that LM bacteria were first phagocytosed mainly by ER-TR9+ marginal zone macrophages (MZMs), then forming infectious foci in close vicinity of the marginal zone (MZ) at 20-h postinfection. At this time point, the IFN-γ-producing cells were accumulating at the same site of infectious foci, around which ER-TR9+ MZMs were clustered but most of bacteria were no longer associated with ER-TR9+ MZMs. These results indicate that innate IFN-γ production by innate lymphocytes takes place at infectious foci formed in close vicinity of the MZ, and they also suggest an important role for the microenvironment of the cells accumulated at infectious foci in inducing the production of innate IFN-γ.
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