Abstract
Microlasers, relying on the strong coupling between active particles and optical microcavity, exhibit fundamental differences from conventional lasers, such as multi-threshold/thresholdless ...behavior and nonclassical photon emission. As light sources, microlasers possess extensive applications in precision measurement, quantum information processing, and biochemical sensing. Here we propose a whispering-gallery-mode microlaser scheme, where ultracold alkaline-earth metal atoms, i.e., gain medium, are tightly confined in a two-color evanescent lattice that is in the ring shape and formed around a microsphere. To suppress the influence of the lattice-induced ac Stark shift on the moderately-narrow-linewidth laser transition, the red-detuned trapping beams operate at a magic wavelength while the wavelength of the blue-detuned trapping beam is set close to the other magic wavelength. The tiny mode volume and high quality factor of the microsphere ensure the strong atom-microcavity coupling in the bad-cavity regime. As a result, both saturation photon and critical atom numbers, which characterize the laser performance, are substantially reduced below unity. We explore the lasing action of the coupled system by using the Monte Carlo approach. Our scheme may be potentially generalized to the microlasers based on the forbidden clock transitions, holding the prospect for microscale active optical clocks in precision measurement and frequency metrology.
Active optomechanics Yu, Deshui; Vollmer, Frank
Communications physics,
03/2022, Letnik:
5, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
Cavity optomechanics explores the coupling between optical and mechanical modes mediated by the radiation pressure force. Unlike the passive scheme, the active optomechanics with optical ...gain directly imposes the mechanical motion upon the lasing dynamics, unveiling the intrinsic properties determined by the system itself. Here we numerically explore the general characteristics of the active optomechanics. The effects of the mechanical oscillation on the macroscopic laser include introducing multiple unstable regimes in the lasing phase, shifting the laser central frequency, broadening the laser spectrum, and degrading the laser frequency stability. Reducing the optical gain down to one active atom highlights the quantum nature of atom–cavity and photon–phonon interactions. The one-atom optomechanical microlaser does not only emit nonclassical photons but also generate nonclassical photon–phonon pairs. Our work extends the cavity optomechanics to the active fashion, paving the way towards optomechanical light sources for photonic integrated circuits, on-chip quantum communication, and biosensing.
To explore the feasibility and mechanism of inhibiting miR-429 to improve the permeability of the blood spinal cord barrier (BSCB)
, and provide a new gene therapy target for enhancing the spinal ...cord microenvironment.
First, the immortalized human brain microvascular endothelial cell line (hCMEC/D3) was transfected with the anti-miR-429 antagonist (antagomiR-429) and its negative control (antagomiR-429-NC), respectively. The miR-429 expression of hCMEC/D3 cells was observed by fluorescence microscopy and real-time fluorescence quantitative PCR to verify the transfection efficiency of antagomiR-429. Then the effect of miR-429 on BSCB permeability was observed
. The experiment was divided into 4 groups. The blank control group (group A) was constructed of normal hCMEC/D3 cells and Ha-sc cells to prepare the BSCB model, the hypoxia-induced group (group B), the hypoxia-induced+antagomiR-429-NC group (group C), and the hypoxia-induced+antagomiR-429 group (group D) were constructed of normal, antagomiR-429-NC tran
Abstract
Parity-time (PT) symmetric lasers exploit the modulation of optical gain and loss and have led to important fundamental demonstrations in non-Hermitian physics. The current theoretical ...analysis of PT-symmetric laser physics is performed on the basis of the adiabatic elimination of the medium polarization. This approximation doesn’t hold true for a more general optical system with strong photon-particle interactions, where the Rabi oscillation of active particles plays a non-negligible role in the lasing action. Here, we propose a model that takes into account the internal dynamics of active particles and numerically investigate the PT symmetry of macroscopic- and microscopic-sized laser systems that operate in the strong-coupling regime. The distinct phase diagrams are drawn according to the features of intracavity photon numbers and emission spectra. Our work extends the PT-symmetric optics from the weak- to the strong-coupling limit, potentially paving the way towards nonclassical PT-symmetric light sources for integrated photonic networks and ultrasensitive sensors.
