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185,102 Research products, page 1 of 18,511

  • Digital Humanities and Cultural Heritage
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  • 2019-2023
  • English

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  • Open Access English
    Authors: 
    Anne Sofie Laulund; Franziska Angelika Schwartz; Lars Christophersen; Mette Kolpen; Peter Østrup Jensen; Henrik Calum; Niels Høiby; Kim Thomsen; Claus Moser;
    Country: Denmark

    Introduction: Chronic wounds have a compromised microcirculation which leads to restricted gas exchange. The majority of these hypoxic wounds is infested with microorganisms congregating in biofilms which further hinders the antibiotic function. We speculate whether this process can be counteracted by hyperbaric oxygen therapy (HBOT). Methodology: Twenty-eight BALB/c mice with third-degree burns were included in the analyses. Pseudomonas aeruginosa embedded in seaweed alginate beads was injected under the eschar to mimic a biofilm infected wound. Challenged mice were randomized to receive either 4 days with 1 x ciprofloxacin combined with 2 × 90 min HBOT at 2.8 standard atmosphere daily, 1 x ciprofloxacin as monotherapy or saline as placebo. The mice were clinically scored, and wound sizes were estimated by planimetry daily. Euthanasia was performed on day 8. Wounds were surgically removed in toto, homogenized and plated for quantitative bacteriology. Homogenate supernatants were used for cytokine analysis. Results: P. aeruginosa was present in all wounds at euthanasia. A significant lower bacterial load was seen in the HBOT group compared to either the monotherapy ciprofloxacin group (p = 0.0008), or the placebo group (p < 0.0001). IL-1β level was significantly lower in the HBOT group compared to the placebo group (p = 0.0007). Both treatment groups had higher osteopontin levels than the placebo group (p = 0.002 and p = 0.004). The same pattern was seen in the S100A9 analysis (p = 0.01 and p = 0.008), whereas no differences were detected between the S100A8, the VEGF or the MMP8 levels in the three groups. Conclusion: These findings show that HBOT improves the bactericidal activity of ciprofloxacin against P. aeruginosa wound biofilm in vivo. HBOT in addition to ciprofloxacin also modulates the host response to a less inflammatory phenotype.

  • Restricted English
    Authors: 
    Pagkalos, Manolis; Scarpato, Andrea;
    Publisher: Bloomsbury Academic
    Country: Netherlands

    This volume fills a gap in current research on the Hellenistic Peloponnese, complementing and challenging traditional interpretations by adopting new perspectives on its complex social and political history in response to emerging trends in research. By examining aspects of the region's interstate relations, contemporary politics and modes of representation that have been relatively little studied to date, it affords a much more well-rounded picture of the Hellenistic Peloponnese and a rich basis for broadening scholarly debate and stimulating further research on the area. Each chapter promotes interdisciplinary approaches to a wide range of ancient evidence and material culture, and offers a renewed understanding of how socio-political transformations unfolded within the region. Together they shed new light on key agents of the period and their interactions, material evidence and political history both in and beyond the Peloponnese – from the enduring Macedonian influence in the 3rd century BCE and the violence and terror tactics deployed within the Achaian Koinon, to strategies of identity construction and memory politics wielded by local elites – and will be crucial points of reference for graduate students and scholars with an interest in the region.

  • Restricted English

    This volume fills a gap in current research on the Hellenistic Peloponnese, complementing and challenging traditional interpretations by adopting new perspectives on its complex social and political history in response to emerging trends in research. By examining aspects of the region's interstate relations, contemporary politics and modes of representation that have been relatively little studied to date, it affords a much more well-rounded picture of the Hellenistic Peloponnese and a rich basis for broadening scholarly debate and stimulating further research on the area. Each chapter promotes interdisciplinary approaches to a wide range of ancient evidence and material culture, and offers a renewed understanding of how socio-political transformations unfolded within the region. Together they shed new light on key agents of the period and their interactions, material evidence and political history both in and beyond the Peloponnese – from the enduring Macedonian influence in the 3rd century BCE and the violence and terror tactics deployed within the Achaian Koinon, to strategies of identity construction and memory politics wielded by local elites – and will be crucial points of reference for graduate students and scholars with an interest in the region.

