Large-scale continuous-variable dual-rail cluster entangled state based on spatial mode comb.

In recent continuous-variable (CV) multipartite entanglement researches, the number of fully inseparable light modes has been increased dramatically by the introduction of a multiplexing scheme in either the time domain or the frequency domain. In this paper, we propose a scheme that a large-scale (≥ 20) CV dual-rail cluster entangled state is established based on a spatial mode comb in a self-imaging optical parametric oscillator, which is pumped by two spatial Laguerre-Gaussian modes with different polarization and identical frequency. A sufficient condition of full inseparability for a CV dual-rail cluster entangled state is used to evaluate the degree of quantum entanglement. It is shown that entanglement exists over a wide range of analyzing frequency and pump parameter. We have found a new scheme that uses the optical parametric cavity to generate a large-scale entanglement based on optical spatial mode comb. The presented system will be hopefully as a practical entangled source for quantum information.

8-beam local oscillator array at 4.7 THz generated by a phase grating and a quantum cascade laser.

We present an 8-beam local oscillator (LO) for the astronomically significant [OI] line at 4.7 THz. The beams are generated using a quantum cascade laser (QCL) in combination with a Fourier phase grating. The grating is fully characterized using a third order distributed feedback (DFB) QCL with a single mode emission at 4.7 THz as the input. The measured diffraction efficiency of 74.3% is in an excellent agreement with the calculated result of 75.4% using a 3D simulation. We show that the power distribution among the diffracted beams is uniform enough for pumping an array receiver. To validate the grating bandwidth, we apply a far-infrared (FIR) gas laser emission at 5.3 THz as the input and find a very similar performance in terms of efficiency, power distribution, and spatial configuration of the diffracted beams. Both results represent the highest operating frequencies of THz phase gratings reported in the literature. By injecting one of the eight diffracted 4.7 THz beams into a superconducting hot electron bolometer (HEB) mixer, we find that the coupled power, taking the optical loss into account, is in consistency with the QCL power value.

Efficiency of multi-beam Fourier phase gratings at 1.4 THz.

We compare the results of simulated and measured power efficiency and far-field beam pattern, for two reflective Fourier phase gratings, designed to generate 2 × 2 and 2 × 4 beams respectively from a single-beam, coherent source at 1.4 THz. The designed surface structures were manufactured on aluminum plates by a computer numerical control (CNC) micro-milling machine. Despite small differences between the designed and fabricated gratings, we measured power efficiencies of both gratings to be around 70%, which is in a good agreement with the simulated values. We also find a good agreement between the simulated and measured diffracted beam size and spatial distribution. We demonstrate the application of both gratings as multiple beam local oscillators to simultaneously pump (or operate) a 4-pixel array of superconducting heterodyne mixers.

[Effect of HIF-2α on regulating CDCP1 to promote hepatocellular carcinoma metastasis].

Objective: To investigate the effect of hypoxia inducible factor 2α (HIF-2α) on regulating CUB domain-containing protein 1 (CDCP1) and its role in hepatocellular carcinoma metastasis. Methods: HIF-2α-knocked down and HIF-2α-stably overexpressing cells (MHCC97H) were prepared by small interfering RNA (siRNA) and lentivirus transfection, respectively. The expression of CDCP1 protein and mRNA in the above cells was detected by western blot and real-time PCR. The effect of HIF-2α on cell invasion ability was determined by Transwell assay. Furthermore, immunohistochemical staining was performed to detect the expression of CDCP1 in human HCC tissue samples. Results: Both HIF-2α and CDCP1 were induced under hypoxic conditions. The activation of CDCP1 under hypoxic conditions was dependent on the expression of HIF-2α.When HIF-2α was overexpressed, the mRNA level of CDCP1 was greatly upregulated (5.92±0.28, P<0.05). When HIF-2α was knocked down by siRNA for 48 h and 72 h, the expression of CDCP1 was significantly downregulated (48 h: 0.25±0.04; 72 h: 0.18±0.02, all P<0.05). Moreover, analysis of human HCC samples showed that CDCP1 expression was correlated with tumor-free survival (P<0.05). Conclusions: The results of this study indicate that the expression of CDCP1 is regulated by HIF-2α and is correlated with the progression of HCC. Inhibition of HIF-2α/CDCP1 may play certain inhibitory role in the metastasis of HCC.

