@article{12913, abstract = {The coexistence of gate-tunable superconducting, magnetic and topological orders in magic-angle twisted bilayer graphene provides opportunities for the creation of hybrid Josephson junctions. Here we report the fabrication of gate-defined symmetry-broken Josephson junctions in magic-angle twisted bilayer graphene, where the weak link is gate-tuned close to the correlated insulator state with a moiré filling factor of υ = −2. We observe a phase-shifted and asymmetric Fraunhofer pattern with a pronounced magnetic hysteresis. Our theoretical calculations of the junction weak link—with valley polarization and orbital magnetization—explain most of these unconventional features. The effects persist up to the critical temperature of 3.5 K, with magnetic hysteresis observed below 800 mK. We show how the combination of magnetization and its current-induced magnetization switching allows us to realise a programmable zero-field superconducting diode. Our results represent a major advance towards the creation of future superconducting quantum electronic devices.}, author = {Díez-Mérida, J. and Díez-Carlón, A. and Yang, S. Y. and Xie, Y. M. and Gao, X. J. and Senior, Jorden L and Watanabe, K. and Taniguchi, T. and Lu, X. and Higginbotham, Andrew P and Law, K. T. and Efetov, Dmitri K.}, issn = {2041-1723}, journal = {Nature Communications}, publisher = {Springer Nature}, title = {{Symmetry-broken Josephson junctions and superconducting diodes in magic-angle twisted bilayer graphene}}, doi = {10.1038/s41467-023-38005-7}, volume = {14}, year = {2023}, } @article{12914, abstract = {We numerically study two methods of measuring tunneling times using a quantum clock. In the conventional method using the Larmor clock, we show that the Larmor tunneling time can be shorter for higher tunneling barriers. In the second method, we study the probability of a spin-flip of a particle when it is transmitted through a potential barrier including a spatially rotating field interacting with its spin. According to the adiabatic theorem, the probability depends on the velocity of the particle inside the barrier. It is numerically observed that the probability increases for higher barriers, which is consistent with the result obtained by the Larmor clock. By comparing outcomes for different initial spin states, we suggest that one of the main causes of the apparent decrease in the tunneling time can be the filtering effect occurring at the end of the barrier.}, author = {Suzuki, Fumika and Unruh, William G.}, issn = {2469-9934}, journal = {Physical Review A}, number = {4}, publisher = {American Physical Society}, title = {{Numerical quantum clock simulations for measuring tunneling times}}, doi = {10.1103/PhysRevA.107.042216}, volume = {107}, year = {2023}, } @article{12915, abstract = {Cu2–xS and Cu2–xSe have recently been reported as promising thermoelectric (TE) materials for medium-temperature applications. In contrast, Cu2–xTe, another member of the copper chalcogenide family, typically exhibits low Seebeck coefficients that limit its potential to achieve a superior thermoelectric figure of merit, zT, particularly in the low-temperature range where this material could be effective. To address this, we investigated the TE performance of Cu1.5–xTe–Cu2Se nanocomposites by consolidating surface-engineered Cu1.5Te nanocrystals. This surface engineering strategy allows for precise adjustment of Cu/Te ratios and results in a reversible phase transition at around 600 K in Cu1.5–xTe–Cu2Se nanocomposites, as systematically confirmed by in situ high-temperature X-ray diffraction combined with differential scanning calorimetry analysis. The phase transition leads to a conversion from metallic-like to semiconducting-like TE properties. Additionally, a layer of Cu2Se generated around Cu1.5–xTe nanoparticles effectively inhibits Cu1.5–xTe grain growth, minimizing thermal conductivity and decreasing hole concentration. These properties indicate that copper telluride based compounds have a promising thermoelectric potential, translated into a high dimensionless zT of 1.3 at 560 K.