250 research outputs found
Plastic Population Effects and Conservative Leaf Traits in a Reciprocal Transplant Experiment Simulating Climate Warming in the Himalayas
Climate warming poses considerable challenges for alpine plant species, especially for competitively inferior ones with resource-conservative adaptations to cold climates. The Himalayas are warming at rates considerably faster than the global average, so it is particularly important to assess how and through which mechanisms alpine plant species are affected there. We employed a demographic approach in a climate change experiment, where vegetation turfs were transplanted reciprocally between the central parts of the study speciesâ (Viola biflora L. var. rockiana) range and the warmer range margin, with a temperature difference of ca. 1°C. In addition, turfs were also transplanted outside the range to warmer habitats, simulating two different scenarios of climate warming, +1 and +4°C. Transplanting to warmer sites negatively impacted population growth rates (λ), survival and clonality, but did not affect growth and fecundity, while the productivity of the plant community increased. The reciprocal transplants to the colder habitat showed the opposite effects, for both V. biflora and the plant community, indicating plastic responses of the study species, driven by changes in plantâplant competition. However, the leaf traits underlying the modeled population growth rates were origin-site specific and not affected by the climate-change treatments over the study period, suggesting local adaptation of growth form to competition in the warmer range margin, and to climate adversity in the colder range center. The transplants outside the present speciesâ range showed consistently stronger reductions in population growth rate and survival, with mortality of 90â100% in the +4°C treatment. This illustrates that climatic changes beyond speciesâ present climatic ranges pose a serious risk for range contraction and extinction for Himalayan alpine species in the near future. As V. biflora seems mostly limited by competition under warming, its persistence in a future climate may become increasingly dependent on keeping competitive effects from the surrounding community low, for instance by management interventions like grazing and mowing
PGC-1 α
Aim. To investigate the effect of Tongxinluo (Txl), a Chinese herbal compound, on diabetic peripheral neuropathy (DPN). Methods and Results. Diabetic rat model was established by peritoneal injection of streptozotocin (STZ). Txl ultrafine powder treatment for 16 weeks from the baseline significantly reversed the impairment of motor nerve conductive velocity (MNCV), mechanical hyperalgesia, and nerve structure. We further proved that Tongxinluo upregulates PGC-1α and its downstream factors including COX IV and SOD, which were involved in mitochondrial biogenesis. Conclusion. Our study indicates that the protective effect of Txl in diabetic neuropathy may be attributed to the induction of PGC-1α and its downstream targets. This finding may further illustrate the pleiotropic effect of the medicine
Human MicroRNA Oncogenes and Tumor Suppressors Show Significantly Different Biological Patterns: From Functions to Targets
MicroRNAs (miRNAs) are small noncoding RNAs which play essential roles in many important biological processes. Therefore, their dysfunction is associated with a variety of human diseases, including cancer. Increasing evidence shows that miRNAs can act as oncogenes or tumor suppressors, and although there is great interest in research into these cancer-associated miRNAs, little is known about them. In this study, we performed a comprehensive analysis of putative human miRNA oncogenes and tumor suppressors. We found that miRNA oncogenes and tumor suppressors clearly show different patterns in function, evolutionary rate, expression, chromosome distribution, molecule size, free energy, transcription factors, and targets. For example, miRNA oncogenes are located mainly in the amplified regions in human cancers, whereas miRNA tumor suppressors are located mainly in the deleted regions. miRNA oncogenes tend to cleave target mRNAs more frequently than miRNA tumor suppressors. These results indicate that these two types of cancer-associated miRNAs play different roles in cancer formation and development. Moreover, the patterns identified here can discriminate novel miRNA oncogenes and tumor suppressors with a high degree of accuracy. This study represents the first large-scale bioinformatic analysis of human miRNA oncogenes and tumor suppressors. Our findings provide help for not only understanding of miRNAs in cancer but also for the specific identification of novel miRNAs as miRNA oncogenes and tumor suppressors. In addition, the data presented in this study will be valuable for the study of both miRNAs and cancer
OSNet & MNetO: Two Types of General Reconstruction Architectures for Linear Computed Tomography in Multi-Scenarios
Recently, linear computed tomography (LCT) systems have actively attracted
attention. To weaken projection truncation and image the region of interest
(ROI) for LCT, the backprojection filtration (BPF) algorithm is an effective
solution. However, in BPF for LCT, it is difficult to achieve stable interior
reconstruction, and for differentiated backprojection (DBP) images of LCT,
multiple rotation-finite inversion of Hilbert transform (Hilbert
filtering)-inverse rotation operations will blur the image. To satisfy multiple
reconstruction scenarios for LCT, including interior ROI, complete object, and
exterior region beyond field-of-view (FOV), and avoid the rotation operations
of Hilbert filtering, we propose two types of reconstruction architectures. The
first overlays multiple DBP images to obtain a complete DBP image, then uses a
network to learn the overlying Hilbert filtering function, referred to as the
Overlay-Single Network (OSNet). The second uses multiple networks to train
different directional Hilbert filtering models for DBP images of multiple
linear scannings, respectively, and then overlays the reconstructed results,
