The strength, position, and width changes of the intertropical convergence zone since the Last Glacial Maximum.

The intertropical convergence zone (ITCZ) plays a key role in regulating tropical hydroclimate and global water cycle through changes in its convection strength, latitudinal position, and width. The long-term variability of the ITCZ, along with the corresponding driving mechanisms, however, remains obscure, mainly because it is difficult to separate different ITCZ variables in paleoclimate proxy records. Here, we report a speleothem oxygen isotope (δ18O) record from southwestern Sulawesi, Indonesia, and compile it with other speleothem records from the Maritime Continent. Using the spatial gradient of speleothem δ18O along a transect across the ITCZ, we constrain ITCZ variabilities over the Maritime Continent during the past 30,000 y. We find that ITCZ convection strength overall intensified from the last glacial period to the Holocene, following changes in climate boundary conditions. The mean position of the regional ITCZ has moved latitudinally no more than 3° in the past 30,000 y, consistent with the deduction from the atmospheric energy framework. However, different from modern observations and model simulations for future warming, the ITCZ appeared narrower during both the late Holocene and most part of the last glacial period, and its expansion occurred during Heinrich stadials and the early-to-mid Holocene. We also find that during the last glacial and deglacial period, prominent millennial-scale ITCZ changes were closely tied to the variability of the Atlantic meridional overturning circulation (AMOC), whereas during the Holocene, they were predominantly modulated by the long-term variability of the Walker circulation.

Hydroclimate changes across the Amazon lowlands over the past 45,000 years.

Reconstructing the history of tropical hydroclimates has been difficult, particularly for the Amazon basin-one of Earth's major centres of deep atmospheric convection. For example, whether the Amazon basin was substantially drier or remained wet during glacial times has been controversial, largely because most study sites have been located on the periphery of the basin, and because interpretations can be complicated by sediment preservation, uncertainties in chronology, and topographical setting. Here we show that rainfall in the basin responds closely to changes in glacial boundary conditions in terms of temperature and atmospheric concentrations of carbon dioxide. Our results are based on a decadally resolved, uranium/thorium-dated, oxygen isotopic record for much of the past 45,000 years, obtained using speleothems from Paraíso Cave in eastern Amazonia; we interpret the record as being broadly related to precipitation. Relative to modern levels, precipitation in the region was about 58% during the Last Glacial Maximum (around 21,000 years ago) and 142% during the mid-Holocene epoch (about 6,000 years ago). We find that, as compared with cave records from the western edge of the lowlands, the Amazon was widely drier during the last glacial period, with much less recycling of water and probably reduced plant transpiration, although the rainforest persisted throughout this time.

236U/238U Analysis of Femtograms of 236U by MC-ICPMS.

A new analytical method has been developed to determine atomic 236U/238U ratios in samples with only femtograms of 236U using a secondary electron multiplier (SEM) on a multicollector high-resolution inductively coupled plasma mass spectrometer (MC-ICPMS). The abundance sensitivity of the 238U tail at 236 atomic mass unit is reduced from 10-6 to 10-10 with the deployment of a retarding potential quadrupole lens. This method features the reduction of polyatomic interferences from hydride, nitride, lead, and plutonium and the evaluation of nonlinear SEM behavior. The instrument sensitivity is 1-2%, and the estimated methodological detection limit of the 236U/238U atomic ratio is as low as 2 × 10-10. Measurements on reference materials with 236U/238U ratios of 10-7-10-9, including the IRMM-075 series and the ETH Zurich in-house standard ZUTRI, demonstrate the accuracy of our MC-ICPMS technique. The analytical precisions (2σ) are ±4% for 5 fg of 236U at a 236U/238U of 1 × 10-8 and ±8% for 2 fg of 236U at a 236U/238U of 4 × 10-9 level. Compared to state-of-the-art accelerator mass spectrometry techniques and triple quadrupole-based ICPMS, our detection limit is not as low, but the required sample size is 3-40 times lower, and the throughput is as high as 3-4 samples per hour. The new MC-ICPMS-SEM technique is sensitive enough for determining 236U/238U in various small natural samples, such as marine carbonates and seawater.

Nonstationary footprints of ENSO in the Mekong River Delta hydrology.

The Mekong River Delta (MRD) is an essential agricultural area for the worldwide rice supply. Floods and droughts triggered by El Niño southern oscillation (ENSO) have been threatening sustenance in the MRD. Sustainable food supplies require understanding the response of the MRD hydrology to the changing ENSO behaviour in recent decades. Here, we reconstructed the annual rainfall maxima in the MRD using the oceanic paleoclimate proxy from coral skeletons and compared them with ENSO indexes. Annual minima of coral-based seawater oxygen isotope (δ18Osw) correlated with annual rainfall maxima, which allowed to extend rainfall data from 1924 to the recent. The annual rainfall maxima based on δ18Osw negatively correlated with the central Pacific El Niño index. This suggested that La Niña and central Pacific El Niño events lead to heavy and light rainy seasons. The heavy rainy season had more serious impacts in recent decades, which likely increases the flood risk. In contrast, the frequency and rainfall amount of the light rainy season has not changed significantly, although a catastrophic drought has hit the MRD. Our finding concludes that the impact of the ENSO event on MRD hydrology is inconsistent in the past century.

High precise dating on the variation of the Asian summer monsoon since 37 ka BP.