}, author = {Xing, Congcong and Zhang, Yu and Xiao, Ke and Han, Xu and Liu, Yu and Nan, Bingfei and Ramon, Maria Garcia and Lim, Khak Ho and Li, Junshan and Arbiol, Jordi and Poudel, Bed and Nozariasbmarz, Amin and Li, Wenjie and Ibáñez, Maria and Cabot, Andreu}, issn = {1936-086X}, journal = {ACS Nano}, number = {9}, pages = {8442--8452}, publisher = {American Chemical Society}, title = {{Thermoelectric performance of surface-engineered Cu1.5–xTe–Cu2Se nanocomposites}}, doi = {10.1021/acsnano.3c00495}, volume = {17}, year = {2023}, } @article{12916, abstract = {We apply a variant of the square-sieve to produce an upper bound for the number of rational points of bounded height on a family of surfaces that admit a fibration over P1 whose general fibre is a hyperelliptic curve. The implied constant does not depend on the coefficients of the polynomial defining the surface. }, author = {Bonolis, Dante and Browning, Timothy D}, issn = {2036-2145}, journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze}, number = {1}, pages = {173--204}, publisher = {Scuola Normale Superiore - Edizioni della Normale}, title = {{Uniform bounds for rational points on hyperelliptic fibrations}}, doi = {10.2422/2036-2145.202010_018}, volume = {24}, year = {2023}, } @article{12919, abstract = {We report the visible light photocatalytic cleavage of trityl thioethers or ethers under pH-neutral conditions. The method results in the formation of the respective symmetrical disulfides and alcohols in moderate to excellent yield. The protocol only requires the addition of a suitable photocatalyst and light rendering it orthogonal to several functionalities, including acid labile protective groups. The same conditions can be used to directly convert trityl-protected thiols into unsymmetrical disulfides or selenosulfides, and to cleave trityl resins in solid phase organic synthesis.}, author = {Murakami, Sho and Brudy, Cosima and Bachmann, Moritz and Takemoto, Yoshiji and Pieber, Bartholomäus}, issn = {1437-210X}, journal = {Synthesis}, keywords = {Organic Chemistry, Catalysis}, number = {09}, pages = {1367--1374}, publisher = {Georg Thieme Verlag}, title = {{Photocatalytic cleavage of trityl protected thiols and alcohols}}, doi = {10.1055/a-1979-5933}, volume = {55}, year = {2023}, } @article{12920, abstract = {The multicomponent approach allows to incorporate several functionalities into a single covalent organic framework (COF) and consequently allows the construction of bifunctional materials for cooperative catalysis. The well-defined structure of such multicomponent COFs is furthermore ideally suited for structure-activity relationship studies. We report a series of multicomponent COFs that contain acridine- and 2,2’-bipyridine linkers connected through 1,3,5-benzenetrialdehyde derivatives. The acridine motif is responsible for broad light absorption, while the bipyridine unit enables complexation of nickel catalysts. These features enable the usage of the framework materials as catalysts for light-mediated carbon−heteroatom cross-couplings. Variation of the node units shows that the catalytic activity correlates to the keto-enamine tautomer isomerism. This allows switching between high charge-carrier mobility and persistent, localized charge-separated species depending on the nodes, a tool to tailor the materials for specific reactions. Moreover, nickel-loaded COFs are recyclable and catalyze cross-couplings even using red light irradiation.}, author = {Traxler, Michael and Reischauer, Susanne and Vogl, Sarah and Roeser, Jérôme and Rabeah, Jabor and Penschke, Christopher and Saalfrank, Peter and Pieber, Bartholomäus and Thomas, Arne}, issn = {1521-3765}, journal = {Chemistry – A European Journal}, keywords = {General Chemistry, Catalysis, Organic Chemistry}, number = {4}, publisher = {Wiley}, title = {{Programmable photocatalytic activity of multicomponent covalent organic frameworks used as metallaphotocatalysts}}, doi = {10.1002/chem.202202967}, volume = {29}, year = {2023}, } @article{12921, abstract = {Visible-light photocatalysis provides numerous useful methodologies for synthetic organic chemistry. However, the mechanisms of these reactions are often not fully understood. Common mechanistic experiments mainly aim to characterize excited state properties of photocatalysts and their interaction with other species. Recently, in situ reaction monitoring using dedicated techniques was shown to be well-suited for the identification of intermediates and to obtain kinetic insights, thereby providing more holistic pictures of the reactions of interest. This minireview surveys these technologies and discusses selected examples where reaction monitoring was used to elucidate the mechanism of photocatalytic reactions.