We examine the different effects of monetary policy actions and central bank communication on China's stock market bubbles with a Time-varying Parameter SVAR model. We find that with negative ...responses of fundamental component and positive responses of bubble component of asset prices, contractionary monetary policy induces the observed stock prices to rise during periods of large bubbles. By contrast, central bank communication acts on the market through expectation guidance and has more significant effects on stock prices in the long run, which implies that central bank communication be used as an effective long-term instrument for the central bank's policymaking.
Abstract
Originally developed for metrology, optical frequency combs are becoming increasingly pervasive in a wider range of research topics including optical communications, spectroscopy, and radio ...or microwave signal processing. However, application demands in these fields can be more challenging as they require compact sources with a high tolerance to temperature variations that are capable of delivering flat comb spectra, high power per tone, narrow linewidth and high optical signal-to-noise ratio. This work reports the generation of a flat, high power frequency comb in the telecom band using a 17 mm fully-integrated silicon core fibre as a parametric mixer. Our all-fibre, cavity-free source combines the material benefits of planar waveguide structures with the advantageous properties of fibre platforms to achieve a 30 nm bandwidth comb source containing 143 tones with <3 kHz linewidth, 12 dB flatness, and >30 dB OSNR over the entire spectral region.
Two-dimensional materials are ideal platforms for intriguing physics and optoelectronic applications because of their ultrathin thicknesses and excellent properties in optics and electronics. Further ...studies on enhancing the interaction between light and two-dimensional materials by combining metallic nanostructures have generated broad interests in recent years, such as enhanced photoluminescence, strong coupling and functional optoelectronics. In this work, an ultrathin circular polarimeter consisting of chiral plasmonic metasurface and monolayer semiconductor is proposed to detect light with different circular polarization within a compact device. A designed chiral plasmonic metasurface with sub-wavelength thickness is integrated with monolayer MoSe2, and the circular-polarization-dependent photocurrent responses of right and left circularly polarized light for both left- and right-handed metasurfaces are experimentally demonstrated. The photoresponse circular dichroism is also obtained, which further indicates the remarkable performance of the proposed device in detecting and distinguishing circularly polarized light. This design offers a great potential to realize multifunctional measurements in an ultrathin and ultracompact two-dimensional device for future integrated optics and optoelectronic applications with circularly polarized light.
The ability to process optical signals without passing into the electrical domain has always attracted the attention of the research community. Processing photons by photons unfolds new scenarios, in ...principle allowing for unseen signal processing and computing capabilities. Optical computation can be seen as a large scientific field in which researchers operate, trying to find solutions to their specific needs by different approaches; although the challenges can be substantially different, they are typically addressed using knowledge and technological platforms that are shared across the whole field. This significant know-how can also benefit other scientific communities, providing lateral solutions to their problems, as well as leading to novel applications. The aim of this Roadmap is to provide a broad view of the state-of-the-art in this lively scientific research field and to discuss the advances required to tackle emerging challenges, thanks to contributions authored by experts affiliated to both academic institutions and high-tech industries. The Roadmap is organized so as to put side by side contributions on different aspects of optical processing, aiming to enhance the cross-contamination of ideas between scientists working in three different fields of photonics: optical gates and logical units, high bit-rate signal processing and optical quantum computing. The ultimate intent of this paper is to provide guidance for young scientists as well as providing research-funding institutions and stake holders with a comprehensive overview of perspectives and opportunities offered by this research field.
Plastid retrograde signaling plays a key role in coordinating the expression of plastid genes and photosynthesis-associated nuclear genes (PhANGs). Although plastid retrograde signaling can be ...substantially compromised by mitochondrial dysfunction, it is not yet clear whether specific mitochondrial factors are required to regulate plastid retrograde signaling. Here, we show that mitochondrial ATP synthase beta-subunit mutants with decreased ATP synthase activity are impaired in plastid retrograde signaling in Arabidopsis thaliana. Transcriptome analysis revealed that the expression levels of PhANGs were significantly higher in the mutants affected in the AT5G08670 gene encoding the mitochondrial ATP synthase beta-subunit, compared to wild-type (WT) seedlings when treated with lincomycin (LIN) or norflurazon (NF). Further studies indicated that the expression of nuclear genes involved in chloroplast and mitochondrial retrograde signaling was affected in the AT5G08670 mutant seedlings treated with LIN. These changes might be linked to the modulation of some transcription factors (TFs), such as LHY (Late Elongated Hypocotyl), PIF (Phytochrome-Interacting Factors), MYB, WRKY, and AP2/ERF (Ethylene Responsive Factors). These findings suggest that the activity of mitochondrial ATP synthase significantly influences plastid retrograde signaling.
Current bias compensation methods for distributed localization consider the time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements noise, but ignore the negative ...influence by the sensor location uncertainties on source localization accuracy. Therefore, a new bias compensation method for distributed localization is proposed to improve the localization accuracy in this paper. This paper derives the theoretical bias of maximum likelihood estimation when the sensor location errors and positioning measurements noise both exist. Using the rough estimate result by MLE to subtract the theoretical bias can obtain a more accurate source location estimation. Theoretical analysis and simulation results indicate that the theoretical bias derived in this paper matches well with the actual bias in moderate noise level so that it can prove the correctness of the theoretical derivation. Furthermore, after bias compensation, the estimate accuracy of the proposed method achieves a certain improvement compared with existing methods.