Rice (
) responds to various abiotic stresses during growth. Plant-specific NAM, ATAF1/2, and CUC2 (NAC) transcription factors (TFs) play an important role in controlling numerous vital growth and ...developmental processes. To date, 170 NAC TFs have been reported in rice, but their roles remain largely unknown. Herein, we discovered that the TF OsNAC006 is constitutively expressed in rice, and regulated by H
O
, cold, heat, abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellin (GA), NaCl, and polyethylene glycol (PEG) 6000 treatments. Furthermore, knockout of
using the CRISPR-Cas9 system resulted in drought and heat sensitivity. RNA sequencing (RNA-seq) transcriptome analysis revealed that
regulates the expression of genes mainly involved in response to stimuli, oxidoreductase activity, cofactor binding, and membrane-related pathways. Our findings elucidate the important role of
in drought responses, and provide valuable information for genetic manipulation to enhance stress tolerance in future plant breeding programs.
► Neonatal rats are anesthetized to determine the developing neurotoxicity of propofol. ► Increased neuroapoptosis is observed after single or multiple propofol administration. ► Repeated propofol ...exposure induces behavioral deficits and neurotransmitter decrease. ► Both neuroapoptosis and decreased neurotransmitter contribute to long-term behavioral deficits.
Previous studies have shown that exposure of the immature brain to drugs that block NMDA glutamate receptors or drugs that potentiate GABAA receptors can trigger widespread neuroapoptosis. Almost all currently used general anesthetics have either NMDA receptor blocking or GABAA receptor enhancing properties. Propofol, a new intravenous anesthetic, is widely used in pediatric anesthesia and intensive care practice whose neurotoxicity on brain development remains unknown. We investigated the effects of neonatal propofol anesthesia on neuroapoptosis and long-term spatial learning/memory functions. Propofol was administered to 7 day-old rats either as a single dose or in 7 doses at concentrations sufficient to maintain a surgical plane of anesthesia. Immunohistochemical studies revealed a significant increase in the levels of caspase-3 in the hippocampal CA1 region after propofol administration. At postnatal day 34, light microscopic observations revealed a significant reduction in neuronal density and apparent morphological changes in the pyramidal cells of rats that had received 7 doses of propofol. These rats showed a longer escape latency/path length, less time spent in the target quadrant and fewer original platform crossings in the Morris Water Maze test. This treatment also produced a remarkable reduction in the levels of excitatory neurotransmitters in the cortex and the hippocampus as measured by high performance liquid chromatography. Repeated exposure to propofol induced exposure-time dependent neuroapoptosis and long-term neurocognitive deficits in neonatal rats. The neurocognitive deficits may be attributed to neuronal loss and a reduction of excitatory neurotransmitter release in the cortex and hippocampus.
Located in the northeastern Hunan Province of South China, the Taolin Pb-Zn deposit is one of many metallic deposits structurally controlled by extensional faults in the central segment of the ...Jiangnan Orogen. The deposit occurs in a tectonic breccia zone between the Mufushan pluton and the Neoproterozoic Lengjiaxi Group. Field and microscopic observations reveal that the hydrothermal ore-forming processes at Taolin can be divided into five stages, from early to late: (1) coarse-grained quartz, (2) quartz + fluorite + chlorite + claybank sphalerite (Sp1) + galena + chalcopyrite, (3) quartz + barite + pale-yellow sphalerite (Sp2) + galena + chalcopyrite, (4) quartz ± chalcopyrite, and (5) fine-grained quartz, in which the stages 2 and 3 are regarded as the main Pb-Zn-forming events. LA-ICP-MS analyses show that Sp1 has higher contents of Fe, Mn, Co, In, and Sn, but lower contents of Ge and Sb, relative to the Sp2. Trace element concentrations of the sphalerite suggest a medium-low temperature hydrothermal event dominated in the Taolin deposit and that the ore fluids gradually decreased in the estimated average temperature and became relatively oxidized from stages 2 to 3. The δ
18
O values of ore fluids calculated from in situ analysis on the stages 2 and 3 quartz suggest the ore fluids are from a mixture of magmatic and meteoric waters. The δ
34
S values of sulfides/sulfates from stages 2 and 3 mineralization indicate a dominating magmatic affinity for sulfur. Further, lead isotope compositions for the stages 2 and 3 sulfides are similar to those of the Mufushan pluton, indicating that the ore metals may have been derived from the latter. We thus propose that the Taolin deposit precipitated from a medium-low temperature magmatic-hydrothermal system most likely related to the Mufushan pluton.
