6,585 results on '"Amberg A"'
Search Results
2. Dynamic hysteresis of an oscillatory contact line
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Shen, Jiaxing, Lee, Yaerim, Li, Yuanzhe, Zaleski, Stéphane, Amberg, Gustav, and Shiomi, Junichiro
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Physics - Fluid Dynamics ,Condensed Matter - Soft Condensed Matter - Abstract
During oscillatory wetting, a phase retardation emerges between contact angle variation and contact line velocity, presenting as a hysteresis loop in their correlation -- an effect we term dynamic hysteresis. This phenomenon is found to be tunable by modifying the surface with different molecular layers. A comparative analysis of dynamic hysteresis, static hysteresis, and contact line friction coefficients across diverse substrates reveals that dynamic hysteresis is not a result of dissipative effects but is instead proportionally linked to the flexibility of the grafted layer on the surface. In the quest for appropriate conditions to model oscillatory contact line motion, we identify the generalized Hocking's linear law and modified Generalized Navier Boundary Condition (GNBC) as alternative options for predicting realistic dynamic hysteresis.
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- 2024
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3. 3D basin modeling of the Lower Saxony Basin, Germany: the role of overpressure in Mesozoic claystones with implications for nuclear waste storage
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Castro-Vera, Leidy, Gaus, Garri, Colling Cassel, Marlise, Amberg, Sebastian, and Littke, Ralf
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- 2025
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4. A study of why we need to reassess full reference image quality assessment with medical images
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Breger, Anna, Biguri, Ander, Landman, Malena Sabaté, Selby, Ian, Amberg, Nicole, Brunner, Elisabeth, Gröhl, Janek, Hatamikia, Sepideh, Karner, Clemens, Ning, Lipeng, Dittmer, Sören, Roberts, Michael, Collaboration, AIX-COVNET, and Schönlieb, Carola-Bibiane
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Electrical Engineering and Systems Science - Image and Video Processing ,Computer Science - Computer Vision and Pattern Recognition - Abstract
Image quality assessment (IQA) is not just indispensable in clinical practice to ensure high standards, but also in the development stage of novel algorithms that operate on medical images with reference data. This paper provides a structured and comprehensive collection of examples where the two most common full reference (FR) image quality measures prove to be unsuitable for the assessment of novel algorithms using different kinds of medical images, including real-world MRI, CT, OCT, X-Ray, digital pathology and photoacoustic imaging data. In particular, the FR-IQA measures PSNR and SSIM are known and tested for working successfully in many natural imaging tasks, but discrepancies in medical scenarios have been noted in the literature. Inconsistencies arising in medical images are not surprising, as they have very different properties than natural images which have not been targeted nor tested in the development of the mentioned measures, and therefore might imply wrong judgement of novel methods for medical images. Therefore, improvement is urgently needed in particular in this era of AI to increase explainability, reproducibility and generalizability in machine learning for medical imaging and beyond. On top of the pitfalls we will provide ideas for future research as well as suggesting guidelines for the usage of FR-IQA measures applied to medical images.
- Published
- 2024
5. 3D basin modeling of the Hils Syncline, Germany: reconstruction of burial and thermal history and implications for petrophysical properties of potential Mesozoic shale host rocks for nuclear waste storage
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Castro-Vera, Leidy, Amberg, Sebastian, Gaus, Garri, Leu, Katharina, and Littke, Ralf
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- 2024
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6. Profiling the heterogeneity of colorectal cancer consensus molecular subtypes using spatial transcriptomics
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Valdeolivas, Alberto, Amberg, Bettina, Giroud, Nicolas, Richardson, Marion, Gálvez, Eric J. C., Badillo, Solveig, Julien-Laferrière, Alice, Túrós, Demeter, Voith von Voithenberg, Lena, Wells, Isabelle, Pesti, Benedek, Lo, Amy A., Yángüez, Emilio, Das Thakur, Meghna, Bscheider, Michael, Sultan, Marc, Kumpesa, Nadine, Jacobsen, Björn, Bergauer, Tobias, Saez-Rodriguez, Julio, Rottenberg, Sven, Schwalie, Petra C., and Hahn, Kerstin
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- 2024
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7. Rethinking Technology in a Hyperconnected World: Beyond the Hype of Inter - connectivity
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Alina Betlej and Małgorzata Skórzewska - Amberg
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new technologies ,social values ,law regulations ,axionormative order ,Philosophy. Psychology. Religion ,Metaphysics ,BD95-131 - Abstract
This paper focuses on the sociological and legal analysis of the effects of the development of rapid technological advancements. The focus is on the need to rethink new technologies and the process of hyperconnectivity. The theoretical discussion is embedded in the framework of the chosen philosophical and social approaches. It starts with the attempt to understand the essence of the discussed changes and poses several questions to be answered. The authors analyze several mediating notions such as social values, axionormative order, legal regulations, the human position towards technological advancements, etc. Further analysis leads to a discussion of the legal context of these problems. The authors search for answers to many fundamental questions to open avenues for building coherent legal pillars of social order based on human values. To achieve these goals, they use a sociological and legal approach that is based mainly on criticism of writing and the analytical and synthetic methods.
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- 2024
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8. Imaging brain tissue architecture across millimeter to nanometer scales
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Michalska, Julia M., Lyudchik, Julia, Velicky, Philipp, Štefaničková, Hana, Watson, Jake F., Cenameri, Alban, Sommer, Christoph, Amberg, Nicole, Venturino, Alessandro, Roessler, Karl, Czech, Thomas, Höftberger, Romana, Siegert, Sandra, Novarino, Gaia, Jonas, Peter, and Danzl, Johann G.