Scheme for efficient extraction of low-frequency signal beyond the quantum limit by frequency-shift detection.

Low-frequency (Hz~kHz) squeezing is very important in many schemes of quantum precision measurement. But it is more difficult than that at megahertz-frequency because of the introduction of laser low-frequency technical noise. In this paper, we propose a scheme to obtain a low-frequency signal beyond the quantum limit from the frequency comb in a non-degenerate frequency and degenerate polarization optical parametric amplifier (NOPA) operating below threshold with type I phase matching by frequency-shift detection. Low-frequency squeezing immune to laser technical noise is obtained by a detection system with a local beam of two-frequency intense laser. Furthermore, the low-frequency squeezing can be used for phase measurement in Mach-Zehnder interferometer, and the signal-to-noise ratio (SNR) can be enhanced greatly.

Background rates of x-ray transition-edge sensor micro-calorimeters under a frequency domain multiplexing readout for solar axion-like particles' detection.

We report on the x-ray background rate measured with transition-edge sensors (TES) micro-calorimeters under frequency-domain multiplexing (FDM) readout as a possible technology for future experiments aiming at a direct detection of axion-like particles. Future axion helioscopes will make use of large magnets to convert axions into photons in the keV range and x-ray detectors to observe them. To achieve this, a detector array with high spectral performance and extremely low background is necessary. TES are single-photon, non-dispersive, high-resolution micro-calorimeters and represent a possible candidate for this application. We have been developing x-ray TES micro-calorimeters and an FDM readout technology in the framework of the space-borne x-ray astronomical observatories. We show that the current generation of our detectors is already a promising technology for a possible axion search experiment, having measured an x-ray background rate of 2.2(2) × 10-4 cm-2 s-1 keV-1 with a cryogenic demonstrator not optimized for this specific application. We then make a prospect to further improve the background rate down to the required value (<10-7 cm-2 s-1 keV-1) for an axion-search experiment, identifying no fundamental limits to reach such a level.

Terahertz wavefronts measured using the Hartmann sensor principle.

We demonstrate for the first time that the Hartmann wavefront sensor (HWS) principle can be applied for characterizing the wavefronts of terahertz (THz) electromagnetic radiation. The THz Hartmann wavefront sensor consists of a metallic plate with an array of holes and a two-dimensional scanable pyro-electric detector. The THz radiation with different wavefronts was generated by a far-infrared gas laser operated at 2.5 THz in combination with a number of objects that result in known wavefronts. To measure the wavefront, a beam passing through an array of holes generates intensity spots, for which the positions of the individual spot centroids are measured and compared with reference positions. The reconstructed wavefronts are in good agreement with the model expectations.

Frequency division multiplexing readout of a transition edge sensor bolometer array with microstrip-type electrical bias lines.

We demonstrate multiplexed readout of 43 transition edge sensor (TES) bolometers operating at 90 mK using a frequency division multiplexing (FDM) readout chain with bias frequencies ranging from 1 to 3.5 MHz and a typical frequency spacing of 32 kHz. We improve the previously reported performance of our FDM system by two important steps. First, we replace the coplanar wires with microstrip wires, which minimize the cross talk from mutual inductance. From the measured electrical cross talk (ECT) map, the ECT of all pixels is carrier leakage dominated. Only five pixels show an ECT level higher than 1%. Second, we reduce the thermal response speed of the TES detectors by a factor of 20 by increasing the heat capacity of the TES, which allows us to bias all TES detectors below 50% in transition without oscillations. We compare the current-voltage curves and noise spectra of the TESs measured in single-pixel mode and multiplexing mode. We also compare the noise equivalent power (NEP) and the saturation power of the bolometers in both modes, where 38 pixels show less than 10% difference in NEP and 5% difference in saturation power when measured in the two different modes. The measured noise spectrum is in good agreement with the simulated noise based on measured parameters from an impedance measurement, confirming that our TES is dominated by phonon noise.

[Comparative analysis on prevalence of tobacco and e-cigarettes uses in junior middle school students in Shanghai, 2013 and 2019].