i.e., Multiple Networks Overlaying (MNetO). In two architectures, we introduce
a Swin Transformer (ST) block to the generator of pix2pixGAN to extract both
local and global features from DBP images at the same time. We investigate two
architectures from different networks, FOV sizes, pixel sizes, number of
projections, geometric magnification, and processing time. Experimental results
show that two architectures can both recover images. OSNet outperforms BPF in
various scenarios. For the different networks, ST-pix2pixGAN is superior to
pix2pixGAN and CycleGAN. MNetO exhibits a few artifacts due to the differences
among the multiple models, but any one of its models is suitable for imaging
the exterior edge in a certain direction.Comment: 13 pages, 13 figure
BPF Algorithms for Multiple Source-Translation Computed Tomography Reconstruction
Micro-computed tomography (micro-CT) is a widely used state-of-the-art
instrument employed to study the morphological structures of objects in various
fields. Object-rotation is a classical scanning mode in micro-CT allowing data
acquisition from different angles; however, its field-of-view (FOV) is
primarily constrained by the size of the detector when aiming for high spatial
resolution imaging. Recently, we introduced a novel scanning mode called
multiple source translation CT (mSTCT), which effectively enlarges the FOV of
the micro-CT system. Furthermore, we developed a virtual projection-based
filtered backprojection (V-FBP) algorithm to address truncated projection,
albeit with a trade-off in acquisition efficiency (high resolution
reconstruction typically requires thousands of source samplings). In this
paper, we present a new algorithm for mSTCT reconstruction,
backprojection-filtration (BPF), which enables reconstructions of
high-resolution images with a low source sampling ratio. Additionally, we found
that implementing derivatives in BPF along different directions (source and
detector) yields two distinct BPF algorithms (S-BPF and D-BPF), each with its
own reconstruction performance characteristics. Through simulated and real
experiments conducted in this paper, we demonstrate that achieving same
high-resolution reconstructions, D-BPF can reduce source sampling by 75%
compared with V-FBP. S-BPF shares similar characteristics with V-FBP, where the
spatial resolution is primarily influenced by the source sampling.Comment: 22 pages, 12 figure
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Zirconium-Catalyzed Atom-Economical Synthesis of 1,1-Diborylalkanes from Terminal and Internal Alkenes
A general and atom-economical synthesis of 1,1-diborylalkanes from alkenes and a borane without the need for an additional H2 acceptor is reported for the first time. The key to our success is the use of an earth-abundant zirconium-based catalyst, which allows a balance of self-contradictory reactivities (dehydrogenative boration and hydroboration) to be achieved. Our method avoids using an excess amount of another alkene as an H2 acceptor, which was required in other reported systems. Furthermore, substrates such as simple long-chain aliphatic alkenes that did not react before also underwent 1,1-diboration in our system. Significantly, the unprecedented 1,1-diboration of internal alkenes enabled the preparation of 1,1-diborylalkanes. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA
High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator
The discovery of the quantum Hall (QH) effect led to the realization of a
topological electronic state with dissipationless currents circulating in one
direction along the edge of a two dimensional electron layer under a strong
magnetic field. The quantum anomalous Hall (QAH) effect shares a similar
physical phenomenon as the QH effect, whereas its physical origin relies on the
intrinsic spin-orbit coupling and ferromagnetism.Here we report the
experimental observation of the QAH state in V-doped (Bi,Sb)2Te3 films with the
zero-field longitudinal resistance down to 0.00013+-0.00007h/e2 (~3.35+-1.76
ohm), Hall conductance reaching 0.9998+-0.0006e2/h and the Hall angle becoming
as high as 89.993+-0.004degree at T=25mK. Further advantage of this system
comes from the fact that it is a hard ferromagnet with a large coercive field
(Hc>1.0T) and a relative high Curie temperature. This realization of robust QAH
state in hard FMTIs is a major step towards dissipationless electronic
applications without external fields.Comment: 16 pages, 4 figures, this is the final version, accepted by Nature
Materials, forthcomin
MaterialâIndependent 3D Patterning Via TwoâPhoton Lithography and Discontinuous Wetting
The fabrication of complex 3D structures composed of micrometer-sized features made of different functional materials is an immensely important and yet highly challenging task. Here, a method is developed to fabricate multimaterial 3D structures with micrometer precision by combining macroscopic 3D printing (digital light processing), with two-photon lithography (2PL) and material-independent discontinuous dewetting. Specifically, 3D inherently superhydrophobic objects are first printed by DLP, followed by creating hydrophilic micropatterns on their surface using 2PL. By exploiting the effect of discontinuous wetting, the selective deposition of solutions of functional materials into microscopic hydrophilic regions on the surface of 3D structures, with high resolution and great design flexibility is demonstrated. Importantly, the method is material-independent and enables the micropatterning of a variety of functional materials dispersed in aqueous solutions including polydopamine, silica, or Ag nanoparticles. As an exemplary application, it is shown that conductive Ag electrodes can be created on the curved surface of 3D-printed objects to construct structural electronics. The flexibility, high resolution, and material diversity in designing multimaterial 3D structures open exciting new functionalities and possibilities in a variety of applications including advanced electronics, soft robotics, and chemical or bioengineering
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