Multi-agent systems arise from diverse fields in natural and artificial systems, such as schooling of fish, flocking of birds, coordination of autonomous agents. In multi-agent systems, a typical and ...basic situation is the case where each agent has the tendency to behave as other agents do in its neighborhood. Through computer simulations,
Vicsek et al. (1995) showed that such a simple local interaction rule can lead to a certain kind of cooperative phenomenon (synchronization) of the overall system, if the initial states are randomly distributed and the size of the system population is large. Since this model is of fundamental importance in understanding the multi-agent systems, it has attracted much research attention in recent years. In this paper, we will present a comprehensive theoretical analysis for this class of multi-agent systems under a random framework with large population, but without imposing any connectivity assumptions as did in almost all of the previous investigations. To be precise, we will show that for any given and fixed model parameters concerning with the interaction radius
r
and the agents’ moving speed
v
, the overall system will synchronize as long as the population size
n
is large enough. Furthermore, to keep the synchronization property as the population size
n
increases, both
r
and
v
can actually be allowed to decrease according to certain scaling rates.
Activation of autophagy flux contributed to resistance of breast cancer (BC) cells to current chemotherapeutic drugs, which seriously limited their therapeutic efficacy and facilitated BC recurrence ...in clinic. However, the detailed mechanisms are still not fully understood. In the present study, we identified that inactivation of AMPK-ULK1 signaling cascade mediated protective autophagy sensitized BC cells to doxorubicin in vitro.
Cell counting kit-8 (CCK-8) assay and colony formation assay were performed to evaluate cell proliferation abilities. Trypan blue staining assay was used to examine cell viability, and Annexin V-FITC/PI double staining method was conducted to determine cell apoptosis. The autophagosomes in BC cells were observed and photographed by electronic microscope (EM). Western Blot analysis was employed to examine genes expressions at protein levels.
The parental doxorubicin-sensitive BC (DS-BC) cells were exposed to increasing concentrations of doxorubicin to establish doxorubicin-resistant BC (DR-BC) cells, and the DR-BC cells were much more resistant to high-dose doxorubicin treatment compared to the DS-BC cells. Interestingly, high-dose doxorubicin specifically increased LC3B-II/I ratio, promoted autophagosomes formation and decreased p62 expression levels to facilitate autophagy in DR-BC cells, instead of DS-BC cells, and the autophagy inhibitor 3-methyladenine (3-MA) enhanced the cytotoxic effects of high-dose doxorubicin on DR-BC cells. In addition, we proved that high-dose doxorubicin triggered protective autophagy in DR-BC cells by activating AMPK-ULK1 pathway. Functionally, high-dose doxorubicin increased the expression levels of phosphorylated AMPK (p-AMPK) and ULK1 (p-ULK1) to activate AMPK-ULK1 pathway in DR-BC cells, and the inhibitors for AMPK (compound C) and ULK1 (SBI-0206965) blocked autophagy to promote cell death and slow down cell growth in DR-BC cells treated with high-dose doxorubicin.
Collectively, our in vitro data indicated that blockage of AMPK-ULK1 signaling cascade mediated protective autophagy might be a promising strategy to increase doxorubicin sensitivity for BC treatment.
We demonstrate pulse generation at a repetition rate of 50 GHz by gain switching an injection-locked distributed feedback (DFB) laser. The small-signal BW of the DFB laser was enhanced from an ...intrinsic BW of 30 GHz to 52 GHz due to the joint effects of photon-photon resonance (PPR) and detuned loading. The detuned loading effect is achieved by exploiting the frequency-dependent cavity loss, which results in an increase of the effective differential gain, and correspondingly, the relaxation oscillation frequency. In addition to small-signal measurements, we show that the PPR and the detuned loading effects can also be utilized to improve large signal gain-switching, despite the dynamic changes of the detuned loading condition due to the large signal chirp. By modulating the laser with 50-GHz RF signals, we obtained 50-GHz repetition rate pulses from the gain-switched laser, confirming that the BW enhancement effects are still valid for large-signal modulation. Subsequently, we optically injection lock the gain-switched laser with strong external seeding light, which suppresses the chirp and creates coherent frequency tones with 50 GHz spacing. The optical injection locking (OIL) further enhances the large-signal BW, resulting in narrower pulse width of 9.5 ps (6.2 ps after deconvolution) in the time domain and three sideband peaks above 70% from the peak in the frequency domain (full width half maximum of 130 GHz). Assuming linear chirp, the pulse could be further compressed to 2.4 ps.
Direct structuring of three-dimensional structures by laser powder bed fusion (LPBF) offers a higher degree of freedom in structural design and solves the difficult problem of traditional machining ...for complex structural parts. Here, we report the energy absorption characteristics of different multicellular structures manufactured via LPBF. We evaluate the energy absorption properties for different multicellular structures triangular multicellular structure, quadrilateral multicellular structure, pentagonal multicellular structure (PMS), hexagonal multicellular structure, and octagonal multicellular structure (OMS) by experimental and numerical calculations. The accuracy of the simulation is verified by comparing the deformation and force–displacement curves of different structures. The PMS has the best overall performance, with specific energy absorption and crushing force efficiency being 3331 mJ and 3165.74 J/kg, respectively. At the same time, the shape memory effect of all structures under 15% deformations is more than 95%. However, partial failure of the OMS occurred within 15% of the deformation. Therefore, the problem of partial failure of the structure under low deformation is a critical problem to be solved urgently in the future.
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