Publications by authors named "SangKi Lee"

The current state-of-the-art climate models when combined together suggest that the anthropogenic weakening of the Atlantic Meridional Overturning Circulation (AMOC) has already begun since the mid-1980s. However, continuous direct observational records during the past two decades have shown remarkable resilience of the AMOC. To shed light on this apparent contradiction, here we attempt to attribute the interdecadal variation of the historical AMOC to the anthropogenic and natural signals, by analyzing multiple climate and surface-forced ocean model simulations together with direct observational data.

View Article and Find Full Text PDF

Future changes to the year-to-year swings between active and inactive North Atlantic tropical cyclone (TC) seasons have received little attention, yet may have great societal implications in areas prone to hurricane landfalls. This work investigates past and future changes in North Atlantic TC activity, focusing on interannual variability and evaluating the contributions from anthropogenic forcing. We show that interannual variability of Atlantic TC activity has already increased, evidenced by an increase in the occurrence of both extremely active and inactive TC seasons.

View Article and Find Full Text PDF

and polymorphisms are associated with endurance exercise ability. This case-control study explored the association of and gene polymorphisms with elite pure endurance in Korean athletes, hypothesizing that individuals with both and genotypes would exhibit superior endurance. We recruited 934 elite athletes (713 males, 221 females) and selected 45 pure endurance athletes (36 males, 9 females) requiring "≥90% aerobic energy metabolism during sports events", in addition to 679 healthy non-athlete Koreans (361 males, 318 females) as controls.

View Article and Find Full Text PDF

At seasonal-to-interannual timescales, Atlantic hurricane activity is greatly modulated by El Niño-Southern Oscillation and the Atlantic Meridional Mode. However, those climate modes develop predominantly in boreal winter or spring and are weaker during the Atlantic hurricane season (June-November). The leading mode of tropical Atlantic sea surface temperature (SST) variability during the Atlantic hurricane season is Atlantic Niño/Niña, which is characterized by warm/cold SST anomalies in the eastern equatorial Atlantic.

View Article and Find Full Text PDF
Article Synopsis
  • Future research on El Niño-Southern Oscillation (ENSO) onset and decay is limited, with this study analyzing projected changes in El Niño events in the 21st Century through a multi-model ensemble of climate models.
  • It finds that El Niño events are expected to (1) develop more rapidly, (2) last longer in the eastern and far eastern Pacific, and (3) exhibit stronger remote impacts through teleconnections.
  • These changes stem from shifts in the tropical Pacific's mean state, alterations in ENSO feedback processes, and increased stochastic westerly wind bursts, potentially leading to more significant global consequences of El Niño.
View Article and Find Full Text PDF
Article Synopsis
  • The COVID-19 pandemic in Korea highlights the impact of corporate social responsibility (CSR) on stock returns and investor behavior during tough economic times.
  • Studies show that firms with strong CSR reputations achieve higher stock returns and experience lower volatility compared to those without CSR.
  • Institutional investors, like pension funds, are more likely to sell off non-CSR stocks, suggesting they view CSR as a way to reduce risk in their portfolios.
View Article and Find Full Text PDF

A 7-step enantioselective synthetic method for preparing (S)(+)-coerulescine is reported through the use of diphenylmethyl tert-butyl α-(2-nitrophenyl)malonate (16% overall yield, >99% ee). Allylation is the key step under phase-transfer catalytic conditions (86% ee). This synthetic method can be used as a practical route for the synthesis of various derivatives of (S)(+)-coerulescine for analyzing its structure-activity relationships against its biological activities.

View Article and Find Full Text PDF

This study evaluated hair samples from 28 subjects who tested positive for ketamine at Seoul Institute National Forensic Service in Korea between 2016 and 2017. Ketamine in the hair was extracted using a solution of 1% hydrochloric acid in methanol for 16 h. Extracts were analyzed using gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS-MS).

