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To trace the surficial responses of lowlands to past climate change, we investigated δ 13 C in total organic carbon (TOC), C/N ratios, magnetic susceptibility (MS), and silicon (Si) intensity (directly proportional to concentration) in wetland sediments collected from the Gimpo area of central Korea, covering 6600–4600 cal yr BP. Two organic layers with high TOC%, negatively depleted δ 13 C TOC values (− 27 to − 29‰), low MS values, and low Si intensities were found at 6200–5900 and 5200–4800 cal yr BP, respectively. These middle Holocene wet periods corresponded to relatively intensified summer monsoon and solar activity periods. The intervening dry period (5900–5200 cal yr BP) with high MS, high Si, and low TOC% corresponded to an intensified dust-activity interval and stronger winter monsoon. This multi-centennial climatic fluctuation of wet periods (6200–5900 cal yr BP and 5200–4800 cal yr BP) and an intervening dry period (5900–5200 cal yr BP) in central Korea was more synchronous with climate change in the arid inner part of China than with that in South China, suggesting possible strong high-latitude-driven climatic influences (e.g., North Atlantic cooling events) during the middle Holocene. [ABSTRACT FROM AUTHOR]

Abstract: Age-controlled pollen stratigraphy from the Paju (UJ-10), Cheonggye (Gwangtong Trench-A), and Hanam (UD-2) sites records the response of vegetation to climate changes and human activity over the past 7000 years in the Han River drainage basin, west-central Korea. The pollen profiles show a transition from natural vegetation to human-disturbed vegetation around 4800 cal BP. During the natural vegetation stage (ca. 7000–4800 cal BP; early Neolithic Age), dense woodlands of mixed deciduous and evergreen broadleaved hardwoods flourished in the surrounding hills and mountains owing to the enhanced East Asian summer monsoon. The human-disturbed vegetation stage (ca. 4800 cal BP–modern; late Neolithic Age to modern) was characterized by transitional forests and open grasslands and can be subdivided into several agricultural stages. During the dry-field cultivation stage (ca. 4800–3000 cal BP; late Neolithic to Bronze ages), humans engaged in dry-field agriculture under cool, dry climatic conditions. The ensuing paddy-field cultivation stage (ca. 3000–800 cal BP; since the Bronze Age) initially developed during an interval of stable, warm, wet conditions from ca. 3000 to ca. 1400 cal BP, during which time people of Bronze and Iron Age cultures engaged in widespread paddy farming. Subsequently, a brief climatic fluctuation (ca. 1400–800 cal BP) caused changes in the agricultural practices of the Unified Silla and Koryo people. During the combined dry-field and paddy-field cultivation stage (ca. 800 cal BP–modern; since the Joseon Dynasty), climatic deterioration affected agricultural practices of the Joseon people and resulted in open forests with wide grasslands during the interval equivalent to the Little Ice Age (1550–1859 AD). Since then, humans in the area have strategically managed pine forests to supply wood for house-building and fuel. [Copyright &y& Elsevier]

Abstract: Organic and inorganic geochemical and mineralogical analyses from core CL4 drilled in the Cheollipo wetland were carried out to investigate the Holocene Climatic Optimum, the formation of pyrite, and the humidity of the Korean western coast during the Holocene time. Lithostratigraphy, mineralogy, major element concentrations and organic contents of the sediments of the CL4 borehole core indicate that the Holocene Climatic Optimum occurred from about 7400 to 4500BP, and that pyrite formed in brackish water tidal flat or salt marsh at least during 7400–6400BP. In addition, sediments coarser in mean grain size and larger in standard deviation corresponded with periods of 8500, 5400, 5000 and 1700BP. During the periods, the coarse sediments seem to have been delivered by high energy storm events. The periods partially overlap with those of high ratios of Si/Al, Na/Al and Na/Ti. These phenomena indicate that the weakly weathered terrigenous sediments were delivered to the Cheollipo borehole core site by storm events. [Copyright &y& Elsevier]