  • Open Access English
    Authors: 
    Artur Sokolovsky; Luca Arnaboldi;

    Although machine learning approaches have been widely used in the field of finance, to very successful degrees, these approaches remain bespoke to specific investigations and opaque in terms of explainability, comparability, and reproducibility. The primary objective of this research was to shed light upon this field by providing a generic methodology that was investigation-agnostic and interpretable to a financial markets practitioner, thus enhancing their efficiency, reducing barriers to entry, and increasing the reproducibility of experiments. The proposed methodology is showcased on two automated trading platform components. Namely, price levels, a well-known trading pattern, and a novel 2-step feature extraction method. The methodology relies on hypothesis testing, which is widely applied in other social and scientific disciplines to effectively evaluate the concrete results beyond simple classification accuracy. The main hypothesis was formulated to evaluate whether the selected trading pattern is suitable for use in the machine learning setting. Across the experiments we found that the use of the considered trading pattern in the machine learning setting is only partially supported by statistics, resulting in insignificant effect sizes (Rebound 7 - $0.64 \pm 1.02$, Rebound 11 $0.38 \pm 0.98$, and rebound 15 - $1.05 \pm 1.16$), but allowed the rejection of the null hypothesis. We showcased the generic methodology on a US futures market instrument and provided evidence that with this methodology we could easily obtain informative metrics beyond the more traditional performance and profitability metrics. This work is one of the first in applying this rigorous statistically-backed approach to the field of financial markets and we hope this may be a springboard for more research. Associated processing files are available at: https://doi.org/10.5281/zenodo.4036850

  • Open Access English
    Authors: 
    Stijn P. Brouwers; Michael Simmler; Pascal Savary; Madeleine F. Scriba;
    Publisher: ETH Zurich
    Country: Switzerland

    Free-stall cubicles are designed so that cows do not defecate in the bedding material, while still providing comfortable lying places. However, fixed cubicle elements, such as the partition and neck rail, restrict available movement space and may hinder cows from performing natural lying down and standing up movement patterns. Although there are various types of cubicle partitions that differ in shape, dimensions, or materials, there is no method other than visual observations to assess their effects on cow welfare. An automated detection system could improve the efficiency and promote objectivity of such assessments. Therefore, the aim of this research was to explore which atypical lying down and standing up behaviors could be detected using body-mounted accelerometers and machine learning. Three leg- and one head-mounted accelerometer set to record at 20 Hz were fitted to 48 lactating dairy cows (Brown Swiss and Holstein × Swiss Fleckvieh). Lying down and standing up events were simultaneously assessed through video observations, by assigning binary presence/absence labels for atypical behaviors, such as lunging the head sideways when standing up and pawing the bedding material before lying down. Different time series classification algorithms were employed for model development using a nested cross-validation strategy. The best performing classifiers were MiniRocket and the deep learning algorithm InceptionTime. Atypical behaviors performed during standing up events, namely Hesitant head lunge and Crawling backwards, were identified as most promising candidates for accelerometer-based detection. These behaviors were detected with balanced accuracies of 0.67 and 0.74, respectively, and their learning curves indicated that more training data might further improve model performance. Overall, achieved performances were not yet satisfactory for application in the evaluation of new dairy cow housing installations. Potentially, ethograms designed for human observers are not optimal for machine learning and adjustments with machine learnability in mind might be necessary. The behaviors identified as promising are good candidates for further development into an efficient and objective method that could complement human observations in the assessment of dairy cow housing installations. Smart Agricultural Technology, 4

  • English
    Authors: 
    Ives, Libby,; Stack‐Morgan, Katie,; Gupta, Sanjeev; Caravaca, Gwénaël; Russell, Patrick; Shuster, David L.; Williams, Amy,; Holm-Alwmark, Sanna; Barnes, Robert; Bell, Jim F.; +20 more
    Publisher: HAL CCSD
    Country: France