Objective: To examine the prevalence and trend of tobacco and e-cigarettes uses and identify the influencing factors for smoking behavior in junior middle school students in Shanghai, and provide data support and scientific basis for the development of tobacco control intervention strategy in adolescents. Methods: Multi-stage stratified random sampling method was used to select junior middle school students in 8 districts and 10 districts in Shanghai in 2013 and in 2019 respectively. Information about tobacco and e-cigarettes uses in the students were collected by using self-administrated questionnaire. The prevalence of tobacco and e-cigarettes uses were calculated, the difference between two years was compared with χ2 test. The influencing factors were identified by multivariate logistic regression analysis. Results: In 2019, the current smoking rate was 0.6% in junior middle school students in Shanghai, and the smoking attempt rate was 2.9%, both were lower than the levels in 2013 (0.7% and 6.9%). The current use rate of e-cigarettes was 0.6% in 2019,with no significant change compared with 2013 (0.6%). The proportion of the students who had heard of e-cigarettes in 2019 (78.4%) was higher than that in 2013 (47.2%). In 2019, the second-hand smoke (SHS) exposure rate at home, in both indoor and outdoor public places and on public transportations was 72.5%, which was slightly lower than the level in 2013 (73.0%), the differences were all significant (P<0.05). In 2019, the students seeing close friend smoking (OR=27.381, 95%CI: 12.037-62.287), seeing someone smoking in school (OR=2.477, 95%CI: 1.155-5.312), believing that SHS may not be harmful (OR=8.471, 95%CI: 1.464-49.005) had higher possibility of smoking. Being aged ≥15 years (compared with being aged ≤12 years, OR=8.688, 95%CI: 1.922-39.266), exposure to SHS in outdoor public place (OR=8.608, 95%CI: 1.048-70.692), close friend smoking (OR=8.115, 95%CI: 1.754-37.545) were positively associated with e-cigarettes use, and believing that smoking results in uncomfortable social contact [compared with believing that smoking results in comfortable social contact (OR=0.105,95%CI: 0.018-0.615)] were negatively associated with e-cigarettes use, the difference was significant (P<0.05). Conclusion: The prevalence of tobacco and e-cigarette uses in junior middle school students in Shanghai remained at a low level in recent years. The SHS exposure rate in junior middle school students is high. Smoking behavior of junior middle school students is closely related to personal attitude and awareness of tobacco, exposure to SHS, peer smoking and the situation of tobacco control in schools. Prevention and intervention should be carried out from multi-dimensions to effectively protect teenagers from tobacco hazards.

Performance and uniformity of a kilo-pixel array of Ti/Au transition-edge sensor microcalorimeters.

Uniform large transition-edge sensor (TES) arrays are fundamental for the next generation of x-ray space observatories. These arrays are required to achieve an energy resolution ΔE < 3 eV full width at half maximum (FWHM) in the soft x-ray energy range. We are currently developing x-ray microcalorimeter arrays for use in the future laboratory and space-based x-ray astrophysics experiments and ground-based spectrometers. In this contribution, we report on the development and the characterization of a uniform 32 × 32 pixel array with 140 × 30 µm2 Ti/Au TESs with the Au x-ray absorber. We report on extensive measurements on 60 pixels in order to show the uniformity of our large TES array. The averaged critical temperature is Tc = 89.5 ± 0.5 mK, and the variation across the array (∼1 cm) is less than 1.5 mK. We found a large region of detector's bias points between 20% and 40% of the normal-state resistance where the energy resolution is constantly lower than 3 eV. In particular, results show a summed x-ray spectral resolution ΔEFWHM = 2.50 ± 0.04 eV at a photon energy of 5.9 keV, measured in a single-pixel mode using a frequency domain multiplexing readout system developed at SRON/VTT at bias frequencies ranging from 1 MHz to 5 MHz. Moreover, we compare the logarithmic resistance sensitivity with respect to temperature and current (α and ß, respectively) and their correlation with the detector's noise parameter M, showing a homogeneous behavior for all the measured pixels in the array.

Electrical cross talk of a frequency division multiplexing readout for a transition edge sensor bolometer array.

