@article{7428, abstract = {In the superconducting regime of FeTe(1−x)Sex, there exist two types of vortices which are distinguished by the presence or absence of zero-energy states in their core. To understand their origin, we examine the interplay of Zeeman coupling and superconducting pairings in three-dimensional metals with band inversion. Weak Zeeman fields are found to suppress intraorbital spin-singlet pairing, known to localize the states at the ends of the vortices on the surface. On the other hand, an orbital-triplet pairing is shown to be stable against Zeeman interactions, but leads to delocalized zero-energy Majorana modes which extend through the vortex. In contrast, the finite-energy vortex modes remain localized at the vortex ends even when the pairing is of orbital-triplet form. Phenomenologically, this manifests as an observed disappearance of zero-bias peaks within the cores of topological vortices upon an increase of the applied magnetic field. The presence of magnetic impurities in FeTe(1−x)Sex, which are attracted to the vortices, would lead to such Zeeman-induced delocalization of Majorana modes in a fraction of vortices that capture a large enough number of magnetic impurities. Our results provide an explanation for the dichotomy between topological and nontopological vortices recently observed in FeTe(1−x)Sex.}, author = {Ghazaryan, Areg and Lopes, P. L.S. and Hosur, Pavan and Gilbert, Matthew J. and Ghaemi, Pouyan}, issn = {24699969}, journal = {Physical Review B}, number = {2}, publisher = {American Physical Society}, title = {{Effect of Zeeman coupling on the Majorana vortex modes in iron-based topological superconductors}}, doi = {10.1103/PhysRevB.101.020504}, volume = {101}, year = {2020}, } @article{8319, abstract = {We demonstrate that releasing atoms into free space from an optical lattice does not deteriorate cavity-generated spin squeezing for metrological purposes. In this work, an ensemble of 500000 spin-squeezed atoms in a high-finesse optical cavity with near-uniform atom-cavity coupling is prepared, released into free space, recaptured in the cavity, and probed. Up to ∼10 dB of metrologically relevant squeezing is retrieved for 700μs free-fall times, and decaying levels of squeezing are realized for up to 3 ms free-fall times. The degradation of squeezing results from loss of atom-cavity coupling homogeneity between the initial squeezed state generation and final collective state readout. A theoretical model is developed to quantify this degradation and this model is experimentally validated.}, author = {Wu, Yunfan and Krishnakumar, Rajiv and Martínez-Rincón, Julián and Malia, Benjamin K. and Hosten, Onur and Kasevich, Mark A.}, issn = {24699934}, journal = {Physical Review A}, number = {1}, publisher = {American Physical Society}, title = {{Retrieval of cavity-generated atomic spin squeezing after free-space release}}, doi = {10.1103/PhysRevA.102.012224}, volume = {102}, year = {2020}, } @article{8766, abstract = {The “procedural” approach to animating ocean waves is the dominant algorithm for animating larger bodies of water in interactive applications as well as in off-line productions — it provides high visual quality with a low computational demand. In this paper, we widen the applicability of procedural water wave animation with an extension that guarantees the satisfaction of boundary conditions imposed by terrain while still approximating physical wave behavior. In combination with a particle system that models wave breaking, foam, and spray, this allows us to naturally model waves interacting with beaches and rocks. Our system is able to animate waves at large scales at interactive frame rates on a commodity PC.