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47,832 Research products, page 1 of 4,784

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  • Open Access English
    Authors: 
    Ivano Baronchelli; G. Rodighiero; Harry I. Teplitz; Claudia Scarlata; Alberto Franceschini; S. Berta; Laia Barrufet; Mattia Vaccari; Matteo Bonato; Laure Ciesla; +15 more
    Publisher: HAL CCSD
    Countries: France, Italy, United States
    Project: EC | HELP (607254)

    For a sample of star forming galaxies in the redshift interval 0.15$<$z$<$0.3, we study how both the relative strength of the AGN infra-red emission, compared to that due to the star formation (SF), and the numerical fraction of AGNs, change as a function of the total stellar mass of the hosting galaxy group (M$^{*}_{\mathrm{group}}$), between $10^{10.25}$ and $10^{11.9}$M$_{\odot}$. Using a multi-component SED fitting analysis, we separate the contribution of stars, AGN torus and star formation to the total emission at different wavelengths. This technique is applied to a new multi-wavelength data-set in the SIMES field (23 not redundant photometric bands), spanning the wavelength range from the UV (GALEX) to the far-IR (Herschel) and including crucial AKARI and WISE mid-IR observations (4.5 \mu m$<\lambda<$24 \mu m), where the BH thermal emission is stronger. This new photometric catalog, that includes our best photo-z estimates, is released through the NASA/IPAC Infrared Science Archive (IRSA). Groups are identified through a friends of friends algorithm ($\sim$62% purity, $\sim$51% completeness). We identified a total of 45 galaxies requiring an AGN emission component, 35 of which in groups and 10 in the field. We find BHAR$\propto ($M$^{*}_{\mathrm{group}})^{1.21\pm0.27}$ and (BHAR/SFR)$\propto ($M$^{*}_{\mathrm{group}})^{1.04\pm0.24}$ while, in the same range of M$^{*}_{\mathrm{group}}$, we do not observe any sensible change in the numerical fraction of AGNs. Our results indicate that the nuclear activity (i.e. the BHAR and the BHAR/SFR ratio) is enhanced when galaxies are located in more massive and richer groups. Comment: 31 pages, 23 figures

  • Open Access English
    Authors: 
    Qian, Lunwen; Hickey, Lee T.; Stahl, Andreas; Werner, Christian R.; Hayes, Ben; Snowdon, Rod J.; Voss-Fels, Kai P.;
    Publisher: Justus-Liebig-Universität Gießen
    Country: Germany

    Abstract In order to meet future food, feed, fibre and bioenergy demands, global yields of all major crops need to be increased significantly. At the same time, the increasing frequency of extreme weather events such as heat and drought necessitate improvements in the environmental resilience of modern crop cultivars. Achieving sustainably increase yields implies rapid improvement of quantitative traits with a very complex genetic architecture and strong environmental interaction. Latest advances in genome analysis technologies today provide molecular information at an ultrahigh resolution, revolutionizing crop genomic research and paving the way for advanced quantitative genetic approaches. These include highly detailed assessment of population structure and genotypic diversity, facilitating the identification of selective sweeps and signatures of directional selection, dissection of genetic variants that underlie important agronomic traits, and genomic selection strategies that not only consider major-effect genes. Single-nucleotide-polymorphism (SNP) markers today represent the genotyping system of choice for crop genetic studies because they occur abundantly in plant genomes and are easy to detect. SNPs are typically biallelic, however, hence their information content compared to multiallelic markers is low, limiting the resolution at which SNP-trait relationships can be delineated. An efficient way to overcome this limitation is to construct haplotypes based on linkage disequilibrium (LD), one of the most important features influencing genetic analyses of crop genomes. Here, we give an overview of the latest advances in genomics-based haplotype analyses in crops, highlighting their importance in the context of polyploidy and genome evolution, linkage drag and, co-selection, We provide examples of how haplotype analyses can complement well-established quantitative genetics frameworks, such as quantitative trait analysis and genomic selection, ultimately providing an effective tool to equip modern crops with environment-tailored characteristics.

