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Concurrent with global warming, the Eurasian continent has experienced frequent cold winters in recent decades. Although still debatable, such Eurasian winter cooling, which was particularly pronounced in the late twentieth century, has been attributed to internal climate variability, the process of which remains elusive. By examining multimodel large ensemble simulations, this study explores the potential sources of internal climate variability responsible for the Eurasian winter cooling trend over 1987–2006. Model simulations show a large ensemble spread in the Eurasian winter temperature trend with an ensemble mean close to zero. A comparison of the ensemble members shows that a circulation pattern favorable for the Eurasian cooling is characterized by the anticyclonic and cyclonic enhancements of sea level pressure (SLP) trend in the subarctic and Aleutian regions, respectively. This dipolar SLP trend is closely related to the deep Arctic warming, the change in midlatitude snow cover, and the enhancement of atmospheric convection over the tropical western Pacific. This result suggests that the Eurasian winter cooling is likely associated not only to the changes in mid- to high-latitude conditions but also to the changes in tropical convection. The possible mechanism of the tropically induced Aleutian low deepening is also discussed. [ABSTRACT FROM AUTHOR]

In the summer of 2020, South Korea experienced record-breaking rainfall due to 15 consecutive heavy rainfall events (HREs) from mid-June to early September. Among them, 11 HREs occurred in late June to mid-August with distinct synoptic characteristics depending on the occurrence period. All HREs from 29 June to 27 July (P1) were triggered by extratropical cyclones, while those from 28 July to 15 August (P2) mainly occurred along the monsoon rainband. We argue that their transition is associated with atmospheric teleconnections. During P1, the western North Pacific subtropical high (WNPSH) anomalously extended westward, but its northward expansion was hindered by the meridional wave train from the suppressed convection over the South China Sea. This condition prevented a northward migration of the monsoon rainband but allowed more extratropical cyclones to pass over the Korean Peninsula, resulting in four HREs. During P2, the South China Sea convection was enhanced, and its circulation response prompted an abrupt northward expansion of the WNPSH with a large pressure gradient along its northern boundary. With intensified southwesterly moisture transport, a monsoon rainband was activated over the Korean Peninsula, producing six HREs. The opposite phases of the summer North Atlantic Oscillation, i.e., negative in P1 but positive in P2, further contributed to the anomalous monsoon circulation by modulating the midlatitude circulation response to the South China Sea convection. This study demonstrates that the nature of summertime HREs in East Asia can be strongly modulated by remote forcings. [ABSTRACT FROM AUTHOR]

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In this study, we examine how the spatial structures of strong and moderate El Niño events have changed due to global warming using the Coupled Model Intercomparison Project Phase 5 (CMIP5) coupled general circulation models (CGCMs) based on a historical run and a Representative Concentration Pathways (RCP)4.5 run. The centre of the maximum anomalous sea surface temperature (SST) in the moderate El Niño has shifted significantly westward from the historical run to the RCP4.5 run; however, this is not seen with the strong El Niño events. Further analysis indicates that the centre of the maximum anomalous SST in the moderate El Niño with a negative Pacific Decadal Oscillation (PDO) phase shifted westward around the international dateline from the historical run to the RCP4.5 run. This is in contrast to the moderate El Niño, which shows a positive PDO phase. We also briefly discuss a possible mechanism on the change in the spatial structure of moderate El Niño with a negative phase of PDO from the historical run to the RCP4.5 run. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the debonding force of orthodontic brackets bonded with two conventional resin adhesives (Resilience L3 and Light Bond) and a resin-reinforced glass ionomer cement (Fuji Ortho LC). For the in vitro part of the study, 80 extracted premolars were randomly divided into four groups. In groups A and B, brackets were bonded to unetched enamel using Fuji Ortho LC cement in wet and dry conditions, respectively. In groups C and D, brackets were bonded to etched enamel using Resilience L3 and Light Bond, respectively. Debonding force was determined using a servohydraulic testing machine at a crosshead speed of 1 mm/min. Data was analyzed using the ANOVA and Tukey-Kramer multiple comparison test at p<0.05. A significant difference was found in debonding force between unetched Fuji Ortho LC and the two conventional resins. There was no significant difference between the two conventional resins or between unetched resin-reinforced glass ionomer in the wet and dry conditions. For the in vivo part of the study, 30 patients were randomly assigned to one of the three bonding material groups. Bracket survival rates and distributions were obtained by following these patients for 1.2 years. Data was analyzed using the Kaplan-Meier product-limit estimates of survivorship function. Bond failure interface was determined using a modified adhesive remnant index (ARI). These results showed no significant difference between survival rates and distributions among the three bonding materials with respect to the type of malocclusion, type of orthodontic treatment, or location of bracket. There were significant differences between survival distributions of males and females in the unetched Fuji Ortho LC group and among type of teeth in the conventional resin groups. The predominant mode of bracket failure for the unetched Fuji Ortho LC cement was at the enamel-adhesive interface, and for conventional resins, the enamel-adhesive interface and the bracket-adhesive interface. These results suggest that resin-reinforced glass ionomer cement can withstand occlusal and orthodontic forces despite having a bond strength lower than that of conventional resin adhesives. [ABSTRACT FROM AUTHOR]

Orthodontic wires containing nickel have been implicated in allergic reactions. The potential for orthodontic wires to cause allergic reactions is related to the pattern and mode of corrosion with subsequent release of metal ions, such as nickel, into the oral cavity. The purpose of this study was to determine if there is a significant difference in the corrosive potential of stainless steel, nickel titanium, nitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium orthodontic wires. At least two specimens of each wire were subjected to potentiostatic anodic dissolution in 0.9% NaCl solution with neutral pH at room temperature. Using a Wenking MP 95 potentiostat and an electrochemical corrosion cell, the breakdown potential of each wire was determined. Photographs were taken of the wire specimens using a scanning electron microscope, and surface changes were qualitatively evaluated. The breakdown potentials of stainless steel, two nickel titanium wires, nitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium were 400 mV, 300 mV, 750 mV, 300 mV, 1800 mV, and >2000 mV, respectively. SEM photographs revealed that some nickel titanium and stainless steel wires were susceptible to pitting and localized corrosion. The results indicate that corrosion occurred readily in stainless steel. Variability in breakdown potential of nickel titanium alloy wires differed across vendors' wires. The nitride coating did not affect the corrosion of the alloy, but epoxy coating decreased corrosion. Titanium wires and epoxy-coated nickel titanium wires exhibited the least corrosive potential. For patients allergic to nickel, the use of titanium or epoxy-coated wires during orthodontic treatment is recommended. [ABSTRACT FROM AUTHOR]