Abstract
Cooling the trapped atoms toward their motional ground states is key to applications of quantum simulation and quantum computation. By utilizing nonreciprocal couplings between two atoms, we ...present an intriguing dark-state cooling scheme in Λ-type three-level structure, which is shown superior than the conventional electromagnetically-induced-transparency cooling in a single atom. The effective nonreciprocal couplings can be facilitated either by an atom–waveguide interface or a free-space photonic quantum link. By tailoring system parameters allowed in dark-state cooling, we identify the parameter regions of better cooling performance with an enhanced cooling rate. We further demonstrate a mapping to the dark-state sideband cooling under asymmetric laser driving fields, which shows a distinct heat transfer and promises an outperforming dark-state sideband cooling assisted by collective spin–exchange interactions.
•Current situation of distributed energy resources and blockchain technology in China is investigated.•Michael Porter five forces model about distributed energy resources are presented and ...analyzed.•Strengths, weaknesses, opportunities and threats of “distributed energy resources+ blockchain technology” are illustrated.•How blockchain technology can promote the development of distributed energy resources in China is studied.•The policy recommendations about improving the competiveness of distributed energy resources in China are proposed.
Distributed energy resources are located near users, which can realize energy cascade utilization and improve the energy utilization efficiency. The features of distributed ledgers and smart contract auto-execution possessed by blockchain technology are in line with the requirements of distributed energy resources in billing and settlement, which provides a direction for the application of blockchain technology in the distributed energy resources. The integration of distributed energy resources in China with blockchain technology may break the existing pattern where the production, transportation, distribution and sales of energy are centralized. This paper first summarizes the current status of distributed energy resources in China and blockchain technology, and then uses the Michael Porter five forces model to analyze the competitiveness of distributed energy resources. The rivalry, threat of new entrants, threat of alternatives, bargaining power of suppliers, and bargaining power of buyers in energy industry are presented and analyzed. Based on the competitiveness analysis, the SWOT model is used to analyze the joint development model of “blockchain technology + distributed energy resources”, and the feasibility of blockchain technology applied to distributed energy resources systems is revealed. Finally, the paper puts forward the key conclusions that blockchain technology can enhance the competitiveness of distributed energy resources as well as relevant policy recommendations.
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Aim: We investigated the historical biogeography and diversification of Gentiana L. (Gentianaceae). Our study depicts the origin and dispersal routes of this alpine genus, and the role of the uplift ...of the Qinghai—Tibet Plateau (QTP) and past climate changes as triggers for its diversification. Location: Tibeto-Himalayan region and world-wide mountain habitats. Methods: Our sampling represents more than 50% of the extant Gentiana species, including all sections across their entire geographical ranges. We investigated the evolutionary history of Gentiana using phylogenetic reconstructions (maximum likelihood and Bayesian inference) of ITS, atpB—rbcl and trnL—trnF sequences, as well as molecular dating with BEAST. We tested two approaches of ancestral area reconstructions (DEC, DIVA) in BioGeoBEARS and investigated diversification rates using BAMM. Results: The common ancestor of Gentiana and subtribe Gentianinae lived in the QTP region at around 34 (25—45) million years ago (Ma), and 40 (29—52) Ma respectively. From the surroundings of the QTP, Gentiana lineages dispersed to eastern China, Taiwan, Europe, North and South America, Australia and New Guinea, from mid-Miocene onward (c. 15 Ma—present), with only one older dispersal event to Europe (c. 37—21 Ma). Diversification rates gradually increased over time, and two switches of diversification rates were identified in Gentianinae (c. 7 Ma, simultaneously in the Pneumonanthe/Cruciata lineage and in Tripterospermum). Main conclusions: Gentiana existed in the QTP region throughout most of its uplift history following the India-Asia collision. This region acted as the primary source area for dispersals to many areas of the world. Because steady increase in diversification rates coincides with the extension of the QTP, we argue that the museum theory rather than the explosive radiation theory prevails for gentians in this region, although rare shifts of diversification rates are associated with niche shifts across the alpine/subalpine ecotone.