View Article and Find Full Text PDF
Article Synopsis
  • Hair analysis is a key method for monitoring drug exposure, particularly for antiepileptics, using an advanced technique called LC-MS/MS to analyze six barbiturates, phenytoin, and topiramate.
  • Three hair extraction methods (simple methanol, acidic methanol, and liquid-liquid extraction) were tested, with methanol incubation emerging as the most effective for achieving reliable results.
  • The LC-MS/MS method demonstrated high precision and accuracy, allowing for the detection of drug concentrations in real hair samples from drug users, thus contributing valuable data for both forensic and clinical toxicology.
View Article and Find Full Text PDF

Following the onset of the strong 2014-2016 El Niño, a decade-long increase of the basin-wide sea level and heat content in the subtropical southern Indian Ocean (SIO) in 2004-2013 ended with an unprecedented drop, which quickly recovered during the weak 2017-2018 La Niña. Here, we show that the 2014-2016 El Niño contributed to the observed cooling through an unusual combination of both the reduced heat advection from the Pacific (dominant in the eastern SIO) and the basin-wide cyclonic wind anomaly that led to shoaling of isotherms (dominant in the western SIO). The ensuing recovery was mainly forced by an anticyclonic wind anomaly associated with stronger trade winds that caused deepening of isotherms and upper-ocean warming, effectively suppressing the 2014-2016 cooling signal propagating from the eastern boundary.

View Article and Find Full Text PDF
Article Synopsis
  • Methamphetamine is a highly addictive stimulant that leads to chronic relapsing addiction.
  • This study used advanced mass spectrometry and network analysis to examine the metabolic changes in human hair linked to heavy methamphetamine abuse.
  • It identified significant disruptions in lipid and amino acid metabolism, highlighting human hair as a valuable tool for diagnosing drug addiction and developing treatment strategies.
View Article and Find Full Text PDF

The northern Gulf of Mexico (GoM) is a region strongly influenced by river discharges of freshwater and nutrients, which promote a highly productive coastal ecosystem that host commercially valuable marine species. A variety of climate and weather processes could potentially influence the river discharges into the northern GoM. However, their impacts on the coastal ecosystem remain poorly described.

View Article and Find Full Text PDF

The persistent energy imbalance at the top of the atmosphere, inferred from satellite measurements, indicates that the Earth's climate system continues to accumulate excess heat. As only sparse and irregular measurements of ocean heat below 2000 m depth exist, one of the most challenging questions in global climate change studies is whether the excess heat has already penetrated into the deep ocean. Here we perform a comprehensive analysis of satellite and in situ measurements to report that a significant deep-ocean warming occurred in the subtropical South Pacific Ocean over the past decade (2005-2014).

View Article and Find Full Text PDF

Congenital cardiovascular anomalies, such as dextrocardia, persistent left superior vena cava (SVC), and pulmonary artery (PA) sling, are rare disorders. These congenital anomalies can occur alone, or coincide with other congenital malformations. In the majority of cases, congenital anomalies are detected early in life by certain signs and symptoms.

View Article and Find Full Text PDF

A mixed infection of (Mab) and (MTB) in the lung is an unusual clinical manifestation and has not yet been reported. A 61-year-old woman had been treated for Mab lung disease and concomitant pneumonia, and was diagnosed with pulmonary tuberculosis (PTB). Despite both anti-PTB and anti-Mab therapy, her entire left lung was destroyed and collapsed.

View Article and Find Full Text PDF
Article Synopsis
  • Rotenone, a neurotoxin from Derris or yam bean, can cause Parkinson-like symptoms and inhibits electron transport.
  • A forensic analysis using liquid chromatography-tandem mass spectrometry detected rotenone in a fatal poisoning case, with a highly accurate and precise method to determine its concentration in blood and other tissues.
  • The case involved a 33-year-old man who ingested a significant amount of rotenone, as evidenced by the high concentration ratios of rotenone in various samples collected postmortem.
View Article and Find Full Text PDF

Phenylalkylamine derivatives, such as methamphetamine (MA), 3,4-methylenedioxymethamphetamine (MDMA), phentermine, fenfluramine, phendimetrazine, amfepramone, and ketamine, are widely abused recreational or anorectic drugs in Korea, and their abuse has become a serious social problem. Hair is a useful specimen to prove chronic use and liquid chromatography-tandem mass spectrometry (LC-MS/MS) has recently become a more popular tool for hair analysis due to sensitivity and simplicity in sample preparation. In order to overcome limitations of standard reversed-phase column to separate low molecular weight amines, we adopted a multi-mode reversed-phase column, Scherzo SS-C18, which was composed of strong ionic ligands and C18 ligands, and used pH gradient elution to separate seven psychotropic phenylalkylamines and their metabolites.

