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Narrowband microwave generation with tuneable frequency is demonstrated by illuminating a photoconductive semiconductor switch (PCSS) with a burst-mode fibre laser. The whole system is composed of a high-power linearly polarized burst-mode pulsed fibre laser and a linear-state PCSS. To obtain a high-performance microwave signal, a desired envelope of burst is necessary and a pulse pre-compensation technique is adopted to avoid envelope distortion induced by the gain-saturation effect. Resulting from the technique, homogenous peak power distribution in each burst is ensured. The maximum energy of the laser burst pulse reaches 200 μJ with a burst duration of 100 ns at the average power of 10 W, corresponding to a peak power of 4 kW. When the PCSS is illuminated by the burst-mode fibre laser, narrowband microwave generation with tuneable frequency (0.80–1.12 GHz) is obtained with a power up to 300 W. To the best of the authors’ knowledge, it is the first demonstration of frequency-tuneable narrowband microwave generation based on a fibre laser. The high-power burst-mode fibre laser reported here has great potential for generating high-power arbitrary microwave signals for a great deal of applicable demands such as smart adaptive radar and intelligent high-power microwave systems.
Understanding the patterns of treatment response is critical for the treatment of patients with schizophrenia; one way to achieve this is through using a longitudinal dynamic process study design.
This study aims to explore the response trajectory of antipsychotics and compare the treatment responses of seven different antipsychotics over 6 weeks in patients with schizoprenia (trial registration: Chinese Clinical Trials Registry Identifier: ChiCTR-TRC-10000934).
Data were collected from a multicentre, randomised open-label clinical trial. Patients were evaluated with the Positive and Negative Syndrome Scale (PANSS) at baseline and follow-up at weeks 2, 4 and 6. Trajectory groups were classified by the method of k-means cluster modelling for longitudinal data. Trajectory analyses were also employed for the seven antipsychotic groups.
The early treatment response trajectories were classified into a high-trajectory group of better responders and a low-trajectory group of worse responders. The results of trajectory analysis showed differences compared with the classification method characterised by a 50% reduction in PANSS scores at week 6. A total of 349 patients were inconsistently grouped by the two methods, with a significant difference in the composition ratio of treatment response groups using these two methods (χ2 = 43.37, P < 0.001). There was no differential contribution of high- and low trajectories to different drugs (χ2 = 12.52, P = 0.051); olanzapine and risperidone, which had a larger proportion in the >50% reduction at week 6, performed better than aripiprazole, quetiapine, ziprasidone and perphenazine.
The trajectory analysis of treatment response to schizophrenia revealed two distinct trajectories. Comparing the treatment responses to different antipsychotics through longitudinal analysis may offer a new perspective for evaluating antipsychotics.
Gust/turbulence–leading edge interaction is a significant source of airfoil broadband noise. An approach often used to predict the sound is based on Amiet’s flat-plate solution. Analytical studies have been conducted to investigate the influences of airfoil geometries, non-uniform mean flows and turbulence statistics, which, however, were often too convoluted. In this work, the problem is revisited by proposing simple corrections to the standard flat-plate solution to account for the effect of non-uniform mean flows of real airfoils. A key step in the method is to use a new space–time transformation that is analogous to the Prandtl–Glauert transformation to simplify the sound governing equation with spatially varying coefficients to a classical wave equation, which is then solved using the Schwarzschild technique as in Amiet’s solution. The impacts of Mach number, wavenumber and airfoil geometry on the prediction accuracy are investigated for both single-frequency and broadband cases, and the results are compared against high-fidelity simulations. It predicts the sound reduction by the airfoil thickness, and reveals that the reduction is caused by the non-uniform streamwise velocity. The limitations of the model are discussed and the approximation errors are estimated. In general, the prediction error increases with the airfoil thickness, the sound frequency and the flow Mach number. Nevertheless, in all cases studied in this work, the proposed correction can effectively improve the prediction accuracy of the flat-plate solution much more efficiently compared to numerical solutions of the Euler equations using computational aeroacoustics.
