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Several autonomous phase-sensitive radio-echo sounders (ApRES) were deployed at Greenland glaciers to investigate ice deformation. Different attenuation settings were tested and it was observed that, in the presence of clipping of the deramped ApRES signal, each setting produced a different result. Specifically, higher levels of clipping associated with lower attenuation produced an apparent linear increase of diurnal vertical cumulative displacement with depth, and obscured the visibility of the basal reflector in the return amplitude. An example with a synthetic deramped signal confirmed that these types of artifacts result from the introduction of harmonics from square-wave-like features introduced by clipping. Apparent linear increase of vertical displacement with depth occurs when the vertical position of a near-surface internal reflector changes in time. Artifacts in the return amplitude may obscure returns from internal reflectors and the basal reflector, making it difficult to detect thickness evolution of the ice and to correctly estimate vertical velocities. Variations in surface melt during ApRES deployments can substantially modulate the received signal strength on short timescales, and we therefore recommend using higher attenuator settings for deployments in such locations.
In this article, we investigate the horizontal trajectory tracking problem for an underactuated stratospheric airship subject to nonvanishing external disturbances and model uncertainties. By transforming the tracking errors into new virtual error variables, we can specify the transient and steady-state tracking performance of the resulting nonlinear system quantitatively, which means that under the proposed control scheme, the tracking errors will converge to prescribed residual sets around the origin before a preselected finite time with decay rates no less than a preassignable value. To address unknown items, minimal learning parameter (MLP) techniques for neural networks (NNs) approximation are employed, which efficaciously relax the computational burden, enhance the robustness against dynamics uncertainties and provide an improved property for disturbances rejection. A finite-time convergent observer (FTCO) is incorporated into the control framework to realise output-feedback control, ensuring that estimation errors are bounded during operation and approach zero within a finite time. Stability analysis proves that all the closed-loop signals are uniformly bounded. The effectiveness and advantages of the proposed control strategy are verified by simulation results.
A new developed spatially targeted mollusciciding technology for snail control was utilised in a research site. This study aims to analyse whether this technology can achieve rational effectiveness compared with the routine method. Snail density was monitored every spring and autumn from 2010 to 2017 at the research site and routine mollusciciding for snail control was then performed. After snail density monitoring in spring 2018, spatially targeted mollusciciding technology was adopted. Log-linear regression and nonlinear regression models were used for snail density prediction in autumn 2018 and the predicted value was compared with the actual snail density in autumn 2018 to verify the effectiveness of the spatially targeted mollusciciding. Monitoring results showed that overall snail density in the research site decreased from 2010 to 2018. The monitored snail density in autumn 2018 was 0.014/0.1 m2. Predicted by the log-linear regression model, the snail density in autumn 2018 would be 0.028 (95% CI 0.11–0.072)/0.1 m2. Predicted by the nonlinear regression model, the snail density growth in autumn 2018 in contrast to spring 2018 would be 79.79% (95% CI 54.81%–104.77%) and the actual value was 55.56%. Therefore, the effectiveness of the first application of spatially targeted mollusciciding was acceptable. However, the validation of its sustainable effectiveness still needs a replicated study comparing areas where targeted and untargeted methods are applied simultaneously and both snail abundance and human infection are monitored.
This study aimed to investigate the clinical characteristics and to analyse the epidemiological features of coronavirus disease 2019 (COVID-19) patients during convalescence. In this study, we enrolled 71 confirmed cases of COVID-19 who were discharged from hospital and transferred to isolation wards from 6 February to 26 March 2020. They were all employees of Zhongnan Hospital of Wuhan University or their family members of which three cases were <18 years of age. Clinical data were collected and analysed statistically. Forty-one cases (41/71, 57.7%) comprised medical faculty, young and middle-aged patients (aged ⩽60 years) accounted for 81.7% (58/71). The average isolation time period for all adult patients was 13.8 ± 6.1 days. During convalescence, RNA detection results of 35.2% patients (25/71) turned from negative to positive. The longest RNA reversed phase time was 7 days. In all, 52.9% of adult patients (36/68) had no obvious clinical symptoms, and the remaining ones had mild and non-specific clinical symptoms (e.g. cough, sputum, sore throat, disorders of the gastrointestinal tract etc.). Chest CT signs in 89.7% of adult patients (61/68) gradually improved, and in the others, the lesions were eventually absorbed and improved after short-term repeated progression. The main chest CT manifestations of adult patients were normal, GGO or fibre streak shadow, and six patients (8.8%) had extrapulmonary manifestations, but there was no significant correlation with RNA detection results (r = −0.008, P > 0.05). The drug treatment was mainly symptomatic support therapy, and antibiotics and antiviral drugs were ineffective. It is necessary to re-evaluate the isolation time and standard to terminate isolation for discharged COVID-19 patients.
