1,856 research outputs found

    New parameterization of air-sea exchange coefficients and its impact on intensity prediction under major tropical cyclones

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    Understanding and quantifying air-sea exchanges of enthalpy and momentum fluxes are crucial for the advanced prediction of tropical cyclone (TC) intensity. Here, we present a new parameterization of air-sea fluxes at extreme wind speeds from 40 m sāˆ’1 to 75 m sāˆ’1, which covers the range of major TCs. Our approach assumes that the TC can reach its maximum potential intensity (MPI) if there are no influences of external forces such as vertical wind shear or other environmental constraints.This method can estimate the ratio of the enthalpy and momentum exchange coefficient (Ck/Cd) under the most intense TCs without direct flux measurements. The estimation showed that Ck/Cd increases with wind speed at extreme winds above 40 m sāˆ’1. Two types of surface layer schemes of the Hurricane Weather and Research Forecast (HWRF) were designed based on the wind speed dependency of the Ck/Cd found at high winds: (i) an increase of Ck/Cd based on decreasing Cd (Cd_DC) and (ii) an increase of Ck/Cd based on increasing Ck (Ck_IC). The modified surface layer schemes were compared to the original HWRF scheme (using nearly fixed Cd and Ck at extreme winds; CTRL) through idealized experiments and real-case predictions. The idealized experiments showed that Cd_DC reduced frictional dissipation in the air-sea interface as well as significantly reduced sea surface cooling, making the TC stronger than other schemes. As a result, Cd_DC reduced the mean absolute error and negative bias by 15.0% (21.0%) and 19.1% (32.0%), respectively, for all lead times of Hurricane Irma in 2017 (Typhoon Mangkhut in 2018) compared to CTRL. This result suggests that new parameterization of Ck/Cd with decreasing Cd at high winds can help improve TC intensity prediction, which currently suffers from underestimating the intensity of the strongest TCs

    An Index to Better Estimate Tropical Cyclone Intensity Change in the Western North Pacific

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    A revised predictor called the net energy gain rate (NGR) is suggested by considering wind dependent drag coefficient based on the existing maximum potential intensity theory. A series of wind speed dependent NGR, known as NGRā€w, is calculated based on preā€tropical cyclone (TC) averaged ocean temperatures from the surface down to 120 m (at 10ā€m intervals) to include the TCā€induced vertical mixing for 13 years (2004ā€“2016) in the western North Pacific. It turns out that the NGR50ā€w (NGRā€w based on temperature averaged over top 50 m) has the highest correlation with 24ā€h TC intensity change compared with the commonly used sea surface temperatureā€based intensification potential (POT), depthā€averaged temperatureā€based POT (POTDAT), and constant drag coefficient in the NGR. To demonstrate the effectiveness of the NGR50ā€w, we designed and conducted experiments for training (2004ā€“2014) and testing (2015ā€“2016). The model with the NGR50ā€w shows greater skill than the model with POTDAT or POT by reducing prediction errors by about 16%

    Massive Concha Bullosa with Secondary Maxillary Sinusitis

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    Concha bullosa is a common anatomic variation of the middle turbinate; however, sinusitis secondary to the concha bullosa is rare. A 52-yr-old woman presented with nasal obstruction and posterior nasal drip. Computed tomography and examination of the nasal cavity revealed septal deviation on the left side, and a massive concha bullosa and maxillary sinusitis on the right side. The lateral lamella of the affected turbinate was removed and the inspissated material was drained. Histopathologic examination of the excised lesion in the concha bullosa revealed bacterial colonies in the mucus plug. We report here on a massive concha bullosa with secondary maxillary sinusitis

    Development of Threat Evaluation Tool for Distributed Network Environment

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    Current information protection systems only detect and warn against individual intrusion, and are not able to provide a collective and synthesized alert message. In this paper, we propose a new Meta-IDS system which is called ``SIA System''. The SIA system can filter redundant alert messages, analyze mixed attacks using correlation alert messages from each sensor and respond to security threats quickly, after classifying them into one of four different statuses. Then we implement the SIA system and test the efficiency of it in the managed networks. Thus we confirm that the SIA system enables security managers to deal with security threats efficiently

