Generalized hydromechanical model for stomatal responses to hydraulic perturbations

Stomata respond in a common pattern to various hydraulic perturbations on any part of the 'soil-plant-air' system: initial transient 'wrong-way' responses and final stationary 'right-way' responses. In order to describe this pattern on the basis of statistical physics, we propose a simple model where turgor pressure of a cell is taken to be a power function of its volume, and obtain results in qualitative agreement with experimental data for responses to a variety of hydraulic perturbations: Firstly, stationary stomatal conductance as a function of the vapor pressure deficit divides into three regimes characterized by sensitivities of the stomatal conductance and the transpiration rate with respect to vapor pressure deficit; secondly, for every hydraulic perturbation, the initial transient 'wrong-way' responses always appear; thirdly, on condition that water is supplied insufficiently, stomatal oscillations are often observed; finally, stomatal responses following leaf excision exhibit, after the initial transient wrong-way responses, slow relaxation to stomatal closing. In particular, comparison of areoles having different numbers of stomata demonstrates that areoles with small numbers of stomata tend to provoke lack of water in the soil as well as in the plant. In addition, our model also describes well dependence of the stomatal conductance on temperature. It may be extended further to describe stomatal responses to other environmental factors such as carbon dioxide, light, and temperature.

Information exchange dynamics of the two-dimensional XY model

Information exchange dynamics of the two-dimensional XY model is studied by means of the entropic sampling algorithm. Combining the analytic and numerical results, we obtain the entropy in the whole range of the energy at various system sizes. The time evolution of the order parameter and of the number of vortices is explored, and the corresponding relaxation times are found to grow algebraically with the system size. Such absence of characteristic time scales in the thermodynamic limit manifests the emergent criticality of the exchanging process of information with the environment. The mechanism of information exchange in the XY model is discussed in terms of the dynamic exponents, in comparison with the Ising model.

Conformationally resolved spectra of acetaminophen by UV-UV hole burning and IR dip spectroscopy in the gas phase

Electronic and vibrational spectra of acetaminophen were measured by using UV-UV hole burning (HB) and IR dip spectroscopy. HB spectra show the coexistence of 4 different species, which include two new ones. Low-frequency transitions in the spectra are reproduced by a one-dimensional periodic potential with a free-rotor basis set for the methyl group. From the analysis, we concluded that acetaminophen has two conformers and each conformer gives two independent transitions starting from the most stable 0a(1) and the hot 1e internal rotational levels. It is also found that the HB spectrum of the trans-conformer in the previous report is that from the 1e excited level, while the HB spectrum of the cis-conformer is contaminated by the transitions of the trans-conformer. Potential curves of the methyl rotational motion are determined both in S(0) and S(1).

Production of size controlled aluminum and alumina nanoparticles via pulsed laser ablation in water

An Al metal plate was ablated by a pulsed Nd-YAG laser to produce nano-structured Al and gamma-Al2O3 in deionized water in the absence of any surfactants or catalysts. In this study, the mean diameter and the width of size distribution of the nanoparticles was influenced by the laser power, resulting in the production of smaller and larger sizes of nanoparticles with higher and lower laser power, respectively. The influence of laser power on the mean diameter and the width of size distribution of as-prepared nanoparticles generated by the laser ablation process was explained by the space homogeneity of the plasma plume, where the nucleation of nanoparticles has occurred. Further explanations of the influence of laser power on the size distribution are proposed. Furthermore, structural and morphological characterization of aluminum and gamma-Al2O3 nanoparticles was conducted by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM).

Direct observation of aluminium ions produced via pulsed laser ablation in liquid: a 'turn-on' fluorescence study

An Al metal plate was ablated by a pulsed Nd-YAG laser to produce nano-structured Al and gamma-Al(2)O(3) in deionized water without any surfactants or catalysts. In this study, direct evidence for the production of Al(3+) ions from the plasma plume is presented for the first time by characterizing the absorption and emission spectra of their [Al(salophen)](+) complex. Very interestingly, a remarkable increase in the fluorescence intensity was observed when the Al(3+) ions, produced via the pulsed laser ablation, complexed with the salophen ligand. This fluorescence 'turn-on' behaviour of [Al(salophen)](+) was investigated by DFT/TD-DFT calculations. Based on these results, mechanisms for the production of aluminium and alumina nanoparticles in the pulsed laser ablation in liquid (PLAL) process are proposed.