}, author = {Madani, Amiera and Pieber, Bartholomäus}, issn = {1867-3899}, journal = {ChemCatChem}, keywords = {Inorganic Chemistry, Organic Chemistry, Physical and Theoretical Chemistry, Catalysis}, number = {7}, publisher = {Wiley}, title = {{In situ reaction monitoring in photocatalytic organic synthesis}}, doi = {10.1002/cctc.202201583}, volume = {15}, year = {2023}, } @article{12922, abstract = {The influence of structural modifications on the catalytic activity of carbon materials is poorly understood. A collection of carbonaceous materials with different pore networks and high nitrogen content was characterized and used to catalyze four reactions to deduce structure–activity relationships. The CO2 cycloaddition and Knoevenagel reaction depend on Lewis basic sites (electron-rich nitrogen species). The absence of large conjugated carbon domains resulting from the introduction of large amounts of nitrogen in the carbon network is responsible for poor redox activity, as observed through the catalytic reduction of nitrobenzene with hydrazine and the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine using hydroperoxide. The material with the highest activity towards Lewis acid catalysis (in the hydrolysis of (dimethoxymethyl)benzene to benzaldehyde) is the most effective for small molecule activation and presents the highest concentration of electron-poor nitrogen species.}, author = {Lepre, Enrico and Rat, Sylvain and Cavedon, Cristian and Seeberger, Peter H. and Pieber, Bartholomäus and Antonietti, Markus and López‐Salas, Nieves}, issn = {1521-3773}, journal = {Angewandte Chemie International Edition}, keywords = {General Chemistry, Catalysis}, number = {2}, publisher = {Wiley}, title = {{Catalytic properties of high nitrogen content carbonaceous materials}}, doi = {10.1002/anie.202211663}, volume = {62}, year = {2023}, } @misc{12933, abstract = {Datasets of the publication "Sex-specific estimation of cis and trans regulation of gene expression in heads and gonads of Drosophila melanogaster".}, author = {Puixeu Sala, Gemma}, publisher = {Institute of Science and Technology Austria}, title = {{Data from: Sex-specific estimation of cis and trans regulation of gene expression in heads and gonads of Drosophila melanogaster}}, doi = {10.15479/AT:ISTA:12933}, year = {2023}, } @misc{12945, abstract = {basic data for use in code for experimental data analysis for manuscript under revision: Dynamic pathogen detection and social feedback shape collective hygiene in ants Casillas-Pérez B, Boďová K, Grasse AV, Tkačik G, Cremer S}, author = {Cremer, Sylvia}, keywords = {collective behavior, host-pathogen interactions, social immunity, epidemiology, social insects, probabilistic modeling}, publisher = {Institute of Science and Technology Austria}, title = {{Data from: "Dynamic pathogen detection and social feedback shape collective hygiene in ants" }}, doi = {10.15479/AT:ISTA:12945}, year = {2023}, } @misc{12949, abstract = {The classical infinitesimal model is a simple and robust model for the inheritance of quantitative traits. In this model, a quantitative trait is expressed as the sum of a genetic and a non-genetic (environmental) component and the genetic component of offspring traits within a family follows a normal distribution around the average of the parents’ trait values, and has a variance that is independent of the trait values of the parents. Although the trait distribution across the whole population can be far from normal, the trait distributions within families are normally distributed with a variance-covariance matrix that is determined entirely by that in the ancestral population and the probabilities of identity determined by the pedigree. Moreover, conditioning on some of the trait values within the pedigree has predictable effects on the mean and variance within and between families. In previous work, Barton et al. (2017), we showed that when trait values are determined by the sum of a large number of Mendelian factors, each of small effect, one can justify the infinitesimal model as limit of Mendelian inheritance. It was also shown that under some forms of epistasis, trait values within a family are still normally distributed.