  • Publication . Doctoral thesis . 2019
    Open Access English
    Authors: 
    Lips, Johannes;
    Publisher: Justus-Liebig-Universität Gießen
    Country: Germany

    This dissertation consists of two parts with different themes, the first part is made up of three articles in the broad category of empirical energy economics. The first paper in this category analyses the impact of changes in the prices of fossil fuels on the electricity prices. The following two articles are closely related and empirically analyse the North American oil industry to see if the financial decisions and conditions of the firms and the oil industry are affected by oil price changes. The final article provides a literature review prepared for the handbook "Corruption and Fraud in Financial Markets: Malpractice, Misconduct and Manipulation.” with an accompanying data analysis on the detection of financial fraud and manipulations using Benford’s law.

  • Open Access English
    Authors: 
    Bijan Nouri; Pascal Moritz Kuhn; Stefan Wilbert; Natalie Hanrieder; Christoph Prahl; Luis F. Zarzalejo; Andreas Kazantzidis; Philippe Blanc; Robert Pitz-Paal;
    Countries: Germany, France

    International audience; Solar irradiance nowcasts can be derived with sky images from all sky imagers (ASI) by detecting and analyzing transient clouds, which are the main contributor of intra-hour solar irradiance variability. The accuracy of ASI based solar irradiance nowcasting systems depends on various processing steps. Two vital steps are the cloud height detection and cloud tracking. This task is challenging, due to the atmospheric conditions that are often complex, including various cloud layers moving in different directions simultaneously.This challenge is addressed by detecting and tracking individual clouds. For this, we developed two distinct ASI nowcasting approaches with four or two cameras and a third hybridized approach. These three systems create individual 3-D cloud models with unique attributes including height, position, size, optical properties and motion. This enables us to describe complex multi-layer conditions.In this paper, derived cloud height and motion vectors are compared with a reference ceilometer (height) and shadow camera system (motion) over a 30 day validation period. The validation data set includes a wide range of cloud heights, cloud motion patterns and atmospheric conditions. Furthermore, limitations of ASI based nowcasting systems due to image resolution and image perspective constrains are discussed.The most promising system is found to be the hybridized approach. This approach uses four ASIs and a voxel carving based cloud modeling combined with a cloud segmentation independent stereoscopic cloud height and tracking detection. We observed for this approach an overall mean absolute error of 648 m for the height, 1.3 m/s for the cloud speed and 16.2° for the motion direction.

  • Open Access English
    Authors: 
    Tatah; Eugene Lendzemo;
    Publisher: Justus-Liebig-Universität Gießen
    Country: Germany

    This research was set up to select maize cultivars and appropriate harvest times to harvest for optimum dry matter, biogas and methane yields in Gießen and Groß-Gerau. Der Versuch wurde in Gießen und Groß-Gerau durchgeführt um Maissorten und geeignete Erntetermine zur Optimierung von Trockenmasse, Biogas- und Methanertrag.

  • Publication . Article . Other literature type . 2015
    Open Access English
    Authors: 
    Köhring, Michael; Böttger, Stefan; Willer, Ulrike; Schade, Wolfgang;
    Country: Germany

    it was designed to work as standalone device and was tested in a biogas plant for several weeks. Gas concentration dependent measurements show a precision better than 1% in a range between 40% and 60% target gas concentration for both sensors. Concentration dependent measurements with different background gases show a considerable decrease in cross sensitivity against the major components of biogas in direct comparison to common absorption based sensors. A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment. The sensor system contains an electronics unit and the two gas sensors

  • Open Access English
    Authors: 
    Sung Heo; Eunseog Cho; Hyung-Ik Lee; Gyeong Su Park; Hee Jae Kang; T. Nagatomi; Pyungho Choi; Byoungdeog Choi;
    Publisher: AIP Publishing LLC