We have characterized and mapped the electrical cross talk (ECT) of a frequency division multiplexing (FDM) system with a transition edge sensor (TES) bolometer array, which is intended for space applications. By adding a small modulation at 120 Hz to the AC bias voltage of one bolometer and measuring the cross talk response in the current noise spectra of the others simultaneously, we have for the first time mapped the ECT level of 61 pixels with a nominal frequency spacing of 32 kHz in a 61 × 61 matrix and a carrier frequency ranging from 1 MHz to 4 MHz. We find that about 94% of the pixels show an ECT level of less than 0.4%. Only the adjacent pixels reach this level, and the ECT for the rest of the pixels is less than 0.1%. We also observe higher ECT levels, up to 10%, between some of the pixels, which have bundled long, parallel coplanar wires connecting TES bolometers to inductor-capacitor filters. In this case, the high mutual inductances dominate. To mitigate this source of ECT, the coplanar wires should be replaced by microstrip wires in the array. Our study suggests that an FDM system can have a relatively low ECT level, e.g., around 0.4% if the frequency spacing is 30 kHz. Our results successfully demonstrate a low electrical cross talk for a space FDM technology.

Frequency shift algorithm: Application to a frequency-domain multiplexing readout of x-ray transition-edge sensor microcalorimeters.

In the frequency-domain multiplexing (FDM) scheme, transition-edge sensors (TESs) are individually coupled to superconducting LC filters and AC biased at MHz frequencies through a common readout line. To make efficient use of the available readout bandwidth and to minimize the effect of non-linearities, the LC resonators are usually designed to be on a regular grid. The lithographic processes, however, pose a limit on the accuracy of the effective filter resonance frequencies. Off-resonance bias carriers could be used to suppress the impact of intermodulation distortions, which, nonetheless, would significantly affect the effective bias circuit and the detector spectral performance. In this paper, we present a frequency shift algorithm (FSA) to allow off-resonance readout of TESs, while preserving the on-resonance bias circuit and spectral performance, demonstrating its application to the FDM readout of an x-ray TES microcalorimeter array. We discuss the benefits in terms of mitigation of the impact of intermodulation distortions at the cost of increased bias voltage and the scalability of the algorithm to multi-pixel FDM readout. We show that with FSA, in the multi-pixel and frequencies shifted on-grid, the line noises due to intermodulation distortion are placed away from the sensitive region in the TES response and the x-ray performance is consistent with the single-pixel, on-resonance level.

[Risk factors for surgical site infection after emergency abdominal surgery: a multicenter cross-sectional study in China].

