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Beyond the perturbative description of the nonlinear optical response of low-index materials
Full text linkWe show that standard approximations in nonlinear optics are violated for situations involving a small value of the linear refractive index. Consequently, the conventional equation for the intensity-dependent refractive index, n(I)=n₀+n₂I, becomes inapplicable in epsilon-near-zero and low-index media, even in the presence of only third-order effects. For the particular case of indium tin oxide, we find that the χ(³), χ(⁵) and χ(⁷) contributions to refraction eclipse the linear term; thus, the nonlinear response can no longer be interpreted as a perturbation in these materials. Although the response is non-perturbative, we find no evidence that the power series expansion of the material polarization diverges
Influence of dwell time and temperature on the measured gloss of printed UV-inks containing aluminum pigments
Full text linkThis study investigates the relationship between measured gloss and the microstructure of printed UV-inks containing aluminum pigments. Using a laboratory flexo printing machine, UV-inks containing leafing-type vacuum metallized pigments were printed onto Chromolux paper and primed MultiArt Gloss paper. The time between printing and curing of the ink (dwell time) was varied between the experimental runs. For some samples, hot air was applied onto the uncured UV-ink during the dwell time. The influence of heat (hot air) and dwell time on gloss and the topography of the pigment layer as well as the influence of the substrate was investigated. Roughness and waviness data were obtained using a confocal microscope (Sensofar PLu Neox), gloss measurements were obtained using an IQ-S gloss meter. It was shown that a longer dwell time as well as hot air has a positive influence on the specular gloss measured on the metallic ink printed on Chromolux paper. Also, good correlations could be found between specular gloss, roughness, and waviness, respectively. For primed Multi Art Gloss paper, however, a longer dwell time and hot air can have a negative influence on specular gloss. Also, correlations between roughness, waviness and specular gloss are not as strong as for Chromolux paper
Facetten der Aufklärungsforschung
Full text linkRezension zu:
Wolloch, Nathaniel (2022): Moderate and Radical Liberalism: The Enlightenment Sources of Liberal Thought. Leiden: Brill. 982 Seiten. £ 167.00
Loughlin, Felicity, und Alexandre Johnston (Hrsg.) (2020): Antiquity and Enlightenment Culture. New Approaches and Perspectives. Leiden: Brill. 247 Seiten. 119.0
αILP: thinking visual scenes as differentiable logic programs
No full textDeep neural learning has shown remarkable performance at learning representations for visual object categorization. However, deep neural networks such as CNNs do not explicitly encode objects and relations among them. This limits their success on tasks that require a deep logical understanding of visual scenes, such as Kandinsky patterns and Bongard problems. To overcome these limitations, we introduce αILP, a novel differentiable inductive logic programming framework that learns to represent scenes as logic programs—intuitively, logical atoms correspond to objects, attributes, and relations, and clauses encode high-level scene information. αILP has an end-to-end reasoning architecture from visual inputs. Using it, αILP performs differentiable inductive logic programming on complex visual scenes, i.e., the logical rules are learned by gradient descent. Our extensive experiments on Kandinsky patterns and CLEVR-Hans benchmarks demonstrate the accuracy and efficiency of αILP in learning complex visual-logical concepts
Organic form and evolution: the morphological problem in twentieth-century italian biology
Full text linkThis paper examines the efforts in evolution research to understand form’s structure that developed in Italy during the first half of the twentieth century. In particular, it analyzes how the organic approach in biology and the study of organic form merged in the morphological research agendas of Giuseppe Colosi (1892–1975) and Giuseppe Levi (1872–1965). These biologists sought to understand form’s inner composition and structure. First, I will briefly outline the morphological practices and frameworks used to study form changes and structures in the early twentieth century. Second, I will discuss what the Italian biologist Antonio Pensa (1874–1970) called the morphological problem. Third, I will examine Colosi’s response to the morphological problem. Fourth, I will analyze Levi’s morphological research program. As a result, this paper paves the way for a more nuanced and varied picture of the so-called "organicism movement" in the first half of the twentieth century by calling attention to morphology as practiced in Italian-speaking biology. In fact, alongside dialectical materialism and holistic biology, two of the main strands within organicism, the architectural approach to evolution as practiced in Italy and elsewhere had a profound impact on twentieth- and twenty-first-century organicism specifically and on evolutionary biology generally
Deep learning study of induced stochastic pattern formation in the gravure printing fluid splitting process
No full textWe use deep learning (DL) algorithms for the phenomenological classification of Saffman-Taylor-instability-driven spontaneous pattern formation at the liquid meniscus in the fluid splitting in a gravure printing press. The DL algorithms are applied to high-speed video recordings of the fluid splitting process between the rotating gravure cylinder and the co-moving planar target substrate. Depending on rotation velocity or printing velocity and gravure raster of the engraved printing cylinder, a variety of transient liquid wetting patterns, e.g., a raster of separate drops, viscous fingers, or more complex, branched liquid bridges appear in the printing nip. We discuss how these patterns are classified with DL methods, and how this could serve the identification of different hydrodynamic flow regimes in the nip, e.g., point or lamella splitting