Abstract: The acetylthiocholine (ATC) – cleaving cholinesterase (ChE) activity in Manila clam, which is widely distributed throughout the coastal environment of Korea, was assayed as a potentially useful biomarker of organophosphorous pesticides (OPs). A clear dose–response relationship was determined between inhibited ChE in adductor muscle of clams and four OPs (methidathion, chlorpyrifos, diazinon, IBP) which are heavily used OPs in Korea. The measured EC50-24 h values of methidathion, chlorpyrifos, diazinon, and IBP for Ruditapes philippinarum were 7.16 μg l−1, 0.34 mg l−1, 3.01 mg l−1, and 3.41 mg l−1, respectively. In field studies, ChE activity in Manila clams collected from 23 stations in the mid-western coastal region demonstrated spatial variation with statistical differences. These results suggest that ChE activity in R. philippinarum is a potential biomarker for assessing organophosphorous pesticide contamination in coastal environments. [Copyright &y& Elsevier]

Abstract: Background: We investigated the association between meteorological parameters and hospital admissions for acute myocardial infarction (AMI) in a temperate and continental climate, Korea. Methods: From the Korean AMI Registry, 2136 Koreans admitted for AMI in four university hospitals in Daegu city from November 2005 to October 2007 were included in this study. We calculated the incidences of AMI per season, per month, and per day-of-week. The meteorological parameters, including air temperature, relative humidity, wind speed, sunshine duration, and a thermo-hydrological index, were provided by the database of the Korea Meteorological Administration. Generalized additive Poisson models were used. Results: Seasonal variations were noted for AMI, characterized by winter peak and summer trough (p <0.001). Monthly occurrence rate of AMI was highest in January and lowest in October (p <0.001). There were significant associations between hospital admissions and meteorological parameters including air temperature, relative humidity, and sunshine duration after controlling for effects of day-of-week, season, and holidays (p <0.05). These associations were stronger in females and the younger age (<65 years) (p <0.01). Conclusions: The incidence of AMI shows seasonal and monthly variations. Meteorological parameters have a significant influence on the occurrence of AMI, particularly in females and the younger age. [ABSTRACT FROM AUTHOR]

Abstract: Terrace stratigraphy of the southeastern coastal areas of Korea has been studied with the help of terrace mapping and geochronology. Coastal terraces include 90–130m upper High Terrace (uHT), 63–86m High Terrace (HT), 36–55m Middle Terrace (MT) and 8–25m Low Terrace (LT) divisions, each of which has been subdivided. Amongst these, LT 2 formed during the late Pleistocene, based on Tephras Aso-4 (MIS 5c), Ata (MIS 5d or 5e) and OSL ages. The age of LT 1–3 ranges from MIS 5e to 5a, based on tephra ages from Aso-4 (ca. 90ka) and Ata (100–125ka). The uplift rate in the SE part of Korea ranges between 0.14 and 0.22mm/a and it is quite small in comparison to the Japanese island arc, or many other tectonically active East and Southeastern Asian regions. [Copyright &y& Elsevier]

Abstract: Mid- and Late-Holocene changes in vegetation, climate and depositional environment have been deduced from pollen records taken from the Gwangtong Trench-A in Cheonggye-cheon, the tributary of the Han River, with time control provided from three radiocarbon ages. A mid-Holocene hypsithermal occurred between ?7000 and 5000BP, when evergreen and deciduous broadleaved trees flourished at mountainous slope surrounding the lowland riverine area. Afterward climate became cooler until 1700BP. During this period, evergreen and deciduous broadleaved trees were replaced by conifers and cool-loving deciduous broadleaved trees of Picea, Pinus (Diploxylon), Larix/Pseudotsuga and Betula. Since 1700BP, the local vegetation change from alder woodlands to sedges caused by human impact has been identified. The depositional environmental change from lowland riverine to fluvial at 1700BP may allow the people to cultivate crops on dryland fields. Human activities are recognized by the first occurrence of buckwheat (Fagopyrum) associated with a sudden increase in maize (Zea) pollen and pioneer tree, P. (Diploxylon) with arboreal pollen concentration decreasing at 1700BP. [Copyright &y& Elsevier]