Objective: Surgical site infection (SSI) is the most common infectious complication after emergency abdominal surgery (EAS). To a large extent, most SSI can be prevented, but there are few relevant studies in China. This study mainly investigated the current situation of SSI occurrence after EAS in China, and further explored risk factors for SSI occurrence. Methods: Multi-center cross-sectional study was conducted. Clinical data of patients undergoing EAS in 33 hospitals across China between May 1, 2019 and June 7, 2019 were prospectively collected, including perioperative data and microbial culture results from infected incisions. The primary outcome was the incidence of SSI after EAS, while the secondary outcomes were postoperative hospital stay, ICU occupancy rate, length of ICU stay, hospitalization cost, and mortality within postoperative 30 days. Univariate and multivariate logistic regression models were used to analyze the risk factors of SSI after EAS. Results: A total of 660 EAS patients aged (47.9±18.3) years were enrolled in this study, including 56.5% of males (373/660). Forty-nine (7.4%) patients developed postoperative SSI. The main pathogen of SSI was Escherichia coli [culture positive rate was 32.7% (16/49)]. As compared to patients without SSI, those with SSI were more likely to be older (median 56 years vs. 46 years, U=19 973.5, P<0.001), male [71.4% (35/49) vs. 56.1% (343/611), χ(2)=4.334, P=0.037] and diabetes [14.3% (7/49) vs. 5.1% (31/611), χ(2)=5.498, P=0.015]; with-lower preoperative hemoglobin (median: 122.0 g/L vs. 143.5 g/L, U=11 471.5, P=0.006) and albumin (median: 35.5 g/L vs. 40.8 g/L, U=9452.0, P<0.001), with higher blood glucose (median: 6.9 mmol/L vs. 6.0 mmol/L, U=17 754.5, P<0.001); with intestinal obstruction [32.7% (16/49) vs. 9.2% (56/611), χ(2)=25.749, P<0.001], with ASA score 3-4 [42.9% (21/49) vs. 13.9% (85/611), χ(2)=25.563, P<0.001] and with high surgical risk [49.0% (24/49) vs. 7.0% (43/611), χ(2)=105.301, P<0.001]. The main operative procedure resulting in SSI was laparotomy [81.6%(40/49) vs. 35.7%(218/611), χ(2)=40.232, P<0.001]. Patients with SSI experienced significantly longer operation time (median: 150 minutes vs. 75 minutes, U=25 183.5, P<0.001). In terms of clinical outcome, higher ICU occupancy rate [51.0% (25/49) vs. 19.5% (119/611), χ(2)=26.461, P<0.001], more hospitalization costs (median: 44 000 yuan vs. 15 000 yuan, U=24 660.0, P<0.001), longer postoperative hospital stay (median: 10 days vs. 5 days, U=23 100.0, P<0.001) and longer ICU occupancy time (median: 0 days vs. 0 days, U=19 541.5, P<0.001) were found in the SSI group. Multivariate logistic regression analysis showed that the elderly (OR=3.253, 95% CI: 1.178-8.985, P=0.023), colorectal surgery (OR=9.156, 95% CI: 3.655-22.937, P<0.001) and longer operation time (OR=15.912, 95% CI:6.858-36.916, P<0.001) were independent risk factors of SSI, while the laparoscopic surgery (OR=0.288, 95% CI: 0.119-0.694, P=0.006) was an independent protective factor for SSI. Conclusions: For patients undergoing EAS, attention should be paid to middle-aged and elderly patients and those of colorectal surgery. Laparoscopic surgery should be adopted when feasible and the operation time should be minimized, so as to reduce the incidence of SSI and to reduce the burden on patients and medical institutions.

Phase locking of a 2.7 THz quantum cascade laser to a microwave reference.

We demonstrate the phase locking of a 2.7 THz metal-metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x12) from a microwave synthesizer at approximately 15 GHz. Both laser and reference radiations are coupled into a bolometer mixer, resulting in a beat signal, which is fed into a phase-lock loop. The spectral analysis of the beat signal confirms that the QCL is phase locked. This result opens the possibility to extend heterodyne interferometers into the far-infrared range.

A six-degree-of-freedom micro-vibration acoustic isolator for low-temperature radiation detectors based on superconducting transition-edge sensors.

Dilution and adiabatic demagnetization refrigerators based on pulse tube cryocoolers are nowadays used in many low temperature physics experiments, such as atomic force and scanning tunneling microscopy, quantum computing, radiation detectors, and many others. A pulse tube refrigerator greatly simplifies the laboratory activities being a cryogen-free system. The major disadvantage of a pulse tube cooler is the high level of mechanical vibrations at the warm and cold interfaces that could substantially affect the performance of very sensitive cryogenic instruments. In this paper, we describe the performance of a very simple mechanical attenuation system used to eliminate the pulse-tube-induced low frequency noise of the superconducting transition-edge sensors under development for the instruments of the next generation of infra-red and X-ray space observatories.

An acetylcholinesterase purified from the greenbug (Schizaphis graminum) with some unique enzymological and pharmacological characteristics.

