分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
摘要： Protein disulfide-isomerase (PIN) was the first protein-folding catalyst to be characterized, half a century ago. It plays critical roles in a variety of physiological events by displaying oxidoreductase and redox-regulated chaperone activities. This review provides a brief history of the identification of PDI as both an enzyme and a molecular chaperone and of the recent advances in studies on the structure and dynamics of PDI, the substrate binding and release, and the cooperation with its partners to catalyze oxidative protein folding and maintain ER redox homeostasis. In this review, we highlight the structural features of PDI, including the high interdomain flexibility, the multiple binding sites, the two synergic active sites, and the redox-dependent conformational changes. (C) 2015 Elsevier Inc. All rights reserved.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We propose to introduce non-minimal couplings of Affleck-Dine (AD) field to gravity by adding the coupling of AD field to the Ricci scalar curvature. As the Jordan frame supergravity always predict $|\Phi|^2 {\cal R}/6$ type coupling for scalars with canonical kinetic terms, we propose a way to realize the required $c_0|\Phi|^2 {\cal R}$-type couplings with generic $c_0$ for canonical complex scalar fields after SUSY breaking. The impacts of such non-minimal gravitational couplings for AD field is shown, especially on the Q-balls formation and the associated gravitational wave (GW) productions. New form of scalar potential for AD field in the Einstein frame is obtained. By numerical simulations, we find that, with non-minimal gravitational coupling to AD field, Q-balls can successfully form even with the choice of non-negative $K$ parameter for $\xi>0$. The associated GW productions as well as their dependences on the $\xi$ parameter are also discussed.
分类： 生物学 >> 生物物理学 >> 衰老生物学 提交时间： 2016-05-05
摘要： microRNA-9 (miR-9) is highly expressed in the nervous system across species and plays essential roles in neurogenesis and axon growth; however, little is known about the mechanisms that link miR-9 with dendrite growth. Using an in vivo model of Drosophila class I dendrite arborization (da) neurons, we show that miR-9a, a Drosophila homolog of mammalian miR-9, downregulates the cadherin protein Flamingo (Fmi) thereby attenuating dendrite development in a non-cell autonomous manner. In miR-9a knockout mutants, the dendrite length of a sensory neuron ddaE was significantly increased. Intriguingly, miR-9a is specifically expressed in epithelial cells but not in neurons, thus the expression of epithelial but not neuronal Fmi is greatly elevated in miR-9a mutants. In contrast, overexpression of Fmi in the neuron resulted in a reduction in dendrite growth, suggesting that neuronal Fmi plays a suppressive role in dendrite growth, and that increased epithelial Fmi might promote dendrite growth by competitively binding to neuronal Fmi. Fmi has been proposed as a G protein-coupled receptor (GPCR), we find that neuronal G protein Gq (Gq), but not Go, may function downstream of Fmi to negatively regulate dendrite growth. Taken together, our results reveal a novel function of miR-9a in dendrite morphogenesis. Moreover, we suggest that Gq might mediate the intercellular signal of Fmi in neurons to suppress dendrite growth. Our findings provide novel insights into the complex regulatory mechanisms of microRNAs in dendrite development, and further reveal the interplay between the different components of Fmi, functioning in cadherin adhesion and GPCR signalling. (c) 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 225-237, 2016
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Using the Floquet Hamiltonian derived based on the time-dependent perturbation theory, we investigated the quasienergy bands of a one-dimensional time-Floquet photonic crystal. The time-Floquet photonic crystal contains two alternating layers labeled as A and B, and the permittivity of A layer is modulated periodically in time. We showed that the quasienergy bands are reciprocal when the modulation function is a function of time only, while the quasienergy bands could be nonreciprocal when the permittivity is modulated in both time and space through an unique combination. In the former case, the coupling between the positive (negative) and positive (negative) bands results in quasienergy gaps, while the coupling between the positive and negative bands leads to pairs of exception points, when the modulation is on the real part of the permittivity. In the latter case, the coupling between the positive (negative) and positive (negative) bands still results in quasienergy gaps. However, the coupling between the positive and negative bands leads to quasienergy gaps at a small modulation speed and pairs of exceptional points at a high modulation speed.
