2,382 research outputs found
Noise Enhanced Stability in Fluctuating Metastable States
We derive general equations for the nonlinear relaxation time of Brownian
diffusion in randomly switching potential with a sink. For piece-wise linear
dichotomously fluctuating potential with metastable state, we obtain the exact
average lifetime as a function of the potential parameters and the noise
intensity. Our result is valid for arbitrary white noise intensity and for
arbitrary fluctuation rate of the potential. We find noise enhanced stability
phenomenon in the system investigated: the average lifetime of the metastable
state is greater than the time obtained in the absence of additive white noise.
We obtain the parameter region of the fluctuating potential where the effect
can be observed. The system investigated also exhibits a maximum of the
lifetime as a function of the fluctuation rate of the potential.Comment: 7 pages, 5 figures, to appear in Phys. Rev. E vol. 69 (6),200
rCBFand the rCMRglucose in experimental hydrocephalus measured by the double tracer method of autoradiography
開始ページ、終了ページ: 冊子体のページ付
Localized thinning for strain concentration in suspended germanium membranes and optical method for precise thickness measurement
We deposited Ge layers on (001) Si substrates by molecular beam epitaxy and used them to fabricate suspended membranes with high uniaxial tensile strain. We demonstrate a CMOS-compatible fabrication strategy to increase strain concentration and to eliminate the Ge buffer layer near the Ge/Si hetero-interface deposited at low temperature. This is achieved by a two-steps patterning and selective etching process. First, a bridge and neck shape is patterned in the Ge membrane, then the neck is thinned from both top and bottom sides. Uniaxial tensile strain values higher than 3% were measured by Raman scattering in a Ge membrane of 76 nm thickness. For the challenging thickness measurement on micrometer-size membranes suspended far away from the substrate a characterization method based on pump-and-probe reflectivity measurements was applied, using an asynchronous optical sampling technique.EC/FP7/628197/EU/Heat Propagation and Thermal Conductivity in Nanomaterials for Nanoscale Energy Management/HEATPRONAN
Pattern formation of reaction-diffusion system having self-determined flow in the amoeboid organism of Physarum plasmodium
The amoeboid organism, the plasmodium of Physarum polycephalum, behaves on
the basis of spatio-temporal pattern formation by local
contraction-oscillators. This biological system can be regarded as a
reaction-diffusion system which has spatial interaction by active flow of
protoplasmic sol in the cell. Paying attention to the physiological evidence
that the flow is determined by contraction pattern in the plasmodium, a
reaction-diffusion system having self-determined flow arises. Such a coupling
of reaction-diffusion-advection is a characteristic of the biological system,
and is expected to relate with control mechanism of amoeboid behaviours. Hence,
we have studied effects of the self-determined flow on pattern formation of
simple reaction-diffusion systems. By weakly nonlinear analysis near a trivial
solution, the envelope dynamics follows the complex Ginzburg-Landau type
equation just after bifurcation occurs at finite wave number. The flow term
affects the nonlinear term of the equation through the critical wave number
squared. Contrary to this, wave number isn't explicitly effective with lack of
flow or constant flow. Thus, spatial size of pattern is especially important
for regulating pattern formation in the plasmodium. On the other hand, the flow
term is negligible in the vicinity of bifurcation at infinitely small wave
number, and therefore the pattern formation by simple reaction-diffusion will
also hold. A physiological role of pattern formation as above is discussed.Comment: REVTeX, one column, 7 pages, no figur
The New BBB Indicator of Positron Emitting Radionuclide Tracer - 45Ti-DTPA
開始ページ、終了ページ: 冊子体のページ付
Treacher Collins syndrome with choanal atresia: a case report and review of disease features
SummaryTreacher Collins Syndrome - or mandibulofacial dysostosis – is a rare condition that presents several craniofacial deformities of different levels. This is a congenital malformation involving the first and second branchial arches. Incidence is estimated to range between 1-40,000 to 1-70,000 of live births. The disorder is characterized by abnormalities of the auricular pinna, hypoplasia of facial bones, antimongoloid slanting palpebral fissures with coloboma of the lower eyelids and cleft palate. Treacher Collins Syndrome is rarely associated with choanal atresia. A multidisciplinary team, including craniofacial surgeon, ophthalmologist, speech therapist, dental surgeon and otorhinolaryngologist, is the most appropriate setting to manage these patients. This study reports a rare case of Treacher Collins Syndrome with choanal atresia, presenting literature review and multidisciplinary intervention
- …