    International audience; The Perseverance rover is exploring a sedimentary deposit within the Late Noachian-aged (4.0-4.8 Ga) Jezero Crater interpreted to be the remnants of a delta. From April 2022 through February 2023, Perseverance investigated the basal 25 m of sediments exposed in the fan’s eastern scarp. Rover instruments collected a suite of imaging, geochemical, mineralogical, and ground-penetrating radar data.Perseverance made detailed observations through two sections of the lower fan ~600 m apart. Similar facies and stratigraphic trends are present in both sections. Each section contains two coarsening-up successions. While some finer-grained units are laterally continuous between the two sections, the coarser-grained bodies that cap each section are laterally discontinuous and do not extend between sections.Both sequences are 10 - 15 m thick. Their lower strata are dominated by sulfate-cemented, planar laminated, very fine- to medium-grained sandstone and siltstone with rare low-angle truncations. Soft-sediment deformation occurs in the form of decimeter-scale lateral folds. Laminae are normally graded. These sequences are capped by meter-scale thick sheets of coarse-grained sandstone, pebbly sandstones, and conglomerates that are variably low-angle cross-bedded, trough cross-bedded, and planar-stratified. Plane beds are massive or normally graded.Two hypotheses for the depositional environment have emerged for this succession: a sub-aerial setting with extensive “overbank” facies and shallow braided channels and a proximal pro-deltaic setting with deposition driven by hyperpycnal flows. These hypotheses will be tested against observations made by Perseverance as it traverses the “Fan Top” and by more comprehensive studies of the “Delta Front” data.

  • Open Access English
    Authors: 
    Dörnemann, Nina; Dette, Holger;

    For a given $p\times n$ data matrix $\textbf{X}_n$ with i.i.d. centered entries and a population covariance matrix $\bf{\Sigma}$, the corresponding sample precision matrix $\hat{\bf\Sigma}^{-1}$ is defined as the inverse of the sample covariance matrix $\hat{\bf{\Sigma}} = (1/n) \bf{\Sigma}^{1/2} \textbf{X}_n\textbf{X}_n^\top \bf{\Sigma}^{1/2}$. We determine the joint distribution of a vector of diagonal entries of the matrix $\hat{\bf\Sigma}^{-1}$ in the situation, where $p_n=p< n$ and $p/n \to y \in [0,1)$ for $n\to\infty$ and $\bf{\Sigma}$ is a diagonal matrix. Remarkably, our results cover both the case where the dimension is negligible in comparison to the sample size and the case where it is of the same magnitude. Our approach is based on a QR-decomposition of the data matrix, yielding a connection to random quadratic forms and allowing the application of a central limit theorem for martingale difference schemes. Moreover, we discuss an interesting connection to linear spectral statistics of the sample covariance matrix. More precisely, the logarithmic diagonal entry of the sample precision matrix can be interpreted as a difference of two highly dependent linear spectral statistics of $\hat{\bf\Sigma}$ and a submatrix of $\hat{\bf\Sigma}$. This difference of spectral statistics fluctuates on a much smaller scale than each single statistic.

  • Open Access English
    Authors: 
    L. Senis; V. Rathore; P. Andersson; K. Johnson; D. Jädernäs; C. Losin; D. Minghetti; J. Wright; D. Schrire;
    Publisher: Uppsala universitet, Tillämpad kärnfysik
    Country: Sweden

    Collimated Gamma Transmission Micro-Densitometry (GTMD) is a novel technique proposed to investigate local density variations of nuclear fuel in PIE, with a high spatial resolution. In this work, the first experimental tests of a gamma micro-densitometer are presented and the performance is characterized. The experimental procedures are described, including the aligning process and the calibration methodology. The results demonstrated that for the calibration samples with a thickness above 5 mm, a local density was obtained with a maximum discrepancy of about 2% and a spatial resolution of about 280 µm. The setup was used for the first test on an irradiated ADOPTTM fuel pellet slice. From the measurement, an average bulk density of about 9.58 g/cm3 was calculated and local density features were observed, possibly related to rim effects or the presence of local cracks. The information acquired also presented valuable information for possible improvements in the setup’s performance.