Emergency department (ED) crowding is associated with increased morbidity and mortality. Its etiology is multifactorial, and frequent ED use (defined as more or equal to five visits per year) is a major contributor to high patient volumes. Our primary objective is to characterize the frequent user population. Our secondary objective is to examine risk factors for frequent emergency use.
We conducted a retrospective cohort study of pediatric emergency department (PED) visits at the Montreal Children’s Hospital using the Système Informatique Urgence (SIURGE), electronic medical record database. We analysed the relation between patient’s characteristics and the number of PED visits over a 1-year period following the index visit.
Patients totalling 52,088 accounted for 94,155 visits. Of those, 2,474 (4.7%) patients had five and more recurrent visits and accounted for 16.6% (15,612 visits) of the total PED visits. Lower level of acuity at index visit (odds ratio [OR] 0.85) was associated with a lower number of recurrent visits. Lower socioeconomic status (social deprivation index OR 1.09, material deprivation index OR 1.08) was associated with a higher number of recurrent visits. Asthma (OR 1.57); infectious ear, nose, and sinus disorders (OR 1.33); and other respiratory disorders (OR 1.56) were independently associated with a higher incidence of a recurrent visit within the year following the first visit.
Our study is the first Canadian study to assess risk factors of frequent pediatric emergency use. The identified risk factors and diagnoses highlight the need for future evidence-based, targeted innovative research evaluating strategies to minimize ED crowding, to improve health outcomes and to improve patient satisfaction.
The Qiangtang Metamorphic Belt (QMB) was considered to have either formed in situ by amalgmation of the North and South Qiangtang blocks or been underthrust from the Jinsha suture and exhumed in the interior of a single ‘Qiangtang Block’. A new Sphaeroschwagerina fusuline fauna discovered in the Raggyorcaka Lake area supports the interpretation that the North and South Qiangtang blocks were separated by a wide ocean during Asselian (Early Permian) time, indicating that the QMB was formed by the suturing of the Palaeotethys Ocean along the Longmu Co-Shuanghu suture.
The mitochondrial genome is maternally inherited in animals, despite the fact that paternal mitochondria enter oocytes during fertilization. Autophagy and ubiquitin-mediated degradation are responsible for the elimination of paternal mitochondria in Caenorhabditis elegans; however, the involvement of these two processes in the degradation of paternal mitochondria in mammals is not well understood. We investigated the localization patterns of light chain 3 (LC3) and ubiquitin in mouse and porcine embryos during preimplantation development. We found that LC3 and ubiquitin localized to the spermatozoon midpiece at 3 h post-fertilization, and that both proteins were colocalized with paternal mitochondria and removed upon fertilization during the 4-cell stage in mouse and the zygote stage in porcine embryos. Sporadic paternal mitochondria were present beyond the morula stage in the mouse, and paternal mitochondria were restricted to one blastomere of 4-cell embryos. An autophagy inhibitor, 3-methyladenine (3-MA), did not affect the distribution of paternal mitochondria compared with the positive control, while an autophagy inducer, rapamycin, accelerated the removal of paternal mitochondria compared with the control. After the intracytoplasmic injection of intact spermatozoon into mouse oocytes, LC3 and ubiquitin localized to the spermatozoon midpiece, but remnants of undegraded paternal mitochondria were retained until the blastocyst stage. Our results show that paternal mitochondria colocalize with autophagy receptors and ubiquitin and are removed after in vitro fertilization, but some remnants of sperm mitochondrial sheath may persist up to morula stage after intracytoplasmic spermatozoon injection (ICSI).
