23 research outputs found
Exploring the link between high performance work systems and innovation
No full textThis study examines processes linking high-performance work systems (HPWS) and innovation performance. I propose that HPWS are positively related to innovative climate, individual creativity, and organizational innovation. This study further investigates the possibility that the relations between HPWS and creativity and innovation are moderated by innovative climate. Based on a sample of R&D units in South Korea, this study provides novel insight into how firms can facilitate innovation process in such a way that creative ideas are successfully produced and implemented for innovation.M.S.Includes bibliographical referencesby Saehee Kan
La variabilité et de l'évolution de carbone-suie en Europe au cours des 140 dernières années, extraites d'une carotte de glace du Caucase
No full textLe carbone-suie, ou "black carbon" (BC), est considéré comme le deuxième plus grand contributeur d'origine anthropique au changement climatique, après le dioxyde de carbone, en raison de son importante capacité à absorber la lumière (Bond et al., 2013). Malgré son influence sur le système climatique, les observations pluriannuelles des teneurs atmosphériques de BC demeurent rares, particulièrement en Europe. Cette étude propose une reconstruction nouvelle de la variabilité passée du BC atmosphérique à partir de l'analyse d'une carotte de glace forée au glacier de l'Elbrus (ELB), situé dans le Caucase en Russie. Un analyseur de carbone-suie SP2 (Single Particle Soot Photometer) a été exploité pour l'analyse du BC réfractaire (rBC) sur 153m de carotte de glace couvrant les derniers 140 ans. Un nouveau système analytique couplant un nébuliseur APEX-Q et le SP2, intégré au sein d'un système d'Analyse en Flux Continu, a été développée et a permis d'obtenir un enregistrement unique quasi-continu du rBC. La glace de l'Elbrus révèle une augmentation marquée des teneurs en rBC entre les années 1870 et 1980, suivie d'une diminution des concentrations jusqu'en 2000 environ. Au cours de la dernière décennie, les concentrations en rBC demeurent stables. Parallèlement, une augmentation des niveaux de fond jusqu'en 1980 indique clairement un impact non négligeable des émissions anthropiques sur la charge en BC atmosphérique à des échelles spatiales très larges, et notamment dans la troposphère libre. Une étude fine des inventaires d'émissions de BC disponibles et la modélisation FLEXPART viennent confirmer que l'augmentation forte de rBC depuis 1920 est principalement due aux émissions anthropiques de BC. Une analyse du gradient est-ouest des dépôts de rBC à haute altitude au cours de la dernière décennie a été réalisée, en comparant l'archive récente (10 ans) de l'Elbrus avec deux autres enregistrements provenant du Col du Dôme (CDD, France) et du Colle Gnifetti (CG, Italie). Les concentrations à l'Elbrus se révèlent deux à trois fois supérieures à celles des autres sites, une différence liée à l'intensité plus forte des sources en Europe de l'Est et confirmée par la modélisation FLEXPART. Les combustions de biomasse se trouvent identifiées comme la principale cause de variabilité interannuelle à l'Elbrus en été. Sur les derniers 10 ans, une diminution statistiquement significative des concentrations en rBC dans la neige est détectée au CDD, un résultat qui s'oppose aux observations réalisées à l'Elbrus où une tendance à l'augmentation au cours des périodes estivales est identifiée. Ces tendances, aussi bien CDD et ELB, sont relativement cohérentes avec les inventaires d'émissions de BC anthropiques disponibles. Ces enregistrements nouveaux et continus de rBC dans plusieurs carottes de glace européennes viennent faire progresser notre compréhension des évolutions passées des sources et de la charge atmosphérique du BC en Europe. Ces enregistrements peuvent participer à une meilleure évaluation de l'efficacité des politiques passées et actuelles de réduction des émissions de BC, ainsi qu'à une amélioration des inventaires d'émission.Black carbon (BC) is considered as the second largest man-made contributor to global warming after carbon dioxide due to its highly light-absorbing ability (Bond et al., 2013). Despite its climatic role, multi-year observations of ambient BC concentrations are scarce, in particular over Europe. In this thesis, we reconstructed past variability of atmospheric BC using an ice core from the Elbrus glacier (ELB), Caucasus in Russia. We have used a single particle soot photometer (SP2) to retrieve refractive BC (rBC) along 153 m of ice core covering the last 140 years. We have developed and validated a novel analytical system coupling of APEX-Q nebulization to SP2 in a Continuous-flow Analysis system to derive a unique quasi-continuous record of rBC. Results reveal a substantial rBC increase since 1870s lasting until 1980, followed by a decrease until ~2000. In the last decade, rBC concentrations remained constant. In parallel, an increase in background concentration until 1980 clearly highlights that anthropogenic BC emissions have substantially affected the atmospheric BC loading on a very large spatial scale, particularly in the free troposphere. A comparison with the estimated BC reaching the ELB site using a BC emission inventory/FLEXPART modeling