Utsunomiya University

About: Utsunomiya University is a education organization based out in Utsunomiya, Japan. It is known for research contribution in the topics: Laser & Holography. The organization has 4139 authors who have published 6812 publications receiving 91975 citations. The organization is also known as: Utsunomiya daigaku.

Calcium dynamics during trap closure visualized in transgenic Venus flytrap.

Abstract: The leaves of the carnivorous plant Venus flytrap, Dionaea muscipula (Dionaea) close rapidly to capture insect prey. The closure response usually requires two successive mechanical stimuli to sensory hairs on the leaf blade within approximately 30 s (refs. 1–4). An unknown biological system in Dionaea is thought to memorize the first stimulus and transduce the signal from the sensory hair to the leaf blade2. Here, we link signal memory to calcium dynamics using transgenic Dionaea expressing a Ca2+ sensor. Stimulation of a sensory hair caused an increase in cytosolic Ca2+ concentration ([Ca2+]cyt) starting in the sensory hair and spreading to the leaf blade. A second stimulus increased [Ca2+]cyt to an even higher level, meeting a threshold that is correlated to the leaf blade closure. Because [Ca2+]cyt gradually decreased after the first stimulus, the [Ca2+]cyt increase induced by the second stimulus was insufficient to meet the putative threshold for movement after about 30 s. The Ca2+ wave triggered by mechanical stimulation moved an order of magnitude faster than that induced by wounding in petioles of Arabidopsis thaliana5 and Dionaea. The capacity for rapid movement has evolved repeatedly in flowering plants. This study opens a path to investigate the role of Ca2+ in plant movement mechanisms and their evolution. A transgenic Venus flytrap expressing a fluorescent calcium sensor allows real-time live quantification of calcium waves triggered by sensory hair movement. The study suggests that calcium levels represent the molecular basis for the memory effect that requires two stimulations within 30 s.

Development of a new method for estimating visceral fat area with multi-frequency bioelectrical impedance.

Abstract: Excessive visceral fat area (VFA) is a major risk factor in such conditions as cardiovascular disease. In assessing VFA, computed tomography (CT) is adopted as the gold standard; however, this method is cost intensive and involves radiation exposure. In contrast, the bioelectrical impedance (BI) method for estimating body composition is simple and noninvasive and thus its potential application in VFA assessment is being studied. To overcome the difference in obtained impedance due to measurement conditions, we developed a more precise estimation method by selecting the optimum body posture, electrode arrangement, and frequency. The subjects were 73 healthy volunteers, 37 men and 36 women, who underwent CT scans to assess VFA and who were measured for anthropometry parameters, subcutaneous fat layer thickness, abdominal tissue area, and impedance. Impedance was measured by the tetrapolar impedance method using multi-frequency BI. Multiple regression analysis was conducted to estimate VFA. The results revealed a strong correlation between VFA observed by CT and VFA estimated by impedance (r = 0.920). The regression equation accurately classified VFA > or = 100 cm(2) in 13 out of 14 men and 1 of 1 woman. Moreover, it classified VFA > or = 100 cm(2) or < 100 cm(2) in 3 out of 4 men and 1 of 1 woman misclassified by waist circumference (W) which was adopted as a simple index to evaluate VFA. Therefore, using this simple and convenient method for estimating VFA, we obtained an accurate assessment of VFA using the BI method.

Chaos via torus breakdown in a piecewise-linear forced van der Pol oscillator with a diode

Abstract: Chaos via torus breakdown in the piecewise-linear forced van de Pol equation is studied rigorously by using the degenerate technique. The model is a negative resistance LC oscillator including a diode driven by a sinusoidal voltage source. The authors investigate an idealized case where the diode is assumed to operate as an ideal switch. In this case, the Poincare map is derived strictly as a one-dimensional return mapping of a circuit onto itself. This mapping clarifies the onset of chaos via torus breakdown observed in this circuit. The authors obtain the critical value of the bifurcation parameter analytically, which gives the boundary between the chaotic region and the torus region. This bridges the gaps between the abstract one-dimensional mapping and the real circuit. >

Estimating visceral fat area by multifrequency bioelectrical impedance.

Abstract: OBJECTIVE We developed a new method of estimating visceral fat area (VFA) using multifrequency bioelectrical impedance (BI). RESEARCH DESIGN AND METHODS We considered abdominal composition as a parallel circuit model composed of VFA and subcutaneous fat area and calculated the impedance of VFA (IP VFA ) from this model. The methods were tested against measures of VFA by computed tomography (CT). Multiple regression analysis was performed on 103 participants to estimate VFA. We cross-validated the regression equation against CT-measured VFA in 30 additional participants. RESULTS The regression equation was VFA = 3.57 × sagittal abdominal diameter + 311.97 × waist-to-height ratio + 0.71 × age + 23.93 × sex + 1.57 × IP VFA (250 kHz) − 174.35 ( r = 0.904, P r = 0.905). CONCLUSIONS Our method using BI is a simple and convenient method for accurately estimating VFA.