Digital map of forest dynamics is emerging as a useful research and management tool. As a key issue to address in developing digital maps of forest dynamics, spatial autocorrelation has been ...distinguished into “true” and “false” gradients. Previous ecological models are mostly focused on either “true” or “false” gradient, and little has been studied to simultaneously account for both gradients in a single model. The main objective of this study was to incorporate both gradients of spatial autocorrelation in a deterministic geospatial model to provide improved accuracy and reliability in future digital maps of forest dynamics. The mapping was based on two underlying assumptions—
unit homogeneity
and
intrinsic stationarity
. This study shows that when the factors causing the spatial non-stationarity have been accounted for, forest states could become a stationary process. A prototype geospatial model was developed for the Alaska boreal forest to study current and future stockings across the region. With areas of the highest basal area increment rate projected to cluster along the major rivers and the lowest near the four major urban developments in Alaska, it was hypothesized that moisture limitation and inappropriate human interference were the main factors affecting the stocking rates. These results could be of unprecedented value, especially for the majority of Alaska boreal region where little information is available.
This study examines messages contributed by scientists and laypeople to an online discussion about genetically modified food in China with the aim to understand whether and how scientists and ...laypeople apply different communication strategies with regard to framing, interaction features, and writing style. Both answers (N = 100) and comments (N = 2416) related to genetically modified food on Zhihu, the most popular social Q&A site in China, were analyzed. The analysis reveals that though there were no significant attitude differences between scientists and laypeople, the two groups tended to frame genetically modified food from quite different perspectives. Also, although scientist users were not perfect rationalists during online discussions, they were more likely to be both high-quality content contributors and active discussion facilitators.
Treeline shift and tree growth often respond to climatic changes and it is critical to identify and quantify their dynamics. Some regions are particularly sensitive to climate change and the Altai ...Mountains, located in Central and East Asia, are showing unequivocal signs. The mean annual temperature in the area has increased by 1.3-1.7 °C in the last century. As this mountain range has ancient and protected forests on alpine slopes, we focus on determining the treeline structure and dynamics. We integrated in situ fine-scale allometric data with analyses from dendrochronological samples, high-resolution 3D drone photos and new satellite images to study the dynamics and underlying causal mechanisms of any treeline movement and growth changes in a remote preserved forest at the Aktru Research Station in the Altai Mountain. We show that temperature increase has a negative effect on mountain tree growth. In contrast, only younger trees grow at higher altitudes and we document a relatively fast upward shift of the treeline. During the last 52 years, treeline moved about 150 m upward and the rate of movement accelerated until recently. Before the 1950s, it never shifted over 2150-2200 m a.s.l. We suggest that a continuous upward expansion of the treeline would be at the expense of meadow and shrub species and radically change this high-mountain ecosystem with its endemic flora. This documented treeline shift represents clear evidence of the increased velocity of climate change during the last century.
Studies on the dynamics of Alaska boreal forest are sporadic and rare, and forest management in the region has been conducted in the absence of a useful growth model. This paper presents a matrix ...stand growth model to study the dynamics and management of Alaska's boreal forest, with harvests and artificial regeneration being accounted for. The model was calibrated with data from 446 constantly monitored permanent sample plots distributed across interior and south-central Alaska, and was tested to be accurate on an independent validation sample. The present model was applied on a most frequent commercial stand in interior Alaska to study a forest management regime that is being commonly used in the region. The simulation was for 300 years with a 40-year cutting cycle, and management outcomes under various permafrost levels and site elevations were investigated with sensitivity analysis. Despite the comparatively low financial returns, current management regime may generally benefit wildlife species by maintaining continuous forest cover and decent stand diversity, and properly managed forests had potential for timber production and wood-based energy. It was predicted by the model that both permafrost and site elevation had substantial impact on the management outcomes. Other variables being held constant at sample mean, net present value of harvests increased from $434 to $831
ha
−1 and the annual volume of harvest more than tripled from 1.68 to 5.75
m
3
ha
−1
y
−1 as permafrost declined from obvious to unlikely. Managers were also advised to focus on stands on medium elevation (300
m), as stands on lower or higher elevations were expected to produce less harvested volume and net present value. For rural Alaska communities suffering from expensive heating costs, it was suggested that approximately 20
ha of properly managed forest could sustain a household's annual heating requirement, while continuous forest coverage and decent diversity could still be maintained.
The link between gut microbes and autism spectrum disorders (ASD) has been already observed in some studies, but some bacterial families/species were found to be inconsistently up or down regulated. ...This issue has been rarely explored in the Chinese population. In this study, we assessed whether or not gut microbiota dysbiosis was associated with children with ASD in China. We enrolled 45 children with ASD (6-9 years of age; 39 boys and 6 girls) and 45 sex- and age-matched neurotypical children. Dietary and other socio-demographic information was obtained via questionnaires. We characterized the composition of the fecal microbiota using bacterial 16S ribosomal RNA (16S rRNA) gene sequencing. The ASD group showed less diversity and richness of gut microbiota than the neurotypical group, as estimated by the abundance-based coverage estimator index and the phylogenetic diversity index. The analysis of beta diversity showed an altered microbial community structure in the ASD group. After adjustment for confounders and multiple testing corrections, no significant group difference was found in the relative abundance of microbiota on the level of the phylum. At the family level, children with ASD had a lower relative abundance of
than the healthy controls. Moreover, a decrease in the relative abundance of genera
, and
was observed in ASD group. This study provides further evidence of intestinal microbial dysbiosis in ASD and sheds light on the characteristics of the gut microbiome of autistic children in China.
