西方代议制民主危机的成因——一种思想史的考察

此次西方抗疫所体现的西方治理模式问题,可以从西方政治体制——代议制民主本身的问题中找到原因。代议制民主是经过美国联邦党人、基佐、柏克、密尔等对代议制代表原则与基本精神的论述而成型的间接民主,是自由主义思想家为防范多数暴政而结合了贵族制与民主制因素的混合政体。然而由于大众民主所驱动的"实际代表制"取代了体现古典共和精神的"实质代表制",代议制民主不可避免地走向"选举式民主",造成诸多民主乱象,凸显了西方民主制度面临的挑战。

Interpreting the biochemical specificity of mouse spinal cord by confocal raman microspectral imaging

Interpreting the biochemical specifcity of spinal cord tissue is the essential requirement for underst.anding the biochemical mechanisms during spinal-cord-related pathological course.In this work,a longitudinal study was implemented to reveal a precise linkage betwoen the spectral features and the molecular composition in er vivo mouse spinal cord tissue by microspectral Raman imaging.It was testified that lipid-rich white matter could be distinguished from gray matter not only by the lipid Raman peaks at 1064,1300,1445 and 1660 cm^(-1),but also by protein(1250 and 1328 cm^(-1))and saccharides(913 and 1137 cm^(-1))distributions.K-means cluster analysis was further applied to visualize the morphological basis of spinal cord tissue by chemical components and their dist ribution patterns.T wo-dimensional chemical images were then generated to visualize the contrast between two different tissue types by integrating the intensitics of the featured Raman bands.All the obtained results ilustrated the biochemical characteristics of spinal cord tssue,as well as some specific substance variances bet ween different tssue types,which formed a solid basis for the molecular investigation of spinal cord pathologi cal alterations.

Simulation Studying Effects of Multiple Primary Aberrations on Donut-shaped Gaussian Beam

In this paper, we demonstrate the variation of donut-shaped depletion pattern which influenced by multiple primary aberrations. The simulation is base on a common stimulation emission of depletion (STED) system composed by Gaussian laser and vortex phase plate. The simulation results are helpful guidelines for analyzing the aberration of depletion patterns in real situations.

Study on the fast elimination of smoke particle based on electro-acoustic coupling agglomeration technology

Fire smoke,which consists large amounts of fine particles,is considered as the fatal factor in fires.In this study,a fast smoke particle elimination method based on electro-acoustic coupling agglomeration technology is proposed.First,the experimental results show that the electro-acoustic coupling agglomeration has higher smoke elimination efficiency compared to single-field.The smoke transmission is much less than 80%after 30s of single acoustic or electric field action,while the coupled field reaches 90%.Then,the effects of acoustic frequency,sound pressure level and voltage on the smoke elimination characteristics are discussed.It is found that the optimal acoustic frequency is 1.5kHz.While as the sound pressure level and voltage increase,the elimination efficiency first increases and then tends to stabilize,the critical values of the sound pressure level and voltage are 135 dB and 7kV.This indicates that there is an optimal combination of the three variables.Finally,through the theoretical analysis of particle movement and the micro-morphology of agglomerates,the particle agglomeration mechanism under the electro-acoustic coupling is analyzed.This study provides a new idea for the fast elimination of fire smoke particle.

Generalized Switched-Capacitor Step-up Multilevel Inverter Employing Single DC Source

In this paper,a new generalized step-up multilevel DC-AC converter is proposed,which is suitable for applications with low-voltage input sources,such as photovoltaic power generation and electric vehicles.This inverter can achieve a high voltage gain by controlling the series-parallel conversion of the DC power supply and capacitors.Only one DC voltage source and a few power devices are employed.The maximum output voltage and the number of output levels can be further increased through the switched-capacitor unit’s extension and the submodule cascaded extension.Moreover,the capacitor voltages are self-balanced without complicated voltage control circuits.The complementary operating mechanism between each pair of switches simplifies the modulation algorithm.The inductiveload ability is fully taken into account in the proposed inverter.Additionally,a remarkable characteristic of the inverter is that the charging and discharging states among different capacitors are synchronous,which reduces the voltage ripple of the frontend capacitors.The circuit structure,the working principle,the modulation strategy,the capacitors and losses analysis are presented in detail.Afterwards,the advantages of the proposed inverter are analyzed by comparing with other recently proposed inverters.Finally,the steady-state and dynamic performance of the proposed inverter is verified and validated by simulation and experiment.

