| 1. |
- Ansmann, A., et al.
(författare)
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Profiling of fine and coarse particle mass : case studies of Saharan dust and Eyjafjallajokull/Grimsvotn volcanic plumes
- 2012
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12:20, s. 9399-9415
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Tidskriftsartikel (refereegranskat)abstract
- The polarization lidar photometer networking (POLIPHON) method introduced to separate coarse-mode and fine-mode particle properties of Eyjafjallajokull volcanic aerosols in 2010 is extended to cover Saharan dust events as well. Furthermore, new volcanic dust observations performed after the Grimsvotn volcanic eruptions in 2011 are presented. The retrieval of particle mass concentrations requires mass-specific extinction coefficients. Therefore, a review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is given. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajokull eruptions in 2010 and (d) the Grimsvotn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic events.
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| 2. |
- Baars, Holger, et al.
(författare)
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An overview of the first decade of Polly(NET) : an emerging network of automated Raman-polarization lidars for continuous aerosol profiling
- 2016
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 16:8, s. 5111-5137
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Tidskriftsartikel (refereegranskat)abstract
- A global vertically resolved aerosol data set covering more than 10 years of observations at more than 20 measurement sites distributed from 63 degrees N to 52 degrees S and 72 degrees W to 124 degrees E has been achieved within the Raman and polarization lidar network Polly(NET). This network consists of portable, remote-controlled multiwavelength-polarization-Raman lidars (Polly) for automated and continuous 24/7 observations of clouds and aerosols. Polly(NET) is an independent, voluntary, and scientific network. All Polly lidars feature a standardized instrument design with different capabilities ranging from single wavelength to multiwavelength systems, and now apply unified calibration, quality control, and data analysis. The observations are processed in near-real time without manual intervention, and are presented online at polly.tropos.de. The paper gives an overview of the observations on four continents and two research vessels obtained with eight Polly systems. The specific aerosol types at these locations (mineral dust, smoke, dust-smoke and other dusty mixtures, urban haze, and volcanic ash) are identified by their Angstrom exponent, lidar ratio, and depolarization ratio. The vertical aerosol distribution at the Polly(NET) locations is discussed on the basis of more than 55 000 automatically retrieved 30 min particle backscatter coefficient profiles at 532 nm as this operating wavelength is available for all Polly lidar systems. A seasonal analysis of measurements at selected sites revealed typical and extraordinary aerosol conditions as well as seasonal differences. These studies show the potential of Polly(NET) to support the establishment of a global aerosol climatology that covers the entire troposphere.
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| 3. |
- Balmann, Alfons, et al.
(författare)
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Market Power in Agricultural Land Markets : Concepts and Empirical Challenges
- 2021
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Ingår i: German Journal of Agricultural Economics (GJAE). - : Deutscher Fachverlag GmbH. - 0002-1121 .- 0515-6866 .- 2191-4028. ; 70:4, s. 213-235
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides review about challenges and opportunities to assess and quantify market power in agricultural land markets. Measuring land market power is challenging because the characteristics of this production factor hinder the direct application of familiar concepts from commodity markets. Immobility, fixed availability, and large heterogeneity of land and potential users contradict assumptions of fictitious point market for homogeneous goods. Moreover, the use of concentration indicators for policy assessments is hampered by two problems. First, defining the relevant regional size of the market is challenging and concentration indicators are not robust with regard to market size and number of actors. Second, high concentration of land ownership or land operation may point at potential market power, but it may also be the result of an efficient allocation of land due to structural change in agriculture. The aforementioned challenges are illustrated with a case study for the Federal State of Brandenburg in Germany. Using available data for land sales, a regression analysis reveals a negative relationship between land use concentration and farmland prices. This result can be interpreted as an indication of market power on the buyer side in agricultural land markets. However, it is hardly possible to translate this finding into recommendations for land market regulations because the evaluation of the potential misuse of dominant positions in land markets requires a case-specific analysis. Providing evidence for the exertion of market power in land markets is extremely complex and deserves further attention from researchers and politicians.
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| 4. |
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| 5. |
- Claussnitzer, Melina, et al.
(författare)
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Leveraging cross-species transcription factor binding site patterns: from diabetes risk Loci to disease mechanisms.
- 2014
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Ingår i: Cell. - : Elsevier BV. - 1097-4172 .- 0092-8674. ; 156:1-2, s. 343-358
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies have revealed numerous risk loci associated with diverse diseases. However, identification of disease-causing variants within association loci remains a major challenge. Divergence in gene expression due to cis-regulatory variants in noncoding regions is central to disease susceptibility. We show that integrative computational analysis of phylogenetic conservation with a complexity assessment of co-occurring transcription factor binding sites (TFBS) can identify cis-regulatory variants and elucidate their mechanistic role in disease. Analysis of established type 2 diabetes risk loci revealed a striking clustering of distinct homeobox TFBS. We identified the PRRX1 homeobox factor as a repressor of PPARG2 expression in adipose cells and demonstrate its adverse effect on lipid metabolism and systemic insulin sensitivity, dependent on the rs4684847 risk allele that triggers PRRX1 binding. Thus, cross-species conservation analysis at the level of co-occurring TFBS provides a valuable contribution to the translation of genetic association signals to disease-related molecular mechanisms.
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| 6. |
- de Jong, Roelof S., et al.