View Article and Find Full Text PDF

Essential tremor is an involuntary trembling of body limbs in people without tremor-related disease. In previous study, suppression of tremor by sensory electrical stimulation was confirmed on the index finger. This study investigates the effect of sensory stimulation on multiple segments and joints of the upper limb.

View Article and Find Full Text PDF

Projections of climate change impacts on coral reefs produced at the coarse resolution (~1°) of Global Climate Models (GCMs) have informed debate but have not helped target local management actions. Here, projections of the onset of annual coral bleaching conditions in the Caribbean under Representative Concentration Pathway (RCP) 8.5 are produced using an ensemble of 33 Coupled Model Intercomparison Project phase-5 models and via dynamical and statistical downscaling.

View Article and Find Full Text PDF

Although cemented tibial fixation of total knee arthroplasty accepted as the gold standard, cementless fixation as a means to supplement disadvantages of cemented fixation continues to be of interest to clinicians. One hundred sixty-eight consecutive knees undergoing primary knee arthroplasty for osteoarthritis were randomly assigned to receive either a cemented (86 knees) or cementless (82 knees) fixation of tibial component. We report the outcomes at 8 to 11years (mean, 9.

View Article and Find Full Text PDF

Propofol, a short-acting and sedative-hypnotic agent, induces and maintains anesthesia. Since it is known to produce mild euphoria and hallucinations, the recreational use of propofol has been a big issue in Korea. Furthermore, many deaths have occurred due to its abuse and misuse.

View Article and Find Full Text PDF

The chemical castration law, which targets child molesters with recidivism, was introduced in Korea in 2011. For this, leuprolide, a gonadotropin-releasing hormone agonist, is used to decrease testosterone production and suppress libido. In order to achieve efficient law enforcement, it is necessary to monitor intentional ingestion of drugs that antagonize the effect of leuprolide.

View Article and Find Full Text PDF

We described the findings of a study into the post-mortem redistribution (PMR) of 76 drugs found in 129 drug-related cases between 2006 and 2009. Seventy six drugs (psychotropic drugs (n=14), antidepressants (n=9), sedatives (n=6) and so on) were simultaneously quantified in cardiac and peripheral blood by gas chromatography-mass spectrometry (GC/MS) or liquid chromatography-tandem mass spectrometry (LC/MS/MS). The absence, possibility or presence of PMR of drugs was determined according to the ratios of cardiac to femoral blood concentrations (C/P ratios).

View Article and Find Full Text PDF
Article Synopsis
  • This study measured the concentration of THCCOOH, a cannabis metabolite, in different hair types (pubic, axillary, beard, and head) from cannabis users.
  • The research involved a complex process of hair sample preparation and analysis using gas chromatography tandem mass spectrometry (GC/MS/MS-NCI).
  • Results showed that pubic hair had higher THCCOOH concentrations than head hair, but no significant difference in concentrations between head and body hair based on urine test results was found.
View Article and Find Full Text PDF
Article Synopsis
  • The paper examines 21 cases of cyanide poisoning via oral ingestion, highlighting the importance of analyzing cyanide concentrations in biological specimens for forensic toxicology.
  • The study found significant variations in cyanide levels across different sample types (heart blood, peripheral blood, and gastric contents), with specific concentration ranges reported.
  • The results indicate a potential postmortem redistribution of cyanide, confirming that death from oral ingestion is possible, and the study presents detailed findings alongside a literature review.
View Article and Find Full Text PDF