}, author = {Jeschke, Stefan and Hafner, Christian and Chentanez, Nuttapong and Macklin, Miles and Müller-Fischer, Matthias and Wojtan, Christopher J}, journal = {Computer Graphics forum}, location = {Online Symposium}, number = {8}, pages = {47--54}, publisher = {Wiley}, title = {{Making procedural water waves boundary-aware}}, doi = {10.1111/cgf.14100}, volume = {39}, year = {2020}, } @article{15055, abstract = {Markov decision processes (MDPs) are the defacto framework for sequential decision making in the presence of stochastic uncertainty. A classical optimization criterion for MDPs is to maximize the expected discounted-sum payoff, which ignores low probability catastrophic events with highly negative impact on the system. On the other hand, risk-averse policies require the probability of undesirable events to be below a given threshold, but they do not account for optimization of the expected payoff. We consider MDPs with discounted-sum payoff with failure states which represent catastrophic outcomes. The objective of risk-constrained planning is to maximize the expected discounted-sum payoff among risk-averse policies that ensure the probability to encounter a failure state is below a desired threshold. Our main contribution is an efficient risk-constrained planning algorithm that combines UCT-like search with a predictor learned through interaction with the MDP (in the style of AlphaZero) and with a risk-constrained action selection via linear programming. We demonstrate the effectiveness of our approach with experiments on classical MDPs from the literature, including benchmarks with an order of 106 states.}, author = {Brázdil, Tomáš and Chatterjee, Krishnendu and Novotný, Petr and Vahala, Jiří}, issn = {2374-3468}, journal = {Proceedings of the 34th AAAI Conference on Artificial Intelligence}, keywords = {General Medicine}, location = {New York, NY, United States}, number = {06}, pages = {9794--9801}, publisher = {Association for the Advancement of Artificial Intelligence}, title = {{Reinforcement learning of risk-constrained policies in Markov decision processes}}, doi = {10.1609/aaai.v34i06.6531}, volume = {34}, year = {2020}, } @article{15057, abstract = {Vaccinia virus–related kinase (VRK) is an evolutionarily conserved nuclear protein kinase. VRK-1, the single Caenorhabditis elegans VRK ortholog, functions in cell division and germline proliferation. However, the role of VRK-1 in postmitotic cells and adult life span remains unknown. Here, we show that VRK-1 increases organismal longevity by activating the cellular energy sensor, AMP-activated protein kinase (AMPK), via direct phosphorylation. We found that overexpression of vrk-1 in the soma of adult C. elegans increased life span and, conversely, inhibition of vrk-1 decreased life span. In addition, vrk-1 was required for longevity conferred by mutations that inhibit C. elegans mitochondrial respiration, which requires AMPK. VRK-1 directly phosphorylated and up-regulated AMPK in both C. elegans and cultured human cells. Thus, our data show that the somatic nuclear kinase, VRK-1, promotes longevity through AMPK activation, and this function appears to be conserved between C. elegans and humans.}, author = {Park, Sangsoon and Artan, Murat and Han, Seung Hyun and Park, Hae-Eun H. and Jung, Yoonji and Hwang, Ara B. and Shin, Won Sik and Kim, Kyong-Tai and Lee, Seung-Jae V.}, issn = {2375-2548}, journal = {Science Advances}, number = {27}, publisher = {American Association for the Advancement of Science}, title = {{VRK-1 extends life span by activation of AMPK via phosphorylation}}, doi = {10.1126/sciadv.aaw7824}, volume = {6}, year = {2020}, } @article{15061, abstract = {The actin cytoskeleton, a dynamic network of actin filaments and associated F-actin–binding proteins, is fundamentally important in eukaryotes. α-Actinins are major F-actin bundlers that are inhibited by Ca2+ in nonmuscle cells. Here we report the mechanism of Ca2+-mediated regulation of Entamoeba histolytica α-actinin-2 (EhActn2) with features expected for the common ancestor of Entamoeba and higher eukaryotic α-actinins. Crystal structures of Ca2+-free and Ca2+-bound EhActn2 reveal a calmodulin-like domain (CaMD) uniquely inserted within the rod domain. Integrative studies reveal an exceptionally high affinity of the EhActn2 CaMD for Ca2+, binding of which can only be regulated in the presence of physiological concentrations of Mg2+. Ca2+ binding triggers an increase in protein multidomain rigidity, reducing conformational flexibility of F-actin–binding domains via interdomain cross-talk and consequently inhibiting F-actin bundling. In vivo studies uncover that EhActn2 plays an important role in phagocytic cup formation and might constitute a new drug target for amoebic dysentery.