confirms that the strong rBC increase since around 1920 is mainly due to anthropogenic BC emissions. Analysis of the East-West gradient of rBC deposited in snow over the last decade is investigated comparing the recent archive (10-year) at ELB with two other records from Col du Dôme (CDD), France, and Colle Gnifetti (CG), Italy. Concentrations at ELB are 2-3 times higher than at other sites, which is linked to source intensity in the Eastern part of Europe, as confirmed by the FLEXPART modelling. Biomass burning is identified as a main cause of inter-annual variability at ELB during summer time. Over the last decade, a statistically significant reduction of rBC concentration in snow is found at CDD, opposite to what is found at ELB with an increasing trend observed for summer periods. These trends are also fairly consistent with anthropogenic BC emissions inventories. Availability of continuous records of rBC in European ice cores improved our understanding of past evolution of atmospheric BC over Europe. They can be used to assess efficiency of past and current emission reduction policies and improve emission inventories
Sulfate alters aerosol absorption properties in East Asian outflow
No full textBlack carbon (BC) and brown carbon (BrC) aerosols that are released from the combustion of fossil fuels and biomass are of great concern because of their light-absorbing ability and great abundance associated with various anthropogenic sources, particularly in East Asia. However, the optical properties of ambient aerosols are dependent on the mixing state and the chemical composition of absorbing and non-absorbing aerosols. Here we examined how, in East Asian outflows, the parameters of the aerosol optical properties can be altered seasonally in conjunction with the mixing state and the chemical composition of aerosols, using 3-year aerosol measurements. Our findings highlight the important role played by sulfate in East Asia during the warm season in both enhancing single scattering albedo (SSA) and altering the absorption properties of aerosols-enhancing mass absorption cross section of BC (MAC(BC)) and reducing MAC of BrC (MAC(BrC),(370)). Therefore we suggest that in global radiative forcing models, particular attention should be paid to the consideration of the accurate treatment of the SO2 emission changes in the coming years in this region that will result from China's air quality policy.Peer reviewe
Oxidation pathways and emission sources of atmospheric particulate nitrate in Seoul: based on δ<SUP>15</SUP>N and Δ<SUP>17</SUP>O measurements
No full textInternational audiencePM2.5 haze pollution driven by secondary inorganic NO3- has been a great concern in East Asia. It is, therefore, imperative to identify its sources and oxidation processes, for which nitrogen and oxygen stable isotopes are powerful tracers. Here, we determined the δ15N (NO3-) and Δ17O (NO3-) of PM2.5 in Seoul during the summer of 2018 and the winter of 2018-2019 and estimated quantitatively the relative contribution of oxidation pathways for particulate NO3- and investigated major NOx emission sources. In the range of PM2.5 mass concentration from 7.5 µg m−3 (summer) to 139.0 µg m−3 (winter), the mean δ15N was −0.7 ‰ ± 3.3 ‰ and 3.8 ‰ ± 3.7 ‰, and the mean Δ17O was 23.2 ‰ ± 2.2 ‰ and 27.7 ‰ ± 2.2 ‰ in the summer and winter, respectively. While OH oxidation was the dominant pathway for NO3- during the summer (87 %), nighttime formation via N2O5 and NO3 was relatively more important (38 %) during the winter, when aerosol liquid water content (ALWC) and nitrogen oxidation ratio (NOR) were higher. Interestingly, the highest Δ17O was coupled with the lowest δ15N and highest NOR during the record-breaking winter PM2.5 episodes, revealing the critical role of photochemical oxidation process in severe winter haze development. For NOx sources, atmospheric δ15N (NOx) estimated from measured δ15N (NO3-) considering isotope fractionation effects indicates vehicle emissions as the most important emission source of NOx in Seoul. The contribution from biogenic soil and coal combustion was slightly increased in summer and winter, respectively. Our results built on a multiple-isotope approach provide the first explicit evidence for NO3- formation processes and major NOx emission sources in the Seoul megacity and suggest an effective mitigation measure to improve PM2.5 pollution
Dust Criteria Derived from Long-Term Filter and Online Observations at Gosan in South Korea
No full textDust and pollution are frequently mixed together in East Asia, causing large uncertainties in assessing climate change and environmental influence and in relevant policymaking. To discern the dust effect on particle mass, we carried out long-term measurements of the mass and key chemical compositions of PM10, PM2.5, and PM1 from August 2007 to February 2012 and collected hourly data of PM10 and PM2.5 concentrations from January 2012 to October 2020 at Gosan, South Korea. The principal component analysis of measured species reveals two dominant factors, pollution and dust, accounting for 46% and 16% of the total variance, respectively. The mode distribution of PM10, PM2.5, and PM1 mass in addition to the dust events helps to provide a robust criterion of the dust impact. Dust can be identified by the mean + standard deviation (σ) of PM10, while the threshold is down to the mean concentration when dust particles experience precipitation. High PM2.5 concentration also presents dust impact; however, the criterion decreases from mean + σ in 2007–2012 to mean in 2012–2020. It indicates that dust is no longer a high-concentration event of PM2.5, but its influence gradually appears in low-concentration particles. Therefore, the dust criterion obtained from long-term PM10 concentration data is robust; however, the standard is based on PM2.5 changes over time and still needs to be determined by follow-up long-term observations
