Fortnightly variability of horizontal salinity gradient affects exchange flow in the Sumjin River estuary

The horizontal salinity gradient has been reported to play a crucial role in fortnightly variability of estuarine exchange flow in short estuaries. However, spatiotemporal variations in the salinity gradient and exchange flow have not been examined over an entire short estuary, as only data observed only at specific points was available. We analyzed the variation in salinity gradient along the entire Sumjin River estuary and its effect on the exchange flow over fortnightly tidal cycles based on observations and numerical model experiments. The salinity gradient and exchange flow were in different phases between the lower and upper estuaries by 6–7 days. The maximum salinity gradient periodically reciprocated along the channel as a result of salt flux changes determined by vertical mixing. The stronger exchange flow (> 0.04 m s-1) changed location from mouth to head of estuary while the tidal range decreased, resulting from variability of the salinity gradient. The horizontal salinity gradient is large enough to overwhelm the vertical mixing effect on the exchange flow. The spatiotemporal changes of strong exchange flow correspond well with the horizontal Richardson number value (> 3). This study suggests that for the health of estuarine ecosystems, it is important to determine the spatiotemporal variation in exchange flow throughout the estuary

The effect of phenylephrine on the onset time of rocuronium

BACKGROUND: Several studies have demonstrated that ephedrine shortens the onset time of muscle relaxants, and it does so probably by increasing the cardiac output. However, elevation of the systemic blood pressure through α adrenergic stimulation via ephedrine may affect the onset of muscle relaxants during the induction of anesthesia. We investigated the effect of phenylephrine, which is a selective α-1 agonist, on the onset time of rocuronium and the intubating conditions in adults after the administration of propofol. METHODS: Sixty-four patients were randomly assigned to two groups. Phenylephrine (0.9 µg/kg) (P group) or the same volume of saline (S group) was injected before rocuronium (0.6 mg/kg) administration. Anesthesia was induced with fentanyl 2 µg/kg and propofol 2 mg/kg. The onset time was defined as the time from the end of rocuronium injection to the time when a single twitch height gets to 0% or the minimum level. A well-trained anesthesiologist who was 'blinded' to the treatment groups evaluated the intubating conditions. The mean arterial pressure and heart rate were recorded before induction, before intubation, immediately after intubation and 1 minute and 2 minutes after intubation. RESULTS: The onset time was 84 ± 18 sec in the P-group and 72 ± 14 sec in the S-group. There was no difference of the intubating conditions, the mean arterial pressure and the heart rate between the two groups. CONCLUSIONS: A small dose of phenylephrine, which has a limited effect on blood pressure, delayed the onset time of rocuronium after the administration of propofol, and the vasoconstriction effect of phenylephrine may affect the prolongation of the rocuronium onset time at the induction of anesthesia with using propofol.ope

Quantification of The Performance of CMIP6 Models for Dynamic Downscaling in The North Pacific and Northwest Pacific Oceans

Selecting a reliable global climate model as the driving forcing in simulations with dynamic downscaling is critical for obtaining a reliable regional ocean climate. With respect to their accuracy in providing physical quantities and long-term trends, we quantify the performances of 17 models from the Coupled Model Inter-comparison Project Phase 6 (CMIP6) over the North Pacific (NP) and Northwest Pacific (NWP) oceans for 1979–2014. Based on normalized evaluation measures, each model’s performance for a physical quantity is mainly quantified by the performance score (PS), which ranges from 0 to 100. Overall, the CMIP6 models reasonably reproduce the physical quantities of the driving variables and the warming ocean heat content and temperature trends. However, their performances significantly depend on the variables and region analyzed. The EC-Earth-Veg and CNRM-CM6-1 models show the best performances for the NP and NWP oceans, respectively, with the highest PS values of 85.89 and 76.97, respectively. The EC-Earth3 model series are less sensitive to the driving variables in the NP ocean, as reflected in their PS. The model performance is significantly dependent on the driving variables in the NWP ocean. Nevertheless, providing a better physical quantity does not correlate with a better performance for trend. However, MRI-ESM2-0 model shows a high performance for the physical quantity in the NWP ocean with warming trends similar to references, and it could thus be used as an appropriate driving forcing in dynamic downscaling of this ocean. This study provides objective information for studies involving dynamic downscaling of the NP and NWP oceans