  • Publication . Article . Other literature type . 2023
    Open Access English
    Authors: 
    Schleihauf, Hanna; Zhang, Zhen; Gomez, Alissa; Engelmann, Jan;
    Project: EC | HelpSeeking (841021)

    Someone is rational in their thinking to the extent that they follow a rational procedure when determining what to believe. So whether someone is rational cannot be determined so much by whether they hold true or false beliefs (outcome-based rationality), but by how they arrived at these beliefs (procedure-based rationality). In this study, we want to answer the question to what extent 4-5-year-old children, 6-7-year-old children, and adults from China and the United States consider the procedure and the outcome in evaluating the rationality of an agent? In a picture book story, participants will be introduced to two characters whose pet ran away. They are trying to find the pet by using either rational (e.g. looking for the pet's traces) or irrational (e.g. using a spinning wheel) procedures that lead them to either the right (pointing at the location where the pet is hiding) or the wrong conclusion (pointing at the location where the pet is not hiding). More precisely, the participants will see three conditions: In an outcome matters condition, both characters are using an irrational procedure to find out where their pet is hiding, but one chooses the correct location, the other the wrong location. In a process matters condition, one of the characters is using a rational and the other is using an irrational procedure, while both choose wrong locations. In a process vs. outcome condition, one character is using an irrational procedure and point to the right location, the other character is using a rational procedure and point to the wrong location.

  • Open Access English
    Authors: 
    Mohammad Jadidi; Hanieh Khalili Param; Yasser Mahmoudi;
    Country: United Kingdom
    Project: UKRI | Fundamental Understanding... (EP/W033542/1), UKRI | Hex-PORTMAN: Heat Flux Sp... (EP/T012242/2)

    The majority of literature studies on composite porous-fluid systems involve fully-developed porous channel flows where the porous media covers the whole length of the channel. These studies utilized periodic boundary conditions at the inlet and outlet. In these systems, the stagnation at the frontal face of the porous block, turbulent separation bubble over the porous-fluid interface, and flow leakage from the porous to non-porous regions do not exist. The existence of these flow features in the case of a finite porous block immersed in a channel flow modifies turbulent interactions across the porous-fluid interface. In contrast to the previous studies, this paper investigates the flow and thermal characteristics of turbulent channel flow containing a porous block with a finite length. To this end, pore-scale large eddy simulations are performed in composite porous-fluid systems with two porosities (53% and 91%) at three Reynolds numbers of 3600, 7200, and 14400. Flow visualization shows that two distinct regions are formed over the interface in low-porosity cases, in contrast to high-porosity cases: Region#1 near the leading edge with organised hairpin structures and high flow leakage; Region#2 away from the leading edge with unorganised hairpin structures and lower flow leakage. In region#1, maximum turbulent fluctuations occur far away from the interface while they approach the interface in region#2. The results showed that by increasing either the Reynolds number or porous length, the location of maximum turbulence statistics approaches the interface. This observation supports earlier findings for fully-developed porous channel flows which are only valid in region#2. Whereas, with a low Reynolds number or a short porous length, the turbulent statistics peak far from the interface, consistent with the observations in region#1. Besides, it was found that increasing the porosity and Reynolds number reduces the flow leakage (from the porous region to the non-porous region) up to 50% and 10%, respectively, which in turn disrupts the patterns of contour-rotating vortex pairs and hairpin structures over the interface. It is further found that for a fixed Reynolds number, the overall Nusselt number for the high-porosity case is 2.6 times higher than that of the low-porosity case. The pressure drop for the low-porosity cases is 1.8 times more than that for the high-porosity cases.