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- 2024
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9. Impact of atrial fibrillation on productivity in working-age patients: an analysis of Swiss-AF prospective cohort study data
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Helena Aebersold, Fabienne Foster-Witassek, Sina Amberg, Miquel Serra-Burriel, Giorgio Moschovitis, Raffaele Zannoni, Stefanie Aeschbacher, Giulio Conte, Jürg H. Beer, Eva Blozik, Leo H. Bonati, David Conen, Stefan Felder, Moa L. Haller, Philipp Krisai, Michael Kühne, Rebecca E. Paladini, Tobias Reichlin, Nicolas Rodondi, Christian Sticherling, Thomas Szucs, Yuki Tomonaga, Stefan Osswald, and Matthias Schwenkglenks
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Medicine - Abstract
AIMS: We aimed to explore atrial fibrillation (AF)-induced productivity losses in working-age atrial fibrillation patients and to estimate atrial fibrillation-related indirect costs. METHODS: Between 2014 and 2017, the Swiss Atrial Fibrillation prospective cohort study (Swiss-AF) enrolled 217 working-age patients with documented atrial fibrillation. Self-reported changes in professional activity and the reasons thereof were descriptively analysed over 8 years of follow-up or until patients reached the retirement age. Results were put into perspective, and indirect costs were planned to be estimated, through comparison with a general population-based, age-, sex- and year-matched comparison sample from the Swiss labour force survey (SLFS). RESULTS: Of 217 analysed Swiss-AF patients, 14.7% reported a professional activity change (9.2% stop, 5.5% reduction) due to atrial fibrillation before the end of observation. Of those working at enrolment (n = 157), 3.8% had a subsequent professional activity change due to atrial fibrillation, 11.6% due to other reasons. Patients were more likely to report an impact of atrial fibrillation on professional activity if they had had atrial fibrillation longer and were closer to the retirement age. Slightly fewer Swiss-AF patients were employed (75%) than in the comparison sample (77%). For those working however, the degree of employment was higher (88% vs 83%). Lack of differences between the Swiss-AF patients and the comparison sample indicated no relevant indirect costs of atrial fibrillation due to lost productivity. CONCLUSION: Only a minority of atrial fibrillation patients reported a negative impact of atrial fibrillation on their professional activity. Professional activity changes due to other reasons were reported more frequently. Compared with the general population, atrial fibrillation did not cause distinct differences.
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- 2025
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10. TinyML4D: Scaling Embedded Machine Learning Education in the Developing World.
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Brian Plancher, Sebastian Büttrich, Jeremy Ellis, Neena Goveas, Laila D. Kazimierski, Jesús Alfonso López Sotelo, Milan Lukic, Diego Mendez 0001, Rosdiadee Nordin, Andrés Oliva Trevisan, Massimo Pavan, Manuel Roveri, Marcus Rüb, Jackline Tum, Marian Verhelst, Salah Abdeljabar, Segun Adebayo, Thomas Amberg, Halleluyah Aworinde, José Bagur, Gregg Barrett, Nabil Benamar, Bharat S. Chaudhari, Ronald Criollo, David Cuartielles, José A. Ferreira Filho, Solomon Gizaw, Evgeni Gousev, Alessandro Grande, Shawn Hymel, Peter Ing, Prashant Manandhar, Pietro Manzoni, Boris Murmann, Eric Pan, Rytis Paskauskas, Ermanno Pietrosemoli, Tales C. Pimenta, Marcelo Rovai, Marco Zennaro, and Vijay Janapa Reddi
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- 2024
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11. Surface functionalization of fibrous material by roll-to-roll low pressure plasma processing
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Amberg, Martin, Hanselmann, Barbara, and Hegemann, Dirk
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- 2025
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12. Exact algorithms for routing electric autonomous mobile robots in intralogistics
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Meyer, Anne, Gschwind, Timo, Amberg, Boris, and Colling, Dominik
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- 2025
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13. The cardiopulmonary benefits of physiologically based cord clamping persist for at least 8 hours in lambs with a diaphragmatic hernia
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Paige J. Riddington, Philip L. J. DeKoninck, Marta Thio, Calum T. Roberts, Risha Bhatia, Janneke Dekker, Aidan J. Kashyap, Benjamin J. Amberg, Karyn A. Rodgers, Alison M. Thiel, Ilias Nitsos, Valerie A. Zahra, Ryan J. Hodges, Stuart B. Hooper, and Kelly J. Crossley
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congenital diaphragmatic hernia ,lung hypoplasia ,neonatal transition ,pulmonary hypertension ,pulmonary blood flow ,pulmonary vascular resistance ,Pediatrics ,RJ1-570 - Abstract
IntroductionInfants with congenital diaphragmatic hernia can suffer severe respiratory insufficiency and pulmonary hypertension after birth. Aerating the lungs before removing placental support (physiologically based cord clamping, PBCC) increases pulmonary blood flow (PBF) and reduces pulmonary vascular resistance (PVR) in lambs with a diaphragmatic hernia (DH). We hypothesized that these benefits of PBCC persist for at least 8 h after birth.MethodsAt ∼138 days of gestation age (dGA), 21 lambs with a surgically induced left-sided DH (∼86 dGA) were delivered via cesarean section. The umbilical cord was clamped either before ventilation onset (immediate cord clamping, ICC, n = 9) or after achieving a tidal volume of 4 ml/kg, with a maximum delay of 10 min (PBCC, n = 12). The lambs were ventilated for 8 h, initially with conventional mechanical ventilation, but were switched to high-frequency oscillatory ventilation after 30 min if required. Ventilatory parameters, cardiopulmonary physiology, and arterial blood gases were measured throughout the study.ResultsPBF increased after ventilation onset in both groups and was higher in the PBCC DH lambs than the ICC DH lambs at 8 h (5.2 ± 1.2 vs. 1.9 ± 0.3 ml/min/g; p
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- 2024
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14. Rapid wetting of shear-thinning fluids
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Yada, Susumu, Bazesefidpar, Kazem, Tammisola, Outi, Amberg, Gustav, and Bagheri, Shervin
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Physics - Fluid Dynamics ,Condensed Matter - Soft Condensed Matter - Abstract
Using experiments and numerical simulations, we investigate the spontaneous spreading of droplets of aqueous glycerol (Newtonian) and aqueous polymer (shear-thinning) solutions on smooth surfaces. We find that in the first millisecond the spreading of the shear-thinning solutions is identical to the spreading of water, regardless of the polymer concentration. In contrast, aqueous glycerol solutions show a different behavior, namely, significantly slower spreading rate than water. In the initial rapid spreading phase, the dominating forces that can resist the wetting are inertial forces and contact-line friction. For the glycerol solutions, an increase in glycerol concentration effectively increases the contact-line friction, resulting in increased resistance to wetting. For the polymeric solutions, however, an increase in polymer concentration does not modify contact-line friction. As a consequence, the energy dissipation at the contact line can not be controlled by varying the amount of additives for shear-thinning fluids. The reduction of the spreading rate of shear-thinning fluids on smooth surfaces in the rapid wetting regime can only be achieved by increasing solvent viscosity. Our results have implications for phase-change applications where the control of the rapid spreading rate is central, such as anti-icing and soldering
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- 2022
15. Resolving Vibrations in a Polyatomic Molecule with Femtometer Precision
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Rupprecht, Patrick, Aufleger, Lennart, Heinze, Simon, Magunia, Alexander, Ding, Thomas, Rebholz, Marc, Amberg, Stefano, Mollov, Nikola, Henrich, Felix, Haverkort, Maurits W., Ott, Christian, and Pfeifer, Thomas
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Physics - Chemical Physics - Abstract
We measure molecular vibrations with femtometer precision using time-resolved x-ray absorption spectroscopy. For a demonstration, a Raman process excites the A$_{1g}$ mode in gas-phase SF$_6$ molecules with an amplitude of $\approx50$ fm, which is probed by a time-delayed soft x-ray pulse at the sulfur $L_{2,3}$-edge. Mapping the extremely small measured energy shifts to internuclear distances requires an understanding of the electronic contributions provided by a many-body ab initio simulation. Our study establishes core-level spectroscopy as a precision tool for time-dependent molecular-structure metrology.
