@article{13998, abstract = {The interaction of strong near-infrared (NIR) laser pulses with wide-bandgap dielectrics produces high harmonics in the extreme ultraviolet (XUV) wavelength range. These observations have opened up the possibility of attosecond metrology in solids, which would benefit from a precise measurement of the emission times of individual harmonics with respect to the NIR laser field. Here we show that, when high-harmonics are detected from the input surface of a magnesium oxide crystal, a bichromatic probing of the XUV emission shows a clear synchronization largely consistent with a semiclassical model of electron–hole recollisions in bulk solids. On the other hand, the bichromatic spectrogram of harmonics originating from the exit surface of the 200 μm-thick crystal is strongly modified, indicating the influence of laser field distortions during propagation. Our tracking of sub-cycle electron and hole re-collisions at XUV energies is relevant to the development of solid-state sources of attosecond pulses.}, author = {Vampa, Giulio and Lu, Jian and You, Yong Sing and Baykusheva, Denitsa Rangelova and Wu, Mengxi and Liu, Hanzhe and Schafer, Kenneth J and Gaarde, Mette B and Reis, David A and Ghimire, Shambhu}, issn = {1361-6455}, journal = {Journal of Physics B: Atomic, Molecular and Optical Physics}, keywords = {Condensed Matter Physics, Atomic and Molecular Physics, and Optics}, number = {14}, publisher = {IOP Publishing}, title = {{Attosecond synchronization of extreme ultraviolet high harmonics from crystals}}, doi = {10.1088/1361-6455/ab8e56}, volume = {53}, year = {2020}, } @article{13999, abstract = {Attosecond chronoscopy has revealed small but measurable delays in photoionization, characterized by the ejection of an electron on absorption of a single photon. Ionization-delay measurements in atomic targets provide a wealth of information about the timing of the photoelectric effect, resonances, electron correlations and transport. However, extending this approach to molecules presents challenges, such as identifying the correct ionization channels and the effect of the anisotropic molecular landscape on the measured delays. Here, we measure ionization delays from ethyl iodide around a giant dipole resonance. By using the theoretical value for the iodine atom as a reference, we disentangle the contribution from the functional ethyl group, which is responsible for the characteristic chemical reactivity of a molecule. We find a substantial additional delay caused by the presence of a functional group, which encodes the effect of the molecular potential on the departing electron. Such information is inaccessible to the conventional approach of measuring photoionization cross-sections. The results establish ionization-delay measurements as a valuable tool in investigating the electronic properties of molecules.}, author = {Biswas, Shubhadeep and Förg, Benjamin and Ortmann, Lisa and Schötz, Johannes and Schweinberger, Wolfgang and Zimmermann, Tomáš and Pi, Liangwen and Baykusheva, Denitsa Rangelova and Masood, Hafiz A. and Liontos, Ioannis and Kamal, Amgad M. and Kling, Nora G. and Alharbi, Abdullah F. and Alharbi, Meshaal and Azzeer, Abdallah M. and Hartmann, Gregor and Wörner, Hans J. and Landsman, Alexandra S. and Kling, Matthias F.}, issn = {1745-2481}, journal = {Nature Physics}, keywords = {General Physics and Astronomy}, number = {7}, pages = {778--783}, publisher = {Springer Nature}, title = {{Probing molecular environment through photoemission delays}}, doi = {10.1038/s41567-020-0887-8}, volume = {16}, year = {2020}, } @inbook{14000, abstract = {This chapter presents an overview of the state of the art in attosecond time-resolved spectroscopy. The theoretical foundations of strong-field light–matter interaction and attosecond pulse generation are described. The enabling laser technologies are reviewed from chirped-pulse amplification and carrier-envelope-phase stabilization to the generation and characterization of attosecond pulses. The applications of attosecond pulses and pulse trains in electron- or ion-imaging experiments are presented, followed by attosecond electron spectroscopy in larger molecules. After this, high-harmonic spectroscopy and its applications to probing charge migration on attosecond time scales is reviewed. The rapidly evolving field of molecular photoionization delays is discussed. Finally, the applications of attosecond transient absorption to probing molecular dynamics are presented.