    The band gap and defect states of MgO thin films were investigated by using reflection electron energy loss spectroscopy (REELS) and high-energy resolution REELS (HR-REELS). HR-REELS with a primary electron energy of 0.3 keV revealed that the surface F center (FS) energy was located at approximately 4.2 eV above the valence band maximum (VBM) and the surface band gap width (E-g(S)) was approximately 6.3 eV. The bulk F center (F-B) energy was located approximately 4.9 eV above the VBM and the bulk band gap width was about 7.8 eV, when measured by REELS with 3 keV primary electrons. From a first-principles calculation, we confirmed that the 4.2 eV and 4.9 eV peaks were FS and FB, induced by oxygen vacancies. We also experimentally demonstrated that the HR-REELS peak height increases with increasing number of oxygen vacancies. Finally, we calculated the secondary electron emission yields (gamma) for various noble gases. He and Ne were not influenced by the defect states owing to their higher ionization energies, but Ar, Kr, and Xe exhibited a stronger dependence on the defect states owing to their small ionization energies. (C) 2015 Author(s).

  • Publication . Preprint . Article . 2010
    Open Access
    Authors: 
    Thomas W. Hertel; Stephanie Rosch;

    Even though much has been written about climate change and poverty as distinct and complex problems, the link between them has received little attention. Understanding this link is vital for the formulation of effective policy responses to climate change. In this article the authors focus on agriculture as a primary means by which the impacts of climate change are transmitted to the poor and as a sector at the forefront of climate change mitigation efforts in developing countries. In so doing, they offer some important insights that may help shape future policies as well as ongoing research in this area. Copyright 2010, Oxford University Press.

  • Open Access
    Authors: 
    C. Stankewitz; H. Fahlenkamp;
    Publisher: Elsevier BV

    Abstract For an efficient integration of a subsequent CO 2 scrubbing in a power plant, it is necessary to analyze the heat sources and sinks which go along with the scrubbing. For this purpose, a model of the CO 2 absorption and desorption process is generated in the equation-based simulation software Aspen Custom Modeler ® . The heat sources and sinks of the scrubbing and the CO 2 compression are integrated in a model of the reference power plant North Rhine-Westphalia. To reduce the loss of efficiency, different measures to use the waste heat, like heat pumps, Organic Rankine- or Kalina cycles are reviewed.

  • Open Access English
    Authors: 
    Manfred J. Müller; Corinna Geisler; Steven B. Heymsfield; Anja Bosy-Westphal;
    Publisher: F1000 Research Limited

    Presently, control of body weight is assumed to exist, but there is no consensus framework of body weight homeostasis. Three different models have been proposed, with a “set point” suggesting (i) a more or less tight and (ii) symmetric or asymmetric biological control of body weight resulting from feedback loops from peripheral organs and tissues (e.g. leptin secreted from adipose tissue) to a central control system within the hypothalamus. Alternatively, a “settling point” rather than a set point reflects metabolic adaptations to energy imbalance without any need for feedback control. Finally, the “dual intervention point” model combines both paradigms with two set points and a settling point between them. In humans, observational studies on large populations do not provide consistent evidence for a biological control of body weight, which, if it exists, may be overridden by the influences of the obesogenic environment and culture on personal behavior and experiences. To re-address the issue of body weight homeostasis, there is a need for targeted protocols based on sound concepts, e.g. lean rather than overweight subjects should be investigated before, during, and after weight loss and weight regain. In addition, improved methods and a multi-level–multi-systemic approach are needed to address the associations (i) between masses of individual body components and (ii) between masses and metabolic functions in the contexts of neurohumoral control and systemic effects. In the future, simplifications and the use of crude and non-biological phenotypes (i.e. body mass index and waist circumference) should be avoided. Since changes in body weight follow the mismatch between tightly controlled energy expenditure at loosely controlled energy intake, control (or even a set point) is more likely to be about energy expenditure rather than about body weight itself.