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- 2022
16. Neural Face Video Compression using Multiple Views
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Volokitin, Anna, Brugger, Stefan, Benlalah, Ali, Martin, Sebastian, Amberg, Brian, and Tschannen, Michael
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Computer Science - Computer Vision and Pattern Recognition - Abstract
Recent advances in deep generative models led to the development of neural face video compression codecs that use an order of magnitude less bandwidth than engineered codecs. These neural codecs reconstruct the current frame by warping a source frame and using a generative model to compensate for imperfections in the warped source frame. Thereby, the warp is encoded and transmitted using a small number of keypoints rather than a dense flow field, which leads to massive savings compared to traditional codecs. However, by relying on a single source frame only, these methods lead to inaccurate reconstructions (e.g. one side of the head becomes unoccluded when turning the head and has to be synthesized). Here, we aim to tackle this issue by relying on multiple source frames (views of the face) and present encouraging results.
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- 2022
17. Droplet impact on asymmetric hydrophobic microstructures
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Yada, Susumu, Lacis, Ugis, van der Wijngaart, Wouter, Lundell, Fredrik, Amberg, Gustav, and Bagheri, Shervin
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Physics - Fluid Dynamics - Abstract
Textured hydrophobic surfaces that repel liquid droplets unidirectionally are found in nature such as butterfly wings and ryegrass leaves and are also essential in technological processes such as self-cleaning and anti-icing. However, droplet impact on such surfaces is not fully understood. Here, we study, using a high-speed camera, droplet impact on surfaces with inclined micropillars. We observed directional rebound at high impact speeds on surfaces with dense arrays of pillars. We attribute this asymmetry to the difference in wetting behavior of the structure sidewalls, causing slower retraction of the contact line in the direction against the inclination compared to with the inclination. The experimental observations are complemented with numerical simulations to elucidate the detailed movement of the drops over the pillars. These insights improve our understanding of droplet impact on hydrophobic microstructures and may be a useful for designing structured surfaces for controlling droplet mobility., Comment: 24 pages, 9 figures
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- 2022
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18. Assessing the suitability of YY males and ZZ females as an invasive species population control method across life histories
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Erickson, Richard A., Thompson, Hannah M., Kageyama, Stacie A., Andriacchi, Grace M., Cupp, Aaron R., Patiño, Reynaldo, and Amberg, Jon J.
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- 2023
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19. Phototoxicity – from molecular descriptors to classification models
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Schmidt Friedemann, Evers Andreas, Amberg Alexander, Hessler Gerhard, Robles Catherine, and Baringhaus Karl-Heinz
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Information technology ,T58.5-58.64 ,Chemistry ,QD1-999 - Published
- 2011
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20. Nanoscale sheared droplet: Volume-of-Fluid, phase-field and no-slip molecular dynamics
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Lācis, Uǧis, Pellegrino, Michele, Sundin, Johan, Amberg, Gustav, Zaleski, Stephané, Hess, Berk, and Bagheri, Shervin
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Physics - Fluid Dynamics - Abstract
The motion of the three-phase contact line between two immiscible fluids and a solid surface arises in a variety of wetting phenomena and technological applications. One challenge in continuum theory is the effective representation of molecular phenomena close to the contact line. Here, we characterize the molecular processes of the moving contact line to assess the accuracy of two different continuum two-phase models. Specifically, molecular dynamics (MD) simulations of a two-dimensional droplet between two moving plates are used to create reference data for different capillary numbers and contact angles. We use a simple-point-charge/extended (SPC/E) water model with particle-mesh Ewald electrostatics treatment. This model provides a very small slip and a more realistic representation of the molecular physics than Lennards-Jones models. The Cahn-Hilliard phase-field model and the Volume-of-Fluid model are calibrated against the drop displacement from MD reference data. It is demonstrated that the calibrated continuum models can accurately capture droplet displacement and droplet breakup for different capillary numbers and contact angles. However, we also observe differences between continuum and atomistic simulations in describing the transient and unsteady droplet behavior, in particular, close to dynamical wetting transitions. The molecular dynamics of the sheared droplet provide insight of the line friction experienced by the advancing and receding contact lines and evidence of large-scale temporal "stick-slip" like oscillations. The presented results will serve as a stepping stone towards developing accurate continuum models for nanoscale hydrodynamics., Comment: 45 pages, 23 figures, 4 tables, 1 supplementary PDF, 2 supplementary movies, 1 supplementary archive, accepted for publication in "Journal of Fluid Mechanics"
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- 2021
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21. Integrated Bus Timetabling and Scheduling with a Mutation-Based Evolutionary Scheme Maximizing Headway Quality and Connections
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Mertens, Lucas, Amberg, Bastian, and Kliewer, Natalia
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- 2024
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22. Navitoclax safety, tolerability, and effect on biomarkers of senescence and neurodegeneration in aged nonhuman primates
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Edward F. Greenberg, Martin J. Voorbach, Alexandra Smith, David R. Reuter, Yuchuan Zhuang, Ji-Quan Wang, Dustin W. Wooten, Elizabeth Asque, Min Hu, Carolin Hoft, Ryan Duggan, Matthew Townsend, Karin Orsi, Karen Dalecki, Willi Amberg, Lori Duggan, Heather Knight, Joseph S. Spina, Yupeng He, Kennan Marsh, Vivian Zhao, Suzanne Ybarra, Jennifer Mollon, Yuni Fang, Aparna Vasanthakumar, Susan Westmoreland, Mathias Droescher, Sjoerd J. Finnema, and Hana Florian
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Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Alzheimer's disease (AD) is the most common global dementia and is universally fatal. Most late-stage AD disease-modifying therapies are intravenous and target amyloid beta (Aβ), with only modest effects on disease progression: there remains a high unmet need for convenient, safe, and effective therapeutics. Senescent cells (SC) and the senescence-associated secretory phenotype (SASP) drive AD pathology and increase with AD severity. Preclinical senolytic studies have shown improvements in neuroinflammation, tau, Aβ, and CNS damage; most were conducted in transgenic rodent models with uncertain human translational relevance. In this study, aged cynomolgus monkeys had significant elevation of biomarkers of senescence, SASP, and neurological damage. Intermittent treatment with the senolytic navitoclax induced modest reversible thrombocytopenia; no serious drug-related toxicity was noted. Navitoclax reduced several senescence and SASP biomarkers, with CSF concentrations sufficient for senolysis. Finally, navitoclax reduced TSPO-PET frontal cortex binding and showed trends of improvement in CSF biomarkers of neuroinflammation, neuronal damage, and synaptic dysfunction. Overall, navitoclax administration was safe and well tolerated in aged monkeys, inducing trends of biomarker changes relevant to human neurodegenerative disease.