Confocal Raman microspectroscopy (CRM) has emerged as a powerful approach to visualize the compositional distribution in lignocellulosic biomass of cell walls. In this work, the applicability of CRM for imaging the topochemical correlation between lignin and hydroxycinnamic acids (HCA) in the Miscanthus sinensis internode was explored. Model compound [p-coumaric acid (PCA) and ferulic acid (FA)] analysis indicated that the band region from 1,152 to 1,197 cm−1 can be used to characterize the distribution of HCA. Raman images calculated by integrating over the area intensity of characteristic spectral regions showed heterogeneous distribution of lignin and HCA at cellular and sub-cellular level. When overlaying the Raman image of lignin and HCA distribution, it was found that these two polymers were co-located in the middle lamella and secondary wall of corresponding cells. Raman images for the band intensity ratio (1,173 cm−1/1,603 cm−1) indicated a clear association between lignin and HCA distribution within morphologically distinct cell wall layers of sclerenchyma fibers and the parenchyma. This is the first time that the spatial correlation between lignin and HCA concentration has been illustrated by a microspectroscopy imaging approach. The results are of importance in extending the current understanding of lignin and aromatics topochemistry in herbaceous biomass.
The aim of the present study was to evaluate the effects of lutein and lycopene supplementation on carotid artery intima–media thickness (CAIMT) in subjects with subclinical atherosclerosis. A total of 144 subjects aged 45–68 years were recruited from local communities. All the subjects were randomly assigned to receive 20 mg lutein/d (n 48), 20 mg lutein/d+20 mg lycopene/d (n 48) or placebo (n 48) for 12 months. CAIMT was measured using Doppler ultrasonography at baseline and after 12 months, and serum lutein and lycopene concentrations were determined using HPLC. Serum lutein concentrations increased significantly from 0·34 to 1·96 μmol/l in the lutein group (P< 0·001) and from 0·35 to 1·66 μmol/l in the combination group (P< 0·001). Similarly, serum lycopene concentrations increased significantly from 0·18 to 0·71 μmol/l in the combination group at month 12 (P< 0·001), whereas no significant change was observed in the placebo group. The mean values of CAIMT decreased significantly by 0·035 mm (P= 0·042) and 0·073 mm (P< 0·001) in the lutein and combination groups at month 12, respectively. The change in CAIMT was inversely associated with the increase in serum lutein concentrations (P< 0·05) in both the active treatment groups and with that in serum lycopene concentrations (β = − 0·342, P= 0·031) in the combination group. Lutein and lycopene supplementation significantly increased the serum concentrations of lutein and lycopene with a decrease in CAIMT being associated with both concentrations. In addition, the combination of lutein and lycopene supplementation was more effective than lutein alone for protection against the development of CAIMT in Chinese subjects with subclinical atherosclerosis, and further studies are needed to confirm whether synergistic effects of lutein and lycopene exist.
Red-emitting phosphor of Ca0.8Zn0.2TiO3:0.2 mol% Pr3+ was synthesized by the hydrothermal method with urea as a mineralizer. The crystalline structure, micromorphology, and luminescent properties of the resultant phosphor were investigated. Results show that elevated calcination temperature does not change the shape of particles that are hollow spheres with a shell thickness of 210–480 nm, and smaller particles are in the middle of the larger ones. The emission intensity at 612 nm originated from 1D2 → 3H4 transition of Pr3+ ions increases with the elevated calcination temperature due to a higher crystallinity. Excitation curves consist of two strong broad bands centered at about 330 and 380 nm and a weaker broad band range from 450 to 500 nm. The sample prepared by the hydrothermal method has better luminescent properties than that of its counterpart prepared by the solid-state method, especially the improvement of near-UV region (380 nm) excitation intensity.