Advanced search in Research products
Research products
arrow_drop_down
Searching FieldsTerms
Any field
arrow_drop_down
includes
arrow_drop_down
Include:
The following results are related to Energy Research. Are you interested to view more results? Visit OpenAIRE - Explore.
47,832 Research products, page 1 of 4,784
  • Open Access English
    Authors: 
    Ivano Baronchelli; G. Rodighiero; Harry I. Teplitz; Claudia Scarlata; Alberto Franceschini; S. Berta; Laia Barrufet; Mattia Vaccari; Matteo Bonato; Laure Ciesla; +15 more
    Publisher: HAL CCSD
    Countries: France, Italy, United States
    Project: EC | HELP (607254)

    For a sample of star forming galaxies in the redshift interval 0.15$<$z$<$0.3, we study how both the relative strength of the AGN infra-red emission, compared to that due to the star formation (SF), and the numerical fraction of AGNs, change as a function of the total stellar mass of the hosting galaxy group (M$^{*}_{\mathrm{group}}$), between $10^{10.25}$ and $10^{11.9}$M$_{\odot}$. Using a multi-component SED fitting analysis, we separate the contribution of stars, AGN torus and star formation to the total emission at different wavelengths. This technique is applied to a new multi-wavelength data-set in the SIMES field (23 not redundant photometric bands), spanning the wavelength range from the UV (GALEX) to the far-IR (Herschel) and including crucial AKARI and WISE mid-IR observations (4.5 \mu m$<\lambda<$24 \mu m), where the BH thermal emission is stronger. This new photometric catalog, that includes our best photo-z estimates, is released through the NASA/IPAC Infrared Science Archive (IRSA). Groups are identified through a friends of friends algorithm ($\sim$62% purity, $\sim$51% completeness). We identified a total of 45 galaxies requiring an AGN emission component, 35 of which in groups and 10 in the field. We find BHAR$\propto ($M$^{*}_{\mathrm{group}})^{1.21\pm0.27}$ and (BHAR/SFR)$\propto ($M$^{*}_{\mathrm{group}})^{1.04\pm0.24}$ while, in the same range of M$^{*}_{\mathrm{group}}$, we do not observe any sensible change in the numerical fraction of AGNs. Our results indicate that the nuclear activity (i.e. the BHAR and the BHAR/SFR ratio) is enhanced when galaxies are located in more massive and richer groups. Comment: 31 pages, 23 figures

  • Open Access English
    Authors: 
    Qian, Lunwen; Hickey, Lee T.; Stahl, Andreas; Werner, Christian R.; Hayes, Ben; Snowdon, Rod J.; Voss-Fels, Kai P.;
    Publisher: Justus-Liebig-Universität Gießen
    Country: Germany

    Abstract In order to meet future food, feed, fibre and bioenergy demands, global yields of all major crops need to be increased significantly. At the same time, the increasing frequency of extreme weather events such as heat and drought necessitate improvements in the environmental resilience of modern crop cultivars. Achieving sustainably increase yields implies rapid improvement of quantitative traits with a very complex genetic architecture and strong environmental interaction. Latest advances in genome analysis technologies today provide molecular information at an ultrahigh resolution, revolutionizing crop genomic research and paving the way for advanced quantitative genetic approaches. These include highly detailed assessment of population structure and genotypic diversity, facilitating the identification of selective sweeps and signatures of directional selection, dissection of genetic variants that underlie important agronomic traits, and genomic selection strategies that not only consider major-effect genes. Single-nucleotide-polymorphism (SNP) markers today represent the genotyping system of choice for crop genetic studies because they occur abundantly in plant genomes and are easy to detect. SNPs are typically biallelic, however, hence their information content compared to multiallelic markers is low, limiting the resolution at which SNP-trait relationships can be delineated. An efficient way to overcome this limitation is to construct haplotypes based on linkage disequilibrium (LD), one of the most important features influencing genetic analyses of crop genomes. Here, we give an overview of the latest advances in genomics-based haplotype analyses in crops, highlighting their importance in the context of polyploidy and genome evolution, linkage drag and, co-selection, We provide examples of how haplotype analyses can complement well-established quantitative genetics frameworks, such as quantitative trait analysis and genomic selection, ultimately providing an effective tool to equip modern crops with environment-tailored characteristics.