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- 2024
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23. Appearance of Natural Cosmetics in Consumer Behavior Related to Cosmetics in Hungary
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Amberg Nóra
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consumer ,natural ,cosmetics ,behavior ,intention ,Environmental sciences ,GE1-350 - Abstract
The aim of this study is to determine what variables influence consumer purchase intentions regarding preferences for natural cosmetics. Data were collected via an online survey from 197 people completed in April-May 2018 in Hungary. The research used a non-parametric test – the Wilcoxon test. Analyses have shown that gender and consumers’ willingness to purchase natural products influence consumers’ willingness to purchase. Environmentally and health-conscious consumer behavior also influences their purchasing intentions for natural cosmetics. Consumer interest in environmental and health issues is growing today, providing a huge opportunity for the natural and organic cosmetics (N&O Cs) industry to develop a strategy that would encourage many consumers to buy organic or natural body care products. The results may also be useful for marketers, online sellers and professionals in identifying and better understanding new trends in natural cosmetics production.
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- 2023
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24. Ubiquitin-specific protease 7 inhibitors reveal a differentiated mechanism of p53-driven anti-cancer activity
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Futran, Alan S., Lu, Tao, Amberg-Johnson, Katherine, Xu, Jiayi, Yang, Xiaoxiao, He, Saidi, Boyce, Sarah, Bell, Jeffrey A., Pelletier, Robert, Suzuki, Takao, Huang, Xianhai, Qian, Heng, Fang, Liping, Xing, Li, Xu, Zhaowu, Kurtz, Stephen E., Tyner, Jeffrey W., Tang, Wayne, Guo, Tao, Akinsanya, Karen, Madge, David, and Jensen, Kristian K.
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- 2024
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25. On the Estimation of the Number of Unreachable Peers in the Bitcoin P2P Network by Observation of Peer Announcements
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Grundmann, Matthias, Amberg, Hedwig, and Hartenstein, Hannes
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Computer Science - Cryptography and Security ,Computer Science - Networking and Internet Architecture - Abstract
Bitcoin is based on a P2P network that is used to propagate transactions and blocks. While the P2P network design intends to hide the topology of the P2P network, information about the topology is required to understand the network from a scientific point of view. Thus, there is a natural tension between the 'desire' for unobservability on the one hand, and for observability on the other hand. On a middle ground, one would at least be interested on some statistical features of the Bitcoin network like the number of peers that participate in the propagation of transactions and blocks. This number is composed of the number of reachable peers that accept incoming connections and unreachable peers that do not accept incoming connections. While the number of reachable peers can be measured, it is inherently difficult to determine the number of unreachable peers. Thus, the number of unreachable peers can only be estimated based on some indicators. In this paper, we first define our understanding of unreachable peers and then propose the PAL (Passive Announcement Listening) method which gives an estimate of the number of unreachable peers by observing ADDR messages that announce active IP addresses in the network. The PAL method allows for detecting unreachable peers that indicate that they provide services useful to the P2P network. In conjunction with previous methods, the PAL method can help to get a better estimate of the number of unreachable peers. We use the PAL method to analyze data from a long-term measurement of the Bitcoin P2P network that gives insights into the development of the number of unreachable peers over five years from 2015 to 2020. Results show that about 31,000 unreachable peers providing useful services were active per day at the end of the year 2020. An empirical validation indicates that the approach finds about 50 % of unreachable peers that provide useful services.
- Published
- 2021
26. AXL receptor tyrosine kinase modulates gonadotropin-releasing hormone receptor signaling
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Pardis Mohammadzadeh, Mina Roueinfar, and Gregory C. Amberg
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TAM receptor tyrosine kinase ,Gas6 ,Matrix metalloproteinase 9 ,Medicine ,Cytology ,QH573-671 - Abstract
Abstract Background Gonadotropin-releasing hormone (GnRH) receptors are essential for reproduction and are expressed in numerous urogenital, reproductive, and non-reproductive cancers. In addition to canonical G protein-coupled receptor signaling, GnRH receptors functionally interact with several receptor tyrosine kinases. AXL is a receptor tyrosine kinase expressed in numerous tissues as well as multiple tumors. Here we tested the hypothesis that AXL, along with its endogenous ligand Gas6, impacts GnRH receptor signaling. Methods We used clonal murine pituitary αT3-1 and LβT2 gonadotrope cell lines to examine the effect of AXL activation on GnRH receptor-dependent signaling outcomes. ELISA and immunofluorescence were used to observe AXL and GnRH receptor expression in αT3-1 and LβT2 cells, as well as in murine and human pituitary sections. We also used ELISA to measure changes in ERK phosphorylation, pro-MMP9 production, and release of LHβ. Digital droplet PCR was used to measure the abundance of Egr-1 transcripts. A transwell migration assay was used to measure αT3-1 and LβT2 migration responses to GnRH and AXL. Results We observed AXL, along with the GnRH receptor, expression in αT3-1 and LβT2 gonadotrope cell lines, as well as in murine and human pituitary sections. Consistent with a potentiating role of AXL, Gas6 enhanced GnRH-dependent ERK phosphorylation in αT3-1 and LβT2 cells. Further, and consistent with enhanced post-transcriptional GnRH receptor responses, we found that Gas6 increased the abundance of Egr-1 transcripts. Suggesting functional significance, in LβT2 cells, Gas6/AXL signaling stimulated LHβ production and enhanced GnRH receptor-dependent generation of pro-MMP9 protein and promoted cell migration. Conclusions Altogether, these data describe a novel role for AXL as a modulator of GnRH receptor signaling. Video Abstract
- Published
- 2023
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27. An Electronic Health Record–Integrated Application for Standardizing Care and Monitoring Patients With Autosomal Dominant Polycystic Kidney Disease Enrolled in a Tolvaptan Clinic: Design and Implementation Study