An acetylcholinesterase (AChE, EC 3.1.1.7) was purified from the greenbug, Schizaphis graminum (Rondani). The maximum velocities (Vmax) for hydrolyzing acetylthiocholine (ATC), acetyl-(beta-methyl) thiocholine (AbetaMTC), propionylthiocholine, and S-butyrylthiocholine were 78.0, 67.0, 37.4, and 2.3 micromol/min/mg, and the Michaelis constants (Km) were 57.6, 60.6, 31.3, and 33.4 microM, respectively. More than 98% of AChE activity was inhibited by 10 microM eserine or BW284C51, but only 7% of the activity was inhibited by ethopropazine at the same concentration. Based on the substrate and inhibitor specificities, the purified enzyme appeared to be a true AChE. Nondenaturing polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing of the purified AChE revealed three molecular forms. The isoelectric points were 7.3 for the major form and 6.3 and 7.1 for two minor forms. The major form of purified AChE showed molecular masses of 129 kDa for its native protein and 72 kDa for its subunits on SDS-PAGE. However, the purified AChE exhibited some distinctive characteristics including: (1) lack of affinity to the affinity ligand 3-(carboxyphenyl) ethyldimethyl ammonium, which has been used widely in purification of AChE from various insect species; and (2) 20-200-fold higher substrate-inhibition thresholds for ATC and AbetaMTC than AChE from other insect species. These biochemical properties may reflect structural differences of AChE purified from the greenbug compared with that from other insect species.

Molecular cloning and characterization of a greenbug (Schizaphis graminum) cDNA encoding acetylcholinesterase possibly evolved from a duplicate gene lineage.

An acetylcholinesterase (AChE, EC 3.1.1.7) cDNA was cloned and characterized from a greenbug (Schizaphis graminum (Rondani)) cDNA library. The complete cDNA (3283 bp) contains a 2028-bp open reading frame encoding 676 amino acid residues. The putative AChE preproenzyme has a 17 amino acid signal peptide, a 78 amino acid activation peptide and a mature enzyme of 581 amino acid residues. The first nine amino acid residues (YTSDDPLII) that were determined by sequencing the N-terminus of a 72-kDa AChE purified from the greenbug matched the nine residues deduced from the cDNA. The key amino acid residues, including the three residues Ser206 (200 in Torpedo), Glu332 (327) and His446 (440) forming a catalytic triad, three pairs of cysteine putatively forming intrachain disulfide bonds, and 10 out of the 14 aromatic residues lining the active site gorge of the Torpedo AChE, are conserved. However, Ser336 (Phe331) in the greenbug substituted an aromatic amino acid residue that is conserved in all other known AChEs. Northern blot analysis of mRNA revealed a 3.7-kb transcript, and Southern blot analysis suggested a single copy of this gene in the greenbug. The deduced amino acid sequence is most similar to AChE1 of the nematodes Caenorhabditis briggsae and C. elegans with 43% identity. Phylogenetic analysis showed that the greenbug AChE formed a cluster with those of nematodes, a squid and ticks, and grouped out of the insect cluster. This result suggests that the cloned gene evolved from a different duplicate gene lineage of insect AChEs.

Comparative toxicity of selected organophosphate insecticides against resistant and susceptible clones of the greenbug, Schizaphis graminum (Homoptera: aphididae).

Comparative toxicity of selected organophosphate (OP) insecticides against resistant and susceptible clones of the greenbug, Schizaphis graminum, were studied both in vitro and in vivo. Two resistant (OR-1 and OR-2) clones of the greenbug showed marginal to high levels of resistance to all seven OPs tested, ranging from 11- to 327-fold greater than those of a susceptible (OSS) clone. The OR-1 clone showed lower levels of resistance to phenyl (parathion and parathion-methyl) and heterocyclic (chlorpyrifos) OPs than to aliphatic OPs (dimethoate, omethoate, disulfoton, and demeton-S-methyl), whereas the OR-2 clone showed a rather broad spectrum of resistance to nearly all OP insecticides examined. In vitro inhibition of acetylcholinesterase (AChE) using six selected OP oxon analogues showed that alterations of AChE were involved in resistance to all OP compounds examined in both the OR-1 and OR-2 clones. Although the levels of insensitivity of AChE to these OPs were relatively low, ranging from 1.1- to 3.8-fold, the insensitivity spectrum of AChE to different OPs was rather broad. The general esterase activity in the OR-1 and OR-2 clones was 1.3-8. 4-fold higher than that in the OSS clone, depending on the substrates used. The AChE activity in both the OR-1 and OR-2 clones was 1.8-fold higher than that in the OSS clone. High resistance levels of the OR-2 clone to phenyl and heterocyclic OPs appeared to be associated with the ability of the esterases to hydrolyze beta-naphthyl acetate and more hydrophobic substrates.