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In this study, high–particulate matter (PM2.5) pollution episodes were examined in Seoul, the capital city of South Korea, which, based on the episode characteristics, were influenced by a distinct meteorological mode, long-range transport (LRT), from two-level meteorological observations: surface and 850–500-hPa level. We performed two-step statistical analysis including principal component (PC) analysis of meteorological variables based on the observation data, followed by multiple linear regression (MLR). The meteorological variables included surface temperature (Tsfc), wind speed (WSsfc), and the east–west (usfc) and north–south (υsfc) components of wind speed, as well as wind components at 850-hPa geopotential height (u850 and υ850, respectively) and the vertical temperature gradient between 850 and 500 hPa. Our two-step analysis of data collected during the period 2018–19 revealed that the dominant factors influencing high-PM2.5 days in Seoul (129 days) were upper-wind characteristics in winter, including positive u850 and negative υ850, that were controlled by the presence of continental anticyclones that increased the likelihood of LRT of PM2.5 pollutants. Regional-scale meteorological variables, including surface and upper-meteorological variables on normal and high-PM2.5 days, showed distinct covariation over Seoul, a megacity in the eastern part of northeast Asia with large anthropogenic emissions. Although this study examined only two atmospheric layers (surface and 500–850 hPa), our results clearly detected high-PM2.5 episodes with LRT characteristics, suggesting the importance of considering both geographical distinctiveness and seasonal meteorological covariability when scaling down continental to local response to emission reduction. [ABSTRACT FROM AUTHOR]

A professional development program for US teachers in the state of Oregon was the context in which this study took place. This five-year hybrid (online and face-to-face) program assisted experienced teachers to adapt their practice to meet the needs of language minority and immigrant students. The positive changes in teacher perceptions and classroom practice are captured in the context of the change process--and not only simply in pre/post fashion. Using classroom observation data combined with threaded online discussions, this study describes patterns and moments of teacher change, and investigates how this multi-layered, differentiated professional development program was effective in training teachers to meet the learning needs of immigrant and language minority students.

The main challenge that hinders lithium-ion batteries in space applications is their poor performance at subzero temperatures. Such poor performance is primarily due to the low ionic conductivity and freezing of the electrolyte, leading to the loss of battery capacity. This research investigates the behavior of lithium-ion batteries at low temperatures by employing electrochemical and material characterization techniques. Based on the electrochemical behavior of the battery cells, lithium-ion batteries' performance declined rapidly at − 30 °C. The major findings indicate that charging at low-temperature conditions increases the impedance, which slows down the reaction kinetics affecting the intercalation of lithium ions. According to the results obtained from the ex situ material characterization analysis, the main factor that induces this behavior is the freezing and the decomposition of the electrolyte at the cathode-electrolyte interphase and the mechanical degradation of the active materials of the cathode. These changes lead to interfacial instability and considerable development of resistance to the flow of charges. The findings in this study contribute to the development of lithium-ion batteries for low temperature and space applications by understanding the behavior of lithium-ion batteries in subzero temperature environments. [ABSTRACT FROM AUTHOR]

Erbium-doped silica films were synthesized using a two-step sol–gel methodology that involved acid and base catalysts, with erbium concentration ranging from 0.2% to 6% and annealing temperatures varying from 500 °C to 900 °C. The photoluminescence spectra showed that the samples exhibiting efficient emission were annealed at 800 °C and 900 °C and doped with 3% and 6% erbium. The X-ray diffraction analysis revealed that the internal structure of the films was influenced by the different annealing temperatures and the doping concentrations. Samples with dominant 4f transitions were modelled. The results suggest that the proposed method is a promising approach for the synthesis of erbium-doped silica films with potential applications in optical devices. [ABSTRACT FROM AUTHOR]

According to the No Child Left Behind (NCLB) Act, states are required "...to ensure that poor and minority children are not taught at higher rates than other children by inexperienced, unqualified, or out-of-field teachers..." Although the NCLB law and State Education Agencies (SEAs) currently offer very clear definitions of "highly-qualified" teachers, "teacher quality" remains a contested term--particularly at local levels. Findings from this study suggest the definition of teacher quality determines, in large part, the extent to which the geographical distribution of quality is equitable. A large urban district in Los Angeles demonstrates how different the distribution appears with each definition of teacher quality. In this study, the evidence will show that the distribution is more unequal if the district uses a stronger set of criteria for teacher quality than using the weaker proxies for quality such as full-credential and NCLB definitions. (Contains 4 notes, 8 tables and 12 figures.)

The present studies explored the role of the medial striatum in learning when task contingencies change. Experiment 1 examined whether the medial striatum is involved in place reversal learning. Testing occurred in a modified cross-maze across two consecutive sessions. Injections of the local anesthetic, bupivacaine, into the medial striatum, did not impair place acquisition, but impaired place reversal learning. The reversal-learning deficit was due to an inability to maintain the new choice pattern following the initial shift. Experiment 2 determined whether changes in acetylcholine (ACh) output occur during the acquisition or reversal learning of a place discrimination. Extracellular ACh output from the medial striatum was assessed in samples collected at 6-min intervals using in vivo microdialysis during behavioral testing. ACh output did not change from basal levels during place acquisition. During reversal learning, ACh output significantly increased as rats began to learn the new choice pattern, and returned to near basal levels as a rat reliably executed the new place strategy. The present results suggest that the medial striatum may be critical for flexible adaptations involving spatial information, and that ACh actions in this area enable the shifting of choice patterns when environmental conditions change. (Contains 5 figures.)