分类： 心理学 >> 应用心理学 提交时间： 2023-09-14
摘要： Objective: Nowadays, young adults are facing stressors from several aspects. They have already become the most anxious groups in Chinese society and in risk of developing a series of anxiety disorders. The theory of challenge-hindrance stress was proposed to explain the positive and negative outcomes of different stressors. It has been widely tested mostly in the field of organization and management. In the current study, we used the challenge-hindrance stress theory to clarify the association between stress in daily life and anxiety. We also examined the HPA-axis function buffering the influence of daily stress on anxiety.Methods: we used the edited Chinese version of challenge-hindrance stress scales to measure challenge and hindrance stress over 6 months. The level of anxiety was measured by state-trait anxiety inventory. We also carried out a Trier Social Stress Test (TSST) in laboratory and recorded the change of cortisol level during the 60 minutes right after the acute stress.Results: Results show that the recent level of hindrance stress positively predicts trait anxiety, but the level of challenge stress does not predict trait anxiety. It is also found that, the cortisol decline rate during the recovery of acute stress moderates the association between stress and anxiety. To be exact, individuals with low cortisol decline rate could not recover to baseline level even after rather long rest, and hindrance stress in their lives would lead to higher level of anxiety. But for individuals who has high cortisol decline rate after acute stress, they recover fast to baseline after the stressor disappear, and they become less anxious although facing the same level of hindrance stressLimitations: Firstly, we only examined anxiety but left other distal outcomes of stress such as wellbeing to be further studied. Secondly, we choose the decline rate of cortisol to represent the HPA-axis function instead of taking different systems into consideration. Thirdly, stress appraisal could be further examined in the challenge-hindrance stress researches in addition to different stressors.Conclusions: The current study checked the association between stress and anxiety under the framework of challenge-hindrance stress. We examined the moderating mechanism of HPA-axis function, and discussed the effect of physiological toughness from the respective of resources and demands.
分类： 地球科学 >> 地理学 提交时间： 2021-12-30 合作期刊: 《干旱区科学》
摘要： The Tarim River is the longest inland river in China and is considered as an important river to protect the oasis economy and environment of the Tarim Basin. However, excessive exploitation and over-utilization of natural resources, particularly water resources, have triggered a series of ecological and environmental problems, such as the reduction in the volume of water in the main river, deterioration of water quality, drying up of downstream rivers, degradation of vegetation, and land desertification. In this study, the land use/land cover change (LUCC) responses to ecological water conveyance in the lower reaches of the Tarim River were investigated using ENVI (Environment for Visualizing Images) and GIS (Geographic Information System) data analysis software for the period of 1990–2018. Multi-temporal remote sensing images and ecological water conveyance data from 1990 to 2018 were used. The results indicate that LUCC covered an area of 2644.34 km2 during this period, accounting for 15.79% of the total study area. From 1990 to 2018, wetland, farmland, forestland, and artificial surfaces increased by 533.42 km2 (216.77%), 446.68 km2 (123.66%), 284.55 km2 (5.67%), and 57.51 km2 (217.96%), respectively, whereas areas covered by grassland and other land use/land cover types, such as Gobi, bare soil, and deserts, decreased by 103.34 km2 (14.31%) and 1218.83 km2 (11.75%), respectively. Vegetation area decreased first and then increased, with the order of 2010<2000<1990<2018. LUCC in the overflow and stagnant areas in the lower reaches of the Tarim River was mainly characterized by fragmentation, irregularity, and complexity. By analyzing the LUCC responses to 19 rounds of ecological water conveyance in the lower reaches of the Tarim River from 2000 to the end of 2018, we proposed guidelines for the rational development and utilization of water and soil resources and formulation of strategies for the sustainable development of the lower reaches of the Tarim River. This study provides scientific guidance for optimal scheduling of water resources in the region.
分类： 地球科学 >> 空间物理学 提交时间： 2016-05-13
摘要： Aerosol Absorbing Index (AAI) can be used for the observation of the absorbing aerosol including dust, biomass burning and volcano ash etc. Recently, with much more aerosol pollution events occurring, atmospheric environment is getting worse in China. The AAI derived from FY-3/TOU has been used for the atmospheric aerosol pollution observation since 2013 by China Meteorological Administration. In this paper, the precision factors analysis of AAI retrieval from TOU is made. Based on the analysis, the wavelengths most suitable for AAI retrieval are 354 nm and 388 nm. Besides, considering the low spatial resolution of TOU (50x50 km(2)), a modified UV sensor is proposed with characters of much smaller size, higher sensitivity (SNR>4000) and higher spatial resolution (<5 km) which is much more suitable for observing aerosol pollution events, especially in urban areas.
