LOSS OF DIFFERENTIATING NEMATOCYTES INDUCED BY REGENERATION AND WOUND HEALING IN HYDRA

Cell death was observed in the nematocyte differentiation pathway in Hydra during head and foot regeneration. This death occurs throughout the regenerating piece, is transient in nature and is selective for committed stenotele and desmoneme precursors. Proliferating nematoblasts are unaffected. Cell death appears to be caused by release of a toxic factor rather than loss of a hormone required for differentiation, since regenerating pieces released a factor that inactivated differentiating nematocytes, and injured animals that had intact head and foot tissue also lost differentiating nematocytes. The inactivated nematocytes are removed by phagocytosis by epitheliomuscular cells

COMMITMENT DURING NEMATOCYTE DIFFERENTIATION IN HYDRA

Nematocytes in Hydra differentiate from interstitial stem cells. Desmonemes differentiate mainly in the distal half of the body column while stenoteles differentiate predominantly in the proximal half. This difference was used to determine the timing of nematocyte-type commitment in the differentiation pathway. Cells were transferred from distal or proximal regions to all positions in the body column to test when the proportion of stenotele and desmoneme differentiation changed to reflect the new environment. In the first experiment, the distal region of the body column was isolated and permitted to regenerate a whole Hydra. In the second experiment, dissociated cells from distal or proximal regions were transplanted into regenerating aggregates of Hydra tissue. Both experiments effectively transferred cells from distal or proximal positions to positions throughout the body column. By comparing the kinetics of stenotele and differentiation with the time required for distal or proximal cells to differentiate stenoteles and desmonemes in accord with their new environment, it was possible to conclude that stenotele and desmoneme commitment occurs during the terminal cell cycle prior to nematocyte differentiation and not at the stem cell. Additional experiments indicated that the number of rounds of cell division preceding differentiation is fixed at the time stem cells enter the nematocyte pathway

Identification of nanoindentation-induced phase changes in silicon by in situ electrical characterization

In situ electrical measurements during nanoindentation of Czochralski grown p-type crystalline silicon (100) have been performed using a conducting diamond Berkovich indenter tip. Through-tip current monitoring with a sensitivity of ∼10pA and extraction of current-voltage curves at various points on the complete load-unload cycle have been used to track the phase transformations of silicon during the loading and unloading cycle. Postindent current-voltage curves prove to be extremely sensitive to phase changes during indentation, as well as to the final phase composition within the indented volume. For example, differences in the final structure are detected by current-voltage measurements even in an unloading regime in which only amorphous silicon is expected to form. The electrical measurements are interpreted with the aid of previously reported transmission electron microscopy and Raman microspectroscopy measurements.This work was funded by the Australian Research Council and WRiota Pty Ltd

Intrinsic gap and exciton condensation in the nu_T=1 bilayer system

We investigate the quasiparticle excitation of the bilayer quantum Hall (QH) system at total filling factor $\nu_{\mathrm{T}} = 1$ in the limit of negligible interlayer tunneling under tilted magnetic field. We show that the intrinsic quasiparticle excitation is of purely pseudospin origin and solely governed by the inter- and intra-layer electron interactions. A model based on exciton formation successfully explains the quantitative behavior of the quasiparticle excitation gap, demonstrating the existence of a link between the excitonic QH state and the composite fermion liquid. Our results provide a new insight into the nature of the phase transition between the two states.Comment: 4 pages, 3 figure

Analyses of Behaviors of Embankment Dams

The design of embankment is carried out based on several assumptions for the dam body and foundation, and the dam is constructed according to the design conditions. Therefore, it is important to evaluate the conforming of assumptions to the design and construction by the observation of behavior of the dam body and foundation. In this report, internal vertical movement, pore-water pressure and surface movement are arranged concerning of 21 embankment dams of Japan in order to optimize the measurement method including frequency and proper installation of instrumentation and consequently to present a guidelines for the safety control of dams

Transient current spectroscopy of a quantum dot in the Coulomb blockade regime

Transient current spectroscopy is proposed and demonstrated in order to investigate the energy relaxation inside a quantum dot in the Coulomb blockade regime. We employ a fast pulse signal to excite an AlGaAs/GaAs quantum dot to an excited state, and analyze the non-equilibrium transient current as a function of the pulse length. The amplitude and time-constant of the transient current are sensitive to the ground and excited spin states. We find that the spin relaxation time is longer than, at least, a few microsecond.Comment: 5 pages, 3 figure

Visualization of scientific arts and some examples of applications

In this paper, implementation and visualization of scientific arts are described using some examples of application in subject research areas, such as sculpture, archeology, fine arts and information aesthetics, which have been discussed through the Scientific Art Session at FLUCOME9, Tallahassee, Florida, 2007-9. In the application to sculpture, stereo visualization techniques, such as anaglyph stereo visualization and integral imaging technique, are introduced to realize the three-dimensional geometry of sculpture to enhance visual impact on the art. The second application is the flow visualization technique for archeology, where the vortices behind the river stones are studied to understand the origin of patterns on Jomon pottery. Interestingly, such vortex patterns also appear in the paintings of fine arts. The third example is the visualization of information aesthetics, where the Web information, such as public media and stock market, are visualized through scientific techniques. These example of visualization of scientific arts provide the present state of the art in interdisciplinary visualization