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J Infect Dis ; 221(11): 1757-1761, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32067043


An ongoing outbreak of pneumonia associated with 2019 novel coronavirus was reported in China. It is unclear whether the virus is infective exists during the incubation period, although person-to-person transmission has been reported elsewhere. We report the epidemiological features of a familial cluster of 4 patients in Shanghai, including an 88-year-old man with limited mobility who was exposed only to asymptomatic family members whose symptoms developed later. The epidemiological evidence has shown possible transmission of 2019 novel coronavirus during the incubation period.

Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/transmissão , Período de Incubação de Doenças Infecciosas , Pneumonia Viral/epidemiologia , Pneumonia Viral/transmissão , Idoso , Idoso de 80 Anos ou mais , Betacoronavirus/isolamento & purificação , China/epidemiologia , Infecções por Coronavirus/diagnóstico , Infecções por Coronavirus/terapia , Família , Evolução Fatal , Feminino , Humanos , Masculino , Pandemias , Pneumonia Viral/diagnóstico , Pneumonia Viral/terapia
Opt Express ; 27(7): 10221-10233, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31045166


We report a coherent terahertz (THz) imaging system that utilises a quantum cascade laser (QCL) operating in pulsed-mode as both the source and detector. The realisation of a short-pulsed THz QCL feedback interferometer permits both high peak powers and improved thermal efficiency, which enables the cryogen-free operation of the system. In this work, we demonstrated pulsed-mode swept-frequency laser feedback interferometry experimentally. Our interferometric detection scheme not only permits the simultaneous creation of both amplitude and phase images, but inherently suppresses unwanted background radiation. We demonstrate that the proposed system utilising microsecond pulses has the potential to achieve 0.25 mega-pixel per second acquisition rates, paving the pathway to video frame rate THz imaging.

Opt Lett ; 43(10): 2225-2228, 2018 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-29762559


We demonstrate a gas spectroscopy technique, using self-mixing in a 3.4 terahertz quantum-cascade laser (QCL). All previous QCL spectroscopy techniques have required additional terahertz instrumentation (detectors, mixers, or spectrometers) for system pre-calibration or spectral analysis. By contrast, our system self-calibrates the laser frequency (i.e., with no external instrumentation) to a precision of 630 MHz (0.02%) by analyzing QCL voltage perturbations in response to optical feedback within a 0-800 mm round-trip delay line. We demonstrate methanol spectroscopy by introducing a gas cell into the feedback path and show that a limiting absorption coefficient of ∼1×10-4 cm-1 is resolvable.