Modification of the gravity model and application to the metropolitan Seoul subway system

The Metropolitan Seoul Subway system is examined through the use of the gravity model. Exponents describing the power-law dependence on the time distance between stations are obtained, which reveals a universality for subway lines of the same topology. In the short (time) distance regime the number of passengers between stations does not grow with the decrease in the distance, thus deviating from the power-law behavior. It is found that such reduction in passengers is well described by the Hill function. Further, temporal fluctuations in the passenger flow data, fitted to the gravity model modified by the Hill function, are analyzed to reveal the Yule-type nature inherent in the structure of Seoul.

Preparation and characterization of acrylated-SiO2@TiO2 hollow hybrid nanospheres

Novel inorganic-organic hybrid hollow nanospheres, acrylated SiO2 and SiO2@TiO2, were synthesized via a sol-gel polymerization, using crown-appended sugar gelator 1 as an organic template for the unique nanospherical structures in demand for a fast expanding area in nanomaterial research. In this work, hollow SiO2 nanospheres were obtained by a simple sol-gel method followed by calcination and rather rough TiO2 nanolayers were coated onto the highly dispersed surface of SiO2 nanospheres and further copolymerization of MPA on the surface of SiO2 and SiO2@TiO2 nanosphseres was successfully conducted. The morphological properties of those hollow nanospheres were characterized by TEM, SEM and powder-XRD. Furthermore, the physical and chemical properties of the synthesized nanocomposites were characterized by the analysis of EDX, FT-IR, TGA and ESCA.

Weibull-type limiting distribution for replicative systems

The Weibull function is widely used to describe skew distributions observed in nature. However, the origin of this ubiquity is not always obvious to explain. In the present paper, we consider the well-known Galton-Watson branching process describing simple replicative systems. The shape of the resulting distribution, about which little has been known, is found essentially indistinguishable from the Weibull form in a wide range of the branching parameter; this can be seen from the exact series expansion for the cumulative distribution, which takes a universal form. We also find that the branching process can be mapped into a process of aggregation of clusters. In the branching and aggregation process, the number of events considered for branching and aggregation grows cumulatively in time, whereas, for the binomial distribution, an independent event occurs at each time with a given success probability.

Emergence of skew distributions in controlled growth processes

Starting from a master equation, we derive the evolution equation for the size distribution of elements in an evolving system, where each element can grow, divide into two, and produce new elements. We then probe general solutions of the evolution equation, to obtain such skew distributions as power-law, log-normal, and Weibull distributions, depending on the growth or division and production. Specifically, repeated production of elements of uniform size leads to power-law distributions, whereas production of elements with the size distributed according to the current distribution as well as no production of new elements results in log-normal distributions. Finally, division into two, or binary fission, bears Weibull distributions. Numerical simulations are also carried out, confirming the validity of the obtained solutions.

Vitamin D effects on pregnancy and the placenta

Vitamin D is a pleiotropic secosteroid hormone important for health and disease prevention. The actions of vitamin D are mediated by the vitamin D receptor that binds the active form of vitamin D [1,25(OH)(2)D] to induce both transcriptional and non-genomic responses. Vitamin D has well known classical functions in calcium uptake and bone metabolism, but more recent work highlights the importance of the nonclassical actions of vitamin D in a variety of cell types. These actions include modulation of the innate and adaptive immune systems and regulation of cell proliferation. Adequate vitamin D intake is essential for maternal and fetal health during pregnancy, and epidemiological data indicate that many pregnant women have sub-optimal vitamin D levels. Notably, vitamin D deficiency correlates with preeclampsia, gestational diabetes mellitus, and bacterial vaginosis, and an increased risk for C-section delivery. Recent work emphasizes the importance of nonclassical roles of vitamin D in pregnancy and the placenta. The placenta produces and responds to vitamin D where vitamin D functions as a modulator of implantation, cytokine production and the immune response to infection. We describe vitamin D metabolism and the cellular responses to vitamin D, and then summarize the role of vitamin D in placental trophoblast, pregnancy and the fetus.