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Maroun Chedid, Fouad T Chebib, Erin Dahlen, Theodore Mueller, Theresa Schnell, Melissa Gay, Musab Hommos, Sundararaman Swaminathan, Arvind Garg, Michael Mao, Brigid Amberg, Kirk Balderes, Karen F Johnson, Alyssa Bishop, Jackqueline Kay Vaughn, Marie Hogan, Vicente Torres, Rajeev Chaudhry, and Ziad Zoghby
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Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
Abstract BackgroundTolvaptan is the only US Food and Drug Administration–approved drug to slow the progression of autosomal dominant polycystic kidney disease (ADPKD), but it requires strict clinical monitoring due to potential serious adverse events. ObjectiveWe aimed to share our experience in developing and implementing an electronic health record (EHR)–based application to monitor patients with ADPKD who were initiated on tolvaptan. MethodsThe application was developed in collaboration with clinical informatics professionals based on our clinical protocol with frequent laboratory test monitoring to detect early drug-related toxicity. The application streamlined the clinical workflow and enabled our nursing team to take appropriate actions in real time to prevent drug-related serious adverse events. We retrospectively analyzed the characteristics of the enrolled patients. ResultsAs of September 2022, a total of 214 patients were enrolled in the tolvaptan program across all Mayo Clinic sites. Of these, 126 were enrolled in the Tolvaptan Monitoring Registry application and 88 in the Past Tolvaptan Patients application. The mean age at enrollment was 43.1 (SD 9.9) years. A total of 20 (9.3%) patients developed liver toxicity, but only 5 (2.3%) had to discontinue the drug. The 2 EHR-based applications allowed consolidation of all necessary patient information and real-time data management at the individual or population level. This approach facilitated efficient staff workflow, monitoring of drug-related adverse events, and timely prescription renewal. ConclusionsOur study highlights the feasibility of integrating digital applications into the EHR workflow to facilitate efficient and safe care delivery for patients enrolled in a tolvaptan program. This workflow needs further validation but could be extended to other health care systems managing chronic diseases requiring drug monitoring.
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- 2024
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28. Protocol for sorting cells from mouse brains labeled with mosaic analysis with double markers by flow cytometry
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Nicole Amberg, Giselle Cheung, and Simon Hippenmeyer
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Single Cell ,Flow Cytometry ,Developmental biology ,Science (General) ,Q1-390 - Abstract
Summary: Mosaic analysis with double markers (MADM) technology enables the generation of genetic mosaic tissue in mice and high-resolution phenotyping at the individual cell level. Here, we present a protocol for isolating MADM-labeled cells with high yield for downstream molecular analyses using fluorescence-activated cell sorting (FACS). We describe steps for generating MADM-labeled mice, perfusion, single-cell suspension, and debris removal. We then detail procedures for cell sorting by FACS and downstream analysis. This protocol is suitable for embryonic to adult mice.For complete details on the use and execution of this protocol, please refer to Contreras et al. (2021).1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
- Published
- 2024
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29. Products of locally cyclic groups
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Amberg, Bernhard and Sysak, Yaroslav
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Mathematics - Group Theory - Abstract
We consider groups of the form $G=AB$ with two locally cyclic subgroups $A$ and $B$. The structure of these groups is determined in the cases when $A$ and $B$ are both periodic or when one of them is periodic and the other is not. Together with a previous study of the case when $A$ and $B$ are torsion-free, this gives a complete classification of all groups that are the product of two locally cyclic groups. It is also shown that the product of a finite number of pairwise permutable periodic locally cyclic subgroups is a locally supersoluble group.
- Published
- 2020
30. Droplet impact on surfaces with asymmetric microscopic features
- Author
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Yada, Susumu, Allais, Blandine, van der Wijngaart, Wouter, Lundell, Fredrik, Amberg, Gustav, and Bagheri, Shervin
- Subjects
Physics - Fluid Dynamics - Abstract
The impact of liquid drops on a rigid surface is central in cleaning, cooling and coating processes in both nature and industrial applications. However, it is not clear how details of pores, roughness and texture on the solid surface influence the initial stages of the impact dynamics. Here, we experimentally study drop impacting at low velocities onto surfaces textured with asymmetric (tilted) ridges. We define the line-friction capillary number $Ca_f={\mu_f V_0}/{\sigma}$ (where $\mu_f$, $V_0$ and $\sigma$ are the line friction, impact velocity and surface tension, respectively) as a measure of the importance of the topology of surface textures for the dynamics of droplet impact. We show that when $Ca_f \ll 1$, the contact line speed in the direction against the inclination of the ridges is set by line-friction, whereas in the direction with inclination the contact line is pinned at acute corners of the ridge. When $Ca_f \sim 1$, the pinning is only temporary until the liquid-vapor interface reaches to the next ridge where a new contact line is formed. Finally, when $Ca_f\gg 1$, the geometric details of non-smooth surfaces play little role., Comment: 12 pages, 7 figures, under consideration for Physical Review Fluids. Revised February 04 2021
- Published
- 2020
- Full Text
- View/download PDF
31. Steady moving contact line of water over a no-slip substrate
- Author
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Lācis, Uǧis, Johansson, Petter, Fullana, Tomas, Hess, Berk, Amberg, Gustav, Bagheri, Shervin, and Zaleski, Stephané
- Subjects
Physics - Fluid Dynamics - Abstract