Comprehensive comparison of paleoclimate change based on records constrained by precise chronology and high-resolution is essential to explore the correlation and interaction within earth climate systems. Here, we propose a new stalagmite-based multidecadal resolved Asian summer monsoon (ASM) record spanning the past thirty-seven thousand years (ka BP, before AD 1950) from Furong Cave, southwestern China. This record is consistent with the published Chinese stalagmite sequences and shows that the dominant controls of the ASM dynamics include not only insolation and solar activity but also suborbital-scale hydroclimate events in the high latitudes of the northern hemisphere, such as the Heinrich events, Bølling-Allerød (BA), and Younger Dryas (YD). Benefit from the unprecedented accurate chronology, the timings of these events are precisely dated, with uncertainties of, at most, 40 years (2σ). The onset of the weak ASM during the YD began at 12.92 ka BP and lasted for 430 years. The occurrence of the 200-yr Older Dryas during the BA period was dated from 13.87 to 14.06 ka BP. The durations of the three Heinrich (H) events, H1, H2, and H3, are 14.33-18.29, 23.77-24.48, and 28.98-30.46 ka BP, respectively. Furong record shows surprisingly variable onset transitions of 980, 210, and 40 years for the corresponding weak ASM events. These discrepancies suggest different influences of the H events on ASM dynamics. During the periods of H 1-3, the obvious difference between our Furong record and NGRIP δ18O record indicated the decoupling correlation between the mid-low latitudes and high latitudes. On the other hand, synchronous climate change in high and low latitudes suggests another possibility which different to the dominant role of Northern high latitudes in triggering global climate change. Our high quality records also indicate a plausible different correlation between the high and mid-low latitudes under glacial and inter-glacial background, especially for the ASM regimes.

Correlations between spiritual beliefs and health-related quality of life of chronic hemodialysis patients in Taiwan.

This study evaluated the correlations between spiritual beliefs and health-related quality of life (HRQOL) of hemodialysis (HD) patients in Taiwan. Participants had to complete two questionnaires: the 36-item Short Form Health Survey Questionnaire and the Royal Free Interview for Spiritual and Religious Beliefs. They were then divided into three groups according to their strength of spiritual beliefs-having no, weak, or strong beliefs. Demographic, clinical, and laboratory data among groups were compared. Correlations between spiritual beliefs and HRQOL were then determined by the analysis of covariance and the post hoc Scheffe tests. Six hundred thirty-three patients completed the study. There were more women in the group of patients with strong beliefs (P = 0.005) and more less-educated patients in the group of patients with weak beliefs (P = 0.005). Patients with no or with strong spiritual beliefs had higher role physical (P = 0.01) and social functioning (SF) (P = 0.001) scores than patients with weak beliefs. After adjustment for gender, age, marital status, education, comorbidities, and time on dialysis, patients with no or with strong spiritual beliefs were found to have higher SF scores (P = 0.02) than patients with weak beliefs. HD patients with no or strong spiritual beliefs had higher SF HRQOL than those with weak spiritual beliefs.

ARF after retrograde pyelography: a case report and literature review.

Acute renal failure (ARF) occasionally occurs after intravenous injection of contrast medium, but complications are rare after retrograde pyelography. After reviewing the reports in the English-language literature, the authors found very few on those complications after retrograde pyelography. The authors present a patient who had ARF after the technique. The patient had a history of hypopharyngeal cancer with underlying serum creatinine level at the high end of the normal limits. Bilateral flank pain and decreased urine amount were noted soon after the procedure of retrograde pyelography. Subsequently, blood urea nitrogen and creatinine levels both elevated, and hemodialysis was needed. Several days later, diuretic phase took place. Thereafter, the symptoms subsided gradually. Pyelorenal extravasation of contrast medium was remarkable during the procedure. There was no evidence of hydronephrosis during the course of ARF. Early awareness and management may prevent the complications of ARF such as acute lung edema and hyperkalemia. Therefore, clinical physicians should be aware of the occurrence of ARF and its clinical presentation after performing retrograde pyelography.

Adiponectin in peritoneal dialysis patients: a comparison with hemodialysis patients and subjects with normal renal function.

BACKGROUND: Adiponectin, a cytokine with anti-inflammatory properties that is secreted from adipose tissue, is associated with insulin resistance. Adiponectin has been shown to be a predictor of cardiovascular events in both the general population and patients undergoing hemodialysis (HD); however, its role in peritoneal dialysis (PD) analogues remains unclear. METHODS: Serum adiponectin levels, measured by means of enzyme-linked immunosorbent assay in subjects with normal renal function and patients undergoing HD or PD (28 subjects in each group), were analyzed to establish the relationship between adiponectin and lipid levels, as well as insulin resistance. In the second study, 104 PD patients were recruited to analyze the relationships between serum adiponectin level and residual renal and peritoneal function and C-reactive protein (CRP) level. Independent factors for serum adiponectin level were determined from multiple linear regression. RESULTS: No significant difference was shown comparing serum adiponectin levels of PD and HD patients; however, both were significantly greater than those of control subjects (P < 0.01). Negative associations were shown between adiponectin and triglyceride (TG; P < 0.01) and insulin levels (P < 0.05) and homeostatic model assessment of insulin resistance (P < 0.01) for the former 2 groups; however, a positive association was shown for high-density lipoprotein (HDL) level (P < 0.05). Neither HD nor PD removed adiponectin significantly, with levels for the PD group negatively associated with residual renal function (P < 0.01) and CRP level (P < 0.001). PD patients administered glucose-lowering agents had lower adiponectin levels; however, lipid-lowering agents and renin-angiotensin blockades did not appear to affect them. Independent determinants for serum adiponectin level in PD patients were TG, HDL, and CRP levels and body mass index, after adjustment for age, sex, PD therapy duration, and diabetes. Adiponectin levels were not associated with left ventricular mass or ejection fraction. As for HD patients, PD patients had high adiponectin levels; adiponectin was not removed effectively using either of the studied dialysis modalities. In addition to a significant relationship with the components of insulin resistance, adiponectin level was associated with CRP level in these patients. CONCLUSION: These results indicate that adiponectin level in PD patients may be a good indicator of cardiovascular disease risk.