Antibunching and superbunching photon correlations in pseudo-natural light

Since Hanbury Brown and Twiss revealed the photon bunching effect of a thermal light source in 1956,almost all studies in correlation optics have been based on light’s intensity fluctuation,regardless of fact that the polarization fluctuation is a basic attribute of natural light.In this work,we uncover the veil of the polarization fluctuation and corresponding photon correlations by proposing a new light source model,termed pseudo-natural light,embodying both intensity and polarization fluctuations.Unexpectedly,the strong antibunching and superbunching effects can be simultaneously realized in such a new source,whose second-order correlation coefficient g^((2))can be continuously modulated across 1.For the symmetric Bernoulli distribution of the polarization fluctuation,particularly,g^((2))can be in principle from 0 to unlimitedly large.In pseudo-natural light,while the bunching effects of both intensity and polarization fluctuations enhance the bunching to superbunching photon correlation,the antibunching correlation of the polarization fluctuation can also be extracted through the procedure of division operation in the experiment.The antibunching effect and the combination with the bunching one will arouse new applications in quantum imaging.As heuristic examples,we carry out high-quality positive or negative ghost imaging,and devise high-efficiency polarization-sensitive and edge-enhanced imaging.This work,therefore,sheds light on the development of multiple and broad correlation functions for natural light.

Changes in hospitalizations for respiratory diseases following the COVID-19 epidemic

Tothe Editor:During the ongoing,coronavirus disease 2019(COVID-19)pandemic,hundreds of millions of people have been infected.The prevention and control measures guided by the Chinese government,including the wearing of,facemasks,maintaininghand hygiene,reducing gatherings,and physical distancing,have become commonplace across China.The protective measures have been confirmed to reduce the risk of severe acute respiratorysyndromecoronavirus 2(SARS-CoV-2)infection.In addition to COVID-19,other respiratory infectious diseases,such as viral pneumonia and bacterial pneumonia,remain a threat to inpatients.Whether the pandemic,and associated protective measures have impacted thespectrum of respiratorydiseases in inpatients in pulmonary and critical care medicine(PCCM)departments remains unclear.

Efficacy of early prone or lateral positioning in patients with severe COVID-19:a single-center prospective cohort

Background:Position intervention has been shown to improve oxygenation,but its role in non-invasively ventilated patients with severe COVID-19 has not been assessed.The objective of this study was to investigate the efficacy of early position intervention on non-invasively ventilated patients with severe COVID-19.Methods:This was a single-center,prospective observational study in consecutive patients with severe COVID-19 managed in a provisional ICU at Renmin Hospital of Wuhan University from 31 January to 15 February 2020.Patients with chest CT showing exudation or consolidation in bilateral peripheral and posterior parts of the lungs were included.Early position intervention(prone or lateral)was commenced for>4 hours daily for 10 days in these patients,while others received standard care.Results:The baseline parameters were comparable between the position intervention group(n=17)and the standard care group(n=35).Position intervention was well-tolerated and increased cumulative adjusted mean difference of SpO_(2)/FiO_(2)(409,95%CI 86 to 733)and ROX index(26,95%CI 9 to 43)with decreased Borg scale(−9,95%CI−15 to−3)during the first 7 days.It also facilitated absorption of lung lesions and reduced the proportion of patients with high National Early Warning Score 2(≥7)on days 7 and 14,with a trend toward faster clinical improvement.Virus shedding and length of hospital stay were comparable between the two groups.Conclusions:This study provides the first evidence for improved oxygenation and lung lesion absorption using early position intervention in non-invasively ventilated patients with severe COVID-19,and warrants further randomized trials.