Fluid–Rock Interactions in Geothermal Reservoirs, Germany: Thermal Autoclave Experiments Using Sandstones and Natural Hydrothermal Brines
No full textAs renewable energy, geothermal can contribute substantially to the energy transition. To generate electricity or to harvest heat, high-saline fluids are tapped by wells of a few kilometres and extracted from hydrothermal reservoirs. After the heat exchanger units have been passed by, these fluids are reinjected into the reservoir. Due to the pressure and temperature differences between the subsurface and the surface, as well as the cooling of the fluids in the power plant, unwanted chemical reactions can occur within the reservoir, in the borehole, and within the power plant itself. This can reduce the permeability of the reservoir as well as the output of the geothermal power plant. This study aims to simulate real subsurface reactions using batch and leaching experiments with sandstone or sandstone powder as solid phase, and deionised water or natural brine as liquid phase. It is demonstrated that fluid composition changes after only a few days. In particular, calcite, aragonite, clay minerals, and zinc phases precipitate from the natural brine. In contrast, in particular minerals containing potassium, arsenic, barium, and silica are dissolved. Due to the experimental set-up, these mineral reactions mainly took place on the surface of the samples, which is why no substantial changes in petrophysical properties could be observed. However, it is assumed that the observed reactions on the reservoir scale have a relevant influence on parameters such as permeability
Novel Aspects in Pattern Formation Arise from Coupling Turing Reaction–Diffusion and Chemotaxis
No full textRecent experimental studies on primary hair follicle formation and feather bud morphogenesis indicate a coupling between Turing-type diffusion driven instability and chemotactic patterning. Inspired by these findings we develop and analyse a mathematical model that couples chemotaxis to a reaction–diffusion system exhibiting diffusion–driven (Turing) instability. While both systems, reaction–diffusion systems and chemotaxis, can independently generate spatial patterns, we were interested in how the coupling impacts the stability of the system, parameter region for patterning, pattern geometry, as well as the dynamics of pattern formation. We conduct a classical linear stability analysis for different model structures, and confirm our results by numerical analysis of the system. Our results show that the coupling generally increases the robustness of the patterning process by enlarging the pattern region in the parameter space. Concerning time scale and pattern regularity, we find that an increase in the chemosensitivity can speed up the patterning process for parameters inside and outside of the Turing space, but generally reduces spatial regularity of the pattern. Interestingly, our analysis indicates that pattern formation can also occur when neither the Turing nor the chemotaxis system can independently generate pattern. On the other hand, for some parameter settings, the coupling of the two processes can extinguish the pattern formation, rather than reinforce it. These theoretical findings can be used to corroborate the biological findings on morphogenesis and guide future experimental studies. From a mathematical point of view, this work sheds a light on coupling classical pattern formation systems from the parameter space perspective
Transkriptionspraktiken in der Kunstkommunikation : Wie man sprachlich an Bilder anknüpft
Full text linkThe article explores the expressions and purposes of linguistic transcription methods in the realm of art communication, taking a linguistic approach. Within the discourse surrounding artworks, a crucial linguistic practice is description. Description can be understood as a purposeful process of translation from one form of sign to another, grounded in the semiotic principle of transcriptivity, as proposed by Jäger (2010). Descriptions of art consistently draw from prior discourses, utilizing them to guide the conceptualisation of visual experiences within the framework of language. They encompass a wide range, from narrative and argumentative discourse within the institutional context of art history to the quest for meaning during conversations in front of artworks, to the multi-modal appropriation of art within the sphere of social media. After theoretical clarifications, the article gives examples of analysis from different domains of art communication. The first concerns the scholarly description of images in art. The second example analysis is devoted to spontaneous oral descriptions of a self-portrait by Frida Kahlo, which were produced as part of a teaching project, and the third case deals with art communication on Twitter/X
Potential benefits of using radioactive ion beams for range margin reduction in carbon ion therapy
Full text linkSharp dose gradients and high biological effectiveness make ions such as ¹²C an ideal tool to treat deep-seated tumors, however, at the same time, sensitive to errors in the range prediction. Tumor safety margins mitigate these uncertainties, but during the irradiation they lead to unavoidable damage to the surrounding healthy tissue. To fully exploit the Bragg peak benefits, a large effort is put into establishing precise range verification methods. Despite positron emission tomography being widely in use for this purpose in ¹²C therapy, the low count rates, biological washout, and broad activity distribution still limit its precision. Instead, radioactive beams used directly for treatment would yield an improved signal and a closer match with the dose fall-off, potentially enabling precise in vivo beam range monitoring. We have performed a treatment planning study to estimate the possible impact of the reduced range uncertainties, enabled by radioactive ¹¹C ions treatments, on sparing critical organs in tumor proximity. Compared to ¹²C treatments, (i) annihilation maps for ¹¹C ions can reflect sub- millimeter shifts in dose distributions in the patient, (ii) outcomes of treatment planning with ¹¹C significantly improve and (iii) less severe toxicities for serial and parallel critical organs can be expected