Depolarization increases cellular light transmission

Application of optical methods to human brain tissue in vivo, e.g., measuring oxyhemoglobin and deoxyhemoglobin concentration changes with near-infrared spectroscopy (NIRS), requires the a priori assumption that background optical properties remain unchanged during measurements1,2. However, fundamental knowledge about light scattering by brain cells per se remains sparse; many factors influence light transmission changes through living brain tissue, bringing into question what is being measured. We have observed slow wave-ring spreads of light transmission changes on the rat cerebral cortex during potassium-induced cortical spreading depression (CSD) and ascribed them to squeezing-out of blood from capillaries by swollen brain cells3,4. However, in rat hippocampal slices, where no blood components were involved, similar light transmission changes were observed during K+-induced CSD and ascribed to cell swelling and dendritic beading5,6,7. Here we show that two-dimensional light scattering changes occur through suspensions of osmotically swollen (depolarized) red blood cells, apparently arising from light scattering changes at the less curved, swollen surface of the steep electrochemical gradient coupled with water activity difference across the plasmic membrane. These optical property changes are likely to be relevant to interpretation of photometry or spectroscopy findings of brain tissue in vivo, where neurons are polarizing and depolarizing during brain function

FABRICATION AND CHARACTERIZATION OF TITANIA-NANOSHEET FILM BY ELECTROPHORETIC DEPOSITION TECHNIQUE

Two-dimensional nanosheets, such as graphene and some oxides, have been investigated because of their unique functional properties. Titania is known as a key material showing a photocatalytic activity as well as a superhydrophilicity by irradiation of ultraviolet light. General preparation method for titania nanosheets has already been reported by Sasaki et al. in 1998.[1] On the other hand, an electrophoretic deposition (EPD) process of colloidal particles in a suspension has been used in various systems in order to create some functional materials and/or devices. In this work, we demonstrate a fabrication of film consisting of titania nanosheet by the simple EPD technique. Titania-nanosheet aqueous suspension was prepared according to the previous report [1]. Dried titania nanosheet powder was obtained to avoid electrolysis of water during EPD process. The dried titania nanosheet powder dispersed in acetone was used as the suspension for the EPD process. The EPD was carried out a constant d.c. voltage mode of 20 V for 300 s. An indium-tin oxide (ITO)-coated glass and a stainless steel plate was used as the anode and cathode, respectively. The two electrodes placed parallel to each other in the suspension. The distance of the electrodes was fixed at 5 mm. The deposition area was set to be 13 mm x 8 mm. The electrophoretically-deposited film was characterized by scanning electron microscope (SEM). Please click Additional Files below to see the full abstract

Functional Magnetic Resonance Imaging of Macaque Monkeys Performing Visually Guided Saccade Tasks Comparison of Cortical Eye Fields with Humans

AbstractThe frontal and parietal eye fields serve as functional landmarks of the primate brain, although their correspondences between humans and macaque monkeys remain unclear. We conducted fMRI at 4.7 T in monkeys performing visually-guided saccade tasks and compared brain activations with those in humans using identical paradigms. Among multiple parietal activations, the dorsal lateral intraparietal area in monkeys and an area in the posterior superior parietal lobule in humans exhibited the highest selectivity to saccade directions. In the frontal cortex, the selectivity was highest at the junction of the precentral and superior frontal sulci in humans and in the frontal eye field (FEF) in monkeys. BOLD activation peaks were also found in premotor areas (BA6) in monkeys, which suggests that the apparent discrepancy in location between putative human FEF (BA6, suggested by imaging studies) and monkey FEF (BA8, identified by microstimulation studies) partly arose from methodological differences

Domain distributions in tetragonal Pb(Zr,Ti)O3 thin films probed by polarized Raman spectroscopy

We have investigated polarized Raman spectra of (001)/(100)-oriented tetragonal epitaxial Pb(ZrxTi1–x)O3 (PZT) thin films (x=~0.35) in which the volume fraction of the polar c domain is systematically varied from 4% to 96%. From polarization analyses using high epitaxial quality films, we have successfully isolated the A1 and B1 phonons from the E phonons, thus offering a distinctive evaluation of the c domains. As increasing c-domain volume, the A1(TO) modes linearly increase in their intensity. A remarkable correlation is found between the A1(1TO)-mode intensity and the c-domain volume for PZT films. We suggest that this correlation as well as the A1(1TO)-mode intensity provide a simple and useful probe for characterization of c-domain volume and ferroelectric properties in PZT-based devices

Quasiscaling in the analysis of the yield ratio π−/π+\pi^-/\pi^+: Mathematical structure and estimation of source size

Recently we have found that integral of the squared Coulomb wave function describing systemcomposed of charged pion and central charged fragment $Z_{eff}$ protons, $|\psi_r(r)|^2$, times pion source function $\rho(r)$ (of the size $\beta$), \intdr |\psi_r(r)|^2 \rho(r), shows a quasiscaling behavior. This is approximately invariant under the following transformation: $(\beta,Z_{eff}) \to (\lambda\beta,\lambda Z_{eff})$; $\lambda >0$. We called such behavior $\beta-Z_{eff}$ quasiscaling. We examine this quasiscaling behavior in detail. In particular we provide a semi-analytical examination of this behavior and confirm it for the exponential pionic source functions in addition to the Gaussian ones and for the production of K mesons as well. When combined with the results of the HBT, a result of the yield ratio allows us to estimate the size of the central charged fragment (CCF) to be $125\le Z_{eff}\le 150$ for Pb+Pb collisions at energy 158 GeV/nucleon. From our estimation, the baryon number density $0.024 \le n_{B}\le0.036$ [1/fm^3] is obtained.Comment: 7 pages, RevTex, 6figure