  • Publication . Doctoral thesis . 2019
    Open Access English
    Authors: 
    Lips, Johannes;
    Publisher: Justus-Liebig-Universität Gießen
    Country: Germany

    This dissertation consists of two parts with different themes, the first part is made up of three articles in the broad category of empirical energy economics. The first paper in this category analyses the impact of changes in the prices of fossil fuels on the electricity prices. The following two articles are closely related and empirically analyse the North American oil industry to see if the financial decisions and conditions of the firms and the oil industry are affected by oil price changes. The final article provides a literature review prepared for the handbook "Corruption and Fraud in Financial Markets: Malpractice, Misconduct and Manipulation.” with an accompanying data analysis on the detection of financial fraud and manipulations using Benford’s law.

  • Open Access English
    Authors: 
    Bijan Nouri; Pascal Moritz Kuhn; Stefan Wilbert; Natalie Hanrieder; Christoph Prahl; Luis F. Zarzalejo; Andreas Kazantzidis; Philippe Blanc; Robert Pitz-Paal;
    Countries: Germany, France

    International audience; Solar irradiance nowcasts can be derived with sky images from all sky imagers (ASI) by detecting and analyzing transient clouds, which are the main contributor of intra-hour solar irradiance variability. The accuracy of ASI based solar irradiance nowcasting systems depends on various processing steps. Two vital steps are the cloud height detection and cloud tracking. This task is challenging, due to the atmospheric conditions that are often complex, including various cloud layers moving in different directions simultaneously.This challenge is addressed by detecting and tracking individual clouds. For this, we developed two distinct ASI nowcasting approaches with four or two cameras and a third hybridized approach. These three systems create individual 3-D cloud models with unique attributes including height, position, size, optical properties and motion. This enables us to describe complex multi-layer conditions.In this paper, derived cloud height and motion vectors are compared with a reference ceilometer (height) and shadow camera system (motion) over a 30 day validation period. The validation data set includes a wide range of cloud heights, cloud motion patterns and atmospheric conditions. Furthermore, limitations of ASI based nowcasting systems due to image resolution and image perspective constrains are discussed.The most promising system is found to be the hybridized approach. This approach uses four ASIs and a voxel carving based cloud modeling combined with a cloud segmentation independent stereoscopic cloud height and tracking detection. We observed for this approach an overall mean absolute error of 648 m for the height, 1.3 m/s for the cloud speed and 16.2° for the motion direction.

  • Open Access English
    Authors: 
    Tatah; Eugene Lendzemo;
    Publisher: Justus-Liebig-Universität Gießen
    Country: Germany

    This research was set up to select maize cultivars and appropriate harvest times to harvest for optimum dry matter, biogas and methane yields in Gießen and Groß-Gerau. Der Versuch wurde in Gießen und Groß-Gerau durchgeführt um Maissorten und geeignete Erntetermine zur Optimierung von Trockenmasse, Biogas- und Methanertrag.

  • Publication . Article . Other literature type . 2015
    Open Access English
    Authors: 
    Köhring, Michael; Böttger, Stefan; Willer, Ulrike; Schade, Wolfgang;
    Country: Germany

    it was designed to work as standalone device and was tested in a biogas plant for several weeks. Gas concentration dependent measurements show a precision better than 1% in a range between 40% and 60% target gas concentration for both sensors. Concentration dependent measurements with different background gases show a considerable decrease in cross sensitivity against the major components of biogas in direct comparison to common absorption based sensors. A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment. The sensor system contains an electronics unit and the two gas sensors

  • Open Access English
    Authors: 
    Sung Heo; Eunseog Cho; Hyung-Ik Lee; Gyeong Su Park; Hee Jae Kang; T. Nagatomi; Pyungho Choi; Byoungdeog Choi;
    Publisher: AIP Publishing LLC