The movement of the triple contact line plays a crucial role in many applications such as ink-jet printing, liquid coating and drainage (imbibition) in porous media. To design accurate computational tools for these applications, predictive models of the moving contact line are needed. However, the basic mechanisms responsible for movement of the triple contact line are not well understood but still debated. We investigate the movement of the contact line between water, vapour and a silica-like solid surface under steady conditions in low capillary number regime. We use molecular dynamics (MD) with an atomistic water model to simulate a nanoscopic drop between two moving plates. We include hydrogen bonding between the water molecules and the solid substrate, which leads to a sub-molecular slip length. We benchmark two continuum methods, the Cahn-Hilliard phase-field (PF) model and a volume-of-fluid (VOF) model, against MD results. We show that both continuum models can reproduce the statistical measures obtained from MD reasonably well, with a trade-off in accuracy. We demonstrate the importance of the phase field mobility parameter and the local slip length in accurately modelling the moving contact line., Comment: 26 pages, 13 figures, 4 tables, post-review version, under consideration for publication in "European Physical Journal Special Topics"
- Published
- 2020
- Full Text
- View/download PDF
32. Correction to: EGFR/Ras-induced CCL20 production modulates the tumour microenvironment
- Author
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Hippe, Andreas, Braun, Stephan Alexander, Oláh, Péter, Gerber, Peter Arne, Schorr, Anne, Seeliger, Stephan, Holtz, Stephanie, Jannasch, Katharina, Pivarcsi, Andor, Buhren, Bettina, Schrumpf, Holger, Kislat, Andreas, Bünemann, Erich, Steinhoff, Martin, Fischer, Jens, Lira, Sérgio A, Boukamp, Petra, Hevezi, Peter, Stoecklein, Nikolas Hendrik, Hoffmann, Thomas, Alves, Frauke, Sleeman, Jonathan, Bauer, Thomas, Klufa, Jörg, Amberg, Nicole, Sibilia, Maria, Zlotnik, Albert, Müller-Homey, Anja, and Homey, Bernhard
- Subjects
Biomedical and Clinical Sciences ,Oncology and Carcinogenesis ,Public Health and Health Services ,Oncology & Carcinogenesis ,Oncology and carcinogenesis - Abstract
The article ‘EGFR/Ras-induced CCL20 production modulates the tumour microenvironment’, written by Andreas Hippe, Stephan Alexander Braun, Péter Oláh, Peter Arne Gerber, Anne Schorr, Stephan Seeliger, Stephanie Holtz, Katharina Jannasch, Andor Pivarcsi, Bettina Buhren, Holger Schrumpf, Andreas Kislat, Erich Bünemann, Martin Steinhoff, Jens Fischer, Sérgio A. Lira, Petra Boukamp, Peter Hevezi, Nikolas Hendrik Stoecklein, Thomas Hoffmann, Frauke Alves, Jonathan Sleeman, Thomas Bauer, Jörg Klufa, Nicole Amberg, Maria Sibilia, Albert Zlotnik, Anja Müller- Homey and Bernhard Homey, was originally published electronically on the publisher’s internet portal on 30 June 2020 without open access. With the author(s)’ decision to opt for Open Choice the copyright of the article changed on 16 September 2021 to © The Author(s) 2021 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/ licenses/by/4.0/. Open Access funding enabled and organized by Projekt DEAL.
- Published
- 2021
33. California Local Option Sales Taxes for Transportation During the Pandemic
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Amberg, Natalie, King, Hannah, Wasserman, Jacob L, Taylor, Brian D, and Wachs, Martin
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California ,transportation ,LOST ,tax ,economy ,pandemic - Published
- 2021
34. Robust and Cost-Efficient Integrated Multiple Depot Vehicle and Crew Scheduling with Controlled Trip Shifting.
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Bastian Amberg and Boris Amberg
- Published
- 2023
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35. A Mutation Based Modular Evolutionary Scheme for Integrated Timetabling and Vehicle Scheduling With headways and Connection Quality Criteria
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Mertens, Lucas, Amberg, Bastian, Kliewer, Natalia, Barbosa-Povoa, Ana Paula, Editorial Board Member, de Almeida, Adiel Teixeira, Editorial Board Member, Gans, Noah, Editorial Board Member, Gupta, Jatinder N. D., Editorial Board Member, Heim, Gregory R., Editorial Board Member, Hua, Guowei, Editorial Board Member, Kimms, Alf, Editorial Board Member, Li, Xiang, Editorial Board Member, Masri, Hatem, Editorial Board Member, Nickel, Stefan, Editorial Board Member, Qiu, Robin, Editorial Board Member, Shankar, Ravi, Editorial Board Member, Slowiński, Roman, Editorial Board Member, Tang, Christopher S., Editorial Board Member, Wu, Yuzhe, Editorial Board Member, Zhu, Joe, Editorial Board Member, Zopounidis, Constantin, Editorial Board Member, Grothe, Oliver, editor, Rebennack, Steffen, editor, and Stein, Oliver, editor
- Published
- 2023
- Full Text
- View/download PDF
36. LOST and Found: The Fall and Rise of Local Option Sales Taxes for Transportation in California Amidst the Pandemic
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King, Hannah, Amberg, Natalie, Wasserman, Jacob L., Taylor, Brian D., Wachs, Martin, Roess, Roger P., Series Editor, Loukaitou-Sideris, Anastasia, editor, Bayen, Alexandre M., editor, Circella, Giovanni, editor, and Jayakrishnan, R., editor
- Published
- 2023
- Full Text
- View/download PDF
37. Integrated Bus Timetabling, Vehicle Scheduling, and Crew Scheduling with a mutation-based evolutionary scheme
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Mertens, Lucas, Amberg, Bastian, and Kliewer, Natalia
- Published
- 2024
- Full Text
- View/download PDF
38. All Is Not LOST: Tracking California’s Local Option Sales Tax Revenues for Transportation During the Pandemic
- Author
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King, Hannah, Amberg, Natalie, Wasserman, Jacob L, Taylor, Brian D, and Wachs, Martin
- Subjects
transportation finance ,COVID-19 ,sales taxes ,taxation ,level of service ,LOST - Abstract
The COVID-19 pandemic dramatically affected transportation systems, including the ability of localities to pay for them. We explore the effects of the pandemic and the associated economic turbulence on local option sales taxes (LOSTs), an increasingly common revenue source for transportation in California and across the U.S. LOSTs have many advantages over alternative finance instruments, and they can raise prodigious amounts of revenue. However, LOST funding relies on consumer spending. During times of economic weakness, spending and therefore LOST revenues will lag. This is precisely the pattern we observe in California counties during the initial months of the pandemic. Fortunately for local transportation budgets, LOST revenues recovered after the initial economic shock of COVID-19, albeit at a lower level than they likely would have otherwise. LOST revenue trends during the pandemic were affected by national and regional economic conditions and government policy as well. This public health crisis illustrates both the pitfalls and resilience of LOSTs during economic downturns and recoveries. The lessons from the pandemic’s effects on LOSTs will be useful for policymakers and analysts in preparing for inevitable future economic fluctuations.