}, author = {Barton, Nicholas H}, keywords = {Quantitative genetics, infinitesimal model}, publisher = {Institute of Science and Technology Austria}, title = {{The infinitesimal model with dominance}}, doi = {10.15479/AT:ISTA:12949}, year = {2023}, } @article{12959, abstract = {This paper deals with the large-scale behaviour of dynamical optimal transport on Zd -periodic graphs with general lower semicontinuous and convex energy densities. Our main contribution is a homogenisation result that describes the effective behaviour of the discrete problems in terms of a continuous optimal transport problem. The effective energy density can be explicitly expressed in terms of a cell formula, which is a finite-dimensional convex programming problem that depends non-trivially on the local geometry of the discrete graph and the discrete energy density. Our homogenisation result is derived from a Γ -convergence result for action functionals on curves of measures, which we prove under very mild growth conditions on the energy density. We investigate the cell formula in several cases of interest, including finite-volume discretisations of the Wasserstein distance, where non-trivial limiting behaviour occurs.}, author = {Gladbach, Peter and Kopfer, Eva and Maas, Jan and Portinale, Lorenzo}, issn = {1432-0835}, journal = {Calculus of Variations and Partial Differential Equations}, number = {5}, publisher = {Springer Nature}, title = {{Homogenisation of dynamical optimal transport on periodic graphs}}, doi = {10.1007/s00526-023-02472-z}, volume = {62}, year = {2023}, } @article{12960, abstract = {Isomanifolds are the generalization of isosurfaces to arbitrary dimension and codimension, i.e., submanifolds of Rd defined as the zero set of some multivariate multivalued smooth function f:Rd→Rd−n, where n is the intrinsic dimension of the manifold. A natural way to approximate a smooth isomanifold M=f−1(0) is to consider its piecewise linear (PL) approximation M^ based on a triangulation T of the ambient space Rd. In this paper, we describe a simple algorithm to trace isomanifolds from a given starting point. The algorithm works for arbitrary dimensions n and d, and any precision D. Our main result is that, when f (or M) has bounded complexity, the complexity of the algorithm is polynomial in d and δ=1/D (and unavoidably exponential in n). Since it is known that for δ=Ω(d2.5), M^ is O(D2)-close and isotopic to M , our algorithm produces a faithful PL-approximation of isomanifolds of bounded complexity in time polynomial in d. Combining this algorithm with dimensionality reduction techniques, the dependency on d in the size of M^ can be completely removed with high probability. We also show that the algorithm can handle isomanifolds with boundary and, more generally, isostratifolds. The algorithm for isomanifolds with boundary has been implemented and experimental results are reported, showing that it is practical and can handle cases that are far ahead of the state-of-the-art. }, author = {Boissonnat, Jean Daniel and Kachanovich, Siargey and Wintraecken, Mathijs}, issn = {1095-7111}, journal = {SIAM Journal on Computing}, number = {2}, pages = {452--486}, publisher = {Society for Industrial and Applied Mathematics}, title = {{Tracing isomanifolds in Rd in time polynomial in d using Coxeter–Freudenthal–Kuhn triangulations}}, doi = {10.1137/21M1412918}, volume = {52}, year = {2023}, } @article{12961, abstract = {Two notes separated by a doubling in frequency sound similar to humans. This “octave equivalence” is critical to perception and production of music and speech and occurs early in human development. Because it also occurs cross-culturally, a biological basis of octave equivalence has been hypothesized. Members of our team previousy suggested four human traits are at the root of this phenomenon: (1) vocal learning, (2) clear octave information in vocal harmonics, (3) differing vocal ranges, and (4) vocalizing together. Using cross-species studies, we can test how relevant these respective traits are, while controlling for enculturation effects and addressing questions of phylogeny. Common marmosets possess forms of three of the four traits, lacking differing vocal ranges. We tested 11 common marmosets by adapting an established head-turning paradigm, creating a parallel test to an important infant study. Unlike human infants, marmosets responded similarly to tones shifted by an octave or other intervals. Because previous studies with the same head-turning paradigm produced differential results to discernable acoustic stimuli in common marmosets, our results suggest that marmosets do not perceive octave equivalence. Our work suggests differing vocal ranges between adults and children and men and women and the way they are used in singing together may be critical to the development of octave equivalence.