    The band gap and defect states of MgO thin films were investigated by using reflection electron energy loss spectroscopy (REELS) and high-energy resolution REELS (HR-REELS). HR-REELS with a primary electron energy of 0.3 keV revealed that the surface F center (FS) energy was located at approximately 4.2 eV above the valence band maximum (VBM) and the surface band gap width (E-g(S)) was approximately 6.3 eV. The bulk F center (F-B) energy was located approximately 4.9 eV above the VBM and the bulk band gap width was about 7.8 eV, when measured by REELS with 3 keV primary electrons. From a first-principles calculation, we confirmed that the 4.2 eV and 4.9 eV peaks were FS and FB, induced by oxygen vacancies. We also experimentally demonstrated that the HR-REELS peak height increases with increasing number of oxygen vacancies. Finally, we calculated the secondary electron emission yields (gamma) for various noble gases. He and Ne were not influenced by the defect states owing to their higher ionization energies, but Ar, Kr, and Xe exhibited a stronger dependence on the defect states owing to their small ionization energies. (C) 2015 Author(s).

  • Publication . Preprint . Article . 2010
    Open Access
    Authors: 
    Thomas W. Hertel; Stephanie Rosch;

    Even though much has been written about climate change and poverty as distinct and complex problems, the link between them has received little attention. Understanding this link is vital for the formulation of effective policy responses to climate change. In this article the authors focus on agriculture as a primary means by which the impacts of climate change are transmitted to the poor and as a sector at the forefront of climate change mitigation efforts in developing countries. In so doing, they offer some important insights that may help shape future policies as well as ongoing research in this area. Copyright 2010, Oxford University Press.

  • Open Access
    Authors: 
    C. Stankewitz; H. Fahlenkamp;
    Publisher: Elsevier BV

    Abstract For an efficient integration of a subsequent CO 2 scrubbing in a power plant, it is necessary to analyze the heat sources and sinks which go along with the scrubbing. For this purpose, a model of the CO 2 absorption and desorption process is generated in the equation-based simulation software Aspen Custom Modeler ® . The heat sources and sinks of the scrubbing and the CO 2 compression are integrated in a model of the reference power plant North Rhine-Westphalia. To reduce the loss of efficiency, different measures to use the waste heat, like heat pumps, Organic Rankine- or Kalina cycles are reviewed.

  • Open Access English
    Authors: 
    Manfred J. Müller; Corinna Geisler; Steven B. Heymsfield; Anja Bosy-Westphal;
    Publisher: F1000 Research Limited

    Presently, control of body weight is assumed to exist, but there is no consensus framework of body weight homeostasis. Three different models have been proposed, with a “set point” suggesting (i) a more or less tight and (ii) symmetric or asymmetric biological control of body weight resulting from feedback loops from peripheral organs and tissues (e.g. leptin secreted from adipose tissue) to a central control system within the hypothalamus. Alternatively, a “settling point” rather than a set point reflects metabolic adaptations to energy imbalance without any need for feedback control. Finally, the “dual intervention point” model combines both paradigms with two set points and a settling point between them. In humans, observational studies on large populations do not provide consistent evidence for a biological control of body weight, which, if it exists, may be overridden by the influences of the obesogenic environment and culture on personal behavior and experiences. To re-address the issue of body weight homeostasis, there is a need for targeted protocols based on sound concepts, e.g. lean rather than overweight subjects should be investigated before, during, and after weight loss and weight regain. In addition, improved methods and a multi-level–multi-systemic approach are needed to address the associations (i) between masses of individual body components and (ii) between masses and metabolic functions in the contexts of neurohumoral control and systemic effects. In the future, simplifications and the use of crude and non-biological phenotypes (i.e. body mass index and waist circumference) should be avoided. Since changes in body weight follow the mismatch between tightly controlled energy expenditure at loosely controlled energy intake, control (or even a set point) is more likely to be about energy expenditure rather than about body weight itself.