ABSTRACT
We provide research findings on the physics of aerosol and droplet dispersion relevant to the hypothesized aerosol transmission of SARS-CoV-2 during the current pandemic. We utilize physics-based modeling at different levels of complexity, along with previous literature on coronaviruses, to investigate the possibility of airborne transmission. The previous literature, our 0D-3D simulations by various physics-based models, and theoretical calculations, indicate that the typical size range of speech and cough originated droplets ( d ⩽ 20 µ m ) allows lingering in the air for O ( 1 h ) so that they could be inhaled. Consistent with the previous literature, numerical evidence on the rapid drying process of even large droplets, up to sizes O ( 100 µ m ) , into droplet nuclei/aerosols is provided. Based on the literature and the public media sources, we provide evidence that the individuals, who have been tested positive on COVID-19, could have been exposed to aerosols/droplet nuclei by inhaling them in significant numbers e.g. O ( 100 ) . By 3D scale-resolving computational fluid dynamics (CFD) simulations, we give various examples on the transport and dilution of aerosols ( d ⩽ 20 µ m ) over distances O ( 10 m ) in generic environments. We study susceptible and infected individuals in generic public places by Monte-Carlo modelling. The developed model takes into account the locally varying aerosol concentration levels which the susceptible accumulate via inhalation. The introduced concept, 'exposure time' to virus containing aerosols is proposed to complement the traditional 'safety distance' thinking. We show that the exposure time to inhale O ( 100 ) aerosols could range from O ( 1 s ) to O ( 1 min ) or even to O ( 1 h ) depending on the situation. The Monte-Carlo simulations, along with the theory, provide clear quantitative insight to the exposure time in different public indoor environments.
ABSTRACT
Methemoglobinemia is an acute and potentially life-threatening condition. It can be congenital but more often acquired. Suspected the diagnosis of this condition is straight forward. In methemoglobinemia red cells are unable to carry oxygen, because the iron of the heme is oxidised from Fe2+ to Fe3+. Symptoms are depended on the level of methemoglobinemia. Intravenous methylene blue is the treatment of choice.
Subject(s)
Methemoglobinemia/diagnosis , Acute Disease , Child , Diagnosis, Differential , Enzyme Inhibitors , Female , Humans , Methylene BlueABSTRACT
PURPOSE: To assess the utility of infrapopliteal percutaneous transluminal angioplasty (PTA) in diabetic patients with end-stage renal disease and chronic critical limb ischemia. MATERIALS AND METHODS: Between 1994 and 2003, 20 consecutive diabetic patients with uremia (mean age, 59 years; age range, 39-73 years) underwent infrapopliteal PTA (total of 26 limbs). Additional infrainguinal lesions were treated in 12 limbs. Three limbs (12%) were classified as having Rutherford category 4 ischemia, 19 (73%) as having category 5 ischemia, and four (15%) as having category 6 ischemia. The mean length of the 58 treated infrapopliteal lesions was 8.8 cm. RESULTS: Angiographic success (<30% residual stenosis) was achieved in 22 of the 26 limbs (85%) and primary clinical success (at least one Rutherford category improvement) was achieved in nine (35%). One major complication was encountered. PTA was successful in producing a patent artery to the ankle level in 18 limbs. Primary clinical success was achieved in eight of those 18 limbs (44%) versus only one of the eight limbs (13%) with no patent artery after angioplasty (P = .01). When including the four repeated interventions, the clinical patency at 1 year (based on physical findings) was 38% (10 of 26 limbs). The rate of major amputations at 3, 6, and 12 months was 23%, 31%, and 35%, respectively, with a tendency of increased frequency among patients treated for more severe ischemia (Rutherford 4 vs 5 vs 6, P = .10). CONCLUSIONS: In diabetic patients with uremia, infrapopliteal PTA should be restricted to limbs without extensive tissue loss with lesions estimated to facilitate accomplishment of at least one patent artery to the ankle level.