    Design, Analysis and Empirical Researches for Solar Heat Collecting System based on Flat Mirrors Combination

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    There has been a dramatic increase of research on energy production using solar energy. This research aims to examine development of concentrating solar collector that is related to mid-high solar energy field. Although the use of dish type solar thermal system has been common in the existing high-efficiency collector technology, several problems have been raised. In order to solve these issues, the frame has been designed as flat plate type with Fresnel lens and the structural stability has been proved by analysis. Furthermore, the experiment that checks collectorrsquos temperature has been performed for the correct works of the stirling engine

    Electrical spin injection and accumulation in CoFe/MgO/Ge contacts at room temperature

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    We first report the all-electrical spin injection and detection in CoFe/MgO/moderately doped n-Ge contact at room temperature (RT), employing threeterminal Hanle measurements. A sizable spin signal of ~170 k{\Omega} {\mu}m^2 has been observed at RT, and the analysis using a single-step tunneling model gives a spin lifetime of ~120 ps and a spin diffusion length of ~683 nm in Ge. The observed spin signal shows asymmetric bias and temperature dependences which are strongly related to the asymmetry of the tunneling process.Comment: 28 pages, 5 figure

    Epigallocatechin-3-gallate protects toluene diisocyanate-induced airway inflammation in a murine model of asthma

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    AbstractEpigallocatechin-3-gallate (EGCG), a major form of tea catechin, has anti-allergic properties. To elucidate the anti-allergic mechanisms of EGCG, we investigated its regulation of matrix metalloproteinase (MMP-9) expression in toluene diisocyanate (TDI)-inhalation lung tissues as well as TNF-Ī± and Th2 cytokine (IL-5) production in BAL fluid. Compared with untreated asthmatic mice those administrated with EGCG had significantly reduced asthmatic reaction. Also, increased reactive oxygen species (ROS) generation by TDI inhalation was diminished by administration of EGCG in BAL fluid. These results suggest that EGCG regulates inflammatory cell migration possibly by suppressing MMP-9 production and ROS generation, and indicate that EGCG may be useful as an adjuvant therapy for bronchial asthma

    Effect of pralidoxime on coronary perfusion pressure during cardiopulmonary resuscitation in a pig model

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    Objective Pralidoxime is widely used for the treatment of organophosphate poisoning. Multiple studies have reported its vasoconstrictive property, which may facilitate the restoration of spontaneous circulation (ROSC) after cardiac arrest by increasing the coronary perfusion pressure (CPP). 2,3-Butanedione monoxime, which belongs to the same oxime family, has been shown to facilitate ROSC by reducing left ventricular ischemic contracture. Because pralidoxime and 2,3-butanedione monoxime have several common mechanisms of action, both drugs may have similar effects on ischemic contracture. Thus, we investigated the effects of pralidoxime administration during cardiopulmonary resuscitation in a pig model with a focus on ischemic contracture and CPP. Methods After 14 minutes of untreated ventricular fibrillation, followed by 8 minutes of basic life support, 16 pigs randomly received either 80 mg/kg of pralidoxime (pralidoxime group) or an equivalent volume of saline (control group) during advanced cardiovascular life support (ACLS). Results Mixed-model analyses of left ventricular wall thickness and chamber area during ACLS revealed no significant group effects or group-time interactions, whereas a mixed-model analysis of the CPP during ACLS revealed a significant group effect (P=0.038) and group-time interaction (P<0.001). Post-hoc analyses revealed significant increases in CPP in the pralidoxime group, starting at 5 minutes after pralidoxime administration. No animal, except one in the pralidoxime group, achieved ROSC; thus, the rate of ROSC did not differ between the two groups. Conclusion In a pig model of cardiac arrest, pralidoxime administered during cardiopulmonary resuscitation did not reduce ischemic contracture; however, it significantly improved CPP
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