Much like ordinary matter, dark matter might consist of elementary particles, and weakly interacting massive particles are one of the prime suspects. During the past decade, the sensitivity of ...experiments trying to directly detect them has improved by three to four orders of magnitude, but solid evidence for their existence is yet to come. We overview the recent progress in direct dark matter detection experiments and discuss future directions.
Abstract
Interest in bringing p- and n-type monolayer semiconducting transition metal dichalcogenides (TMD) into contact to form rectifying pn diode has thrived since it is crucial to control the ...electrical properties in two-dimensional (2D) electronic and optoelectronic devices. Usually this involves vertically stacking different TMDs with pn heterojunction or, laterally manipulating carrier density by gate biasing. Here, by utilizing a locally reversed ferroelectric polarization, we laterally manipulate the carrier density and created a WSe
2
pn homojunction on the supporting ferroelectric BiFeO
3
substrate. This non-volatile WSe
2
pn homojunction is demonstrated with optical and scanning probe methods and scanning photoelectron micro-spectroscopy. A homo-interface is a direct manifestation of our WSe
2
pn diode, which can be quantitatively understood as a clear rectifying behavior. The non-volatile confinement of carriers and associated gate-free pn homojunction can be an addition to the 2D electron–photon toolbox and pave the way to develop laterally 2D electronics and photonics.
This paper aims to reconcile the inconsistent findings about the effects of CEO transformational leadership (CTL) on firm performance by using upper echelon theory to hypothesize and empirically ...demonstrate that CTL triggers exploratory innovation in a firm, which in turn has an inverted U-shaped effect on firm performance. In other words, CTL may only lead to better firm performance at moderate levels of exploratory innovation through optimal utilization of a firm's scarce resources and may actually hurt firm performance at higher levels of exploratory innovation because of suboptimal resource utilization. We also show that CTL's most detrimental effect on firm performance occurs when the contingencies of high technology uncertainty and low demand uncertainty are combined. Data from multiple sources within 288 Chinese firms support most of our hypotheses and provide insights into the complex mechanism by which CTL affects firm performance, especially in an increasingly uncertain global economic environment.
Aculenes are a unique class of norsequiterpenes (C14) that are produced by Aspergillus aculeatus. The nordaucane skeleton in aculenes A–D may be derived from an ent‐daucane precursor through ...demethylation, however, the enzymes involved remain unexplored. We identified the biosynthetic gene cluster and characterized the biosynthetic pathway based on gene inactivation, feeding experiments, and heterologous reconstitution in Saccharomyces cerevisiae and Aspergillus oryzae. We discovered that three cytochrome P450 monoxygenases are required to catalyze the stepwise demethylation process. AneF converts the 12‐methyl group into a carboxylic acid and AneD installs the 10‐hydroxy group for later tautomerization and stabilization. Finally, AneG installs an electron‐withdrawing carbonyl group at the C‐2 position, which triggers C‐12 decarboxylation to yield the nordaucane skeleton. Additionally, a terpene cyclase (AneC) was found that forms a new product (dauca‐4,7‐diene).
Long time no C: Aculenes are a class of norsesquiterpenes (C14) that are derived from daucane sesquiterpenes (C15), but the biosynthetic basis of the demethylation remained unknown. Three novel P450 monooxygenases were discovered to catalyze a stepwise demethylation process, and a new ent‐daucane cyclase was also discovered. This work sheds light on how nature performs enzymatic demethylation and reveals new tools to expand chemical diversity.
Recent advances in next-generation sequencing approaches have revolutionized our understanding of transcriptional expression in diverse systems. However, measurements of transcription do not ...necessarily reflect gene translation, the process of ultimate importance in understanding cellular function. To circumvent this limitation, biochemical tagging of ribosome subunits to isolate ribosome-associated mRNA has been developed. However, this approach, called TRAP, lacks quantitative resolution compared to a superior technology, ribosome profiling. Here, we report the development of an optimized ribosome profiling approach in Drosophila. We first demonstrate successful ribosome profiling from a specific tissue, larval muscle, with enhanced resolution compared to conventional TRAP approaches. We next validate the ability of this technology to define genome-wide translational regulation. This technology is leveraged to test the relative contributions of transcriptional and translational mechanisms in the postsynaptic muscle that orchestrate the retrograde control of presynaptic function at the neuromuscular junction. Surprisingly, we find no evidence that significant changes in the transcription or translation of specific genes are necessary to enable retrograde homeostatic signaling, implying that post-translational mechanisms ultimately gate instructive retrograde communication. Finally, we show that a global increase in translation induces adaptive responses in both transcription and translation of protein chaperones and degradation factors to promote cellular proteostasis. Together, this development and validation of tissue-specific ribosome profiling enables sensitive and specific analysis of translation in Drosophila.