}, author = {Baykusheva, Denitsa Rangelova and Wörner, Hans Jakob}, booktitle = {Molecular Spectroscopy and Quantum Dynamics}, editor = {Marquardt, Roberto and Quack, Martin}, isbn = {9780128172353}, pages = {113--161}, publisher = {Elsevier}, title = {{Attosecond Molecular Dynamics and Spectroscopy}}, doi = {10.1016/b978-0-12-817234-6.00009-x}, year = {2020}, } @unpublished{14028, abstract = {The present review addresses the technical advances and the theoretical developments to realize and rationalize attosecond-science experiments that reveal a new dynamical time scale (10−15-10−18 s), with a particular emphasis on molecular systems and the implications of attosecond processes for chemical dynamics. After a brief outline of the theoretical framework for treating non-perturbative phenomena in Section 2, we introduce the physical mechanisms underlying high-harmonic generation and attosecond technology. The relevant technological developments and experimental schemes are covered in Section 3. Throughout the remainder of the chapter, we report on selected applications in molecular attosecond physics, thereby addressing specific phenomena mediated by purely electronic dynamics: charge localization in molecular hydrogen, charge migration in biorelevant molecules, high-harmonic spectroscopy, and delays in molecular photoionization.}, author = {Baykusheva, Denitsa Rangelova and Wörner, Hans Jakob}, pages = {2002.02111}, title = {{Attosecond molecular spectroscopy and dynamics}}, doi = {10.48550/arXiv.2002.02111}, year = {2020}, } @unpublished{14095, abstract = {The Habitable Exoplanet Observatory, or HabEx, has been designed to be the Great Observatory of the 2030s. For the first time in human history, technologies have matured sufficiently to enable an affordable space-based telescope mission capable of discovering and characterizing Earthlike planets orbiting nearby bright sunlike stars in order to search for signs of habitability and biosignatures. Such a mission can also be equipped with instrumentation that will enable broad and exciting general astrophysics and planetary science not possible from current or planned facilities. HabEx is a space telescope with unique imaging and multi-object spectroscopic capabilities at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities allow for a broad suite of compelling science that cuts across the entire NASA astrophysics portfolio. HabEx has three primary science goals: (1) Seek out nearby worlds and explore their habitability; (2) Map out nearby planetary systems and understand the diversity of the worlds they contain; (3) Enable new explorations of astrophysical systems from our own solar system to external galaxies by extending our reach in the UV through near-IR. This Great Observatory science will be selected through a competed GO program, and will account for about 50% of the HabEx primary mission. The preferred HabEx architecture is a 4m, monolithic, off-axis telescope that is diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two starlight suppression systems: a coronagraph and a starshade, each with their own dedicated instrument.}, author = {Gaudi, B. Scott and Seager, Sara and Mennesson, Bertrand and Kiessling, Alina and Warfield, Keith and Cahoy, Kerri and Clarke, John T. and Shawn Domagal-Goldman, Shawn Domagal-Goldman and Feinberg, Lee and Guyon, Olivier and Kasdin, Jeremy and Mawet, Dimitri and Plavchan, Peter and Robinson, Tyler and Rogers, Leslie and Scowen, Paul and Somerville, Rachel and Stapelfeldt, Karl and Stark, Christopher and Stern, Daniel and Turnbull, Margaret and Amini, Rashied and Kuan, Gary and Martin, Stefan and Morgan, Rhonda and Redding, David and Stahl, H. Philip and Webb, Ryan and Oscar Alvarez-Salazar, Oscar Alvarez-Salazar and Arnold, William L. and Arya, Manan and Balasubramanian, Bala and Baysinger, Mike and Bell, Ray and Below, Chris and Benson, Jonathan and Blais, Lindsey and Booth, Jeff and Bourgeois, Robert and Bradford, Case and Brewer, Alden and Brooks, Thomas and Cady, Eric and Caldwell, Mary and Calvet, Rob and Carr, Steven and Chan, Derek and Cormarkovic, Velibor and Coste, Keith and Cox, Charlie and Danner, Rolf and Davis, Jacqueline and Dewell, Larry and Dorsett, Lisa and Dunn, Daniel and East, Matthew and Effinger, Michael and Eng, Ron and Freebury, Greg and Garcia, Jay and Gaskin, Jonathan and Greene, Suzan and Hennessy, John and Hilgemann, Evan and Hood, Brad and Holota, Wolfgang and Howe, Scott and Huang, Pei and Hull, Tony and