分类： 生物学 >> 生态学 提交时间： 2017-11-17
摘要： Background: Lipoic acid is a cofactor for a-keto acid dehydrogenase system that is involved in the central energy metabolism. In the apicomplexan parasite, Plasmodium, lipoic acid protein ligase 1 (LplA1) and LplA2 catalyse the ligation of acquired lipoic acid to the dehydrogenase complexes in the mitochondrion. The enzymes LipB and LipA mediate lipoic acid synthesis and ligation to the enzymes in the apicoplast. These enzymes in the lipoic acid metabolism machinery have been shown to play important roles in the biology of Plasmodium parasites, but the relationship between the enzymes is not fully elucidated. Methods: We used an anhydrotetracycline (ATc)-inducible transcription system to generate transgenic P. berghei parasites in which the lplA1 gene was conditionally knocked out (LplA1-cKO). Phenotypic changes and the lplA1 and lplA2 gene expression profiles of cloned LplA1-cKO parasites were analysed.Results: LplA1-cKO parasites showed severely impaired growth in vivo in the first 8 days of infection, and retarded blood-stage development in vitro, in the absence of ATc. However, these parasites resumed viability in the late stage of infection and mounted high levels of parasitemia leading to the death of the hosts. Although lplA1 mRNA expression was regulated tightly by ATc during the whole course of infection, lplA2 mRNA expression was significantly increased in the late stage of infection only in the LplA1-cKO parasites that were not exposed to ATc. Conclusions: The lplA2 gene can be activated as an alternative pathway to compensate for the loss of LplA1 activity and to maintain lipoic acid metabolism.
分类： 化学 >> 化学物理学 提交时间： 2023-12-09
摘要： Based on the energy conversion of the dynamic electric effect from the solid/liquid contact double electric layer is the dynamic electromotive potential, this paper studies the static appearance and the release of the electric field energy of the solid/liquid contact double electric layer, so a special capacitor (P/L/N capacitor) of solid conductor P / polar liquid L / solid conductor N is constructed. The observations based on experiments are as follows: (i) the contact double electric layer derived from the internal potential difference polarization of the solid conductor / polar liquid is equivalent to the external electric field polarization of the ordinary capacitor. The formation process of the contact double electric layer is the spontaneous charging process of the P/L/N capacitor, and the P/L/N capacitor still shows the electric field energy of the contact double electric layer. (ii) Because the polarized external potential difference of the solid conductor / polar liquid contacting the double electric layer is always less than the internal potential difference, the short-circuit P/L/N capacitor also has a continuous electromotive force after the discharge, statically releasing the electric field energy contacting the double electric layer. (iii) The contact double electric layer of solid conductor / polar liquid is produced spontaneously caused by mutual contact, and it is also a self-organizing process of absorbing the environmental heat energy into the electric field energy of the contact double electric layer. P/L/N capacitors realize thermoelectric conversion by releasing the electric field energy of the contact double electric layer. The above-mentioned phenomenon provides the possibility for the development of self-generated capacitors and self-supplied power supply.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Noise-like pulses (NLP) are extremely sought after in many fields. Here, we experimentally and numerically investigated the generation of noise-like pulses in an all-normal-dispersion fiber laser with weak spectrum filtering. With the insertion of the grating as a tunable spectrum filter, the laser operates at a stable dissipative soliton state with a 3.84 ps duration. Replacing the grating with a mirror, NLPs with double-scale intensity autocorrelation trace is ultimately attained. Numerical simulations are performed in detail and demonstrated that with the absence of a spectrum filter, the stable state cannot be established but form the random pulse cluster. The random pulse cluster achieves dynamic stability with suitable feedback, and the NLP is ultimately generated. The NLP here is directly evolved by the initial noise, and no other states occur during its evolution. These explorations could deepen the understanding of NLP and enrich the complex dynamics of the ANDi ultrafast fiber laser.
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： We recalculate the two-loop beta functions for three gauge couplings taking into account all low energy threshold corrections in split supersymmetry (split-SUSY) which assumes a very high scalar mass scale MSMSM_S . We find that in split-SUSY with a gaugi
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： We propose to split the sparticle spectrum from the hierarchy between the GUT scale and the Planck scale. A split supersymmetric model, which gives non-universal gaugino masses, is built with proper high dimensional operators in the framework of SO(10) GU
分类： 物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-12-28
摘要： From generalized gravity mediation we build a SUGRA scenario in which the gluino is much heavier than the electroweak gauginos at the GUT scale. We find that such a non-universal gaugino scenario with very heavy gluino at the GUT scale can be naturally ob
分类： 物理学 >> 核物理学 提交时间： 2016-09-20
摘要： We interpret the recent ATLAS multi-jet search results using 20.3 fb-1 data at sqrt(s)=8 TeV in the context of searching for excited quarks. Within the effective field theory framework, using the null results of that search, our analysis shows that the excited quark mass below 5 TeV can be excluded at the 95% confidence level. Our analysis also indicates that when the validation of effective field theory is considered, the limit can be largely compromised.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-15
摘要： In split-supersymmetry (split-SUSY), gluino is a metastable particle and thus can freeze out in the early universe. The late decay of such a long-life gluino into the lightest supersymmetric particle (LSP) may provide much of the cosmic dark-matter content. In this work, assuming the LSP is gravitino produced from the late decay of the metastable gluino, we examine the Wilkinson microwave anisotropy probe (WMAP) dark-matter constraints on the gluino mass. We find that to provide the full abundance of dark matter, the gluino must be heavier than about 14 TeV and thus not accessible at the CERN large hadron collider (LHC).