Many MRI studies have cited major depression, with or without anti-depressive treatment, associated with structural plasticity changing in several brain regions. Few of these studies researched the effect of the anti-depressive treatment, electroconvulsive therapy (ECT), on depression.
To assess the influence of ECT on the brain structure change during the treatment process by utilizing the voxel-based morphometry (VBM) analysis.
To determine whether ECT alter brain structure.
We performed HAMD ratings and MRI scans on 12 depressive patients during ECT, analyzing the data by VBM with SPM8 software's family-wise error correction (FWE).
The researchers found volumes changes in white matter in 37 regions between pre-ECT and post-ECT1, but only one region changing between pre-ECT and post-ECT8. Seven regions changing in grey matter between pre-ECT and post-ECT 1⌧but none regions changing between pre-ECT and post-ECT8.
The density changes in several brain regions after a single ECT stimuli, but return to the original level after completing the eighth ECT. Our finding supports that ECT may play a temporary role in treating major depression but do not permanently alter the structures of brain.
The coronal heating problem is a long-standing perplexing issue. In this study, 13 solar activity indexes are used to investigate their phase relation with the sunspot number (SSN). Only three of them are found to statistically significantly lag the SSN (large-scale magnetic activity) by about one solar rotation period; the three indexes are total solar irradiance (TSI), the modified coronal index, and the solar wind velocity; the former two indexes may represent the long-term variation of energy quantity of the heated photosphere and corona, respectively. The Mount Wilson Sunspot Index (MWSI) and the Magnetic Plage Strength Index (MPSI), which reflect the large- and small-scale magnetic field activities, respectively, are also utilised to investigate their phase relations with the three indexes. The three indexes are found to be much more intimately related to MPSI than to MWSI, and MWSI statistically significantly leads TSI by about one rotation period. The heated corona is found to pulse perfectly in step with the small-scale magnetic activity rather than the large-scale magnetic activity; furthermore, combined with observations, our statistical evidence should thus attribute coronal heating firmly to small-scale magnetic activity phenomena, such as spicules, micro-flares, nano-flares, and others. The photosphere and the corona are synchronously heated, which should seemingly prefer magnetic reconnection heating to wave heating. In the long term, such a coronal heating way is inferred effective. Statistically, it is also small-scale magnetic activity phenomena that produce TSI enhancement. Coronal heating and solar wind acceleration are found to be synchronous, as standard models require.
Feathers play a critical role in thermoregulation and directly influence poultry production. Poor feathering adversely affects living appearance and carcass quality, thus reducing profits. However, producers tend to ignore the importance of feather development and do not know the laws of feather growth and development. The objective of this study was to fit growth curves to describe the growth and development of feathers in yellow-feathered broilers during the embryonic and posthatching periods using different nonlinear functions (Gompertz, logistic and Bertalanffy). Feather mass and length were determined during the embryonic development and posthatching stages to identify which growth model most accurately described the feather growth pattern. The results showed that chick embryos began to grow feathers at approximately embryonic (E) day 10, and the feathers grew rapidly from E13 to E17. There was little change from E17 to the day of hatching (DOH). During the embryonic period, the Gompertz function (Y = 798.48e−203 431exp(−0.87t), Akaike’s information criterion (AIC) = −0.950 × 103, Bayesian information criterion (BIC) = −0.711 × 103 and mean square error (MSE) = 559.308) provided the best fit for the feather growth curve compared with the other two functions. After hatching, feather mass and length changed little from the DOH to day (D) 14, increased rapidly from D21 to D91 and then grew slowly after D91. The first stage of feather molting occurred from 2 to 3 weeks of age when the down feathers were mostly shed and replaced with juvenile feathers, and the second stage occurred at approximately 13 to 15 weeks of age. The three nonlinear functions could overall fit the feather growth curve well, but the Bertalanffy model (Y = 116.88 × (1−0.86e−0.02t)3, AIC = 1.065 × 105, BIC = 1.077 × 105 and MSE = 11.308) showed the highest degree of fit among the models. Therefore, the Gompertz model exhibited the best goodness of fit for the feather growth curve during the embryonic development, while the Bertalanffy model was the most suitable model due to its accurate ability to predict the growth and development of feathers during the growth period, which is an important commercial characteristic of yellow-feathered chickens.
