Expression of Heterologous OsDHAR Gene Improves Glutathione (GSH)-Dependent Antioxidant System and Maintenance of Cellular Redox Status in Synechococcus elongatus PCC 7942.

An excess of reactive oxygen species (ROS) can cause severe oxidative damage to cellular components in photosynthetic cells. Antioxidant systems, such as the glutathione (GSH) pools, regulate redox status in cells to guard against such damage. Dehydroascorbate reductase (DHAR, EC 1.8.5.1) catalyzes the glutathione-dependent reduction of oxidized ascorbate (dehydroascorbate) and contains a redox active site and glutathione binding-site. The DHAR gene is important in biological and abiotic stress responses involving reduction of the oxidative damage caused by ROS. In this study, transgenic Synechococcus elongatus PCC 7942 (TA) was constructed by cloning the Oryza sativa L. japonica DHAR (OsDHAR) gene controlled by an isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible promoter (Ptrc) into the cyanobacterium to study the functional activities of OsDHAR under oxidative stress caused by hydrogen peroxide exposure. OsDHAR expression increased the growth of S. elongatus PCC 7942 under oxidative stress by reducing the levels of hydroperoxides and malondialdehyde (MDA) and mitigating the loss of chlorophyll. DHAR and glutathione S-transferase activity were higher than in the wild-type S. elongatus PCC 7942 (WT). Additionally, overexpression of OsDHAR in S. elongatus PCC 7942 greatly increased the glutathione (GSH)/glutathione disulfide (GSSG) ratio in the presence or absence of hydrogen peroxide. These results strongly suggest that DHAR attenuates deleterious oxidative effects via the glutathione (GSH)-dependent antioxidant system in cyanobacterial cells. The expression of heterologous OsDHAR in S. elongatus PCC 7942 protected cells from oxidative damage through a GSH-dependent antioxidant system via GSH-dependent reactions at the redox active site and GSH binding site residues during oxidative stress

Electrical spin injection and accumulation in CoFe/MgO/Ge contacts at room temperature

We first report the all-electrical spin injection and detection in CoFe/MgO/moderately doped n-Ge contact at room temperature (RT), employing threeterminal Hanle measurements. A sizable spin signal of ~170 k{\Omega} {\mu}m^2 has been observed at RT, and the analysis using a single-step tunneling model gives a spin lifetime of ~120 ps and a spin diffusion length of ~683 nm in Ge. The observed spin signal shows asymmetric bias and temperature dependences which are strongly related to the asymmetry of the tunneling process.Comment: 28 pages, 5 figure

A Comparison of the Intrinsic Shapes of Two Different Types of Dwarf Galaxies: Blues Compact Dwarfs and Dwarf Ellipticals

We measure the apparent shapes for a sample of 62 blue compact dwarf galaxies (BCDs), and compare them with the apparent shapes for a sample of 80 dwarf elliptical galaxies (dEs). The BCDs are flatter, on average, than the dEs, but the difference is only marginally significant. We then use both non-parametric and parametric techniques to determine possible distributions of intrinsic shapes for the BCDs. The hypothesis that BCDs are oblate spheroids can be ruled out with a high confidence level ($> 99$), but the hypothesis that they are prolate spheroids cannot be excluded. The apparent shapes of BCDs are totally consistent with the hypothesis that they are triaxial ellipsoids. If the intrinsic axis ratios, $\beta$ and $\gamma$, are distributed according to a Gaussian with means $\beta_0$ and $\gamma_0$ and standard deviation $\sigma$, we find the best-fitting distribution for BCDs has $(\beta_0,\gamma_0,\sigma)= (0.66,0.55,0.16)$, while that for dEs has $(\beta_0,\gamma_0,\sigma)= (0.85,0.64,0.24)$. Our results are consistent with the hypothesis that BCDs have a close evolutionary relation with dEs.Comment: total 23 pages, 9 figures, and 1 Table, submitted to ApJ on Sep 19 1997. Email addresses: [email protected], [email protected], [email protected], [email protected], [email protected]

Antiphase synchronization of two nonidentical pendulums

We numerically study the synchronization of two nonidentical pendulum motions, pivoting on a common movable frame in the point of view of the dynamic phase transition. When the difference in the pendulum lengths is not too large, it is shown that the system settles down into the dynamic state of the antiphase synchronization with the phase difference $\pi$. We observe that there is a bistable region where either the antiphase synchronized state or the desynchronized state can be stabilized. We also find that there exists a hysteresis effect around the dynamic phase transition as the length difference is adiabatically changed.Comment: 4 pages, 4 figure

Phenotyping of rice in salt stress environment using high-throughput infrared imaging

Phenotyping of rice (Oryza sativa L. cv. Donggin) in salt stress environment using infrared imaging was conducted. Results were correlated with the most frequently used physiological parameters such as stomatal conductance, relative water content and photosynthetic parameters. It was observed that stomatal conductance (R2 = –0.618) and relative water content (R2 = –0.852) were significantly negatively correlated with average plant temperature (thermal images), while dark-adapted quantum yield (Fv/Fm, R2 = –0.325) and performance index (R2 = –0.315) were not consistent with plant temperature. Advantages of infrared thermography and utilization of this technology for the selection of stress tolerance physiotypes are discussed in detail