}, author = {Pinotsis, Nikos and Zielinska, Karolina and Babuta, Mrigya and Arolas, Joan L. and Kostan, Julius and Khan, Muhammad Bashir and Schreiner, Claudia and Testa Salmazo, Anita P and Ciccarelli, Luciano and Puchinger, Martin and Gkougkoulia, Eirini A. and Ribeiro, Euripedes de Almeida and Marlovits, Thomas C. and Bhattacharya, Alok and Djinovic-Carugo, Kristina}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences}, number = {36}, pages = {22101--22112}, publisher = {Proceedings of the National Academy of Sciences}, title = {{Calcium modulates the domain flexibility and function of an α-actinin similar to the ancestral α-actinin}}, doi = {10.1073/pnas.1917269117}, volume = {117}, year = {2020}, } @article{15064, abstract = {We call a continuous self-map that reveals itself through a discrete set of point-value pairs a sampled dynamical system. Capturing the available information with chain maps on Delaunay complexes, we use persistent homology to quantify the evidence of recurrent behavior. We establish a sampling theorem to recover the eigenspaces of the endomorphism on homology induced by the self-map. Using a combinatorial gradient flow arising from the discrete Morse theory for Čech and Delaunay complexes, we construct a chain map to transform the problem from the natural but expensive Čech complexes to the computationally efficient Delaunay triangulations. The fast chain map algorithm has applications beyond dynamical systems.}, author = {Bauer, U. and Edelsbrunner, Herbert and Jablonski, Grzegorz and Mrozek, M.}, issn = {2367-1734}, journal = {Journal of Applied and Computational Topology}, number = {4}, pages = {455--480}, publisher = {Springer Nature}, title = {{Čech-Delaunay gradient flow and homology inference for self-maps}}, doi = {10.1007/s41468-020-00058-8}, volume = {4}, year = {2020}, } @article{15063, abstract = {We consider the least singular value of a large random matrix with real or complex i.i.d. Gaussian entries shifted by a constant z∈C. We prove an optimal lower tail estimate on this singular value in the critical regime where z is around the spectral edge, thus improving the classical bound of Sankar, Spielman and Teng (SIAM J. Matrix Anal. Appl. 28:2 (2006), 446–476) for the particular shift-perturbation in the edge regime. Lacking Brézin–Hikami formulas in the real case, we rely on the superbosonization formula (Comm. Math. Phys. 283:2 (2008), 343–395).}, author = {Cipolloni, Giorgio and Erdös, László and Schröder, Dominik J}, issn = {2690-1005}, journal = {Probability and Mathematical Physics}, keywords = {General Medicine}, number = {1}, pages = {101--146}, publisher = {Mathematical Sciences Publishers}, title = {{Optimal lower bound on the least singular value of the shifted Ginibre ensemble}}, doi = {10.2140/pmp.2020.1.101}, volume = {1}, year = {2020}, } @inproceedings{15059, abstract = {In this paper we present a room temperature radiometer that can eliminate the need of using cryostats in satellite payload reducing its weight and improving reliability. The proposed radiometer is based on an electro-optic upconverter that boosts up microwave photons energy by upconverting them into an optical domain what makes them immune to thermal noise even if operating at room temperature. The converter uses a high-quality factor whispering gallery mode (WGM) resonator providing naturally narrow bandwidth and therefore might be useful for applications like microwave hyperspectral sensing. The upconversion process is explained by providing essential information about photon conversion efficiency and sensitivity. To prove the concept, we describe an experiment which shows state-of-the-art photon conversion efficiency n=10-5 per mW of pump power at the frequency of 80 GHz.