- Published
- 2021
39. Transportation Sales Taxes in Los Angeles: Lessons from 40 Years of Experience
- Author
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Amberg, Natalie L, Wachs, Martin, and Marks, Jeremy S
- Subjects
LOST ,local option ,sales tax ,Los Angeles ,tax ,Metro ,transportation ,transit - Published
- 2021
40. The Landscape of California’s Local Option Sales Taxes
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Dasmalchi, Eric and Amberg, Natalie
- Subjects
LOST ,local option ,sales tax ,California ,transit ,finance ,funding ,transportation ,planning - Published
- 2021
41. Daylighting Public Funding Streams: Increasing Equitable Access to Public Transit Across California
- Author
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Amberg, Natalie and Dasmalchi, Eric
- Subjects
California ,program design ,transit ,transportation finance - Abstract
This report presents research into the funding categories and other characteristics of active Local Option Sales Taxes (LOSTs) throughout California, with specific focus on the extent to which they make resources available for public transit and the political context that makes it so. LOSTs have grown increasingly popular as a funding mechanism for transportation in California in the context of declining funding from other sources.We find that while LOSTs are increasingly common in California, they vary widely with regards to how they fund transit. In general, LOSTs in rural areas of the state fund transit less, with some of our conversations revealing a preference for additional funds in those areas but others asserting that between LOST funding and other resources such as Transportation Development Act (TDA) funds, rural transit has adequate resources, at least to provide the current level of service. In attempting to characterize which resources are available to transit from each LOST, we also looked closely at local return funds—funds passed on to cities and other local jurisdictions to spend as they see fit, often within some sort of eligibility constraint. Depending on the LOST measure, these funds can either make up a small component or most of the funding program. While our research did reveal that in many cases these funds could be put towards transit, or at least transit-supportive infrastructure such as bus lanes and shelters, we find no evidence of local jurisdictions doing so. Our findings suggest that this is due to local officials and voters seeing road maintenance as the top priority, coupled in some cases with a lack of familiarity with how to support effective public transit.
- Published
- 2021
42. A study of why we need to reassess full reference image quality assessment with medical images.
- Author
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Anna Breger, Ander Biguri, Malena Sabaté Landman, Ian Selby, Nicole Amberg, Elisabeth Brunner, Janek Gröhl, Sepideh Hatamikia, Clemens Karner, Lipeng Ning, Sören Dittmer, Michael Roberts, AIX-COVNET Collaboration, and Carola-Bibiane Schönlieb
- Published
- 2024
- Full Text
- View/download PDF
43. Relations of Research and Teaching in Legal Education: International Legal Framework and Selected National Solutions
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Maciej Perkowski, Izabela Kraśnicka, Anna Drabarz, Wojciech Zoń, Maciej Oksztulski, Małgorzata Skórzewska-Amberg, and Ewa M. Kwiatkowska
- Subjects
legal education ,scientific research ,academic teachers ,Law - Abstract
The aim of the article is to provide an overview of the international and EU law framework concerning the relation between the research and teaching. The analysis of internal regulations of selected European states is provided for a broader vision and comparative perspective. Such an overview constitutes the initial ground for further research and evaluation of the applicable law and its implementation. The article constitutes a summary of the initial phase of the research project dedicated to the impact of the legal research on legal education based on the projects funded by the Polish National Science Centre.
- Published
- 2023
- Full Text
- View/download PDF
44. Kompetenzorientierte Spielsituationen (E-Book): Planen, gestalten, begleiten, dokumentieren
- Author
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Luzia Bürgi, Lucia Amberg, Luzia Bürgi, Lucia Amberg
- Published
- 2023
45. Purification of Human Cytoplasmic Actins From Saccharomyces cerevisiae
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Brian Haarer, David Amberg, and Jessica Henty-Ridilla
- Subjects
Biology (General) ,QH301-705.5 - Abstract
Eukaryotic cells rely on actin to support cellular structure, motility, transport, and a wide variety of other cytoplasmic functions and nuclear activities. Humans and other mammals express six closely related isoforms of actin, four of which are found primarily in skeletal, cardiac, and smooth muscle tissues. The final two isoforms, β and γ, are found in non-muscle cells. Due to the ease of purification, many biochemical studies surveying the functions of actin and its regulators have been carried out with protein purified from skeletal muscle. However, it has become increasingly clear that some activities are isoform specific, necessitating more accessible sources of non-muscle actin isoforms. Recent innovations permit the purification of non-muscle actins from human cell culture and heterologous systems, such as insect cell culture and the yeast Pichia pastoris. However, these systems generate mixtures of actin types or require additional steps to remove purification-related tags. We have developed strains of Saccharomyces cerevisiae (budding yeast) that express single untagged isoforms of either human non-muscle actin (β or γ) as their sole actin, allowing the purification of individual homogeneous actin isoforms by conventional purification techniques.Key features• Easy growth of yeast as a source of human cytoplasmic actin isoforms.• Uses well-established actin purification methods.• The tag-free system requires no post-purification processing.Graphical overviewIsolating human cytoplasmic actins from yeast
- Published
- 2023
- Full Text
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46. Transportation Sales Taxes in Los Angeles: Lessons from Forty Years of Experience
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Wachs, Martin, Amberg, Natalie L, and Marks, Jeremy S
- Subjects
California ,sales tax ,transportation ,finance ,transit - Abstract
This is the second study of voter-approved transportation sales taxes in Los Angeles County performed by the UCLA Institute of Transportation Studies with support from the Haynes Foundation. The earlier study examined the history of the four half cent sales taxes enacted by voters in Los Angeles County between 1980 and 2016. The current study looked in depth at four issues raised but not addressed in the first one. We report on the extent to which the “local return” provisions of the four measures fund transportation programs and projects in the cities and unincorporated areas of the county. We also explored tradeoffs between accountability to the voters through audits and taxpayer advisory committees in comparison with the county’s flexibility to change program elements through amendments when conditions change. Accountability to the voters was enhanced in the later sales tax measures but amendment procedures have been used to respond to changing needs in the county. We examined lawsuits brought against Metro regarding implementation of the sales taxes and found that there have been rather few. The COVID-19 pandemic struck while the study was underway and in response the report also explores the impacts of the pandemic on transportation sales tax revenues and program expenditures. The transportation sales taxes through the end of year 2020 have been the most important and resilient LA Metro funding sources during the pandemic. Sales tax revenue declined but far less than did federal and state sources of finance and revenues from fares paid by passengers.