Additive manufacturing (AM) has enabled the fabrication of innovative, geometrically complex components of metallic materials with minimal material waste. However, the application of AM in processing ...Ni superalloys remains challenging because of the high crack susceptibility. To address this problem, a computationally design method was applied to design novel Ni superalloys with low crack proneness as well as decent service performance. Different types of crack formation mechanisms during AM processing, i.e., the hot tear cracks and strain-age cracks, have been considered, while a series of corresponding criteria to quantitively describe the crack susceptibility were parallelly analyzed. To select the most proper criteria as optimization index in alloy design regime, a series of prototype alloys with wide range of alloying elements were printed, with their crack behaviors being quantitively captured. The freezing range criterion and strain-age crack criterion were then determined as the optimization index in the design routine. A genetic algorithm was applied to probe the compositional search domain, while a Pareto front linking the hot tear crack criterion and strain-age crack criterion was constructed by combining results of two separate optimization routes. Novel Ni compositions with optimized crack resistance as well as decent microstructural features were thereby identified. The new solutions are predicted to possess fairly better crack formation resistance compared to existing Ni superalloys. Moreover, the newly designed alloys manage to computationally outperform the existing printable alloys in all aspects of temperature capability, creep properties and oxidation resistance.
Genetic mutations in TAR DNA-binding protein 43 (TARDBP, also known as TDP-43) cause amyotrophic lateral sclerosis (ALS), and an increase in the presence of TDP-43 (encoded by TARDBP) in the ...cytoplasm is a prominent histopathological feature of degenerating neurons in various neurodegenerative diseases. However, the molecular mechanisms by which TDP-43 contributes to ALS pathophysiology remain elusive. Here we have found that TDP-43 accumulates in the mitochondria of neurons in subjects with ALS or frontotemporal dementia (FTD). Disease-associated mutations increase TDP-43 mitochondrial localization. In mitochondria, wild-type (WT) and mutant TDP-43 preferentially bind mitochondria-transcribed messenger RNAs (mRNAs) encoding respiratory complex I subunits ND3 and ND6, impair their expression and specifically cause complex I disassembly. The suppression of TDP-43 mitochondrial localization abolishes WT and mutant TDP-43-induced mitochondrial dysfunction and neuronal loss, and improves phenotypes of transgenic mutant TDP-43 mice. Thus, our studies link TDP-43 toxicity directly to mitochondrial bioenergetics and propose the targeting of TDP-43 mitochondrial localization as a promising therapeutic approach for neurodegeneration.
Alumina ceramics with different sintering temperatures in argon atmosphere were obtained using stereolithography-based 3D printing. The effects of sintering temperature on microstructure and physical ...and mechanical properties were investigated. The results show that the average particle size, shrinkage, bulk density, crystallite size, flexural strength, Vickers hardness, and nanoindentation hardness increased with the increase in sintering temperature, whereas the open porosity decreased with increasing sintering temperature. No change was observed in phase composition, chemical bond, atomic ratio, and surface roughness. For the sintered samples, the shrinkage in Z direction is much greater than that in
X
or
Y
direction. The optimum sintering temperature in argon atmosphere is 1350 °C with a shrinkage of 3.0%, 3.2%, and 5.5% in X, Y, and Z directions, respectively, flexural strength of 26.7 MPa, Vickers hardness of 198.5 HV, nanoindentation hardness of 33.1 GPa, bulk density of 2.5 g/cm3, and open porosity of 33.8%. The optimum sintering temperature was 70 °C higher than that sintering in air atmosphere when achieved the similar properties.
Walnut shell, a renewable and easy-accessible agricultural biowaste, was utilized as a precursor for the preparation of activated carbon materials with KOH activation in this study. After a series of ...activation processes, therefore, the activated carbon derived from walnut shells achieved a specific surface area of 1016.4 m
2
/g. With the advantage of low cost and environmental friendly, the prepared carbon materials have superior electrochemical performance and excellent prospects in the application of supercapacitor electrodes. The morphology and textural properties of the AC samples were examined by N
2
adsorption–desorption, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and FTIR spectra. All the electrode samples exhibited excellent electrochemical performance. The AC-650 electrode achieved a maximum specific capacitance of 169.2 F/g at current density of 0.5 A/g in 6 M KOH electrolyte. This work provided an effective approach for the treatment and utilization of agricultural biowastes, which was worthwhile for economic, environmental, and societal viewpoints.
In this work, the microstructure and tensile properties of DD32 single-crystal (SC) superalloy repaired by laser metal forming (LMF) using pulsed laser have been studied in detail. The ...microstructures of the deposited samples and the tensile-ruptured samples were characterized by optical microscopy (OM), transmission electron microscope (TEM) and scanning electron microscope (SEM). Due to high cooling rate, the primary dendrite spacing in the deposited area (17.2 μm) was apparently smaller than that in the substrate area (307 μm), and the carbides in the deposited samples were also smaller compared with that in the substrate area. The formation of (γ+γ′) eutectic in the initial layer of repaired SC was inhibited because of the high cooling rate. As the deposition proceeded, the cooling rate decreased, and the (γ+γ′) eutectic increased gradually. The (γ+γ′) eutectic at heat-affected zone (HAZ) in the molten pool dissolved partly because of the high temperature at HAZ, but there were still residual eutectics. Tensile test results showed that tensile behavior of repaired SC at different temperatures was closely related to the MC carbides, solidification porosity, γ′ phase, and (γ+γ′) eutectic. At moderate temperature, the samples tested fractured preferentially at the substrate area due to the fragmentation of the coarse MC carbide in the substrate area. At elevated temperature, the (γ+γ′) eutectic and solidification porosity in the deposited area became the source of cracks, which deteriorated the high-temperature properties and made the samples rupture at the deposited area preferentially.
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