Background Clinical characteristics of patients with the coronavirus disease 2019 (COVID-19) may present differently within and outside the epicenter of Wuhan, China. More clinical investigations are needed. Objective The study was aimed to describe the clinical characteristics, laboratory parameters, and therapeutic methods of COVID-19 patients in Hunan, China. Setting The First Hospital of Changsha, First People's Hospital of Huaihua, and the Central Hospital of Loudi, Hunan province, China. Methods This was a retrospective multi-center case-series analysis. Patients with confirmed COVID-19 diagnosis hospitalized at the study centers from January 17 to February 10, 2020, were included. The following data were obtained from electronic medical records: demographics, medical history, exposure history, underlying comorbidities, symptoms, signs, laboratory findings, computer tomography scans, and treatment measures. Main outcome measure Epidemiological, clinical, laboratory, and radiological characteristics and treatments. Results A total of 54 patients were included (51 had the common-type COVID-19, three had the severe-type), the median age was 41, and 52% of them were men. The median time from the first symptoms to hospital admission was seven days. Among patients with the common-type COVID-19, the median length of stay was nine days, and 21 days among patients with severe COVID-19. The most common symptoms at the onset of illness were fever (74.5%), cough (56.9%), and fatigue (43.1%) among patients in the common-type group. Fourteen patients (37.8%) had a reduced WBC count, 23 (62.2%) had reduced eosinophil ratio, and 21 (56.76%) had decreased eosinophil count. The most common patterns on chest-computed tomography were ground-glass opacity (52.2%) and patchy bilateral shadowing (73.9%). Pharmacotherapy included recombinant human interferon α2b, lopinavir/ritonavir, novaferon, antibiotics, systematic corticosteroids and traditional Chinese medicine prescription. The outcome of treatment indicated that in patients with the common-type COVID-19, interferon-α2b, but not novaferon, had some benefits, antibiotics treatment was not needed, and corticosteroids should be used cautiously. Conclusion As of February 10, 2020, the symptoms of COVID-19 patients in Hunan province were relatively mild comparing to patients in Wuhan, the epicenter. We observed some treatment benefits with interferon-α2b and corticosteroid therapies but not with novaferon and antibiotic treatment in our study population.
The short time Fourier transform (STFT) cannot resolve rapid velocity changes in most photonic Doppler velocimetry (PDV) data. A practical analysis method based on the continuous wavelet transform (CWT) was presented to overcome this difficulty. The adaptability of the wavelet family predicates that the continuous wavelet transform uses an adaptive time window to estimate the instantaneous frequency of signals. The local frequencies of signal are accurately determined by finding the ridge in the spectrogram of the CWT and then are converted to target velocity according to the Doppler effects. A performance comparison between the CWT and STFT is demonstrated by a plate-impact experiment data. The results illustrate that the new method is automatic and adequate for analysis of PDV data.
An all-optical framing camera has been developed to obtain serial images of high temporal and spatial resolution with identical spatial benchmark, identical temporal benchmark, and identical chromatic benchmark in a single shot. A train of laser probe pulses with identical wavelength coaxially illuminate the target and form sequentially timed images by means of parallel coherence shutters. A coherence shutter only selects one of the probe pulses to form a nonmultiplexing hologram. The other probe pulses superpose incoherently on the hologram as the background. By this method, each hologram is entirely separated from the others both in spatial and temporal domains. Two kinds of ultrafast physical process experiments, including laser driving air and laser driving aluminum foil, were performed to verify the feasibility of the parallel coherence shutters.
The diagnosis of the initiation and growth of detonation in high explosives (HEs) is important in detonation physics. We designed and experimentally demonstrated a non-invasive high-precision free-space terahertz-wave Doppler interferometric velocimetry (TDV) design for diagnosing the transient detonation processes in HEs. The system can non-intrusively record the propagation of the shock/detonation wavefront inside HEs continuously and measure key detonation parameters (position/displacement, detonation velocity, etc.). A detailed quasi-optical design for TDV is discussed. The terahertz penetration ability and the refractive index of representative HEs are presented in the frequency range of 0.2–1.4 THz. Additionally, a typical shock-to-detonation transition of an insensitive high explosive was studied using a prototype 0.212 THz TDV system, which demonstrated the high precision of displacement measurements made using I/Q demodulation. Furthermore, the performance of the TDV technique is discussed. TDV may enable non-invasive and high-precision diagnostics for detonation and shockwave physics.
A fiber interferometry for transverse velocity measurement has been developed. This diagnostic is similar to photonic Doppler velocimetry in the way in which laser propagates and couples. The interferometer mainly consists of a fiber coupler, an emitting probe, and two receiving probes. A pair of scattered laser beams mix in the coupler and generates fringes with frequency proportional to transverse velocity. Measurement of transverse velocity is independent of longitudinal velocity. The feasibility of the technique has been verified by rotating wheel experiment and shock loading experiment.
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