Abstract
Human mitochondrial chaperonin mHsp60 is essential for mitochondrial function by assisting folding of mitochondrial proteins. Unlike the double-ring bacterial GroEL, mHsp60 exists as a ...heptameric ring that is unstable and dissociates to subunits. The structural dynamics has been implicated for a unique mechanism of mHsp60. We purified active heptameric mHsp60, and determined a cryo-EM structure of mHsp60 heptamer at 3.4 Å. Of the three domains, the equatorial domains contribute most to the inter-subunit interactions, which include a four-stranded β sheet. Our structural comparison with GroEL shows that mHsp60 contains several unique sequences that directly decrease the sidechain interactions around the β sheet and indirectly shorten β strands by disengaging the backbones of the flanking residues from hydrogen bonding in the β strand conformation. The decreased inter-subunit interactions result in a small inter-subunit interface in mHsp60 compared to GroEL, providing a structural basis for the dynamics of mHsp60 subunit association. Importantly, the unique sequences are conserved among higher eukaryotic mitochondrial chaperonins, suggesting the importance of structural dynamics for eukaryotic chaperonins. Our structural comparison with the single-ring mHsp60-mHsp10 shows that upon mHsp10 binding the shortened inter-subunit β sheet is restored and the overall inter-subunit interface of mHsp60 increases drastically. Our structural basis for the mHsp10 induced stabilization of mHsp60 subunit interaction is consistent with the literature that mHsp10 stabilizes mHsp60 quaternary structure. Together, our studies provide structural bases for structural dynamics of the mHsp60 heptamer and for the stabilizing effect of mHsp10 on mHsp60 subunit association.
Medical instruments that are not autoclavable but may become contaminated with high‐risk human papillomaviruses (HPVs) during use must be thoroughly disinfected to avoid the possibility of iatrogenic ...transmission of infection. There is an expectation that prolonged soaking of instruments in the United States Food and Drug Administration‐cleared chemical disinfectant solutions will result in high‐level decontamination, but HPV16 and HPV18 are known to be resistant to commonly used formulations. However, they are susceptible to a variety of oxidative agents, including those based on chlorine. Here, we tested the efficacy of homogeneous hypochlorous acid (HOCl) solutions against mature infectious virions of HPV16 and HPV18 dried onto butadiene styrene coupons and ultrasonic probes. Both viruses were inactivated to >4 log reduction value (LRV) after 15 s on coupons and 5 min on ultrasonic probes. Morphologic changes became evident within those contact times by transmission electron microscopy when HPV16 virus‐like particles were exposed to HOCl under identical conditions. Mass spectrometry analysis of trypsin‐digested products of L1 capsid proteins exposed to HOCl showed that mostly conserved residues were modified by oxidation and that these changes rapidly lead to instability of the protein demonstrable on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). Modifications to these residues may contribute to rapid virus inactivation. The use of homogeneous HOCl solutions for HPV decontamination provides a highly effective means of assuring the safety of nonautoclavable medical instruments.
Non‐enveloped RNA viruses pervade all domains of life. In a cell, they co‐assemble from viral RNA and capsid proteins. Virus‐like particles can form in vitro where virtually any non‐cognate ...polyanionic cargo can be packaged. How only viral RNA gets selected for packaging in vivo, in presence of myriad other polyanionic species, has been a puzzle. Through a combination of charge detection mass spectrometry and cryo‐electron microscopy, it is determined that co‐assembling brome mosaic virus (BMV) coat proteins and nucleic acid oligomers results in capsid structures and stoichiometries that differ from the icosahedral virion. These previously unknown shell structures are strained and less stable than the native one. However, they contain large native structure fragments that can be recycled to form BMV virions, should a viral genome become available. The existence of such structures suggest the possibility of a previously unknown regulatory pathway for the packaging process inside cells.
When RNA viruses assemble inside a cell, they must package selectively their viral genome. How do virus capsids avoid packaging non‐cognate cargo that might out‐compete virus genomes? This work identifies differences in the structure and stoichiometry of native shells with respect to shells encapsulating nucleic acid oligomers. The differences suggest the possibility of a regulatory pathway for the packaging process.
Design and Analysis of Stability-Guaranteed PUFs Wei-Che Wang; Yona, Yair; Diggavi, Suhas N. ...
