36 research outputs found
A vector spectrum analyzer of 55.1 THz spectral bandwidth and 99 kHz frequency resolution
The analysis of optical spectra - emission or absorption - has been arguably
the most powerful approach for discovering and understanding matters. The
invention and development of many kinds of spectrometers have equipped us with
versatile yet ultra-sensitive diagnostic tools for trace gas detection, isotope
analysis, and resolving hyperfine structures of atoms and molecules. With
proliferating data and information, urgent and demanding requirements have been
placed today on spectrum analysis with ever-increasing spectral bandwidth and
frequency resolution. These requirements are especially stringent for broadband
laser sources that carry massive information, and for dispersive devices used
in information processing systems. In addition, spectrum analyzers are expected
to probe the device's phase response where extra information is encoded. Here
we demonstrate a novel vector spectrum analyzer (VSA) that is capable to
characterize passive devices and active laser sources in one setup. Such a
dual-mode VSA can measure loss, phase response and dispersion property of
passive devices. It also can coherently map a broadband laser spectrum into the
RF domain. The VSA features a bandwidth of 55.1 THz (1260 to 1640 nm),
frequency resolution of 99 kHz, and dynamic range of 56 dB. Meanwhile, our
fiber-based VSA is compact and robust. It requires neither high-speed
modulators and photodetectors, nor any active feedback control. Finally, we
successfully employ our VSA for applications including characterization of
integrated dispersive waveguides, mapping frequency comb spectra, and coherent
light detection and ranging (LiDAR). Our VSA presents an innovative approach
for device analysis and laser spectroscopy, and can play a critical role in
future photonic systems and applications for sensing, communication, imaging,
and quantum information processing
Topology hierarchy of transition metal dichalcogenides built from quantum spin Hall layers
The evolution of the physical properties of two-dimensional material from
monolayer limit to the bulk reveals unique consequences from dimension
confinement and provides a distinct tuning knob for applications. Monolayer
1T'-phase transition metal dichalcogenides (1T'-TMDs) with ubiquitous quantum
spin Hall (QSH) states are ideal two-dimensional building blocks of various
three-dimensional topological phases. However, the stacking geometry was
previously limited to the bulk 1T'-WTe2 type. Here, we introduce the novel
2M-TMDs consisting of translationally stacked 1T'-monolayers as promising
material platforms with tunable inverted bandgaps and interlayer coupling. By
performing advanced polarization-dependent angle-resolved photoemission
spectroscopy as well as first-principles calculations on the electronic
structure of 2M-TMDs, we revealed a topology hierarchy: 2M-WSe2, MoS2, and
MoSe2 are weak topological insulators (WTIs), whereas 2M-WS2 is a strong
topological insulator (STI). Further demonstration of topological phase
transitions by tunning interlayer distance indicates that band inversion
amplitude and interlayer coupling jointly determine different topological
states in 2M-TMDs. We propose that 2M-TMDs are parent compounds of various
exotic phases including topological superconductors and promise great
application potentials in quantum electronics due to their flexibility in
patterning with two-dimensional materials
Adenovirus-Vectored Drug-Vaccine Duo as a Rapid-Response Tool for Conferring Seamless Protection against Influenza
Few other diseases exert such a huge toll of suffering as influenza. We report here that intranasal (i.n.) administration of E1/E3-defective (ΔE1E3) adenovirus serotype 5 (Ad5) particles rapidly induced an anti-influenza state as a means of prophylactic therapy which persisted for several weeks in mice. By encoding an influenza virus (IFV) hemagglutinin (HA) HA1 domain, an Ad5-HA1 vector conferred rapid protection as a prophylactic drug followed by elicitation of sustained protective immunity as a vaccine for inducing seamless protection against influenza as a drug-vaccine duo (DVD) in a single package. Since Ad5 particles induce a complex web of host responses, which could arrest influenza by activating a specific arm of innate immunity to impede IFV growth in the airway, it is conceivable that this multi-pronged influenza DVD may escape the fate of drug resistance that impairs the current influenza drugs
De-escalating chemotherapy for stage I–II gastric neuroendocrine carcinoma? A real-world competing risk analysis
Abstract Background The role of adjuvant chemotherapy in gastric neuroendocrine neoplasms (GNEC) has not been well clarified yet. The study was designed to investigate the potential effect of adjuvant chemotherapy in stage I–II GNEC patients and construct a predictive nomogram. Method Stage I–II GNEC patients were included in the Surveillance, Epidemiology, and End Results (SEER) database and divided into chemotherapy and no-chemotherapy groups. We used Kaplan–Meier survival analyses, propensity score matching (PSM), and competing risk analyses. The predictive nomogram was then built and validated. Results Four hundred four patients with stage I–II GNEC were enrolled from the SEER database while 28 patients from Hangzhou TCM Hospital were identified as the external validation cohort. After PSM, similar 5-year cancer-specific survival was observed in two groups. The outcomes of competing risk analysis indicated a similar 5-year cumulative incidence of cancer-specific death (CSD) between the two cohorts (35.4% vs. 31.4%, p = 0.731). And there was no significant relation between chemotherapy and CSD in the multivariate competing risks regression analysis (HR, 0.79; 95% CI, 0.48–1.31; p = 0.36). Furthermore, based on the variables from the multivariate analysis, a competing event nomogram was created to assess the 1-, 3-, and 5-year risks of CSD. The 1-, 3-, and 5-year area under the receiver operating characteristic curve (AUC) values were 0.770, 0.759, and 0.671 in the training cohort, 0.809, 0.782, and 0.735 in the internal validation cohort, 0.786, 0.856, and 0.770 in the external validation cohort. Furthermore, calibration curves revealed that the expected and actual probabilities of CSD were relatively consistent. Conclusion Stage I–II GNEC patients could not benefit from adjuvant chemotherapy after surgery. De-escalation of chemotherapy should be considered for stage I–II GNEC patients. The proposed nomogram exhibited excellent prediction ability
Chemogenetic and optogenetic stimulation of zona incerta GABAergic neurons ameliorates motor impairment in Parkinson’s disease
Summary: Parkinson’s disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra and leads to progressive motor dysfunction. While studies have focused on the basal ganglia network, recent evidence suggests neuronal systems outside the basal ganglia are also related to PD pathogenesis. The zona incerta (ZI) is a predominantly inhibitory subthalamic region for global behavioral modulation. This study investigates the role of GABAergic neurons in the ZI in a mouse model of 6-hydroxydopamine (6-OHDA)-induced PD. First, we found a decrease in GABA-positive neurons in the ZI, and then the mice used chemogenetic/optogenetic stimulation to activate or inhibit GABAergic neurons. The motor performance of PD mice was significantly improved by chemogenetic/optogenetic activation of GABAergic neurons, and repeated chemogenetic activation of ZI GABAergic neurons increased the dopamine content in the striatum. Our work identifies the role of ZI GABAergic neurons in regulating motor behaviors in 6-OHDA-lesioned PD model mice