Hunt, Ron and Hurd, Kevin and Johnson, Sandra and Kissil, Andrew and Knight, Brent and Kolenz, Daniel and Kraus, Oliver and Krist, John and Li, Mary and Lisman, Doug and Mandic, Milan and Mann, John and Marchen, Luis and Colleen Marrese-Reading, Colleen Marrese-Reading and McCready, Jonathan and McGown, Jim and Missun, Jessica and Miyaguchi, Andrew and Moore, Bradley and Nemati, Bijan and Nikzad, Shouleh and Nissen, Joel and Novicki, Megan and Perrine, Todd and Pineda, Claudia and Polanco, Otto and Putnam, Dustin and Qureshi, Atif and Richards, Michael and Riggs, A. J. Eldorado and Rodgers, Michael and Rud, Mike and Saini, Navtej and Scalisi, Dan and Scharf, Dan and Schulz, Kevin and Serabyn, Gene and Sigrist, Norbert and Sikkia, Glory and Singleton, Andrew and Shaklan, Stuart and Smith, Scott and Southerd, Bart and Stahl, Mark and Steeves, John and Sturges, Brian and Sullivan, Chris and Tang, Hao and Taras, Neil and Tesch, Jonathan and Therrell, Melissa and Tseng, Howard and Valente, Marty and Buren, David Van and Villalvazo, Juan and Warwick, Steve and Webb, David and Westerhoff, Thomas and Wofford, Rush and Wu, Gordon and Woo, Jahning and Wood, Milana and Ziemer, John and Arney, Giada and Anderson, Jay and Jesús Maíz-Apellániz, Jesús Maíz-Apellániz and Bartlett, James and Belikov, Ruslan and Bendek, Eduardo and Cenko, Brad and Douglas, Ewan and Dulz, Shannon and Evans, Chris and Faramaz, Virginie and Feng, Y. Katherina and Ferguson, Harry and Follette, Kate and Ford, Saavik and García, Miriam and Geha, Marla and Gelino, Dawn and Götberg, Ylva Louise Linsdotter and Hildebrandt, Sergi and Hu, Renyu and Jahnke, Knud and Kennedy, Grant and Kreidberg, Laura and Isella, Andrea and Lopez, Eric and Marchis, Franck and Macri, Lucas and Marley, Mark and Matzko, William and Mazoyer, Johan and McCandliss, Stephan and Meshkat, Tiffany and Mordasini, Christoph and Morris, Patrick and Nielsen, Eric and Newman, Patrick and Petigura, Erik and Postman, Marc and Reines, Amy and Roberge, Aki and Roederer, Ian and Ruane, Garreth and Schwieterman, Edouard and Sirbu, Dan and Spalding, Christopher and Teplitz, Harry and Tumlinson, Jason and Turner, Neal and Werk, Jessica and Wofford, Aida and Wyatt, Mark and Young, Amber and Zellem, Rob}, booktitle = {arXiv}, title = {{The habitable exoplanet observatory (HabEx) mission concept study final report}}, doi = {10.48550/arXiv.2001.06683}, year = {2020}, } @unpublished{14096, abstract = {A binary neutron star merger has been observed in a multi-messenger detection of gravitational wave (GW) and electromagnetic (EM) radiation. Binary neutron stars that merge within a Hubble time, as well as many other compact binaries, are expected to form via common envelope evolution. Yet five decades of research on common envelope evolution have not yet resulted in a satisfactory understanding of the multi-spatial multi-timescale evolution for the systems that lead to compact binaries. In this paper, we report on the first successful simulations of common envelope ejection leading to binary neutron star formation in 3D hydrodynamics. We simulate the dynamical inspiral phase of the interaction between a 12M⊙ red supergiant and a 1.4M⊙ neutron star for different initial separations and initial conditions. For all of our simulations, we find complete envelope ejection and final orbital separations of af≈1.3-5.1R⊙ depending on the simulation and criterion, leading to binary neutron stars that can merge within a Hubble time. We find αCE-equivalent efficiencies of ≈0.1-2.7 depending on the simulation and criterion, but this may be specific for these extended progenitors. We fully resolve the core of the star to ≲0.005R⊙ and our 3D hydrodynamics simulations are informed by an adjusted 1D analytic energy formalism and a 2D kinematics study in order to overcome the prohibitive computational cost of simulating these systems. The framework we develop in this paper can be used to simulate a wide variety of interactions between stars, from stellar mergers to common envelope episodes leading to GW sources.