This interdisciplinary book covers the fundamentals of optical whispering gallery mode (WGM) microcavities, light-matter interaction, and biomolecular structure with a focus on applications in ...biosensing. Novel biosensors based on the hybridization of WGM microcavities and localized surface plasmon resonances (LSPRs) in metal nanoparticles have emerged as the most sensitive microsystem biodetection technology that boasts single molecule detection capability without the need for amplification and labeling of the analyte. The book provides an ample survey of the physical mechanisms of WGMs and LSPRs for detecting affinity, concentration, size, shape and orientation of biomarkers, while informing the reader about different classes of biomolecules, their optical properties and their importance in label-free clinical diagnostics. For the more advanced reader, advanced applications of WGMs and LSPRs in exploring the fundamental nature of quantum physics are discussed.
The composition of the continental crust of the North China Craton (NCC) is more felsic than that of the average bulk crust, which is regarded to be the result of the delamination of the thickened ...lower crust during Mesozoic. However, whether the thickened continental crust existed and when the delamination event happened along the southern margin of the NCC are still debated. Here, we report geochronological, geochemical and Sr-Nd-Hf-Pb isotopic evidence that granitoids from the Late Jurassic Wuzhangshan pluton and the Early Cretaceous Huashani complex were derived by partial melting of the lower crust with different thickness. Our new data shows that the two lithofacies of the Wuzhangshan pluton were mainly formed between ca. 157 and 156 Ma, whereas the five lithofacies of the Huashani complex were mainly emplaced between ca. 132 and 125 Ma. The Wuzhangshan pluton and the earlier four lithofacies granitoids of the Huashani complex (ca. 160–125 Ma) both display adakitic geochemical features, which are characterized by as high SiO2 (63.26–72.71 wt%), Al2O3 (13.97–16.89 wt%) and Sr (413–1218 ppm) contents, and low Y (6.30–14.98 ppm) and YbN (1.55–4.43), and high Sr/Y (33−112) and (La/Yb)N (11.53–29.72) ratios. They also have high (87Sr/86Sr)i (0.7066–0.7086), and low εNd(t) (−9.9 to −18.8) and εHf(t) (−11 to −26) values, and two-stage Nd and Hf model ages ranging from 2.4 to 1.7 Ga and 2.7 to 1.7 Ga, respectively. In contrast, the late Early Cretaceous (ca. 125–110 Ma) granitoids have higher SiO2 (71.30–76.78 wt%) and lower Sr (64–333 ppm) contents, and lower Sr/Y (17–29) and (La/Yb)N (13.25–18.36) ratios, and similar εNd(t) (−10 to −16) and relatively higher εHf(t) (−10 to −14) values. These geochemical variations suggest that the ca.160–125 Ma granitoids were most probably produced by partial melting of thickened crust (>45 km) with eclogite, garnet amphibolite or amphibolite residues, whereas that the ca. 125–110 Ma granitoids were formed by partial melting of the thinner crust (<33 km). We thus suggest that the NCC likely underwent a synchronous tectonic transformation at ca. 125 Ma from a compressional setting with thickened crust to an intensive extensional setting with thinner crust at ca. 125 Ma, which demonstrates that the lower crust was most likely delaminated.
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•The Late Mesozoic granitoids in the SNCC were mainly produced by partial melting of the amphibolite of the Taihua group.•The older (ca. 160–125 Ma) granitoids display adakitic geochemical features indicating from a thickened crust.•The younger (ca. 125–110 Ma) granitoids show distinct geochemical features implying from a thinner crust.•A tectonic transformation from compression to extension of SNCC at 125 Ma is proposed in this study.
This paper explores applications of stochastic response surface method (SRSM) in the small-signal stability analysis of the power system with probabilistic uncertainties in correlated photovoltaic ...and loads. A detailed model is provided to simulate the dynamics in the PV system. SRSM is presented to approximate the critical damping ratio as a function of independent standard random variables, which are transformed from correlated loads and irradiance by Nataf transformation. Two applications of SRSM are explored, namely, estimating the probability of power system small-signal instability, and providing the emergency control when the system damping is reduced suddenly. The modified two-area four-machine system and IEEE 39-bus 10-machine standard system are used to test SRSM and its applications.
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