Role of spinon and spinon singlet pair excitations on phase transitions in d−waved-wave superconductors

We examine the roles of massless Dirac spinon and spin singlet pair excitations on the phase transition in $d-wave$ superconductors. Although the massless spinon excitations in the presence of the spin singlet pair excitations do not alter the nature of the phase transition at $T = 0$, that is, the XY universality class, they are seen to induce an additional attractive interaction potential between vortices, further stabilizing vortex-antivortex pairs at low temperature for lightly doped high $T_c$ samples.Comment: 5 pages, 1 figur

Modelling The Cancer Growth Process By Stochastic Delay Diffferential Equations Under Verhults And Gompertz's Law

In this paper, the uncontrolled environmental factors are perturbed into the intrinsic growth rate factor of deterministic equations of the growth process. The growth process under two different laws which are Verhults and Gompertz’s law are considered, thus leading to stochastic delay differential equations (SDDEs) of logistic and Gompertzian, respectively. Gompertzian deterministic model has been proved to fit well the clinical data of cancerous growth, however the performance of stochastic model towards clinical data is yet to be confirmed. The prediction quality of logistic and Gompertzian SDDEs are evaluating by comparing the simulated results with the clinical data of cervical cancer growth. The parameter estimation of stochastic models is computed by using simulated maximum likelihood method. We adopt 4-stage stochastic Runge-Kutta to simulate the solution of stochastic models

The Intrinsic Shapes of Low-Surface-Brightness Dwarf Irregular Galaxies and Comparison to Other Types of Dwarf Galaxies

In this paper, we measure the ellipticities of 30 LSB dI galaxies and compare the ellipticity distribution with that of 80 dEs (Ryden & Terndrup 1994; Ryden et al. 1998) and 62 BCDs (Sung et al. 1998). We find that the ellipticity distribution of LSB dIs is very similar to that of BCDs, and marginally different from that of dEs. We then determine the distribution of intrinsic shapes of dI galaxies and compare to those of other type dwarf galaxies under various assumptions. First, we assume that LSB dIs are either all oblate or all prolate, and use non-parametric analysis to find the best-fitting distribution of intrinsic shapes. With this assumption, we find that the scarcity of nearly circular LSB dIs implies, at the 99% confidence level, that they cannot be a population of randomly oriented oblate or prolate objects. Next, we assume that dIs are triaxial, and use parametric analysis to find permissible distributions of intrinsic shapes. We find that if the intrinsic axis ratios, $\beta$ and $\gamma$, are distributed according to a Gaussian with means $\beta_0$ and $\gamma_0$ and a common standard deviation of $\sigma$, the best-fitting set of parameters for LSB dIs is $(\beta_0,\gamma_0,\sigma) = (0.66,0.50,0.15)$, and the best fit for BCDs is $(\beta_0,\gamma_0,\sigma) = (0.66,0.55,0.16)$, while the best fit for dEs is $(\beta_0,\gamma_0,\sigma) = (0.78,0.69,0.24)$. The dIs and BCDs thus have a very similar shape distribution, given this triaxial hypothesis, while the dEs peak at a somewhat more spherical shape. Our results are consistent with an evolutionary scenario in which the three types of dwarf galaxy have a close relation with each other.Comment: total 18 pages, 4 figures, and 3 Tables, submitted to Astrophysical Journal on Mar 5 199

The Early Light Curve of a Type Ia Supernova 2021hpr in NGC 3147: Progenitor Constraints with the Companion Interaction Model

The progenitor system of Type Ia supernovae (SNe Ia) is expected to be a close binary system of a carbon/oxygen white dwarf (WD) and a non-degenerate star or another WD. Here, we present results from a high-cadence monitoring observation of SN 2021hpr in a spiral galaxy, NGC 3147, and constraints on the progenitor system based on its early multi-color light curve data. First, we classify SN 2021hpr as a normal SN Ia from its long-term photometric and spectroscopic data. More interestingly, we found a significant "early excess" in the light curve over a simple power-law $\sim t^{2}$ evolution. The early light curve evolves from blue to red and blue during the first week. To explain this, we fitted the early part of $BVRI$-band light curves with a two-component model of the ejecta-companion interaction and a simple power-law model. The early excess and its color can be explained by shock cooling emission due to a companion star having a radius of $8.84\pm0.58$$R_{\odot}$. We also examined HST pre-explosion images with no detection of a progenitor candidate, consistent with the above result. However, we could not detect signs of a significant amount of the stripped mass from a non-degenerate companion star ($\lesssim0.003\,M_{\odot}$ for H$\alpha$ emission). The early excess light in the multi-band light curve supports a non-degenerate companion in the progenitor system of SN 2021hpr. At the same time, the non-detection of emission lines opens a door for other methods to explain this event.Comment: 26 pages, 13 figures + appendix, Accepted for publication in Ap