}, author = {Jamie A. P. Law-Smith, Jamie A. P. Law-Smith and Everson, Rosa Wallace and Enrico Ramirez-Ruiz, Enrico Ramirez-Ruiz and Mink, Selma E. de and Son, Lieke A. C. van and Götberg, Ylva Louise Linsdotter and Zellmann, Stefan and Alejandro Vigna-Gómez, Alejandro Vigna-Gómez and Renzo, Mathieu and Wu, Samantha and Schrøder, Sophie L. and Foley, Ryan J. and Tenley Hutchinson-Smith, Tenley Hutchinson-Smith}, booktitle = {arXiv}, title = {{Successful common envelope ejection and binary neutron star formation in 3D hydrodynamics}}, doi = {10.48550/arXiv.2011.06630}, year = {2020}, } @article{14125, abstract = {Motivation: Recent technological advances have led to an increase in the production and availability of single-cell data. The ability to integrate a set of multi-technology measurements would allow the identification of biologically or clinically meaningful observations through the unification of the perspectives afforded by each technology. In most cases, however, profiling technologies consume the used cells and thus pairwise correspondences between datasets are lost. Due to the sheer size single-cell datasets can acquire, scalable algorithms that are able to universally match single-cell measurements carried out in one cell to its corresponding sibling in another technology are needed. Results: We propose Single-Cell data Integration via Matching (SCIM), a scalable approach to recover such correspondences in two or more technologies. SCIM assumes that cells share a common (low-dimensional) underlying structure and that the underlying cell distribution is approximately constant across technologies. It constructs a technology-invariant latent space using an autoencoder framework with an adversarial objective. Multi-modal datasets are integrated by pairing cells across technologies using a bipartite matching scheme that operates on the low-dimensional latent representations. We evaluate SCIM on a simulated cellular branching process and show that the cell-to-cell matches derived by SCIM reflect the same pseudotime on the simulated dataset. Moreover, we apply our method to two real-world scenarios, a melanoma tumor sample and a human bone marrow sample, where we pair cells from a scRNA dataset to their sibling cells in a CyTOF dataset achieving 90% and 78% cell-matching accuracy for each one of the samples, respectively.}, author = {Stark, Stefan G and Ficek, Joanna and Locatello, Francesco and Bonilla, Ximena and Chevrier, Stéphane and Singer, Franziska and Aebersold, Rudolf and Al-Quaddoomi, Faisal S and Albinus, Jonas and Alborelli, Ilaria and Andani, Sonali and Attinger, Per-Olof and Bacac, Marina and Baumhoer, Daniel and Beck-Schimmer, Beatrice and Beerenwinkel, Niko and Beisel, Christian and Bernasconi, Lara and Bertolini, Anne and Bodenmiller, Bernd and Bonilla, Ximena and Casanova, Ruben and Chevrier, Stéphane and Chicherova, Natalia and D'Costa, Maya and Danenberg, Esther and Davidson, Natalie and gan, Monica-Andreea Dră and Dummer, Reinhard and Engler, Stefanie and Erkens, Martin and Eschbach, Katja and Esposito, Cinzia and Fedier, André and Ferreira, Pedro and Ficek, Joanna and Frei, Anja L and Frey, Bruno and Goetze, Sandra and Grob, Linda and Gut, Gabriele and Günther, Detlef and Haberecker, Martina and Haeuptle, Pirmin and Heinzelmann-Schwarz, Viola and Herter, Sylvia and Holtackers, Rene and Huesser, Tamara and Irmisch, Anja and Jacob, Francis and Jacobs, Andrea and Jaeger, Tim M and Jahn, Katharina and James, Alva R and Jermann, Philip M and Kahles, André and Kahraman, Abdullah and Koelzer, Viktor H and Kuebler, Werner and Kuipers, Jack and Kunze, Christian P and Kurzeder, Christian and Lehmann, Kjong-Van and Levesque, Mitchell and Lugert, Sebastian and Maass, Gerd and Manz, Markus and Markolin, Philipp and Mena, Julien and Menzel, Ulrike and Metzler, Julian M and Miglino, Nicola and Milani, Emanuela S and Moch, Holger and Muenst, Simone and Murri, Riccardo and Ng, Charlotte KY and Nicolet, Stefan and Nowak, Marta and Pedrioli, Patrick GA and Pelkmans, Lucas and Piscuoglio, Salvatore and Prummer, Michael and Ritter, Mathilde and Rommel, Christian and Rosano-González, María L and Rätsch, Gunnar and Santacroce, Natascha and Castillo, Jacobo Sarabia del and Schlenker, Ramona and Schwalie, Petra C and Schwan, Severin and Schär, Tobias and Senti, Gabriela and Singer, Franziska and Sivapatham, Sujana and Snijder, Berend and Sobottka, Bettina and Sreedharan, Vipin T and Stark, Stefan and Stekhoven, Daniel J and Theocharides, Alexandre PA and Thomas, Tinu M and Tolnay, Markus and Tosevski, Vinko and Toussaint, Nora C and Tuncel, Mustafa A and Tusup, Marina and Drogen, Audrey Van and Vetter, Marcus and Vlajnic, Tatjana and Weber, Sandra and Weber, Walter P and Wegmann, Rebekka and Weller, Michael and Wendt, Fabian and Wey, Norbert and Wicki, Andreas and Wollscheid, Bernd and Yu, Shuqing and Ziegler, Johanna and Zimmermann, Marc and Zoche, Martin and