| 1. |
- Renard, Jean-Baptiste, et al.
(författare)
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LOAC : a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 1
- 2016
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 9:4, s. 1721-1742
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Tidskriftsartikel (refereegranskat)abstract
- The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of mu m. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12 degrees, and is almost insensitive to the refractive index of the particles; the second one is around 60 degrees and is strongly sensitive to the refractive index of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 mu m and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is +/- 20% when concentrations are higher than 1 particle cm 3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about +/- 60% for concentrations smaller than 10 2 particle cm(-3). Also, the uncertainties in size calibration are +/- 0.025 mu m for particles smaller than 0.6 mu m, 5% for particles in the 0.7-2 mu m range, and 10% for particles greater than 2 mu m. The measurement accuracy of sub-micronic particles could be reduced in a strongly turbid case when concentration of particles > 3 mu m exceeds a few particles cm(-3). Several campaigns of cross-comparison of LOAC with other particle counting instruments and remote sensing photometers have been conducted to validate both the size distribution derived by LOAC and the retrieved particle number density. The typology of the aerosols has been validated in well-defined conditions including urban pollution, desert dust episodes, sea spray, fog, and cloud. Comparison with reference aerosol mass monitoring instruments also shows that the LOAC measurements can be successfully converted to mass concentrations.
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| 2. |
- Renard, Jean-Baptiste, et al.
(författare)
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LOAC : a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 2
- 2016
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 9:8, s. 3673-3686
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Tidskriftsartikel (refereegranskat)abstract
- In the companion (Part I) paper, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter), based on scattering measurements at angles of 12 and 60A degrees. That allows for some typology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size-segregated counting in a large diameter range from 0.2aEuro-A mu m up to possibly more than 100aEuro-A mu m depending on sampling conditions (Renard et al., 2016). Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10-20aEuro-A mu m in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAVs) and at ground level. We illustrate here the first LOAC airborne results obtained from a UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vienna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment - ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.
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| 3. |
- Bisin, Alberto, et al.
(författare)
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Bend it like Beckham : Ethnic identity and integration
- 2016
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Ingår i: European Economic Review. - : Elsevier BV. - 0014-2921 .- 1873-572X. ; 90, s. 146-164
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Tidskriftsartikel (refereegranskat)abstract
- We propose a theoretical framework to study the determinants of ethnic and religious identity along two distinct motivational processes: cultural distinction and cultural conformity. Under cultural conformity, ethnic identity is reduced by neighborhood integration, which weakens group loyalties and prejudices. On the contrary, under cultural distinction, ethnic minorities are more motivated in retaining their own distinctive cultural heritage the more integrated are the neighborhoods where they reside and work. Using data on ethnic preferences and attitudes provided by the Fourth National Survey of Ethnic Minorities in the UK we find evidence that might be consistent with intense ethnic and religious identity mostly formed as a cultural distinction mechanism. Consistently, we document that ethnic identities might be more intense in mixed than in segregated neighborhoods.
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| 4. |
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| 5. |
- Bisin, Alberto, et al.
(författare)
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Ethnic Identity and Labor-Market Outcomes of Immigrants in Europe
- 2011
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Ingår i: Economic Policy. - : Oxford University Press (OUP). - 0266-4658 .- 1468-0327. ; 26:65, s. 57-92
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Tidskriftsartikel (refereegranskat)abstract
- We study the relationship between ethnic identity and labour market outcomes of non-EU immigrants in Europe. Using the European Social Survey, we find that there is a penalty to be paid for immigrants with a strong identity. Being a first generation immigrant leads to a penalty of about 17% while second-generation immigrants have a probability of being employed that is not statistically different from that of natives. However, when they have a strong identity, second-generation immigrants have a lower chance of finding a job than natives. Our analysis also reveals that the relationship between ethnic identity and employment prospects may depend on the type of integration and labour market policies implemented in the country where the immigrant lives. More flexible labour markets help immigrants to access the labour market but do not protect those who have a strong ethnic identity.
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| 6. |
- Bisin, Alberto, et al.
(författare)
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Formation and persistence of oppositional identities
- 2011
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Ingår i: European Economic Review. - : Elsevier BV. - 0014-2921 .- 1873-572X. ; 55:8, s. 1046-1071
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Tidskriftsartikel (refereegranskat)abstract
- We develop a dynamic model of identity formation that explains why ethnic minorities may choose to adopt oppositional identities (i.e. some individuals may reject or not the dominant culture) and why this behavior may persist over time. We first show that the prevalence of an oppositional culture in the minority group cannot always be sustained in equilibrium. Indeed, because the size of the majority group is larger, there is an imposed process of exposition to role models from the majority group that favors the diffusion of mainstream values in the minority community. In spite of this, an oppositional culture in the minority group can nevertheless be sustained in steady state if there is enough cultural segmentation in terms of role models, or if the size of the minority group is large enough, or if the degree of oppositional identity it implies is high enough. We also demonstrate that the higher the level of harassment and the number of racist individuals in the society, the more likely an oppositional minority culture will emerge. We finally show that ethnic identity and socialization effort can be more intense in mixed rather than segregated neighborhoods.
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| 7. |
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| 8. |
- Verdier, Thierry, et al.
(författare)
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The role of cultural leaders in the transmission of preferences
- 2015
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Ingår i: Economics Letters. - : Elsevier BV. - 0165-1765 .- 1873-7374. ; 136, s. 158-161
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the population dynamics of preference traits in a model of intergenerational cultural transmission with cultural leaders who compete for oblique socialization. We show that by adding this new channel in the transmission of preferences, i.e. cultural leaders, in steady-state, there cannot be an equilibrium with total assimilation or total integration of the population.
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