Advanced search in Research products
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Searching FieldsTerms
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Include:
The following results are related to Digital Humanities and Cultural Heritage. Are you interested to view more results? Visit OpenAIRE - Explore.
185,102 Research products, page 1 of 18,511
  • Open Access English
    Authors: 
    Anne Sofie Laulund; Franziska Angelika Schwartz; Lars Christophersen; Mette Kolpen; Peter Østrup Jensen; Henrik Calum; Niels Høiby; Kim Thomsen; Claus Moser;
    Country: Denmark

    Introduction: Chronic wounds have a compromised microcirculation which leads to restricted gas exchange. The majority of these hypoxic wounds is infested with microorganisms congregating in biofilms which further hinders the antibiotic function. We speculate whether this process can be counteracted by hyperbaric oxygen therapy (HBOT). Methodology: Twenty-eight BALB/c mice with third-degree burns were included in the analyses. Pseudomonas aeruginosa embedded in seaweed alginate beads was injected under the eschar to mimic a biofilm infected wound. Challenged mice were randomized to receive either 4 days with 1 x ciprofloxacin combined with 2 × 90 min HBOT at 2.8 standard atmosphere daily, 1 x ciprofloxacin as monotherapy or saline as placebo. The mice were clinically scored, and wound sizes were estimated by planimetry daily. Euthanasia was performed on day 8. Wounds were surgically removed in toto, homogenized and plated for quantitative bacteriology. Homogenate supernatants were used for cytokine analysis. Results: P. aeruginosa was present in all wounds at euthanasia. A significant lower bacterial load was seen in the HBOT group compared to either the monotherapy ciprofloxacin group (p = 0.0008), or the placebo group (p < 0.0001). IL-1β level was significantly lower in the HBOT group compared to the placebo group (p = 0.0007). Both treatment groups had higher osteopontin levels than the placebo group (p = 0.002 and p = 0.004). The same pattern was seen in the S100A9 analysis (p = 0.01 and p = 0.008), whereas no differences were detected between the S100A8, the VEGF or the MMP8 levels in the three groups. Conclusion: These findings show that HBOT improves the bactericidal activity of ciprofloxacin against P. aeruginosa wound biofilm in vivo. HBOT in addition to ciprofloxacin also modulates the host response to a less inflammatory phenotype.

  • Restricted English
    Authors: 
    Pagkalos, Manolis; Scarpato, Andrea;
    Publisher: Bloomsbury Academic
    Country: Netherlands

    This volume fills a gap in current research on the Hellenistic Peloponnese, complementing and challenging traditional interpretations by adopting new perspectives on its complex social and political history in response to emerging trends in research. By examining aspects of the region's interstate relations, contemporary politics and modes of representation that have been relatively little studied to date, it affords a much more well-rounded picture of the Hellenistic Peloponnese and a rich basis for broadening scholarly debate and stimulating further research on the area. Each chapter promotes interdisciplinary approaches to a wide range of ancient evidence and material culture, and offers a renewed understanding of how socio-political transformations unfolded within the region. Together they shed new light on key agents of the period and their interactions, material evidence and political history both in and beyond the Peloponnese – from the enduring Macedonian influence in the 3rd century BCE and the violence and terror tactics deployed within the Achaian Koinon, to strategies of identity construction and memory politics wielded by local elites – and will be crucial points of reference for graduate students and scholars with an interest in the region.

  • Restricted English

    This volume fills a gap in current research on the Hellenistic Peloponnese, complementing and challenging traditional interpretations by adopting new perspectives on its complex social and political history in response to emerging trends in research. By examining aspects of the region's interstate relations, contemporary politics and modes of representation that have been relatively little studied to date, it affords a much more well-rounded picture of the Hellenistic Peloponnese and a rich basis for broadening scholarly debate and stimulating further research on the area. Each chapter promotes interdisciplinary approaches to a wide range of ancient evidence and material culture, and offers a renewed understanding of how socio-political transformations unfolded within the region. Together they shed new light on key agents of the period and their interactions, material evidence and political history both in and beyond the Peloponnese – from the enduring Macedonian influence in the 3rd century BCE and the violence and terror tactics deployed within the Achaian Koinon, to strategies of identity construction and memory politics wielded by local elites – and will be crucial points of reference for graduate students and scholars with an interest in the region.