}, author = {Wasiak, Michal and Botello, Gabriel Santamaria and Abdalmalak, Kerlos Atia and Sedlmeir, Florian and Rueda Sanchez, Alfredo R and Segovia-Vargas, Daniel and Schwefel, Harald G. L. and Munoz, Luis Enrique Garcia}, booktitle = {14th European Conference on Antennas and Propagation}, location = {Copenhagen, Denmark}, publisher = {IEEE}, title = {{Compact millimeter and submillimeter-wave photonic radiometer for cubesats}}, doi = {10.23919/eucap48036.2020.9135962}, year = {2020}, } @inproceedings{15074, abstract = {We introduce a new graph problem, the token dropping game, and we show how to solve it efficiently in a distributed setting. We use the token dropping game as a tool to design an efficient distributed algorithm for the stable orientation problem, which is a special case of the more general locally optimal semi-matching problem. The prior work by Czygrinow et al. (DISC 2012) finds a locally optimal semi-matching in O(Δ⁵) rounds in graphs of maximum degree Δ, which directly implies an algorithm with the same runtime for stable orientations. We improve the runtime to O(Δ⁴) for stable orientations and prove a lower bound of Ω(Δ) rounds.}, author = {Brandt, Sebastian and Keller, Barbara and Rybicki, Joel and Suomela, Jukka and Uitto, Jara}, booktitle = {34th International Symposium on Distributed Computing}, location = {Virtual}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Brief announcement: Efficient load-balancing through distributed token dropping}}, doi = {10.4230/LIPIcs.DISC.2020.40}, volume = {179}, year = {2020}, } @inproceedings{15077, abstract = {We consider the following dynamic load-balancing process: given an underlying graph G with n nodes, in each step t≥ 0, one unit of load is created, and placed at a randomly chosen graph node. In the same step, the chosen node picks a random neighbor, and the two nodes balance their loads by averaging them. We are interested in the expected gap between the minimum and maximum loads at nodes as the process progresses, and its dependence on n and on the graph structure. Variants of the above graphical balanced allocation process have been studied previously by Peres, Talwar, and Wieder [Peres et al., 2015], and by Sauerwald and Sun [Sauerwald and Sun, 2015]. These authors left as open the question of characterizing the gap in the case of cycle graphs in the dynamic case, where weights are created during the algorithm’s execution. For this case, the only known upper bound is of 𝒪(n log n), following from a majorization argument due to [Peres et al., 2015], which analyzes a related graphical allocation process. In this paper, we provide an upper bound of 𝒪 (√n log n) on the expected gap of the above process for cycles of length n. We introduce a new potential analysis technique, which enables us to bound the difference in load between k-hop neighbors on the cycle, for any k ≤ n/2. We complement this with a "gap covering" argument, which bounds the maximum value of the gap by bounding its value across all possible subsets of a certain structure, and recursively bounding the gaps within each subset. We provide analytical and experimental evidence that our upper bound on the gap is tight up to a logarithmic factor.}, author = {Alistarh, Dan-Adrian and Nadiradze, Giorgi and Sabour, Amirmojtaba}, booktitle = {47th International Colloquium on Automata, Languages, and Programming}, location = {Saarbrücken, Germany, Virtual}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Dynamic averaging load balancing on cycles}}, doi = {10.4230/LIPIcs.ICALP.2020.7}, volume = {168}, year = {2020}, } @inproceedings{15082, abstract = {Two plane drawings of geometric graphs on the same set of points are called disjoint compatible if their union is plane and they do not have an edge in common. For a given set S of 2n points two plane drawings of perfect matchings M1 and M2 (which do not need to be disjoint nor compatible) are disjoint tree-compatible if there exists a plane drawing of a spanning tree T on S which is disjoint compatible to both M1 and M2. We show that the graph of all disjoint tree-compatible perfect geometric matchings on 2n points in convex position is connected if and only if 2n ≥ 10. Moreover, in that case the diameter of this graph is either 4 or 5, independent of n.