This study traces coastal sand dune development processes in East Asia during the Holocene to understand climate and environmental changes. We used optically stimulated luminescence (OSL) dating to examine periods of activation and stabilization of dunes along the western coast of the Korean Peninsula. The results from the Taean Chollipo, Seocheon Dasari, and Gochang Sabanri dunes were then compared with those from previous studies to establish a broad understanding of coastal dune development in this region. Sedimentation rates were calculated for the three dunes, and their development periods were classified through statistical analysis that included data from previous studies. We defined five main periods of late Holocene dune development (<0.1 ka, 0.2–0.5 ka, 1.2–2.0 ka, 2.5–3.2 ka, and 5.5–6.5 ka). These correlated to periods of sea level decrease and global cooling determined by ice rafted debris records. We concluded that the development of coastal dunes in western Korea was influenced by sea level decreases, and global cooling events were enhanced by the East Asian winter monsoon. In addition, human activity increases also contributed to the development of the dunes. This study showed how coastal sand dunes can be evaluated as important indicators of global climate change. These results improved our understanding of how paleoclimate changes affected environmental conditions in East Asia and how coastal dune development periods can be used to reconstruct paleo-environmental conditions. • Coastal sand dunes are developed along the western coast of the Korean Peninsula. • Five main periods of late Holocene dune development were determined by OSL. • Main periods were -less than 0.1, 0.2–0.5, 1.2–2.0, 2.5–3.2, and 5.5–6.5 ka. • Main periods were agreed with sea level decrease and global cooling in the Holocene. [ABSTRACT FROM AUTHOR]

To trace the environmental change that occurred at a coastal area during the Holocene, we performed radiocarbon dating and geochemical analyses using sedimentary cores recovered from the Beolgyo tidal flats on the south coast of Korea. The δ 13 C values of total organic carbon (TOC), which represent relative inputs of terrestrial (or freshwater) and marine organic sources, revealed a long-term increasing trend from −27.5 to −21.7‰ during the period between 10,000 and 3000 cal BP, suggesting an evolutionary series of fluvial-dominant to marine-dominant environments, coupled with weakened summer monsoon intensity. From 3000 cal BP to the present, the δ 13 C TOC decreased gradually from −21.7 to −24‰, indicating enhancement of freshwater input during this time. The observed long-term environmental change was divided into six stages based on the averages of the total sulfur content (TS%) and the organic carbon to sulfur ratio (C/S), proxies for paleosalinity. On multi-centennial to millennial timescales, higher C/S ratios and lower TS% were linked to higher δ 13 C TOC values, indicating strong freshwater input at Stage 2 (∼8300–7400 cal BP), Stage 4 (∼4500–3300 cal BP), and Stage 6 (∼1100 cal BP to present). Strong freshwater discharge events synchronously occurred at 4300 cal BP and 3600 cal BP along the south coast of Korea. Further testing should be carried out in other East Asian coastal areas. This study suggests that sedimentary δ 13 C TOC values and C/S ratios can be used in Asian coastal regions to trace past freshwater input events and summer monsoon intensity during relatively stable sea level periods (e.g., the middle to late Holocene). [ABSTRACT FROM AUTHOR]

Abstract: Our study aimed to compare cognitive status and declines in AD with/without small vessel disease (SVD) and SIVD at baseline and 1-year follow-up. Patients with Alzheimer's disease without small vessel disease (AD(−)SVD) (n =148), Alzheimer's disease with small vessel disease (AD(+)SVD) (n =94) and SIVD (n =60) were recruited from database of multiple centers in Korea. Basic demographics and detailed neuropsychological results were compared. AD, regardless of SVD, showed worse memory and better executive function than SIVD at baseline. Mini-Mental State Examination scores and visual memory function declined more in AD than those in SIVD whereas Barthel Activities of Daily Living (B-ADL) scores declined more in SIVD. AD showed different patterns of cognitive impairment compared with SIVD. After 1 year, AD showed more rapid cognitive decline in some domains. Further investigations with longer follow-up duration may be needed to confirm the cumulative effects of SVD in AD and different patterns of decline between AD and SIVD. [Copyright &y& Elsevier]