  • Open Access English
    Authors: 
    Artur Sokolovsky; Luca Arnaboldi;

    Although machine learning approaches have been widely used in the field of finance, to very successful degrees, these approaches remain bespoke to specific investigations and opaque in terms of explainability, comparability, and reproducibility. The primary objective of this research was to shed light upon this field by providing a generic methodology that was investigation-agnostic and interpretable to a financial markets practitioner, thus enhancing their efficiency, reducing barriers to entry, and increasing the reproducibility of experiments. The proposed methodology is showcased on two automated trading platform components. Namely, price levels, a well-known trading pattern, and a novel 2-step feature extraction method. The methodology relies on hypothesis testing, which is widely applied in other social and scientific disciplines to effectively evaluate the concrete results beyond simple classification accuracy. The main hypothesis was formulated to evaluate whether the selected trading pattern is suitable for use in the machine learning setting. Across the experiments we found that the use of the considered trading pattern in the machine learning setting is only partially supported by statistics, resulting in insignificant effect sizes (Rebound 7 - $0.64 \pm 1.02$, Rebound 11 $0.38 \pm 0.98$, and rebound 15 - $1.05 \pm 1.16$), but allowed the rejection of the null hypothesis. We showcased the generic methodology on a US futures market instrument and provided evidence that with this methodology we could easily obtain informative metrics beyond the more traditional performance and profitability metrics. This work is one of the first in applying this rigorous statistically-backed approach to the field of financial markets and we hope this may be a springboard for more research. Associated processing files are available at: https://doi.org/10.5281/zenodo.4036850

  • Open Access English
    Authors: 
    Stijn P. Brouwers; Michael Simmler; Pascal Savary; Madeleine F. Scriba;
    Publisher: ETH Zurich
    Country: Switzerland

    Free-stall cubicles are designed so that cows do not defecate in the bedding material, while still providing comfortable lying places. However, fixed cubicle elements, such as the partition and neck rail, restrict available movement space and may hinder cows from performing natural lying down and standing up movement patterns. Although there are various types of cubicle partitions that differ in shape, dimensions, or materials, there is no method other than visual observations to assess their effects on cow welfare. An automated detection system could improve the efficiency and promote objectivity of such assessments. Therefore, the aim of this research was to explore which atypical lying down and standing up behaviors could be detected using body-mounted accelerometers and machine learning. Three leg- and one head-mounted accelerometer set to record at 20 Hz were fitted to 48 lactating dairy cows (Brown Swiss and Holstein × Swiss Fleckvieh). Lying down and standing up events were simultaneously assessed through video observations, by assigning binary presence/absence labels for atypical behaviors, such as lunging the head sideways when standing up and pawing the bedding material before lying down. Different time series classification algorithms were employed for model development using a nested cross-validation strategy. The best performing classifiers were MiniRocket and the deep learning algorithm InceptionTime. Atypical behaviors performed during standing up events, namely Hesitant head lunge and Crawling backwards, were identified as most promising candidates for accelerometer-based detection. These behaviors were detected with balanced accuracies of 0.67 and 0.74, respectively, and their learning curves indicated that more training data might further improve model performance. Overall, achieved performances were not yet satisfactory for application in the evaluation of new dairy cow housing installations. Potentially, ethograms designed for human observers are not optimal for machine learning and adjustments with machine learnability in mind might be necessary. The behaviors identified as promising are good candidates for further development into an efficient and objective method that could complement human observations in the assessment of dairy cow housing installations. Smart Agricultural Technology, 4