The AlGaN/GaN/InGaN/GaN double heterojunction high electron mobility transistors (DH-HEMTs) sample has been grown by MOCVD on (0 0 0 1) sapphire substrate. The structure features a 7 nm In0.046Ga0.954N interlayer determined by Rutherford backscattering (RBS). Since the polarization field in the InGaN interlayer is opposite to it in the AlGaN layer, an additional potential barrier is introduced between the two-dimensional electron gas (2DEG) channel and buffer, leading to enhanced carrier confinement and improved buffer isolation. The GaN layers between the AlGaN layer and InGaN interlayer are divided into two layers consisting of GaN channel layer which provides high mobility 2DEG grown at 1070 °C and GaN spacer layer grown at the same temperature as InGaN interlayer (800 °C) to prevent indium diffusion. RBS measurement confirms that the 3 nm GaN spacer layer isolates the InGaN interlayer well and free from diffusion. Hall measurement has been performed, the mobility as high as 1552 cm2/V s at room temperature is obtained and the sheet carrier density is 1.55 × 1013 cm−2. The average sheet resistance is 331 Ω/sq, respectively. The mobility obtained in this paper is about 20% higher than similar structures reported.
The driving mechanism of solar flares and coronal mass ejections is a topic of ongoing debate, apart from the consensus that magnetic reconnection plays a key role during the impulsive process. While present solar research mostly depends on observations and theoretical models, laboratory experiments based on high-energy density facilities provide the third method for quantitatively comparing astrophysical observations and models with data achieved in experimental settings. In this article, we show laboratory modeling of solar flares and coronal mass ejections by constructing the magnetic reconnection system with two mutually approaching laser-produced plasmas circumfused of self-generated megagauss magnetic fields. Due to the Euler similarity between the laboratory and solar plasma systems, the present experiments demonstrate the morphological reproduction of flares and coronal mass ejections in solar observations in a scaled sense, and confirm the theory and model predictions about the current-sheet-born anomalous plasmoid as the initial stage of coronal mass ejections, and the behavior of moving-away plasmoid stretching the primary reconnected field lines into a secondary current sheet conjoined with two bright ridges identified as solar flares.
We report the fabrication of AlGaN/GaN high electron mobility transistors (MIS-HEMTs) with a high breakdown voltage by employing a metal-insulator-semiconductor (MIS) gate structure using Si3N4 insulator. The Si3N4 films were deposited by plasma enhanced chemical vapor deposition (PECVD) as the surface passivation, interlayer films and the gate dielectric. In comparison with Schottky-gate HEMTs, the gate leakage currents of MIS-HEMTs exhibited three orders of magnitude reduction. With similar device structures, the off-state breakdown voltage of MIS-HEMTs was 1050 V with a specific on-resistance of 4.0 mΩ cm2, whereas the breakdown voltage and specific on-resistance of SG-HEMTs were 740 V and 4.4 mΩ cm2, respectively. In addition, the MIS-HEMTs exhibited little current slump in the pulsed measurements and possessed faster switch speed than Si MOSFET. We demonstrate that AlGaN/GaN MIS-HEMTs are promising not only for microwave applications but also for high power switching applications.
Skutterudites are among the most exciting thermoelectric (TE) materials that could be used for various intermediate temperature applications. This study summarized our recent work on n-type partially filled skutterudites. By combining theoretical and experimental approaches, we revealed the underlying mechanism of void filling in the intrinsic lattice voids in CoSb3. With that, the electronegativity selection rule is established for the current stable filled skutterudites and further used for the discovery of a few novel filled CoSb3 compounds. The correlation between the thermal/electrical transport properties and impurity fillers in n-type partially filled skutterudites was also carefully investigated. Our results provide fundamental understanding to how those filler impurities affect electronic structures and lattice dynamics. Based on these basic understanding on transport mechanisms and sophisticated strategy in materials synthesis, TE figure of merit for n-type materials were continually increased from 1.1 to 1.4 and then to 1.7 for single-, double-, and triple-filled skutterudites.
A useful procedure is described to rapidly obtain Bragg-reflection intensities from the FULLPROF suite, and the Bragg intensities can then be input into the GEST and the PECKCRYST programs for crystal-structure determination of small molecules. An example on using the new procedure for the structure determination from powder diffraction determination of hydrochlorothiazide (C7H8ClN3O4S2) is presented, and the powder-structure results obtained by the PECKCRYST program are in good agreement with previously reported single-crystal results.
