Nitric Oxide Signaling in Plants

Nitric oxide (NO) is an integral part of cell signaling mechanisms in animals and plants. In plants, its enzymatic generation is still controversial. Evidence points to nitrate reductase being important, but the presence of a nitric oxide synthase-like enzyme is still contested. Regardless, NO has been shown to mediate many developmental stages in plants, and to be involved in a range of physiological responses, from stress management to stomatal aperture closure. Downstream from its generation are alterations of the actions of many cell signaling components, with post-translational modifications of proteins often being key. Here, a collection of papers embraces the differing aspects of NO metabolism in plants.

Control of aperture closure during reach-to-grasp movements in immersive haptic-free virtual reality

Virtual reality (VR) has garnered much interest as a training environment for motor skill acquisition, including for neurological rehabilitation of upper extremities. While the focus has been on gross upper limb motion, VR applications that involve reaching for, and interacting with, virtual objects are growing. The absence of true haptics in VR when it comes to hand-object interactions raises a fundamentally important question: can haptic-free immersive virtual environments (hf-VEs) support naturalistic coordination of reach-to-grasp movements? This issue has been grossly understudied, and yet is of significant importance in the development and application of VR across a number of sectors. In a previous study (Furmanek et al. 2019), we reported that reach-to-grasp movements are similarly coordinated in both the physical environment (PE) and hf-VE. The most noteworthy difference was that the closure phase—which begins at maximum aperture and lasts through the end of the movement—was longer in hf-VE than in PE, suggesting that different control laws might govern the initiation of closure between the two environments. To do so, we reanalyzed data from Furmanek et al. (2019), in which the participants reached to grasp three differently sized physical objects, and matching 3D virtual object renderings, placed at three different locations. Our analysis revealed two key findings pertaining to the initiation of closure in PE and hf-VE. First, the respective control laws governing the initiation of aperture closure in PE and hf-VE both included state estimates of transport velocity and acceleration, supporting a general unified control scheme for implementing reach-to-grasp across physical and virtual environments. Second, aperture was less informative to the control law in hf-VE. We suggest that the latter was likely because transport velocity at closure onset and aperture at closure onset were less independent in hf-VE than in PE, ultimately resulting in aperture at closure onset having a weaker influence on the initiation of closure. In this way, the excess time and muscular effort needed to actively bring the fingers to a stop at the interface of a virtual object was factored into the control law governing the initiation of closure in hf-VE. Crucially, this control law remained applicable, albeit with different weights in hf-VE, despite the absence of terminal haptic feedback and potential perceptual differences.

A Discourse Structural Overview of the Prophecy of Micah

After a short introduction, the methodology underlying this study is explained in terms of the so-called breaks, bonds, bounds, and bumps of discourse organization, as revealed by five principal literary-structural markers: aperture, closure, bonding, juncture, and peak. These diagnostic features are then applied to present a sequential summary of the compositional arrangement (cycles, stanzas, strophes) of the entire prophetic book of Micah. The significance of this type of detailed discourse analysis for both understanding the biblical text and translating it is briefly pointed out and illustrated.

Microstructure and composition of the periderm of conulariids

Transmitted light and scanning electron imaging of sectioned specimens ofConulariaandParaconularia, prepared using HCl etching and critical point drying, revealed that their periderm is composed of extremely thin (approximately 0.5–3 µm), variably distinct microlamellae that are alternately organic poor and organic rich. Organic-rich microlamellae are cross-connected by slender strands of organic matter originally embedded in calcium phosphate, which in etched specimens has been dissolved. Microlamellae may be organized in thicker (approximately 5–75 µm) layers, or macrolamellae, that vary in color and organic matter content, possibly owing to changes in the ambient paleoenvironment. Thickening of the periderm to form transverse ribs and internal carinae was achieved through gradual thickening of individual microlamellae. In the core of the transverse ribs and internal carinae the distinction between organic-rich and organic-poor microlamellae may be reduced, owing to organic material becoming dominant over (former) mineral matter or vice versa. Combined with observations of plicated aperture closure in thin-walled conulariids, includingArchaeoconularia slateri(Reed, 1933) (Upper Ordovician, Scotland) showing smooth folding of midline carinae through angles greater than 90°, these results suggest a structure and original flexibility in the organic-rich biocomposite forming the conulariid periderm that supports its homology to the chitinous lamellar periderm of coronate scyphozoans.

FEM Analyses for T-H-M-M Coupling Processes in Dual-Porosity Rock Mass under Stress Corrosion and Pressure Solution

The models of stress corrosion and pressure solution established by Yasuhara et al. were introduced into the 2D FEM code of thermo-hydro-mechanical-migratory coupling analysis for dual-porosity medium developed by the authors. Aiming at a hypothetical model for geological disposal of nuclear waste in an unsaturated rock mass from which there is a nuclide leak, two computation conditions were designed. Then the corresponding two-dimensional numerical simulation for the coupled thermo-hydro-mechanical-migratory processes were carried out, and the states of temperatures, rates and magnitudes of aperture closure, pore and fracture pressures, flow velocities, nuclide concentrations and stresses in the rock mass were investigated. The results show: the aperture closure rates caused by stress corrosion are almost six orders higher than those caused by pressure solution, and the two kinds of closure rates climb up and then decline, furthermore tend towards stability; when the effects of stress corrosion and pressure solution are considered, the negative fracture pressures in near field rise very highly; the fracture aperture and porosity are decreases in the case 1, so the relative permeability coefficients reduce, therefore the nuclide concentrations in pore and fracture in this case are higher than those in case 2.