IEEE transactions on information forensics and security,
2018-April, 2018-4-00, Letnik:
13, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The lack of stability is one of the limitations that constrain physical unclonable function (PUF) from being put in widespread practical use. In this paper, we propose a weak PUF and a strong PUF ...that are both completely stable. These PUFs are called locally enhanced defectivity physical unclonable function (LEDPUF). An LEDPUF is a pure functional PUF that does not require any kinds of correction schemes as conventional parametric PUFs do. The source of randomness of an LEDPUF is extracted from locally enhance defectivity without affecting other parts of the chip. In this paper, we construct a weak LEDPUF by forming arrays of directed self-assembly random connections, and the strong LEDPUF is implemented by using the weak LEDPUF as the key of a keyed-hash message authentication code. Our simulation and statistical results show that the entropy of the weak LEDPUF bits is close to ideal, and the inter-chip Hamming distances of both weak and strong LEDPUFs are about 50%, which means that these LEDPUFs are not only stable but also unique. We develop a new unified framework for evaluating the security of PUFs, based on password security, by using information theoretic tools of guesswork. The guesswork model allows us to quantitatively compare, with a single unified metric, PUFs with varying levels of stability, bias, and available side information. In addition, it generalizes other measures to evaluate the security level, such as min-entropy and mutual information. We evaluate the guesswork-based security of some measured static random access memory and ring oscillator PUFs as an example and compare them with an LEDPUF to show that the stability has a more severe impact on the PUF security than biased responses. Furthermore, we find the guesswork of two new problems: guesswork under the probability of attack failure and the guesswork of strong PUFs that are used for authentication.
Actin cytoskeleton is essential for root hair formation. However, the underlying molecular mechanisms of actin dynamics in root hair formation in response to abiotic stress are largely undiscovered. ...Here, genetic analysis showed that actin-depolymerizing protein ADF7 and actin-bundling protein VILLIN1 (VLN1) were positively and negatively involved in root hair formation of Arabidopsis respectively. Moreover, RT-qPCR, GUS staining, western blotting, and genetic analysis revealed that ADF7 played an important role in inhibiting the expression and function of VLN1 during root hair formation. Filament actin (F-actin) dynamics observation and actin pharmacological experiments indicated that ADF7-inhibited-VLN1 pathway led to the decline of F-actin bundling and thick bundle formation, as well as the increase of F-actin depolymerization and turnover to promote root hair formation. Furthermore, the F-actin dynamics mediated by ADF7-inhibited-VLN1 pathway was associated with the reactive oxygen species (ROS) accumulation in root hair formation. Finally, ADF7-inhibited-VLN1 pathway was critical for osmotic stress-induced root hair formation. Our work demonstrates that ADF7 inhibits VLN1 to regulate F-actin dynamics in root hair formation in response to osmotic stress, providing the novel evidence on the F-actin dynamics and their molecular mechanisms in root hair formation and in abiotic stress.
The upper bound theorem is used in conjunction with Hill’s quadratic yield criterion for determining the force required to upset a solid cylinder. The kinematically admissible velocity field accounts ...for the singular behavior of the real velocity field in the vicinity of the friction surface if the maximum friction law is adopted. The regime of sticking is also taken into consideration. The effect of this regime on the upper bound limit load is revealed. In particular, the kinematically admissible velocity field that includes the regime of sticking may result in a lower upper bound than that with no sticking. The boundary value problem is classified by a great number of geometric and material parameters. Therefore, a systematic parametric analysis of the effect of these parameters on the compression force is practically impossible. An advantage of the solution found is that it provides a quick estimate of this force for any given set of parameters.
Recently, perovskite (PV) oxides with ABO3 structures have attracted considerable interest from scientists owing to their functionality. In this study, CaFeOx is introduced to reveal the resistive ...switching properties and mechanism of oxygen vacancy transition in PV and brownmillerite (BM) structures. BM‐CaFeO2.5 is grown on an Nb‐STO conductive substrate epitaxially. CaFeOx exhibits excellent endurance and reliability. In addition, the CaFeOx also demonstrates an electroforming‐free characteristic and multilevel resistance properties. To construct the switching mechanism, high‐resolution transmission electron microscopy is used to observe the topotactic phase change in CaFeOx. In addition, scanning TEM and electron energy loss spectroscopy show the structural evolution and valence state variation of CaFeOx after the switching behavior. This study not only reveals the switching mechanism of CaFeOx, but also provides a PV oxide option for the dielectric material in resistive random‐access memory (RRAM) devices.
A complex oxide CaFeOx (CFO) is introduced as the dielectric layer in resistive random‐access memory (RRAM), demonstrating excellent RRAM properties, such as electroforming‐free and multilevel data storage. This study provides not only the switching mechanism of the CFO RRAM devices, but also the novel aspect for the RRAM dielectric materials.
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