Zuend, Gregor and Rätsch, Gunnar and Lehmann, Kjong-Van}, issn = {1367-4811}, journal = {Bioinformatics}, keywords = {Computational Mathematics, Computational Theory and Mathematics, Computer Science Applications, Molecular Biology, Biochemistry, Statistics and Probability}, number = {Supplement_2}, pages = {i919--i927}, publisher = {Oxford University Press}, title = {{SCIM: Universal single-cell matching with unpaired feature sets}}, doi = {10.1093/bioinformatics/btaa843}, volume = {36}, year = {2020}, } @inproceedings{14186, abstract = {The goal of the unsupervised learning of disentangled representations is to separate the independent explanatory factors of variation in the data without access to supervision. In this paper, we summarize the results of Locatello et al., 2019, and focus on their implications for practitioners. We discuss the theoretical result showing that the unsupervised learning of disentangled representations is fundamentally impossible without inductive biases and the practical challenges it entails. Finally, we comment on our experimental findings, highlighting the limitations of state-of-the-art approaches and directions for future research.}, author = {Locatello, Francesco and Bauer, Stefan and Lucic, Mario and Rätsch, Gunnar and Gelly, Sylvain and Schölkopf, Bernhard and Bachem, Olivier}, booktitle = {The 34th AAAI Conference on Artificial Intelligence}, isbn = {9781577358350}, issn = {2374-3468}, location = {New York, NY, United States}, number = {9}, pages = {13681--13684}, publisher = {Association for the Advancement of Artificial Intelligence}, title = {{A commentary on the unsupervised learning of disentangled representations}}, doi = {10.1609/aaai.v34i09.7120}, volume = {34}, year = {2020}, } @inproceedings{14187, abstract = {We propose a novel Stochastic Frank-Wolfe (a.k.a. conditional gradient) algorithm for constrained smooth finite-sum minimization with a generalized linear prediction/structure. This class of problems includes empirical risk minimization with sparse, low-rank, or other structured constraints. The proposed method is simple to implement, does not require step-size tuning, and has a constant per-iteration cost that is independent of the dataset size. Furthermore, as a byproduct of the method we obtain a stochastic estimator of the Frank-Wolfe gap that can be used as a stopping criterion. Depending on the setting, the proposed method matches or improves on the best computational guarantees for Stochastic Frank-Wolfe algorithms. Benchmarks on several datasets highlight different regimes in which the proposed method exhibits a faster empirical convergence than related methods. Finally, we provide an implementation of all considered methods in an open-source package.}, author = {Négiar, Geoffrey and Dresdner, Gideon and Tsai, Alicia and Ghaoui, Laurent El and Locatello, Francesco and Freund, Robert M. and Pedregosa, Fabian}, booktitle = {Proceedings of the 37th International Conference on Machine Learning}, location = {Virtual}, pages = {7253--7262}, title = {{Stochastic Frank-Wolfe for constrained finite-sum minimization}}, volume = {119}, year = {2020}, } @inproceedings{14188, abstract = {Intelligent agents should be able to learn useful representations by observing changes in their environment. We model such observations as pairs of non-i.i.d. images sharing at least one of the underlying factors of variation. First, we theoretically show that only knowing how many factors have changed, but not which ones, is sufficient to learn disentangled representations. Second, we provide practical algorithms that learn disentangled representations from pairs of images without requiring annotation of groups, individual factors, or the number of factors that have changed. Third, we perform a large-scale empirical study and show that such pairs of observations are sufficient to reliably learn disentangled representations on several benchmark data sets. Finally, we evaluate our learned representations and find that they are simultaneously useful on a diverse suite of tasks, including generalization under covariate shifts, fairness, and abstract reasoning. Overall, our results demonstrate that weak supervision enables learning of useful disentangled representations in realistic scenarios.