- Published
- 2021
47. Beyond sense-specific processing: decoding texture in the brain from touch and sonified movement
- Author
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Landelle, C., Caron-Guyon, J., Nazarian, B., Anton, J.L., Sein, J., Pruvost, L., Amberg, M., Giraud, F., Félician, O., Danna, J., and Kavounoudias, A.
- Published
- 2023
- Full Text
- View/download PDF
48. Droplet leaping governs microstructured surface wetting
- Author
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Yada, Susumu, Bagheri, Shervin, Hansson, Jonas, Do-Quang, Minh, Lundell, Fredrik, van der Wijngaart, Wouter, and Amberg, Gustav
- Subjects
Physics - Fluid Dynamics ,Condensed Matter - Soft Condensed Matter - Abstract
Microstructured surfaces that control the direction of liquid transport are not only ubiquitous in nature, but they are also central to technological processes such as fog/water harvesting, oil-water separation, and surface lubrication. However, a fundamental understanding of the initial wetting dynamics of liquids spreading on such surfaces is lacking. Here, we show that three regimes govern microstructured surface wetting on short time scales: spread, stick, and contact line leaping. The latter involves establishing a new contact line downstream of the wetting front as the liquid leaps over specific sections of the solid surface. Experimental and numerical investigations reveal how different regimes emerge in different flow directions during wetting of periodic asymmetrically microstructured surfaces. These insights improve our understanding of rapid wetting in droplet impact, splashing, and wetting of vibrating surfaces and may contribute to advances in designing structured surfaces for the mentioned applications., Comment: 9 pages, 5 figures, under consideration for Soft Matter
- Published
- 2019
- Full Text
- View/download PDF
49. EGFR/Ras-induced CCL20 production modulates the tumour microenvironment
- Author
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Hippe, Andreas, Braun, Stephan Alexander, Oláh, Péter, Gerber, Peter Arne, Schorr, Anne, Seeliger, Stephan, Holtz, Stephanie, Jannasch, Katharina, Pivarcsi, Andor, Buhren, Bettina, Schrumpf, Holger, Kislat, Andreas, Bünemann, Erich, Steinhoff, Martin, Fischer, Jens, Lira, Sérgio A, Boukamp, Petra, Hevezi, Peter, Stoecklein, Nikolas Hendrik, Hoffmann, Thomas, Alves, Frauke, Sleeman, Jonathan, Bauer, Thomas, Klufa, Jörg, Amberg, Nicole, Sibilia, Maria, Zlotnik, Albert, Müller-Homey, Anja, and Homey, Bernhard
- Subjects
Biomedical and Clinical Sciences ,Oncology and Carcinogenesis ,Immunology ,Cancer ,2.1 Biological and endogenous factors ,Aetiology ,Animals ,Cells ,Cultured ,Chemokine CCL20 ,ErbB Receptors ,Extracellular Signal-Regulated MAP Kinases ,Humans ,Male ,Mice ,Mice ,Inbred C57BL ,Neoplasm Staging ,Neoplasms ,Neovascularization ,Pathologic ,Receptors ,CCR6 ,Signal Transduction ,Tumor Microenvironment ,ras Proteins ,Public Health and Health Services ,Oncology & Carcinogenesis ,Oncology and carcinogenesis - Abstract
BackgroundThe activation of the EGFR/Ras-signalling pathway in tumour cells induces a distinct chemokine repertoire, which in turn modulates the tumour microenvironment.MethodsThe effects of EGFR/Ras on the expression and translation of CCL20 were analysed in a large set of epithelial cancer cell lines and tumour tissues by RT-qPCR and ELISA in vitro. CCL20 production was verified by immunohistochemistry in different tumour tissues and correlated with clinical data. The effects of CCL20 on endothelial cell migration and tumour-associated vascularisation were comprehensively analysed with chemotaxis assays in vitro and in CCR6-deficient mice in vivo.ResultsTumours facilitate progression by the EGFR/Ras-induced production of CCL20. Expression of the chemokine CCL20 in tumours correlates with advanced tumour stage, increased lymph node metastasis and decreased survival in patients. Microvascular endothelial cells abundantly express the specific CCL20 receptor CCR6. CCR6 signalling in endothelial cells induces angiogenesis. CCR6-deficient mice show significantly decreased tumour growth and tumour-associated vascularisation. The observed phenotype is dependent on CCR6 deficiency in stromal cells but not within the immune system.ConclusionWe propose that the chemokine axis CCL20-CCR6 represents a novel and promising target to interfere with the tumour microenvironment, and opens an innovative multimodal strategy for cancer therapy.
- Published
- 2020
50. Desymmetrization of difluoromethylene groups by C-F bond activation.
- Author
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Butcher, Trevor, Yang, Jonathan, Amberg, Willi, Watkins, Nicholas, Wilkinson, Natalie, and Hartwig, John
- Subjects
Alkenes ,Carbon ,Catalysis ,Cations ,Fluorine ,Halogenation ,Hydrogen ,Iridium ,Organophosphorus Compounds ,Oxidation-Reduction ,Palladium - Abstract
Tertiary stereogenic centres containing one fluorine atom are valuable for medicinal chemistry because they mimic common tertiary stereogenic centres containing one hydrogen atom, but they possess distinct charge distribution, lipophilicity, conformation and metabolic stability1-3. Although tertiary stereogenic centres containing one hydrogen atom are often set by enantioselective desymmetrization reactions at one of the two carbon-hydrogen (C-H) bonds of a methylene group, tertiary stereocentres containing fluorine have not yet been constructed by the analogous desymmetrization reaction at one of the two carbon-fluorine (C-F) bonds of a difluoromethylene group3. Fluorine atoms are similar in size to hydrogen atoms but have distinct electronic properties, causing C-F bonds to be exceptionally strong and geminal C-F bonds to strengthen one another4. Thus, exhaustive defluorination typically dominates over the selective replacement of a single C-F bond, hindering the development of the enantioselective substitution of one fluorine atom to form a stereogenic centre5,6. Here we report the catalytic, enantioselective activation of a single C-F bond in an allylic difluoromethylene group to provide a broad range of products containing a monofluorinated tertiary stereogenic centre. By combining a tailored chiral iridium phosphoramidite catalyst, which controls regioselectivity, chemoselectivity and enantioselectivity, with a fluorophilic activator, which assists the oxidative addition of the C-F bond, these reactions occur in high yield and selectivity. The design principles proposed in this work extend to palladium-catalysed benzylic substitution, demonstrating the generality of the approach.
- Published
- 2020
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