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
Chang, Shenghai
Sun, Dapeng
Liang, Huanhuan
Li, Jun
Guo, Lu
Wang, Xiangli
Guan, Chengcheng
Boruah, Bhargavi M.
Yuan, Lingmin
Feng, Feng
Yang, Mingrui
Liu, Yingfang
Wang, Jia
Wang, Jiawei
Wang, Hong-Wei
Wojdyla, Justyna
Wang, Meitian
Li, Lanjuan
Liu, Yingfang
Wang, Lulan
摘要： Replication and transcription of influenza virus genome mainly depend on its RNA-dependent RNA polymerase (RdRP), composed of the PA, PB1, and PB2 subunits. Although extensively studied, the underlying mechanism of the RdRP complex is still unclear. Here we report the biochemical characterization of influenza RdRP subcomplex comprising PA, PB1, and N terminus of PB2, which exist as dimer in solution and can assemble into a tetramer state, regulated by vRNA promoter. Using single-particle cryo-electron microscopy, we have reconstructed the RdRP tetramer complex at 4.3 angstrom, highlighting the assembly and interfaces between monomers within the tetrameric structure. The individual RdRP subcomplex contains all the characterized motifs and appears as a cage-like structure. High-throughput mutagenesis profiling revealed that residues involved in the oligomer state formation are critical for viral life cycle. Our results lay a solid base for understanding the mechanism of replication of influenza and other negative-stranded RNA viruses.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： We show that Maxwell's demon-like nonreciprocity can be supported in a class of non-Hermitian gyrotropic metasurfaces in the linear regime. The proposed metasurface functions as a transmission-only Maxwell's demon operating at a pair of photon energies. Based on multiple scattering theory, we construct a dual-dipole model to explain the underlying mechanism that leads to the antisymmetric nonreciprocal transmission. The results may inspire new designs of compact nonreciprocal devices for photonics.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： In this paper, we present a dual-mode adaptive singular value decomposition ghost imaging (A-SVD GI), which can be easily switched between the modes of imaging and edge detection. It can adaptively localize the foreground pixels via a threshold selection method. Then only the foreground region is illuminated by the singular value decomposition (SVD) - based patterns, consequently retrieving high-quality images with fewer sampling ratios. By changing the selecting range of foreground pixels, the A-SVD GI can be switched to the mode of edge detection to directly reveal the edge of objects, without needing the original image. We investigate the performance of these two modes through both numerical simulations and experiments. We also develop a single-round scheme to halve measurement numbers in experiments, instead of separately illuminating positive and negative patterns in traditional methods. The binarized SVD patterns, generated by the spatial dithering method, are modulated by a digital micromirror device (DMD) to speed up the data acquisition. This dual-mode A-SVD GI can be applied in various applications, such as remote sensing or target recognition, and could be further extended for multi-modality functional imaging/detection.
分类： 物理学 >> 核物理学 提交时间： 2016-09-18
摘要： Considering the mass splitting between three active neutrinos, we represent the new constraints on the sum of neutrino mass ∑mν by updating the anisotropic analysis of Baryon Acoustic Oscillation (BAO) scale in the CMASS and LOWZ galaxy samples from Data Release 12 of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS DR12). Combining the BAO data of 6dFGS, MGS, LOWZ and CMASS with Planck~2015 data of temperature anisotropy and polarizations of Cosmic Microwave Background (CMB), we find that the 95% C.L. upper bounds on ∑mν refer to ∑mν,NH<0.18 eV for normal hierarchy (NH), ∑mν,IH<0.20 eV for inverted hierarchy (IH) and ∑mν,DH<0.15 eV for degenerate hierarchy (DH) respectively, and the normal hierarchy is slightly preferred than the inverted one (Δχ2≡χ2NH−χ2IH≃−3.4). In addition, the additional relativistic degrees of freedom and massive sterile neutrinos are neither favored at present.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-15
摘要： We split the two-Higgs-doublet model by assuming very different vevs for the two doublets: the vev is at weak scale (174 GeV) for the doublet Phi(1) and at neutrino-mass scale (10(-2) - 10(-3) eV) for the doublet Phi(2). Phi(1) is responsible for giving masses to all fermions except neutrinos; while Phi(2) is responsible for giving neutrino masses through its tiny vev without introducing the see-saw mechanism. Among the predicted five physical scalars H, h, A(0) and H-+/-, the CP-even scalar h is as light as 10(-2) - 10(-3) eV while the others are at weak scale. We identify h as the cosmic-dark-energy field and the other CP-even scalar H as the Standard Model Higgs boson; while the CP-odd A(0) and the charged H-+/- are the exotic scalars to be discovered at future colliders. Also we demonstrate a possible dynamical origin for the doublet Phi(2) from neutrino condensation caused by some unknown dynamics.
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