CdS nanocrystals embedded in sodium borosilicate glass were synthesized through sol-gel process. The CdS nanocrystals were usually 10 to 20 nm in size. The microstructure of CdS nanocrystals was determined to be of the hexagonal phase. The morphology and microstructure of the glass were examined using diverse techniques including scanning-probe microscopy (SPM), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy dispersion x-ray spectra (EDAX), and high-resolution TEM (HRTEM). The linear optical absorption spectrum of the glass showed a blue shift as a result of quantum-size effect. Furthermore, the third-order optical nonlinearities of the glass were studied by Z-scan technique at a wavelength of 770 nm. The results showed that the third-order optical nonlinear refractive index γ, absorption coefficient β, and susceptibility χ(3) were determined to be −2.16 × 10−16 m2/W, 6.32 × 10−11 m/W, and 1.20 × 10−10 esu, respectively, which were greater than those reported previously for CdS nanocrystals embedded in different matrices.
In plants, acid invertases are known to be the key enzymes cleaving sucrose into reducing sugars (RS) (glucose and fructose). To improve the quality of potato (Solanum tuberosum L.) chips, which is largely influenced by RS accumulation in tubers stored at low temperature, a part of acid invertase cDNA with hairpin RNA (hpRNA) structure was transformed into potato cv. N2. Detection of polymerase chain reaction (PCR) amplification and Northern blotting suggested that the RNA interference (RNAi) vector was successfully transformed into cv. N2. The analysis of acid invertase activity in the plantlets and microtubers of RNAi transgenic lines indicated that the expression of the acid invertase was significantly repressed by the activity of RNAi of plantlets by an average 69.8% (with the exception of line Ni-1) with a maximal decrease of 78% (line Ni-4), and the highest decrease of activity in microtubers of 68%. Compared with that of well-inhibited antisense inv transgenic plants, the comparative downregulation of RNAi suggests a distinct alteration of endogenous acid invertase activity and a potential strategy for post-transcriptional gene silencing (PTGS) in modulation of cold-sweetening in potato.
We report recent progress in 2G-HTS wire technology at Superpower Inc. The throughputs of 4mm-wide tape have reached 750m/h for sputtering AlO3+Y2O3 base layer, 360m/h for IBAD MgO template, 345m/h for sputtering Homo-epi MgO+LMO buffer, 180m/h for MOCVD REBCO. Critical current (Ic) of 813A/cm-width at 77K and self-field has been achieved on 1 meter length of 12mm-wide tape in which the thickness of GdYBCO film is 3.3 microns. Ic in a magnetic field has been significantly improved through composition modification, doping and MOCVD condition optimization. Ic of 185.6A/cm-width at 77K and 1Tesla has been obtained. For Ic on long lengths, 314A/cm-width on 202m, 221A/cm-width on 610m and 170A/cm-width on 935m have been achieved. A coil of 19.1mm diameter we made with our 2G wires generated 26.8T magnetic field in the magnet. A 30m-long cable made with nearly 10,000 meters of Superpower 2G wires showed excellent overall performance and has been installed and energized in the power grid.
This paper studies many fundamental aspects of a newly proposed multi-class traffic flow model. For the first time it presents a complete discussion on the hyperbolicity of the system; and based upon this, the admissible waves of the Riemann problem are deeply investigated. Many important conclusions are made in discussions, and the related physical meanings are interpreted. For the confirmation of main conclusions, numerical examples are given at the end.
Single crystal Mn thin films have been successfully grown on GaAs(001) substrates for the first time by molecular beam epitaxy. The bulk atomic structure of the manganese films is determined to be the face-centered-cubic metastable phase with the lattice parameter of 0.362 nm, by in situ reflection high energy electron diffraction (RHEED) and ex situ x-ray diffraction (XRD).