}, author = {Wagner, Bernhard and Šlipogor, Vedrana and Oh, Jinook and Varga, Marion and Hoeschele, Marisa}, issn = {1467-7687}, journal = {Developmental Science}, number = {5}, publisher = {Wiley}, title = {{A comparison between common marmosets (Callithrix jacchus) and human infants sheds light on traits proposed to be at the root of human octave equivalence}}, doi = {10.1111/desc.13395}, volume = {26}, year = {2023}, } @phdthesis{12964, abstract = {Pattern formation is of great importance for its contribution across different biological behaviours. During developmental processes for example, patterns of chemical gradients are established to determine cell fate and complex tissue patterns emerge to define structures such as limbs and vascular networks. Patterns are also seen in collectively migrating groups, for instance traveling waves of density emerging in moving animal flocks as well as collectively migrating cells and tissues. To what extent these biological patterns arise spontaneously through the local interaction of individual constituents or are dictated by higher level instructions is still an open question however there is evidence for the involvement of both types of process. Where patterns arise spontaneously there is a long standing interest in how far the interplay of mechanics, e.g. force generation and deformation, and chemistry, e.g. gene regulation and signaling, contributes to the behaviour. This is because many systems are able to both chemically regulate mechanical force production and chemically sense mechanical deformation, forming mechano-chemical feedback loops which can potentially become unstable towards spatio and/or temporal patterning. We work with experimental collaborators to investigate the possibility that this type of interaction drives pattern formation in biological systems at different scales. We focus first on tissue-level ERK-density waves observed during the wound healing response across different systems where many previous studies have proposed that patterns depend on polarized cell migration and arise from a mechanical flocking-like mechanism. By combining theory with mechanical and optogenetic perturbation experiments on in vitro monolayers we instead find evidence for mechanochemical pattern formation involving only scalar bilateral feedbacks between ERK signaling and cell contraction. We perform further modeling and experiment to study how this instability couples with polar cell migration in order to produce a robust and efficient wound healing response. In a following chapter we implement ERK-density coupling and cell migration in a 2D active vertex model to investigate the interaction of ERK-density patterning with different tissue rheologies and find that the spatio-temporal dynamics are able to both locally and globally fluidize a tissue across the solid-fluid glass transition. In a last chapter we move towards lower spatial scales in the context of subcellular patterning of the cell cytoskeleton where we investigate the transition between phases of spatially homogeneous temporal oscillations and chaotic spatio-temporal patterning in the dynamics of myosin and ROCK activities (a motor component of the actomyosin cytoskeleton and its activator). Experimental evidence supports an intrinsic chemical oscillator which we encode in a reaction model and couple to a contractile active gel description of the cell cortex. The model exhibits phases of chemical oscillations and contractile spatial patterning which reproduce many features of the dynamics seen in Drosophila oocyte epithelia in vivo. However, additional pharmacological perturbations to inhibit myosin contractility leaves the role of contractile instability unclear. We discuss alternative hypotheses and investigate the possibility of reaction-diffusion instability.