What do you mean when you pay for performance? Conditional effects of pay-for-performance on job satisfaction and performance
No full textDrawing on the psychology theory of self-determination and economic perspectives on pay-for-performance, this study proposes that the effects of pay for performance (PFP) on job satisfaction, which in turn affects performance outcomes, can be influenced by the organizational contexts that support employee autonomy, competence, and relatedness. I specifically expect that PFP has a positive impact on job satisfaction and performance outcomes if an organization adopts PFP along with HR practices that support employee autonomy, competence, and relatedness. On the contrary, if an organization uses PFP without such HR practices, PFP may negatively influence job satisfaction and performance outcomes. While the direct effects of PFP on performance outcomes are positive, the total effects of PFP on performance outcomes may also be conditioned by those organizational contexts because of the conditional indirect effects. I tested this model in two independent studies using data collected from workplace sites. Study 1 employed a hierarchical linear modeling with multi-level data from R&D units. Study 2 tested the same model at the organizational level using a nationally representative longitudinal data. I also discuss the implications for theory and research on PFP.Ph.D.Includes bibliographical reference
Robust Evidence of <sup>14</sup>C, <sup>13</sup>C, and <sup>15</sup>N Analyses Indicating Fossil Fuel Sources for Total Carbon and Ammonium in Fine Aerosols in Seoul Megacity.
No full textTHE RELATIONSHIP BETWEEN RADIOGRAPHIC DENTAL ABNORMALITIES AND AGE AT INITIAL TREATMENT OF PEDIATRIC CANCER
No full textOxidative potential of urban PM2.5 in relation to chemical composition: Importance of fossil driven sources
No full textFor a comprehensive evaluation of the key factors determining the oxidative potential (OP) of PM2.5, 75 samples of PM2.5 were collected in urban Seoul, South Korea, during 2019–2021, and dithiothreitol consumption (DTTv) was measured using a DTT assay, coupled with an analysis of major constituents and stable isotope ratios of PM2.5. For the entire sample set, the mean DTTv value was 0.58 ± 0.48 nmol m−3 min−1 for PM2.5 of 29.1 ± 12.2. DTTv exhibited a general dependence on of PM2.5 concentrations and major constituents, including NO4+, SO42-, NH4+, and organic carbon (OC). Specifically, NO3– and NH4+ demonstrated the most robust correlation with DTTv during the cold season, whereas only elemental carbon (EC) showed a significant correlation with DTTv in the warm season. The δ13C of total carbon (TC) and δ15N of total nitrogen (TN) displayed an inverse correlation concerning DTT activities, suggesting the significant contribution from solid fossil fuels and biomass burning to the oxidative potential of PM2.5, particularly during the cold season when PM2.5 was notably high. In contrast, vehicle emissions were found to influence DTTv even at low PM2.5 levels in warm seasons. This study provides insights into the intricate dynamics influencing the oxidative potential of PM2.5
Robust Evidence of <sup>14</sup>C, <sup>13</sup>C, and <sup>15</sup>N Analyses Indicating Fossil Fuel Sources for Total Carbon and Ammonium in Fine Aerosols in Seoul Megacity
No full textCarbon- and nitrogen-containing
aerosols are ubiquitous in urban
atmospheres and play important roles in air quality and climate change.
We determined the 14C fraction modern (fM) and δ13C of total carbon (TC) and
δ15N of NH4+ in the PM2.5 collected in Seoul megacity during April 2018 to December
2019. The seasonal mean δ13C values were similar
to −25.1‰ ± 2.0‰ in warm and −24.2‰
± 0.82‰ in cold seasons. Mean δ15N values
were higher in warm (16.4‰ ± 2.8‰) than in cold
seasons (4.0‰ ± 6.1‰), highlighting the temperature
effects on atmospheric NH3 levels and phase-equilibrium
isotopic exchange during the conversion of NH3 to NH4+. While 37% ± 10% of TC was apportioned to
fossil-fuel sources on the basis of fM values, δ15N indicated a higher contribution of
emissions from vehicle exhausts and electricity generating units (power-plant
NH3 slip) to NH3: 60% ± 26% in warm season
and 66% ± 22% in cold season, based on a Bayesian isotope-mixing
model. The collective evidence of multiple isotope analysis reasonably
supports the major contribution of fossil-fuel-combustion sources
to NH4+, in conjunction with TC, and an increased
contribution from vehicle emissions during the severe PM2.5 pollution episodes. These findings demonstrate the efficacy of a
multiple-isotope approach in providing better insight into the major
sources of PM2.5 in the urban atmosphere