The association between eosinophil count and cholelithiasis among people with Clonorchis sinensis infection is still uncertain. We conducted a cross-sectional study to investigate the associations among Clonorchis sinensis infection, eosinophil count and cholelithiasis. The study included 4628 participants from January to December 2018. The levels of eosinophil count were divided into four groups according to the quartiles of eosinophil count. Spearman's rank correlation was performed to assess the association between eosinophil counts and Clonorchis sinensis egg counts. Multiple regression analysis was performed to evaluate the relationships among C. sinensis infection, eosinophil count and cholelithiasis after adjusting for three models. The prevalence of C. sinensis infection was 38.72% (1792/4628), and the prevalence of cholelithiasis was 6.03% (279/4628). The infection rate of C. sinensis was higher in the cholelithiasis group than in the non-cholelithiasis group (63.08% vs. 37.16%, P < 0.001). Significant differences were found among various eosinophil count quartiles for C. sinensis infection, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyltranspeptidase (γ-GT), triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), creatinine (CRE), blood urea nitrogen (BUN), uric acid (UA) and non-alcoholic fatty liver disease (NAFLD) (all P < 0.001). A significant positive correlation was found between eosinophil count and log-transformed C. sinensis egg count (r = 0.9477, P < 0.001). Multiple logistic regression analysis revealed that light and moderate intensities of C. sinensis infection were associated with cholelithiasis (P < 0.01 and P < 0.001, respectively), and C. sinensis infection with eosinophil count ranging from 0.05 to 0.5 × 109/l were associated with cholelithiasis (P < 0.05). In conclusion, our findings suggest that the light and moderate infections of C. sinensis with eosinophil count ranging from 0.05 to 0.5 × 109/l may be associated with a higher risk of cholelithiasis.
To examine the relationship between the therapeutic effect of intratympanic methylprednisolone perfusion and histone acetylation in refractory sudden sensorineural hearing loss.
Thirty-four refractory sudden sensorineural hearing loss patients were enrolled and treated with intratympanic methylprednisolone perfusion. Pure tone average, acetylated histone H3, acetylated histone H4 and histone deacetylase 2 (HDAC2) were measured in peripheral blood mononuclear cells before and after intratympanic methylprednisolone perfusion. Sixteen healthy volunteers were recruited to obtain normal reference values.
Pure tone average in sudden sensorineural hearing loss patients improved from 84.14 ± 13.54 dB to 73.56 ± 18.45 dB after intratympanic methylprednisolone perfusion. Up-regulations in HDAC2 protein level, and down-regulations in histone H3 and H4 acetylation were observed in the intratympanic methylprednisolone perfusion sensitive group (pure tone average gain of 15 dB or more), while no significant changes were observed in the intratympanic methylprednisolone perfusion insensitive group (pure tone average gain of less than 15 dB).
Intratympanic methylprednisolone perfusion can improve hearing in a considerable number of refractory sudden sensorineural hearing loss patients. The therapeutic effect is closely related to reduced histone acetylation.
While assessing the environmental impact of nuclear power plants, researchers have focused their attention on radiocarbon (14C) owing to its high mobility in the environment and important radiological impact on human beings. The 10 MW high-temperature gas-cooled reactor (HTR-10) is the first pebble-bed gas-cooled test reactor in China that adopted helium as primary coolant and graphite spheres containing tristructural-isotropic (TRISO) coated particles as fuel elements. A series of experiments on the 14C source terms in HTR-10 was conducted: (1) measurement of the specific activity and distribution of typical nuclides in the irradiated graphite spheres from the core, (2) measurement of the activity concentration of 14C in the primary coolant, and (3) measurement of the amount of 14C discharged in the effluent from the stack. All experimental data on 14C available for HTR-10 were summarized and analyzed using theoretical calculations. A sensitivity study on the total porosity, open porosity, and percentage of closed pores that became open after irradiating the matrix graphite was performed to illustrate their effects on the activity concentration of 14C in the primary coolant and activity amount of 14C in various deduction routes.
The very high temperature reactor (VHTR) is a development of the high-temperature gas-cooled reactors (HTGRs) and one of the six proposed Generation IV reactor concept candidates. The 10 MW high temperature gas-cooled reactor (HTR-10) is the first pebble-bed gas-cooled test reactor in China. A sampling system for the measurement of carbon-14 (14C) was established in the helium purification system of the HTR-10 primary loop, which could sample 14C from the coolant at three locations. The results showed that activity concentration of 14C in the HTR-10 primary coolant was 1.2(1) × 102 Bq/m3 (STP). The production mechanisms, distribution characteristics, reduction routes, and release types of 14C in HTR-10 were analyzed and discussed. A theoretical model was built to calculate the amount of 14C in the core of HTR-10 and its concentration in the primary coolant. The activation reaction of 13C has been identified to be the dominant 14C source in the core, whereas in the primary coolant, it is the activation of 14N. These results can supplement important information for the source term analysis of 14C in HTR-10 and promote the study of 14C in HTGRs.
