Evaluation of most similar neighbour and random forest methods for imputing forest inventory variables using data from target and auxiliary stands

We report the results from modelling standing volume, above-ground biomass and stem count with the aim of exploring the potential of two non-parametric approaches to estimate forest attributes. The models were built based on spectral and 3D information extracted from airborne optical and laser scanner data. The survey was completed across two geographically adjacent temperate forest sites in southwestern Germany, using spatially and temporally comparable remote-sensing data collected by similar instruments. Samples from the auxiliary reference stands (called off-site samples) were combined with random, random stratified and systematically stratified samples from the target area for prediction of standing volume, above-ground biomass and stem count in the target area. A range of combinations was used for the modelling process, comprising the most similar neighbour (MSN) and random forest (RF) imputation methods, three sampling designs and two predictor subset sizes. An evolutionary genetic algorithm (GA) was applied to prune the predictor variables. Diagnostic tools, including root mean square error (RMSE), bias and standard error of imputation, were employed to evaluate the results. The results showed that RF produced more accurate results than MSN (average improvement of 3.5% for a single-neighbour case with selected predictors), yet was more biased than MSN (average bias of 5.13% with RF compared to 2.44% with MSN for stem volume in a single-neighbour case with selected predictors). Combining systematically stratified auxiliary samples from the target data set with the reference data set yielded more accurate results compared to those from random and stratified random samples. Combining additional data was most influential when an intensity of up to 40% of supplementary samples was appended to the reference set. The use of GA-selected predictors resulted in reduced bias of the models. By means of bootstrap simulations of RMSE, the simulations were shown to lie within the applied non-parametric confidence intervals. The achieved results are concluded to be helpful for modelling the mentioned forest attributes by means of airborne remote-sensing data.     

Experiencing Nature: Embodying Animals in Immersive Virtual Environments Increases Inclusion of Nature in Self and Involvement With Nature

Immersive virtual environments (IVEs) produce simulations that mimic unmediated sensory experiences. 3 experiments (N = 228) tested how different modalities increase environmental involvement by allowing users to inhabit the body of animals in IVEs or watch the experience on video. Embodying sensory‐rich experiences of animals in IVEs led to greater feeling of embodiment, perception of being present in the virtual world, and interconnection between the self and nature compared to video. Heightened interconnection with nature elicited greater perceptions of imminence of the environmental risk and involvement with nature, which persisted for 1 week. Although the effect sizes were small to moderate, findings suggest that embodied experiences in IVEs may be an effective tool to promote involvement with environmental issues.     

A Novel Magnetic Hardening Mechanism for Nd-Fe-B Permanent Magnets Based on Solid-State Phase Transformation

Permanent magnets based on neodymium-iron-boron (Nd-Fe-B) alloys provide the highest performance and energy density, finding usage in many high-tech applications. Their magnetic performance relies on the intrinsic properties of the hard-magnetic Nd₂Fe₁₄B phase combined with control over the microstructure during production. In this study, a novel magnetic hardening mechanism is described in such materials based on a solid-state phase transformation. Using modified Nd-Fe-B alloys of the type Nd₁₆Fe_bal-x-y-zCo_xMo_yCu_zB₇ for the first time it is revealed how the microstructural transformation from the metastable Nd₂Fe₁₇B_x phase to the hard-magnetic Nd₂Fe₁₄B phase can be thermally controlled, leading to an astonishing increase in coercivity from ≈200 kAm⁻¹ to almost 700 kAm⁻¹. Furthermore, after thermally treating a quenched sample of Nd₁₆Fe₅₆Co₂₀Mo₂Cu₂B₇, the presence of Mo leads to the formation of fine FeMo₂B₂ precipitates, in the range from micrometers down to a few nanometers. These precipitates are responsible for the refinement of the Nd₂Fe₁₄B grains and so for the high coercivity. This mechanism can be incorporated into existing manufacturing processes and can prove to be applicable to novel fabrication routes for Nd-Fe-B magnets, such as additive manufacturing.     

Paying attention to adult learners online: The pedagogy and politics of community

Our article profiles the evolution of a fully online writing course designed for adult learners in our university's Prior Learning Assessment Program. Based on our own observations and experiences teaching adult learners online, we question if the virtual learning environment presents different challenges and prospects for the adult learner versus the traditional student learner, along with an extension and complication of the more social metaphors of “virtual community.” Moreover, because of the changing demographic from traditional to adult students, we argue that this change also fosters a change in the relationship between teachers and students. In chronicling this relationship, we note problems when the labor of adult education becomes invisible to those supervising online instructors. Because of these “invisible” labor issues, we argue that successful online instruction must include a range of interactions between students and instructors that extend the more public concept of community to better acknowledge the importance of personal, private interaction. Thus, we conclude with a call to rethink our online writing pedagogies to be more flexible to adult learner needs and learning styles, simultaneously recognizing the impact of adult online education on faculty workload.     