  • English
    Authors: 
    Ives, Libby,; Stack‐Morgan, Katie,; Gupta, Sanjeev; Caravaca, Gwénaël; Russell, Patrick; Shuster, David L.; Williams, Amy,; Holm-Alwmark, Sanna; Barnes, Robert; Bell, Jim F.; +20 more
    Publisher: HAL CCSD
    Country: France

    International audience; The Perseverance rover is exploring a sedimentary deposit within the Late Noachian-aged (4.0-4.8 Ga) Jezero Crater interpreted to be the remnants of a delta. From April 2022 through February 2023, Perseverance investigated the basal 25 m of sediments exposed in the fan’s eastern scarp. Rover instruments collected a suite of imaging, geochemical, mineralogical, and ground-penetrating radar data.Perseverance made detailed observations through two sections of the lower fan ~600 m apart. Similar facies and stratigraphic trends are present in both sections. Each section contains two coarsening-up successions. While some finer-grained units are laterally continuous between the two sections, the coarser-grained bodies that cap each section are laterally discontinuous and do not extend between sections.Both sequences are 10 - 15 m thick. Their lower strata are dominated by sulfate-cemented, planar laminated, very fine- to medium-grained sandstone and siltstone with rare low-angle truncations. Soft-sediment deformation occurs in the form of decimeter-scale lateral folds. Laminae are normally graded. These sequences are capped by meter-scale thick sheets of coarse-grained sandstone, pebbly sandstones, and conglomerates that are variably low-angle cross-bedded, trough cross-bedded, and planar-stratified. Plane beds are massive or normally graded.Two hypotheses for the depositional environment have emerged for this succession: a sub-aerial setting with extensive “overbank” facies and shallow braided channels and a proximal pro-deltaic setting with deposition driven by hyperpycnal flows. These hypotheses will be tested against observations made by Perseverance as it traverses the “Fan Top” and by more comprehensive studies of the “Delta Front” data.

  • Open Access English
    Authors: 
    Dörnemann, Nina; Dette, Holger;

    For a given $p\times n$ data matrix $\textbf{X}_n$ with i.i.d. centered entries and a population covariance matrix $\bf{\Sigma}$, the corresponding sample precision matrix $\hat{\bf\Sigma}^{-1}$ is defined as the inverse of the sample covariance matrix $\hat{\bf{\Sigma}} = (1/n) \bf{\Sigma}^{1/2} \textbf{X}_n\textbf{X}_n^\top \bf{\Sigma}^{1/2}$. We determine the joint distribution of a vector of diagonal entries of the matrix $\hat{\bf\Sigma}^{-1}$ in the situation, where $p_n=p< n$ and $p/n \to y \in [0,1)$ for $n\to\infty$ and $\bf{\Sigma}$ is a diagonal matrix. Remarkably, our results cover both the case where the dimension is negligible in comparison to the sample size and the case where it is of the same magnitude. Our approach is based on a QR-decomposition of the data matrix, yielding a connection to random quadratic forms and allowing the application of a central limit theorem for martingale difference schemes. Moreover, we discuss an interesting connection to linear spectral statistics of the sample covariance matrix. More precisely, the logarithmic diagonal entry of the sample precision matrix can be interpreted as a difference of two highly dependent linear spectral statistics of $\hat{\bf\Sigma}$ and a submatrix of $\hat{\bf\Sigma}$. This difference of spectral statistics fluctuates on a much smaller scale than each single statistic.

  • Open Access English
    Authors: 
    L. Senis; V. Rathore; P. Andersson; K. Johnson; D. Jädernäs; C. Losin; D. Minghetti; J. Wright; D. Schrire;
    Publisher: Uppsala universitet, Tillämpad kärnfysik
    Country: Sweden

    Collimated Gamma Transmission Micro-Densitometry (GTMD) is a novel technique proposed to investigate local density variations of nuclear fuel in PIE, with a high spatial resolution. In this work, the first experimental tests of a gamma micro-densitometer are presented and the performance is characterized. The experimental procedures are described, including the aligning process and the calibration methodology. The results demonstrated that for the calibration samples with a thickness above 5 mm, a local density was obtained with a maximum discrepancy of about 2% and a spatial resolution of about 280 µm. The setup was used for the first test on an irradiated ADOPTTM fuel pellet slice. From the measurement, an average bulk density of about 9.58 g/cm3 was calculated and local density features were observed, possibly related to rim effects or the presence of local cracks. The information acquired also presented valuable information for possible improvements in the setup’s performance.