An improved variational optimization approach is established to optimize and analyse the propulsion efficiency of the high-altitude contra-rotating propellers for high-altitude airships based on the Vortex Lattice Lifting Line Method. The optimum radial circulation distribution, chord and pitch distribution are optimized under the maximum lift-to-drag ratio of aerofoils. To consider the effects of the actual Reynolds number and the Mach number of each aerofoil section, aerodynamics such as lift coefficient, drag coefficient and lift-to-ratio are obtained by interpolating a CFD database, which is established by numerical simulations under different Reynolds number, Mach number and angles-of-attack. The improved method is verified by validation cases on a high-altitude CRP using the three-dimensional steady Reynolds-averaged Navier-Stokes solver and moving reference frames technique. The optimization results of thrust, torque and efficiency for both the individual front/rear propeller and CRP are shown to agree reasonably well with the CFD results. Using the improved approach, the influence of blade numbers, diameter, rotation speeds, axial distance and torque ratio on the optimum efficiency of CRPs is illustrated in detail by conducting parametric studies.
We examine the potential for management-worker alliances when employees have substantial voting rights, and how such alliances affect the balance of power between managers and shareholders. We find that substantial employee voting rights exacerbate the manager-shareholder conflicts. Specifically, they entrench incumbent managers and allow them to pursue value-destroying acquisitions by undercutting the disciplinary influence of the corporate control market. Importantly, employee support for managers is conditional on favorable treatment of employees. Our findings are consistent with Pagano and Volpin’s theory of worker-management alliances and highlight the potential risks associated with large employee voting power.
The triplite LiFeSO4F displays both the highest potential ever reported for an Fe-based compound, as well as a comparable specific energy with that of popular LiFePO4. The synthesis is still a challenge because the present approaches are connected with long time, special equipments or organic reagents, etc. In this work, the triplite LiFeSO4F powder was synthesized through an ambient two-step solid-state route. The reaction process and phase purity were analyzed, coupled with structure refinement and electrochemical test.
Four complete platysiagid fish specimens are described from the Luoping Biota, Anisian (Middle Triassic), Yunnan Province, southwest China. They are small fishes with bones and scales covered with ganoine. All characters observed, such as nasals meeting in the midline, a keystone-like dermosphenotic, absence of post-rostral bone, two infraorbitals between dermosphenotic and jugal, large antorbital, and two postcleithra, suggest that the new materials belong to a single, new Platysiagum species, P. sinensis sp. nov. Three genera are ascribed to Platysiagidae: Platysiagum, Helmolepis and Caelatichthys. However, most specimens of the first two genera are imprints or fragmentary. The new, well-preserved specimens from the Luoping Biota provide more detailed anatomical information than before, and thus help amend the concept of the Platysiagidae. The Family Platysiagidae was previously classed in the Perleidiformes. Phylogenetic analysis indicates that the Platysiagidae is a member of basal Neopterygii, and its origin seems to predate that of Perleidiformes. Moreover, platysiagid fishes are known from the Middle Triassic of the western Tethys region. The newly found specimens of platysiagids from Luoping provide additional evidence that both eastern and western sides of the Tethys Ocean were biogeographically more connected than previously thought.
Knowledge, attitudes and practices (KAP) of the population regarding severe fever with thrombocytopenia syndrome (SFTS) in endemic areas of Lu'an in China were assessed before and after an intervention programme. The pre-intervention phase was conducted using a sample of 425 participants from the 12 selected villages with the highest rates of endemic SFTS infection. A predesigned interview questionnaire was used to assess KAP. Subsequently, an intervention programme was designed and applied in the selected villages. KAP was re-assessed for each population in the selected villages using the same interview questionnaire. Following 2 months of the programme, 339 participants had completed the re-assessed survey. The impact of the intervention programme was evaluated using suitable statistical methods. A significant increase in the KAP and total KAP scores was noted following the intervention programme, whereas the proportion of correct knowledge, the positive attitudes and the effective practices toward SFTS of respondents increased significantly. The intervention programme was effective in improving KAP level of SFTS in populations that were resident in endemic areas.