Abstract: The SCI, the MCI, and the Alzheimer''s disease (AD) are on a spectrum of disease progression; therefore, identification of the earliest signs of cognitive deterioration is becoming a crucial issue. The goal of this study was to examine symptom characteristics and distinguish predictive symptoms in patients with MCI compared with SCI, using caregiver questionnaires. We assessed the Korean Dementia Screening Questionnaire (KDSQ) and Seoul Instrumental activities of Daily Living (S-IADL) of 344 subjects with SCI and 697 with MCI. Multivariate logistic regression analyses were conducted after adjusting for age, sex, and educational status. Common and rare symptoms were similar between the SCI and MCI groups. The most distinguishing features of KDSQ were ‘Finds it hard to go somewhere on his/her own using public transportation’ (odds ratio=OR=4.56, p <0.0001), ‘Has difficulty in operating appliances’ (OR=2.47, p =0.001), and ‘Keeps repeating the same question’ (OR=2.03, p <0.0001). In S-IADL, the most outstanding features were ‘using household appliances’ (OR=3.99, p <0.0001), ‘taking medication’ (OR=2.38, p =0.01), and ‘using public transportation’ (OR=1.94, p =0.04). The dysfunction in ‘using household appliance’ and ‘using public transportation’ reflect the possibility of MCI rather than SCI. Therefore, it is suggested that these symptoms also have a discriminative and predictive power in identifying SCI. [Copyright &y& Elsevier]

Background: Little is known about the clinical characteristics of patients with situational syncope such as defecation syncope (DS) or micturition syncope (MS) compared with those with common vasovagal syncope (VVS). Methods: Among 680 consecutive patients, who underwent a head-up tilt test between January 2006 and November 2010, 282 patients (40.4± 16.7 years; 48.6% men) diagnosed as DS (n = 38), MS (n = 38), or common VVS (n = 208) were included. Results: Ages at diagnosis (38.7± 17.3 vs 48.3± 14.1 vs 42.0± 13.8, P = 0.004) and the first syncope (33.7± 18.4 vs 44.5± 15.3 vs 37.5± 14.6, P = 0.002) were significantly less in patients with common VVS than those with DS or MS, respectively. The patients with MS were more likely to be men (73.7%, P = 0.036), whereas patients with DS were more commonly women (73.7%). No sexual preference was observed in patients with common VVS. Body mass index was significantly lower (P = 0.047) and syncopal episodes were more recurrent (P = 0.049) in patients with common VVS than those with DS or MS. The frequency of drinking alcohol before syncope was significantly higher in patients with MS (39.5%, P < 0.001). Conclusions: DS tended to occur in older women, whereas MS tended to occur in middle-aged men and drinking alcohol was an important precipitating factor for MS. However, common VVS was observed more in a thin and young population, which was more recurrent compared with those situational syncopes. (PACE 2011;1-7) [ABSTRACT FROM AUTHOR]

Abstract: Marine isotope stage 3 (MIS3), spanning from 25 to 60ka BP, was a time of substantial environmental change that included changes in the global ice volume and atmospheric composition, with resultant regional climate changes. To understand past vegetation responses to such environmental changes in Korea, we estimated the abundance of C3 and C4 plants using the C/N and carbon isotope ratios of sedimentary organic matter. The MIS3 sedimentary unit at the Cheollipo site, located in a western coastal area of Korea, is characterized by a dark to light gray colored sedimentary unit (3.05 to 5.05m in elevation, MIS3), which is between an underlain oxidized yellowish sedimentary unit (<3.05m in elevation) and an overlain oxidized yellowish sedimentary unit (>5.05m in elevation). The estimated abundance of C4 plants varied between 60 and 10% during the MIS3. The suborbital-scale variation in the estimated percentage of C4 plants was similar to those reported in continental ice volume and the East Asian monsoon intensity, suggesting that C4 plants prevailed under colder and drier conditions (intensified winter monsoon), whereas C3 plants have favored a warmer and wetter climate (intensified summer monsoon). Compared with high latitude regions (e.g., Chinese Loess Plateau and Lake Baikal) where low summer temperature suppressed aridity and pCO2 influences during the last glacial period, vegetation change in Cheollipo area may have more sensitively responded to aridity change which had been affected by the summer/winter monsoon intensity. The climate change in the western coastal area (Yellow Sea side) of Korea during the late Pleistocene may have been controlled by regional climate change coupled with continental ice volume change. [ABSTRACT FROM AUTHOR]