}, author = {Aichholzer, Oswin and Obmann, Julia and Patak, Pavel and Perz, Daniel and Tkadlec, Josef}, booktitle = {36th European Workshop on Computational Geometry}, location = {Würzburg, Germany, Virtual}, title = {{Disjoint tree-compatible plane perfect matchings}}, year = {2020}, } @article{6748, abstract = {Fitting a function by using linear combinations of a large number N of `simple' components is one of the most fruitful ideas in statistical learning. This idea lies at the core of a variety of methods, from two-layer neural networks to kernel regression, to boosting. In general, the resulting risk minimization problem is non-convex and is solved by gradient descent or its variants. Unfortunately, little is known about global convergence properties of these approaches. Here we consider the problem of learning a concave function f on a compact convex domain Ω⊆ℝd, using linear combinations of `bump-like' components (neurons). The parameters to be fitted are the centers of N bumps, and the resulting empirical risk minimization problem is highly non-convex. We prove that, in the limit in which the number of neurons diverges, the evolution of gradient descent converges to a Wasserstein gradient flow in the space of probability distributions over Ω. Further, when the bump width δ tends to 0, this gradient flow has a limit which is a viscous porous medium equation. Remarkably, the cost function optimized by this gradient flow exhibits a special property known as displacement convexity, which implies exponential convergence rates for N→∞, δ→0. Surprisingly, this asymptotic theory appears to capture well the behavior for moderate values of δ,N. Explaining this phenomenon, and understanding the dependence on δ,N in a quantitative manner remains an outstanding challenge.}, author = {Javanmard, Adel and Mondelli, Marco and Montanari, Andrea}, issn = {1941-7330}, journal = {Annals of Statistics}, number = {6}, pages = {3619--3642}, publisher = {Institute of Mathematical Statistics}, title = {{Analysis of a two-layer neural network via displacement convexity}}, doi = {10.1214/20-AOS1945}, volume = {48}, year = {2020}, } @article{15070, abstract = {This workshop focused on interactions between the various perspectives on the moduli space of Higgs bundles over a Riemann surface. This subject draws on algebraic geometry, geometric topology, geometric analysis and mathematical physics, and the goal was to promote interactions between these various branches of the subject. The main current directions of research were well represented by the participants, and the talks included many from both senior and junior participants.}, author = {Anderson, Lara and Hausel, Tamás and Mazzeo, Rafe and Schaposnik, Laura}, issn = {1660-8933}, journal = {Oberwolfach Reports}, keywords = {Organic Chemistry, Biochemistry}, number = {2}, pages = {1357--1417}, publisher = {European Mathematical Society}, title = {{Geometry and physics of Higgs bundles}}, doi = {10.4171/owr/2019/23}, volume = {16}, year = {2020}, } @article{8741, abstract = {In ecology, climate and other fields, (sub)systems have been identified that can transition into a qualitatively different state when a critical threshold or tipping point in a driving process is crossed. An understanding of those tipping elements is of great interest given the increasing influence of humans on the biophysical Earth system. Complex interactions exist between tipping elements, e.g. physical mechanisms connect subsystems of the climate system. Based on earlier work on such coupled nonlinear systems, we systematically assessed the qualitative long-term behaviour of interacting tipping elements. We developed an understanding of the consequences of interactions on the tipping behaviour allowing for tipping cascades to emerge under certain conditions. The (narrative) application of these qualitative results to real-world examples of interacting tipping elements indicates that tipping cascades with profound consequences may occur: the interacting Greenland ice sheet and thermohaline ocean circulation might tip before the tipping points of the isolated subsystems are crossed. The eutrophication of the first lake in a lake chain might propagate through the following lakes without a crossing of their individual critical nutrient input levels. The possibility of emerging cascading tipping dynamics calls for the development of a unified theory of interacting tipping elements and the quantitative analysis of interacting real-world tipping elements.