Emotion recognition based on electroencephalography (EEG) is a significant task in the brain-computer interface field. Recently, many deep learning-based emotion recognition methods are demonstrated ...to outperform traditional methods. However, it remains challenging to extract discriminative features for EEG emotion recognition, and most methods ignore useful information in channel and time. This article proposes an attention-based convolutional recurrent neural network (ACRNN) to extract more discriminative features from EEG signals and improve the accuracy of emotion recognition. First, the proposed ACRNN adopts a channel-wise attention mechanism to adaptively assign the weights of different channels, and a CNN is employed to extract the spatial information of encoded EEG signals. Then, to explore the temporal information of EEG signals, extended self-attention is integrated into an RNN to recode the importance based on intrinsic similarity in EEG signals. We conducted extensive experiments on the DEAP and DREAMER databases. The experimental results demonstrate that the proposed ACRNN outperforms state-of-the-art methods.
Twin-field quantum key distribution can overcome the secret key capacity of repeaterless quantum key distribution via single-photon interference. However, to compensate for the channel fluctuations ...and lock the laser fluctuations, the techniques of phase tracking and phase locking are indispensable in experiment, which drastically increase experimental complexity and hinder free-space realization. We herein present an asynchronous measurement-device-independent quantum key distribution protocol that can surpass the secret key capacity even without phase tracking and phase locking. Leveraging the concept of time multiplexing, asynchronous two-photon Bell-state measurement is realized by postmatching two interference detection events. For a 1 GHz system, the new protocol reaches a transmission distance of 450 km without phase tracking. After further removing phase locking, our protocol is still capable of breaking the capacity at 270 km. Intriguingly, when using the same experimental techniques, our protocol has a higher key rate than the phase-matching-type twin-field protocol. In the presence of imperfect intensity modulation, it also has a significant advantage in terms of the transmission distance over the sending-or-not-sending-type twin-field protocol. With high key rates and accessible technology, our work provides a promising candidate for practical scalable quantum communication networks.
Postsynthetic ion exchange of Co2(μ-Cl)2(btta) (MAF-X27-Cl, H2bbta =1H,5H-benzo(1,2-d:4,5-d′)bistriazole) possessing open metal sites on its pore surface yields a material Co2(μ-OH)2(bbta) ...(MAF-X27-OH) functionalized by both open metal sites and hydroxide ligands, giving drastically improved electrocatalytic activities for the oxygen evolution reaction (an overpotential of 292 mV at 10.0 mA cm–2 in 1.0 M KOH solution). Isotope tracing experiments further confirm that the hydroxide ligands are involved in the OER process to provide a low-energy intraframework coupling pathway.
A
bstract
Chiral and deconfinement phase transitions at finite temperature
T
and quark number chemical potential
μ
are simultaneously studied in the quenched dynamical holographic QCD model within ...the Einstein-Dilaton-Maxwell framework. By calculating the corresponding order parameters, i.e., the chiral condensate and Polyakov loop, it is shown that the transition lines of these two phase transitions are separated in the
T − μ
plane. The deconfinement phase transition is shown to be always of crossover type and the transition line depends weakly on the baryon number density. Differently, the chiral transition is of crossover at small baryon number density and it turns to be of first order at sufficient large baryon number density. A critical endpoint (CEP), at which the transition becomes second order type, appears in the chiral transition line. This is the first time to realize the CEP of chiral phase transition in the (
T, μ
) plane using the holographic EMD (Einstein-Maxwell-Dilaton) model for two flavour case. It is observed that between these two phase transition lines, there is a region with chiral symmetry restored and color degrees still confined, which could be considered as the quarkyonic phase. Qualitatively, this behavior is in consistent with the result in the Polyakov-loop improved Nambu-Jona-Lasinio (PNJL) model.
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