Little is known about risk factors for 6-month major adverse cardiac events (MACEs) in 30-day survivors after acute myocardial infarction (AMI). We investigated predictors of 6-month MACE in 30-day survivors after MI from the Korea Acute Myocardial Infarction Registry (KAMIR). From November 2005 to January 2008, 9,706 patients (6,983 men, mean age 64.0 ± 12.4 years) who survived >30 days after AMI were analyzed. The primary end point was 6-month MACEs including death, MI, and revascularization. During 6-month follow-up, 317 patients (3.2%) had MACEs including 66 (0.6%) deaths, 23 (0.2%) recurrent MIs, and 218 (2.2%) revascularizations. In multivariate logistic regression analysis, factors reflecting demographics (body mass index), severity of left ventricular systolic dysfunction (Killip class >I, in-hospital cardiogenic shock, use of intra-aortic balloon pump), residual myocardial ischemia (previous coronary heart disease, multivessel disease), and electrical instability (ventricular tachycardia/ventricular fibrillation on admission) were independent predictors of 6-month MACEs after adjustment for clinical, angiographic, and procedural data. Plasma level of N-terminal pro–B-type natriuretic peptide provided an additional prognostic value predicting 6-month MACEs. In conclusion, this study provides useful prognostic information for clinicians to advise patients who have survived the acute phase of MI. More intensive management is needed in survivors after MI with these high-risk features. [Copyright &y& Elsevier]

Abstract: The 18.820m long sediment core MW-1 from the Yeongsan Estuary consists of five primary unconsolidated to semi-consolidated units, ranging in age from late Pleistocene to Holocene, overlying a Cretaceous-aged basement. From oldest to youngest, these units include units-1, 2, 3 (fluvial units), unit-4 (paleosol unit), and unit-5 (Holocene estuarine deposits). Units-1, 2, and 3 are interpreted as in-channel or overbank deposits. Plant materials included within the units and the TOC/TN (total organic carbon/total nitrogen) ratios (11–14) are also indicative of terrestrial origin. Unit-2 yields radiocarbon date of 37,700 14C yrBP. Unit-4, the paleosol unit, is estimated to be originally deposited in fluvial setting such as the area of floodplain or backswamp away from the main channel, based on the sporadic distribution of the stagnant freshwater acritarch Pseudoschizaea and algae Spirogyra. The timing of deposition of the original sediments of the paleosol unit is constrained by radiocarbon age of underlying fluvial sediments (unit-2). The timing of pedogenesis is around the Last Glacial Maximum when sea level of the Yellow Sea was lowered, temperature was lowered, rainfall was reduced, and the inland was sparsely vegetated. Estuarine deposits (unit-5) are interpreted to be deposited during the Holocene marine transgression. [Copyright &y& Elsevier]

Objective: This study was done to verify the validity and the reliability of the newly developed Computerized Dementia Screening Test (CDST) to be easily used in the primary care setting of Korea. Design: Comparison of the results of CDST between 103 healthy control subjects and 41 patients who were diagnosed as having mild cognitive impairment or early dementia, having a clinical dementia rate of 0.5–1 from one health examination center and two neurology clinics in university hospitals. Measurements: In order to estimate the criterion-related validity, logistic regression analysis for dementia was done using the four individual test results of CDST, age and educational level. The correlation between Korean Mini-Mental State Examination (K-MMSE) and the predicted probability of mild cognitive impairment and early dementia from the logistic regression was measured to verify its validity. The reliability of CDST was measured by test–retest reliability. Results: The sensitivity and specificity of CDST were 75.6% and 94.2%, respectively, if the cut-off point was set to be 0.5 in the logistic regression model. The Pearson''s Correlation Coefficient between K-MMSE and the predicted probability of mild cognitive impairment and early dementia from the logistic regression analysis was 0.59 (P<0.001). The overall test–retest reliability using the predicted probability of dementia from the logistic regression analysis of CDST was 0.89 (P=0.01). Conclusion: The validity and reliability of CDST is adequate for use as a screening tool to identify mild cognitive impairment and early dementia in Korean primary care. [Copyright &y& Elsevier]