}, author = {Klose, Ann Kristin and Karle, Volker and Winkelmann, Ricarda and Donges, Jonathan F.}, issn = {20545703}, journal = {Royal Society Open Science}, number = {6}, publisher = {The Royal Society}, title = {{Emergence of cascading dynamics in interacting tipping elements of ecology and climate: Cascading dynamics in tipping elements}}, doi = {10.1098/rsos.200599}, volume = {7}, year = {2020}, } @article{7687, abstract = {A working group, which was established within the Network of Repository Managers (RepManNet), has dealt with common certifications for repositories. In addition, current requirements of the research funding agencies FWF and EU were also taken into account. The Core Trust Seal was examined in more detail. For this purpose, a questionnaire was sent to those organizations that are already certified with CTS in Austria. The answers were summarized and evaluated anonymously. It is recommended to go for a repository certification. Moreover, the development of a DINI certificate in Austria is strongly suggested.}, author = {Ernst, Doris and Novotny, Gertraud and Schönher, Eva Maria}, issn = {1022-2588}, journal = {Mitteilungen der Vereinigung Österreichischer Bibliothekarinnen und Bibliothekare}, number = {1}, pages = {46--59}, publisher = {Vereinigung Osterreichischer Bibliothekarinnen und Bibliothekare}, title = {{(Core Trust) Seal your repository!}}, doi = {10.31263/voebm.v73i1.3491}, volume = {73}, year = {2020}, } @article{15079, abstract = {Large complex systems tend to develop universal patterns that often represent their essential characteristics. For example, the cumulative effects of independent or weakly dependent random variables often yield the Gaussian universality class via the central limit theorem. For non-commutative random variables, e.g. matrices, the Gaussian behavior is often replaced by another universality class, commonly called random matrix statistics. Nearby eigenvalues are strongly correlated, and, remarkably, their correlation structure is universal, depending only on the symmetry type of the matrix. Even more surprisingly, this feature is not restricted to matrices; in fact Eugene Wigner, the pioneer of the field, discovered in the 1950s that distributions of the gaps between energy levels of complicated quantum systems universally follow the same random matrix statistics. This claim has never been rigorously proved for any realistic physical system but experimental data and extensive numerics leave no doubt as to its correctness. Since then random matrices have proved to be extremely useful phenomenological models in a wide range of applications beyond quantum physics that include number theory, statistics, neuroscience, population dynamics, wireless communication and mathematical finance. The ubiquity of random matrices in natural sciences is still a mystery, but recent years have witnessed a breakthrough in the mathematical description of the statistical structure of their spectrum. Random matrices and closely related areas such as log-gases have become an extremely active research area in probability theory. This workshop brought together outstanding researchers from a variety of mathematical backgrounds whose areas of research are linked to random matrices. While there are strong links between their motivations, the techniques used by these researchers span a large swath of mathematics, ranging from purely algebraic techniques to stochastic analysis, classical probability theory, operator algebra, supersymmetry, orthogonal polynomials, etc.}, author = {Erdös, László and Götze, Friedrich and Guionnet, Alice}, issn = {1660-8933}, journal = {Oberwolfach Reports}, number = {4}, pages = {3459--3527}, publisher = {European Mathematical Society}, title = {{Random matrices}}, doi = {10.4171/owr/2019/56}, volume = {16}, year = {2020}, } @article{15072, abstract = {The interaction among fundamental particles in nature leads to many interesting effects in quantum statistical mechanics; examples include superconductivity for charged systems and superfluidity in cold gases. It is a huge challenge for mathematical physics to understand the collective behavior of systems containing a large number of particles, emerging from known microscopic interactions. In this workshop we brought together researchers working on different aspects of many-body quantum mechanics to discuss recent developments, exchange ideas and propose new challenges and research directions.