The North Pacific Oxygen Uptake Rates Over the Past Half-Century

The transport of dissolved oxygen (O2) from the surface ocean into the interior is a critical process sustaining aerobic life in mesopelagic ecosystems, but its rates and sensitivity to climate variations are poorly understood. Using a circulation model constrained to historical variability by assimilation of observations, we show that the North Pacific thermocline effectively takes up O2 primarily by expanding the area through which O2-rich mixed layer water is detrained into the thermocline. The outcrop area during the critical winter season varies in concert with the Pacific Decadal Oscillation (PDO). When the central North Pacific Ocean is in a cold phase, the winter outcrop window for the Central Mode Water class (CMW; a neutral density range of γ = 25.6 - 26.6) expands southward allowing more O2-rich surface water to enter the ocean’s interior. An increase in volume flux of water to the CMW density class is partly compensated by a reduced supply to the shallower densities of Subtropical Mode Water (γ = 24.0 - 25.5). The thermocline has become better oxygenated since the 1980s due partly to strong O2 uptake. Positive O2 anomalies appear first near the outcrop and subsequently downstream in the subtropical gyre. In contrast to the O2 variations within the ventilated thermocline, observed O2 in Intermediate Water (density range of γ = 26.7 – 27.2) shows a declining trend over the past half-century, a trend not explained by the open ocean water mass formation rate

Genome-Based Construction of the Metabolic Pathways of Orientia tsutsugamushi and Comparative Analysis within the Rickettsiales Order

Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular bacterium that belongs to the order of Rickettsiales. Recently, we have reported that O. tsutsugamushi has a unique genomic structure, consisting of highly repetitive sequences, and suggested that it may provide valuable insight into the evolution of intracellular bacteria. Here, we have used genomic information to construct the major metabolic pathways of O. tsutsugamushi and performed a comparative analysis of the metabolic genes and pathways of O. tsutsugamushi with other members of the Rickettsiales order. While O. tsutsugamushi has the largest genome among the members of this order, mainly due to the presence of repeated sequences, its metabolic pathways have been highly streamlined. Overall, the metabolic pathways of O. tsutsugamushi were similar to Rickettsia but there were notable differences in several pathways including carbohydrate metabolism, the TCA cycle, and the synthesis of cell wall components as well as in the transport systems. Our results will provide a useful guide to the postgenomic analysis of O. tsutsugamushi and lead to a better understanding of the virulence and physiology of this intracellular pathogen

An evaluation of the thermal properties and albedo of a macrotidal flat

The thermal properties of sediment and the albedo are critical in calculating the heat flux of a tidal flat. However, they are not well known because of the difficulties of sampling and observing tidal flats. We use extensive field observations of a macrotidal flat on the western coast of Korea to determine its sediment heat capacity and albedo. The estimated heat capacity of the upper 0.1 m is 3.65 x 106 J m¯³ K¯¹ with a water content of 70%. Heat capacity decreases with depth to 2.96 x 106 J m¯³ K¯¹ at 0.4 m depth. Estimated thermal diffusivities are 0.47–0.63 x 10¯⁶ m² s¯¹ and 0.38–0.64 x 10¯⁶ m² s¯¹ in spring and summer, respectively. The calculated albedo is a strong function of the solar altitude and the atmospheric transmittance. Atmospheric transmittance is especially important to the albedo when the solar altitude is low. Seasonal mean albedos are 0.13 and 0.15 in spring and summer, respectively. The heat capacity and albedo values obtained above were verified by using them to make independent heat flux estimates at other stations. Estimates based on heat capacity were correlated to albedo-based heat flux estimates with an r² greater than 0.7

Global estimate of submarine groundwater discharge based on an observationally constrained radium isotope model

© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Geophysical Research Letters 41 (2014): 8438–8444, doi:10.1002/2014GL061574.Along the continental margins, rivers and submarine groundwater supply nutrients, trace elements, and radionuclides to the coastal ocean, supporting coastal ecosystems and, increasingly, causing harmful algal blooms and eutrophication. While the global magnitude of gauged riverine water discharge is well known, the magnitude of submarine groundwater discharge (SGD) is poorly constrained. Using an inverse model combined with a global compilation of 228Ra observations, we show that the SGD integrated over the Atlantic and Indo-Pacific Oceans between 60°S and 70°N is (12 ± 3) × 1013 m3 yr−1, which is 3 to 4 times greater than the freshwater fluxes into the oceans by rivers. Unlike the rivers, where more than half of the total flux is discharged into the Atlantic, about 70% of SGD flows into the Indo-Pacific Oceans. We suggest that SGD is the dominant pathway for dissolved terrestrial materials to the global ocean, and this necessitates revisions for the budgets of chemical elements including carbon.This work was supported by the Ministry of Oceans and Fisheries, Korea, through the Korea Institute of Marine Science and Technology (KIMST) (20120176) and National Research Foundation (NRF) of Korea (2013R1A2A1A05004343 and 2013R1A1A1058203). Charette and Moore's contributions were supported by the US National Science Foundation through the GEOTRACES project

Crystal structures of murine norovirus-1 RNA-dependent RNA polymerase in complex with 2-thiouridine or ribavirin

AbstractMurine norovirus-1 (MNV-1) shares many features with human norovirus (HuNoV) and both are classified within the norovirus genus of Caliciviridae family. MNV-1 is used as the surrogate for HuNoV research since it is the only form that can be grown in cell culture. HuNoV and MNV-1 RNA dependent RNA polymerase (RdRp) proteins with the sequence identity of 59% show essentially identical conformations. Here we report the first structural evidence of 2-thiouridine (2TU) or ribavirin binding to MNV-1 RdRp, based on the crystal structures determined at 2.2Å and 2.5Å resolutions, respectively. Cellular and biochemical studies revealed stronger inhibitory effect of 2TU on the replication of MNV-1 in RAW 264.7 cells, compared to that of ribavirin. Our complex structures highlight the key interactions involved in recognition of the nucleoside analogs which block the active site of the viral RNA polymerase

Ductographic Findings of Breast Cancer

Ductography has become the gold standard for the evaluation of patients exhibiting pathologic nipple discharges. In nine patients (age range, 29-67 years; median age, 51 years) with invasive (n=5) or intraductal (n=4) cancer, ductographic findings were recorded, then correlated with mammographic and sonographic findings. Common ductographic findings included complete ductal obstruction, multiple irregular filling defects in the nondilated peripheral ducts, ductal wall irregularities, periductal contrast extravasation, and ductal displacement. Faint microcalcifications or ill-defined masses, which were not opacified by contrast material, were often discovered adjacent to ductal abnormalities. Mammographically and sonographically occult diffusely spreading intraductal cancers often manifested as pathologic nipple discharge. In such cases, meticulous ductographic examinations and interpretations were crucial in order not to miss breast cancers

Delayed-Onset Continuous Bruxism with Olivary Hypertrophy After Top of the Basilar Syndrome

Delayed-onset continuous bruxism due to brain stem infarction has not yet been reported. A 49-year old man presented with quadriplegia and ophthalmoplegia. Brain MRI showed acute infarction in the bilateral midbrain, right thalamus and the superior cerebellum. One month later, the patient developed bruxism which persisted during sleep. A palatal myoclonus was not observed. Follow up MRI taken 4 months later showed bilateral olivary hypertrophy. We suggest that the patient's bruxism may be related to the olivary hypertrophy. The bruxism generator may be located in the pontine-reticular-formation (PRF). Bilateral large midbrain lesions interrupting the cortical inhibition may have produced bilateral olivary hypertrophy, which could stimulate the PRF, producing continuous bruxism