Identification of the relationship between Chinese Adiantum reniforme var. sinense and Canary Adiantum reniforme

© 2014 Wang et al.; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated

Different Responses in Root Water Uptake of Summer Maize to Planting Density and Nitrogen Fertilization

Modifying farming practices combined with breeding has the potential to improve water and nutrient use efficiency by regulating root growth, but achieving this goal requires phenotyping the roots, including their architecture and ability to take up water and nutrients from different soil layers. This is challenging due to the difficulty of in situ root measurement and opaqueness of the soil. Using stable isotopes and soil coring, we calculated the change in root water uptake of summer maize in response to planting density and nitrogen fertilization in a 2-year field experiment. We periodically measured root-length density, soil moisture content, and stable isotopes delta O-18 and delta D in the plant stem, soil water, and precipitation concurrently and calculated the root water uptake based on the mass balance of the isotopes and the Bayesian inference method coupled with the Markov Chain Monte Carlo simulation. The results show that the root water uptake increased asymptotically with root-length density and that nitrogen application affected the locations in soil from which the roots acquired water more significantly than planting density. In particular, we find that reducing nitrogen application promoted root penetration to access subsoil nutrients and consequently enhanced their water uptake from the subsoil, while increasing planting density benefited water uptake of the roots in the topsoil. These findings reveal that it is possible to manipulate plant density and fertilization to improve water and nutrient use efficiency of the summer maize and the results thus have imperative implications for agricultural production

The IPAC-NC field campaign: a pollution and oxidization pool in the lower atmosphere over Huabei, China

In the past decades, regional air pollution characterized by photochemical smog and grey haze-fog has become a severe environmental problem in China. To investigate this, a field measurement campaign was performed in the Huabei region, located between 32–42° N latitude in eastern China, during the period 2 April–16 May 2006 as part of the project "Influence of Pollution on Aerosols and Cloud Microphysics in North China" (IPAC-NC). It appeared that strong pollution emissions from urban and industrial centers tend to accumulate in the lower atmosphere over the central area of Huabei. We observed widespread, very high SO<sub>2</sub> mixing ratios, about 20–40 ppbv at 0.5–1.5 km altitude and 10–30 ppbv at 1.5–3.0 km altitude. Average CO mixing ratios were 0.65–0.7 ppmv at 0.5–1.5 km altitude, and very high CO around 1 ppmv was observed during some flights, and even higher levels at the surface. We find the high pollution concentrations to be associated with enhanced levels of OH and HO<sub>2</sub> radicals, calculated with a chemical box model constrained by the measurements. In the upper part of the boundary layer and in the lower free troposphere, high CO and SO<sub>2</sub> compete with relatively less NO<sub>2</sub> in reacting with OH, being efficiently recycled through HO<sub>2</sub>, preventing a net loss of HO<sub>x</sub> radicals. In addition to reactive hydrocarbons and CO, the oxidation of SO<sub>2</sub> causes significant ozone production over Huabei (up to ~13% or 2.0 ppbv h<sup>−1</sup> at 0.8 km altitude). Our results indicate that the lower atmosphere over Huabei is not only strongly polluted but also acts as an oxidation pool, with pollutants undergoing very active photochemistry over this part of China

Linking black-hole growth with host galaxies: The accretion-stellar mass relation and its cosmic evolution

Previous studies suggest that the growth of supermassive black holes (SMBHs) may be fundamentally related to host-galaxy stellar mass ($M_\star$). To investigate this SMBH growth-$M_\star$ relation in detail, we calculate long-term SMBH accretion rate as a function of $M_\star$ and redshift [$\overline{\rm BHAR}(M_\star, z)$] over ranges of $\log(M_\star/M_\odot)=\text{9.5--12}$ and $z=\text{0.4--4}$. Our $\overline{\rm BHAR}(M_\star, z)$ is constrained by high-quality survey data (GOODS-South, GOODS-North, and COSMOS), and by the stellar mass function and the X-ray luminosity function. At a given $M_\star$, $\overline{\rm BHAR}$ is higher at high redshift. This redshift dependence is stronger in more massive systems (for $\log(M_\star/M_\odot)\approx 11.5$, $\overline{\rm BHAR}$ is three decades higher at $z=4$ than at $z=0.5$), possibly due to AGN feedback. Our results indicate that the ratio between $\overline{\rm BHAR}$ and average star formation rate ($\overline{\rm SFR}$) rises toward high $M_\star$ at a given redshift. This $\overline{\rm BHAR}/\overline{\rm SFR}$ dependence on $M_\star$ does not support the scenario that SMBH and galaxy growth are in lockstep. We calculate SMBH mass history [$M_{\rm BH}(z)$] based on our $\overline{\rm BHAR}(M_\star, z)$ and the $M_\star(z)$ from the literature, and find that the $M_{\rm BH}$-$M_\star$ relation has weak redshift evolution since $z\approx 2$. The $M_{\rm BH}/M_\star$ ratio is higher toward massive galaxies: it rises from $\approx 1/5000$ at $\log M_\star\lesssim 10.5$ to $\approx 1/500$ at $\log M_\star \gtrsim 11.2$. Our predicted $M_{\rm BH}/M_\star$ ratio at high $M_\star$ is similar to that observed in local giant ellipticals, suggesting that SMBH growth from mergers is unlikely to dominate over growth from accretion.Comment: 27 pages, 21 figures, 2 tables; MNRAS accepte

The Fourth Element: Characteristics, Modelling, and Electromagnetic Theory of the Memristor

In 2008, researchers at HP Labs published a paper in {\it Nature} reporting the realisation of a new basic circuit element that completes the missing link between charge and flux-linkage, which was postulated by Leon Chua in 1971. The HP memristor is based on a nanometer scale TiO$_2$ thin-film, containing a doped region and an undoped region. Further to proposed applications of memristors in artificial biological systems and nonvolatile RAM (NVRAM), they also enable reconfigurable nanoelectronics. Moreover, memristors provide new paradigms in application specific integrated circuits (ASICs) and field programmable gate arrays (FPGAs). A significant reduction in area with an unprecedented memory capacity and device density are the potential advantages of memristors for Integrated Circuits (ICs). This work reviews the memristor and provides mathematical and SPICE models for memristors. Insight into the memristor device is given via recalling the quasi-static expansion of Maxwell's equations. We also review Chua's arguments based on electromagnetic theory.Comment: 28 pages, 14 figures, Accepted as a regular paper - the Proceedings of Royal Society

Visible-light-enhanced gating effect at the LaAlO₃/SrTiO₃ interface

Electrical field and light-illumination have been two most widely used stimuli in tuning the conductivity of semiconductor devices. Via capacitive effect electrical field modifies the carrier density of the devices, while light-illumination generates extra carriers by exciting trapped electrons into conduction band1. Here, we report on an unexpected light illumination enhanced field effect in a quasi-two-dimensional electron gas (q2DEG) confined at the LaAlO3/SrTiO3 (LAO/STO) interface which has been the focus of emergent phenomenon exploration2-14. We found that light illumination greatly accelerates and amplifies the field effect, driving the field-induced resistance growth which originally lasts for thousands of seconds into an abrupt resistance jump more than two orders of magnitude. Also, the field-induced change in carrier density is much larger than that expected from the capacitive effect, and can even be opposite to the conventional photoelectric effect. This work expands the space for novel effect exploration and multifunctional device design at complex oxide interfaces