The ventral pallidum mediates disruption of prepulse inhibition of the acoustic startle response induced by dopamine agonists, but not by NMDA antagonists

Prepulse inhibition (PPI) of the acoustic startle response is observed when the startling noise pulse is preceded by a weak, non-startling stimulus. PPI has been considered as a measure for sensorimotor gating mechanisms. Disruption of PPI can be found in schizophrenic patients as well as after blockade of NMDA receptors or stimulation of dopamine receptors in rats. The neuronal circuitry which regulates PPI consists of cortico-limbic brain structures where the nucleus accumbens (NAC) plays a key role. The NAC exerts its modulating effects on PPI by way of a projection from the ventral pallidum (VP) to the pedunculopontine tegmental nucleus (PPTg). We recently postulated that the reduction of PPI by intra-NAC infusion of glycine-site NMDA antagonists is not mediated by the VP. We tested here this hypothesis in rats with excitotoxic lesions of the VP which were systemically treated with apomorphine or MK-801 or received intraNAC infusions of dopamine or the glycine-site NMDA antagonist 7-chlorokynurenic acid. Lesioned rats showed a marked deficit in PPI after MK-801 and 7-chlorokynurenate treatment but not after apomorphine or dopamine injection, in contrast to sham-lesioned controls showing deficits in PPI under all conditions. These data provide behavioral evidence for the existence of a pathway which does not include the VP for the mediation of sensorimotor gating deficits. We propose that a direct connection between the NAC and PPTg may be responsible for the effects of NMDA/glycine receptor blockade, whereas the VP is an indispensable relay for the disruptive effects on PPI exerted by the NAC dopamine system.     

On the necessity of explicit cross-layer data formats in near-data processing systems

Distributed and Parallel Databases - Massive data transfers in modern data-intensive systems resulting from low data-locality and data-to-code system design hurt their performance and scalability....     

Evaluation of a Novel Thiol–Norbornene-Functionalized Gelatin Hydrogel for Bioprinting of Mesenchymal Stem Cells

Introduction: Three-dimensional bioprinting can be considered as an advancement of the classical tissue engineering concept. For bioprinting, cells have to be dispersed in hydrogels. Recently, a novel semi-synthetic thiolene hydrogel system based on norbornene-functionalized gelatin (GelNB) and thiolated gelatin (GelS) was described that resulted in the photoclick hydrogel GelNB/GelS. In this study, we evaluated the printability and biocompatibility of this hydrogel system towards adipose-tissue-derived mesenchymal stem cells (ASCs). Methods: GelNB/GelS was synthesized with three different crosslinking densities (low, medium and high), resulting in different mechanical properties with moduli of elasticity between 206 Pa and 1383 Pa. These hydrogels were tested for their biocompatibility towards ASCs in terms of their viability, proliferation and differentiation. The extrusion-based bioprinting of ASCs in GelNB/GelS-high was performed to manufacture three-dimensional cubic constructs. Results: All three hydrogels supported the viability, proliferation and chondrogenic differentiation of ASCs to a similar extent. The adipogenic differentiation of ASCs was better supported by the softer hydrogel (GelNB/GelS-low), whereas the osteogenic differentiation was more pronounced in the harder hydrogel (GelNB/GelS-high), indicating that the differentiation fate of ASCs can be influenced via the adaption of the mechanical properties of the GelNB/GelS system. After the ex vivo chondrogenic differentiation and subcutaneous implantation of the bioprinted construct into immunocompromised mice, the production of negatively charged sulfated proteoglycans could be observed with only minimal inflammatory signs in the implanted material. Conclusions: Our results indicate that the GelNB/GelS hydrogels are very well suited for the bioprinting of ASCs and may represent attractive hydrogels for subsequent in vivo tissue engineering applications.     

On the hydration of grain boundaries and bulk of proton conducting BaZr0.7Pr0.2Y0.1O3-δ

We report here for the first time bulk and grain boundary conductivities from impedance spectra of a ceramic proton conductor (BaZr_0.7Pr_0.2Y_0.1O_3-δ) taken during hydration and H/D isotope exchange transients (at 400 °C). The results suggest that water moves quickly along grain boundary cores, and then interact from there with the space charge layers and, in turn, grain interiors. Hydration and H/D isotope exchange have simple monotonic effects on the bulk conductivity in line with what is expected from it being dominated by protons. The transients for grain boundary conductivity exhibit however hysteresis: During hydration, the core charge and grain boundary resistance appear to go through transient minima related to non-equilibrium distributions of defects between the core and grain interior – notably because protons diffuse faster than oxygen vacancies between the grain boundary and grain interior. At equilibrium, hydration increases the core charge and the depletion of positive charge carriers in the space charge layers. During H/D isotope exchange relatively fast hysteretic transients indicate that the space charge layers experience changes in charge carrier (D⁺ vs. H⁺) mobility as well as in D₂O vs. H₂O hydration thermodynamics.     

世界上第一条新型气体绝缘高压输电线路

介绍瑞士日内瓦机场的气体绝缘输电线路（GIL）工程,涉及工程的系统设计、技术指标和施工方法等。阐述GIL具有运营成本低、安全性和可靠性高、电磁场强度低和无老化等优越性。