(författare)
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4MOST-4-metre Multi-Object Spectroscopic Telescope
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147
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Konferensbidrag (refereegranskat)abstract
- 4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with similar to 2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; similar to 1600 fibres go to two spectrographs with resolution R> 5000 (lambda similar to 390-930 nm) and similar to 800 fibres to a spectrograph with R> 18,000 (lambda similar to 392-437 nm & 515-572 nm & 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020. This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].
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| 7. |
- Grossmann, Igor, et al.
(författare)
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Insights into the accuracy of social scientists' forecasts of societal change
- 2023
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Ingår i: Nature Human Behaviour. - : Springer Nature. - 2397-3374. ; 7, s. 484-501
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Tidskriftsartikel (refereegranskat)abstract
- How well can social scientists predict societal change, and what processes underlie their predictions? To answer these questions, we ran two forecasting tournaments testing the accuracy of predictions of societal change in domains commonly studied in the social sciences: ideological preferences, political polarization, life satisfaction, sentiment on social media, and gender-career and racial bias. After we provided them with historical trend data on the relevant domain, social scientists submitted pre-registered monthly forecasts for a year (Tournament 1; N = 86 teams and 359 forecasts), with an opportunity to update forecasts on the basis of new data six months later (Tournament 2; N = 120 teams and 546 forecasts). Benchmarking forecasting accuracy revealed that social scientists' forecasts were on average no more accurate than those of simple statistical models (historical means, random walks or linear regressions) or the aggregate forecasts of a sample from the general public (N = 802). However, scientists were more accurate if they had scientific expertise in a prediction domain, were interdisciplinary, used simpler models and based predictions on prior data. How accurate are social scientists in predicting societal change, and what processes underlie their predictions? Grossmann et al. report the findings of two forecasting tournaments. Social scientists' forecasts were on average no more accurate than those of simple statistical models.
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| 8. |
- Haynes, Roger, et al.
(författare)
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The 4MOST instrument concept overview
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147, s. 91476-91476
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Konferensbidrag (refereegranskat)abstract
- The 4MOST([1]) instrument is a concept for a wide-field, fibre-fed high multiplex spectroscopic instrument facility on the ESO VISTA telescope designed to perform a massive (initially >25x10(6) spectra in 5 years) combined all-sky public survey. The main science drivers are: Gaia follow up of chemo-dynamical structure of the Milky Way, stellar radial velocities, parameters and abundances, chemical tagging; eROSITA follow up of cosmology with x-ray clusters of galaxies, X-ray AGN/galaxy evolution to z similar to 5, Galactic X-ray sources and resolving the Galactic edge; Euclid/LSST/SKA and other survey follow up of Dark Energy, Galaxy evolution and transients. The surveys will be undertaken simultaneously requiring: highly advanced targeting and scheduling software, also comprehensive data reduction and analysis tools to produce high-level data products. The instrument will allow simultaneous observations of similar to 1600 targets at R similar to 5,000 from 390-900nm and similar to 800 targets at R>18,000 in three channels between similar to 395-675nm (channel bandwidth: 45nm blue, 57nm green and 69nm red) over a hexagonal field of view of similar to 4.1 degrees2. The initial 5-year 4MOST survey is currently expect to start in 2020. We provide and overview of the 4MOST systems: opto-mechanical, control, data management and operations concepts; and initial performance estimates.
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| 9. |
- Ritter, Matthias, et al.
(författare)
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Revisiting the relationship between land price and parcel size
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Hedonic land price models often use parcel size as an explanatory variable. Empirical analyses, however, are rather ambiguous regarding the direction and the size of the effect of this variable on farmland values. The objective of this paper is to investigate this size-price relation in detail and to derive recommendations for an appropriate specification of hedonic land price models. Our analysis consists of three steps. First, we conduct a meta-analysis based on a comprehensive literature review. Second, we analyze a dataset of more than 80,000 land transactions in Saxony-Anhalt, Germany, using the non-parametric locally weighted scatterplot smoothing (LOWESS) estimator. This unconditional smoothing algorithm identifies negative size-price relations for very small and large plots, whereas it finds a positive relation for medium plot. We use this finding in our third step, a hedonic land price model, in which the size-price relation is modelled conditional on land and buyer characteristics. From these steps, we conclude that the complex relationship between land price and plot size cannot be captured by a simple functional form since it is affected by several economic factors, such as economies of size, transaction cost, and financial constraints.
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| 10. |
- Ritter, Matthias, et al.
(författare)
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Revisiting the relationship between land price and parcel size in agriculture
- 2020
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Ingår i: Land use policy. - : Elsevier. - 0264-8377 .- 1873-5754. ; 97
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Tidskriftsartikel (refereegranskat)abstract
- Hedonic land price models often use parcel size as an explanatory variable. Empirical analyses, however, are rather ambiguous regarding the direction and the size of the effect of this variable on farmland values. The objective of this paper is to investigate this size–price relation for agricultural land use in detail and to derive recommendations for an appropriate specification of hedonic land price models. Our analysis consists of three steps. First, we conduct a meta-analysis based on a comprehensive literature review. Second, we analyze a dataset of more than 80,000 agricultural land transactions in Saxony-Anhalt, Germany, using the nonparametric locally weighted scatterplot smoothing (LOWESS) estimator. This unconditional smoothing algorithm identifies negative size–price relations for very small and large plots, whereas it finds a positive relation for medium plots. We use this finding in our third step, a hedonic land price model, in which the size–price relation is modeled conditional on land and buyer characteristics. From these steps, we conclude that the complex relationship between land price and plot size cannot be captured by a simple functional form since it is affected by several economic factors, such as economies of size, transaction costs, and financial constraints.
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