}, author = {Boocock, Daniel R}, isbn = {978-3-99078-032-9}, issn = {2663-337X}, pages = {146}, publisher = {Institute of Science and Technology Austria}, title = {{Mechanochemical pattern formation across biological scales}}, doi = {10.15479/at:ista:12964}, year = {2023}, } @article{12972, abstract = {Embroidery is a long-standing and high-quality approach to making logos and images on textiles. Nowadays, it can also be performed via automated machines that weave threads with high spatial accuracy. A characteristic feature of the appearance of the threads is a high degree of anisotropy. The anisotropic behavior is caused by depositing thin but long strings of thread. As a result, the stitched patterns convey both color and direction. Artists leverage this anisotropic behavior to enhance pure color images with textures, illusions of motion, or depth cues. However, designing colorful embroidery patterns with prescribed directionality is a challenging task, one usually requiring an expert designer. In this work, we propose an interactive algorithm that generates machine-fabricable embroidery patterns from multi-chromatic images equipped with user-specified directionality fields.We cast the problem of finding a stitching pattern into vector theory. To find a suitable stitching pattern, we extract sources and sinks from the divergence field of the vector field extracted from the input and use them to trace streamlines. We further optimize the streamlines to guarantee a smooth and connected stitching pattern. The generated patterns approximate the color distribution constrained by the directionality field. To allow for further artistic control, the trade-off between color match and directionality match can be interactively explored via an intuitive slider. We showcase our approach by fabricating several embroidery paths.}, author = {Liu, Zhenyuan and Piovarci, Michael and Hafner, Christian and Charrondiere, Raphael and Bickel, Bernd}, issn = {1467-8659}, journal = {Computer Graphics Forum}, keywords = {embroidery, design, directionality, density, image}, location = {Saarbrucken, Germany}, number = {2}, pages = {397--409}, publisher = {Wiley}, title = {{Directionality-aware design of embroidery patterns}}, doi = {10.1111/cgf.14770 }, volume = {42}, year = {2023}, } @inproceedings{12976, abstract = {3D printing based on continuous deposition of materials, such as filament-based 3D printing, has seen widespread adoption thanks to its versatility in working with a wide range of materials. An important shortcoming of this type of technology is its limited multi-material capabilities. While there are simple hardware designs that enable multi-material printing in principle, the required software is heavily underdeveloped. A typical hardware design fuses together individual materials fed into a single chamber from multiple inlets before they are deposited. This design, however, introduces a time delay between the intended material mixture and its actual deposition. In this work, inspired by diverse path planning research in robotics, we show that this mechanical challenge can be addressed via improved printer control. We propose to formulate the search for optimal multi-material printing policies in a reinforcement learning setup. We put forward a simple numerical deposition model that takes into account the non-linear material mixing and delayed material deposition. To validate our system we focus on color fabrication, a problem known for its strict requirements for varying material mixtures at a high spatial frequency. We demonstrate that our learned control policy outperforms state-of-the-art hand-crafted algorithms.}, author = {Liao, Kang and Tricard, Thibault and Piovarci, Michael and Seidel, Hans-Peter and Babaei, Vahid}, booktitle = {2023 IEEE International Conference on Robotics and Automation}, issn = {1050-4729}, keywords = {reinforcement learning, deposition, control, color, multi-filament}, location = {London, United Kingdom}, pages = {12345--12352}, publisher = {IEEE}, title = {{Learning deposition policies for fused multi-material 3D printing}}, doi = {10.1109/ICRA48891.2023.10160465}, volume = {2023}, year = {2023}, } @inproceedings{12979, abstract = {Color and gloss are fundamental aspects of surface appearance. State-of-the-art fabrication techniques can manipulate both properties of the printed 3D objects. However, in the context of appearance reproduction, perceptual aspects of color and gloss are usually handled separately, even though previous perceptual studies suggest their interaction. Our work is motivated by previous studies demonstrating a perceived color shift due to a change in the object's gloss, i.e., two samples with the same color but different surface gloss appear