}, author = {Hainzl, Christian and Schlein, Benjamin and Seiringer, Robert and Warzel, Simone}, issn = {1660-8933}, journal = {Oberwolfach Reports}, number = {3}, pages = {2541--2603}, publisher = {European Mathematical Society}, title = {{Many-body quantum systems}}, doi = {10.4171/owr/2019/41}, volume = {16}, year = {2020}, } @inproceedings{15071, abstract = {A mesophilic methanogenic culture, designated JL01, was isolated from Holocene permafrost in the Russian Arctic [1]. After long-term extensive cultivation at 15°C it turned out to be a tied binary culture of archaeal (JL01) and bacterial (Sphaerochaeta associata GLS2) strains. Strain JL01 was a strict anaerobe and grew on methanol, acetate and methylamines as energy and carbon sources. Cells were irregular coccoid, non-motile, non-spore-forming, and Gram-stainpositive. Optimum conditions for growth were 24-28 oC, pH 6.8–7.3 and 0.075-0.1 M NaCl. Phylogenetic tree reconstructions based on 16S rRNA and concatenated alignment of broadly conserved protein-coding genes revealed its close relation to Methanosarcina mazei S-6 T (similarity 99.5%). The comparison of whole genomic sequences (ANI) of the isolate and the type strain of M.mazei was 98.5%, which is higher than the values recommended for new species. Thus strain JL01 (=VKM B-2370=JCM 31898) represents the first M. mazei isolated from permanently subzero Arcticsediments. The long-term co-cultivation of JL01 with S. associata GLS2T showed the methane production without any additional carbon and energy sources. Genome analysis of S. associata GLS2T revealed putative genes involved in methanochondroithin catabolism.}, author = {Oshurkova, Viktoriia and Troshina, Olga and Trubitsyn, Vladimir and Ryzhmanova, Yana and Bochkareva, Olga and Shcherbakova, Viktoria}, booktitle = {Proceedings of 1st International Electronic Conference on Microbiology}, location = {Virtual}, publisher = {MDPI}, title = {{Characterization of methanosarcina mazei JL01 isolated from holocene arctic permafrost and study of the archaeon cooperation with bacterium Sphaerochaeta associata GLS2T}}, doi = {10.3390/ecm2020-07116}, year = {2020}, } @article{15153, abstract = {Mammalian circadian rhythms are generated by a transcription-based feedback loop in which CLOCK:BMAL1 drives transcription of its repressors (PER1/2, CRY1/2), which ultimately interact with CLOCK:BMAL1 to close the feedback loop with ~24 hr periodicity. Here we pinpoint a key difference between CRY1 and CRY2 that underlies their differential strengths as transcriptional repressors. Both cryptochromes bind the BMAL1 transactivation domain similarly to sequester it from coactivators and repress CLOCK:BMAL1 activity. However, we find that CRY1 is recruited with much higher affinity to the PAS domain core of CLOCK:BMAL1, allowing it to serve as a stronger repressor that lengthens circadian period. We discovered a dynamic serine-rich loop adjacent to the secondary pocket in the photolyase homology region (PHR) domain that regulates differential binding of cryptochromes to the PAS domain core of CLOCK:BMAL1. Notably, binding of the co-repressor PER2 remodels the serine loop of CRY2, making it more CRY1-like and enhancing its affinity for CLOCK:BMAL1.}, author = {Fribourgh, Jennifer L and Srivastava, Ashutosh and Sandate, Colby R and Michael, Alicia Kathleen and Hsu, Peter L and Rakers, Christin and Nguyen, Leslee T and Torgrimson, Megan R and Parico, Gian Carlo G and Tripathi, Sarvind and Zheng, Ning and Lander, Gabriel C and Hirota, Tsuyoshi and Tama, Florence and Partch, Carrie L}, issn = {2050-084X}, journal = {eLife}, keywords = {General Immunology and Microbiology, General Biochemistry, Genetics and Molecular Biology, General Medicine, General Neuroscience}, publisher = {eLife Sciences Publications}, title = {{Dynamics at the serine loop underlie differential affinity of cryptochromes for CLOCK:BMAL1 to control circadian timing}}, doi = {10.7554/elife.55275}, volume = {9}, year = {2020}, }