  • Publication . Article . Other literature type . 2023
    Open Access English
    Authors: 
    Schleihauf, Hanna; Zhang, Zhen; Gomez, Alissa; Engelmann, Jan;
    Project: EC | HelpSeeking (841021)

    Someone is rational in their thinking to the extent that they follow a rational procedure when determining what to believe. So whether someone is rational cannot be determined so much by whether they hold true or false beliefs (outcome-based rationality), but by how they arrived at these beliefs (procedure-based rationality). In this study, we want to answer the question to what extent 4-5-year-old children, 6-7-year-old children, and adults from China and the United States consider the procedure and the outcome in evaluating the rationality of an agent? In a picture book story, participants will be introduced to two characters whose pet ran away. They are trying to find the pet by using either rational (e.g. looking for the pet's traces) or irrational (e.g. using a spinning wheel) procedures that lead them to either the right (pointing at the location where the pet is hiding) or the wrong conclusion (pointing at the location where the pet is not hiding). More precisely, the participants will see three conditions: In an outcome matters condition, both characters are using an irrational procedure to find out where their pet is hiding, but one chooses the correct location, the other the wrong location. In a process matters condition, one of the characters is using a rational and the other is using an irrational procedure, while both choose wrong locations. In a process vs. outcome condition, one character is using an irrational procedure and point to the right location, the other character is using a rational procedure and point to the wrong location.

  • Open Access English
    Authors: 
    Mohammad Jadidi; Hanieh Khalili Param; Yasser Mahmoudi;
    Country: United Kingdom
    Project: UKRI | Fundamental Understanding... (EP/W033542/1), UKRI | Hex-PORTMAN: Heat Flux Sp... (EP/T012242/2)

    The majority of literature studies on composite porous-fluid systems involve fully-developed porous channel flows where the porous media covers the whole length of the channel. These studies utilized periodic boundary conditions at the inlet and outlet. In these systems, the stagnation at the frontal face of the porous block, turbulent separation bubble over the porous-fluid interface, and flow leakage from the porous to non-porous regions do not exist. The existence of these flow features in the case of a finite porous block immersed in a channel flow modifies turbulent interactions across the porous-fluid interface. In contrast to the previous studies, this paper investigates the flow and thermal characteristics of turbulent channel flow containing a porous block with a finite length. To this end, pore-scale large eddy simulations are performed in composite porous-fluid systems with two porosities (53% and 91%) at three Reynolds numbers of 3600, 7200, and 14400. Flow visualization shows that two distinct regions are formed over the interface in low-porosity cases, in contrast to high-porosity cases: Region#1 near the leading edge with organised hairpin structures and high flow leakage; Region#2 away from the leading edge with unorganised hairpin structures and lower flow leakage. In region#1, maximum turbulent fluctuations occur far away from the interface while they approach the interface in region#2. The results showed that by increasing either the Reynolds number or porous length, the location of maximum turbulence statistics approaches the interface. This observation supports earlier findings for fully-developed porous channel flows which are only valid in region#2. Whereas, with a low Reynolds number or a short porous length, the turbulent statistics peak far from the interface, consistent with the observations in region#1. Besides, it was found that increasing the porosity and Reynolds number reduces the flow leakage (from the porous region to the non-porous region) up to 50% and 10%, respectively, which in turn disrupts the patterns of contour-rotating vortex pairs and hairpin structures over the interface. It is further found that for a fixed Reynolds number, the overall Nusselt number for the high-porosity case is 2.6 times higher than that of the low-porosity case. The pressure drop for the low-porosity cases is 1.8 times more than that for the high-porosity cases.