as they have different colors. In this paper, we conduct new experiments which support this observation and provide insights into the magnitude and direction of the perceived color change. We use the observations as guidance to design a new method that estimates and corrects the color shift enabling the fabrication of objects with the same perceived color but different surface gloss. We formulate the problem as an optimization procedure solved using differentiable rendering. We evaluate the effectiveness of our method in perceptual experiments with 3D objects fabricated using a multi-material 3D printer and demonstrate potential applications. }, author = {Condor, Jorge and Piovarci, Michael and Bickel, Bernd and Didyk, Piotr}, booktitle = {SIGGRAPH ’23 Conference Proceedings}, isbn = {9798400701597}, keywords = {color, gloss, perception, color compensation, color management}, location = {Los Angeles, CA, United States}, publisher = {Association for Computing Machinery}, title = {{Gloss-aware color correction for 3D printing}}, doi = {10.1145/3588432.3591546}, year = {2023}, } @article{12984, abstract = {Tattoos are a highly popular medium, with both artistic and medical applications. Although the mechanical process of tattoo application has evolved historically, the results are reliant on the artisanal skill of the artist. This can be especially challenging for some skin tones, or in cases where artists lack experience. We provide the first systematic overview of tattooing as a computational fabrication technique. We built an automated tattooing rig and a recipe for the creation of silicone sheets mimicking realistic skin tones, which allowed us to create an accurate model predicting tattoo appearance. This enables several exciting applications including tattoo previewing, color retargeting, novel ink spectra optimization, color-accurate prosthetics, and more.}, author = {Piovarci, Michael and Chapiro, Alexandre and Bickel, Bernd}, issn = {1557-7368}, journal = {Transactions on Graphics}, keywords = {appearance, modeling, reproduction, tattoo, skin color, gamut mapping, ink-optimization, prosthetic}, location = {Los Angeles, CA, United States}, number = {4}, publisher = {Association for Computing Machinery}, title = {{Skin-Screen: A computational fabrication framework for color tattoos}}, doi = {10.1145/3592432}, volume = {42}, year = {2023}, } @article{13033, abstract = {Current methods for assessing cell proliferation in 3D scaffolds rely on changes in metabolic activity or total DNA, however, direct quantification of cell number in 3D scaffolds remains a challenge. To address this issue, we developed an unbiased stereology approach that uses systematic-random sampling and thin focal-plane optical sectioning of the scaffolds followed by estimation of total cell number (StereoCount). This approach was validated against an indirect method for measuring the total DNA (DNA content); and the Bürker counting chamber, the current reference method for quantifying cell number. We assessed the total cell number for cell seeding density (cells per unit volume) across four values and compared the methods in terms of accuracy, ease-of-use and time demands. The accuracy of StereoCount markedly outperformed the DNA content for cases with ~ 10,000 and ~ 125,000 cells/scaffold. For cases with ~ 250,000 and ~ 375,000 cells/scaffold both StereoCount and DNA content showed lower accuracy than the Bürker but did not differ from each other. In terms of ease-of-use, there was a strong advantage for the StereoCount due to output in terms of absolute cell numbers along with the possibility for an overview of cell distribution and future use of automation for high throughput analysis. Taking together, the StereoCount method is an efficient approach for direct cell quantification in 3D collagen scaffolds. Its major benefit is that automated StereoCount could accelerate research using 3D scaffolds focused on drug discovery for a wide variety of human diseases.}, author = {Zavadakova, Anna and Vistejnova, Lucie and Belinova, Tereza and Tichanek, Filip and Bilikova, Dagmar and Mouton, Peter R.}, issn = {2045-2322}, journal = {Scientific Reports}, keywords = {Multidisciplinary}, number = {1}, publisher = {Springer Nature}, title = {{Novel stereological method for estimation of cell counts in 3D collagen scaffolds}}, doi = {10.1038/s41598-023-35162-z}, volume = {13}, year = {2023}, }