}, author = {Locatello, Francesco and Poole, Ben and Rätsch, Gunnar and Schölkopf, Bernhard and Bachem, Olivier and Tschannen, Michael}, booktitle = {Proceedings of the 37th International Conference on Machine Learning}, location = {Virtual}, pages = {6348–6359}, title = {{Weakly-supervised disentanglement without compromises}}, volume = {119}, year = {2020}, } @article{14195, abstract = {The idea behind the unsupervised learning of disentangled representations is that real-world data is generated by a few explanatory factors of variation which can be recovered by unsupervised learning algorithms. In this paper, we provide a sober look at recent progress in the field and challenge some common assumptions. We first theoretically show that the unsupervised learning of disentangled representations is fundamentally impossible without inductive biases on both the models and the data. Then, we train over 14000 models covering most prominent methods and evaluation metrics in a reproducible large-scale experimental study on eight data sets. We observe that while the different methods successfully enforce properties “encouraged” by the corresponding losses, well-disentangled models seemingly cannot be identified without supervision. Furthermore, different evaluation metrics do not always agree on what should be considered “disentangled” and exhibit systematic differences in the estimation. Finally, increased disentanglement does not seem to necessarily lead to a decreased sample complexity of learning for downstream tasks. Our results suggest that future work on disentanglement learning should be explicit about the role of inductive biases and (implicit) supervision, investigate concrete benefits of enforcing disentanglement of the learned representations, and consider a reproducible experimental setup covering several data sets.}, author = {Locatello, Francesco and Bauer, Stefan and Lucic, Mario and Rätsch, Gunnar and Gelly, Sylvain and Schölkopf, Bernhard and Bachem, Olivier}, journal = {Journal of Machine Learning Research}, publisher = {MIT Press}, title = {{A sober look at the unsupervised learning of disentangled representations and their evaluation}}, volume = {21}, year = {2020}, } @inproceedings{14326, abstract = {Learning object-centric representations of complex scenes is a promising step towards enabling efficient abstract reasoning from low-level perceptual features. Yet, most deep learning approaches learn distributed representations that do not capture the compositional properties of natural scenes. In this paper, we present the Slot Attention module, an architectural component that interfaces with perceptual representations such as the output of a convolutional neural network and produces a set of task-dependent abstract representations which we call slots. These slots are exchangeable and can bind to any object in the input by specializing through a competitive procedure over multiple rounds of attention. We empirically demonstrate that Slot Attention can extract object-centric representations that enable generalization to unseen compositions when trained on unsupervised object discovery and supervised property prediction tasks. }, author = {Locatello, Francesco and Weissenborn, Dirk and Unterthiner, Thomas and Mahendran, Aravindh and Heigold, Georg and Uszkoreit, Jakob and Dosovitskiy, Alexey and Kipf, Thomas}, booktitle = {34th International Conference on Neural Information Processing Systems}, isbn = {9781713829546}, issn = {1049-5258}, location = {Virtual}, pages = {11525--11538}, publisher = {Neural Information Processing Systems Foundation}, title = {{Object-centric learning with slot attention}}, volume = {33}, year = {2020}, } @misc{14592, abstract = {Cryo-electron microscopy (cryo-EM) of cellular specimens provides insights into biological processes and structures within a native context. However, a major challenge still lies in the efficient and reproducible preparation of adherent cells for subsequent cryo-EM analysis. This is due to the sensitivity of many cellular specimens to the varying seeding and culturing conditions required for EM experiments, the often limited amount of cellular material and also the fragility of EM grids and their substrate. Here, we present low-cost and reusable 3D printed grid holders, designed to improve specimen preparation when culturing challenging cellular samples directly on grids. The described grid holders increase cell culture reproducibility and throughput, and reduce the resources required for cell culturing. We show that grid holders can be integrated into various cryo-EM workflows, including micro-patterning approaches to control cell seeding on grids, and for generating samples for cryo-focused ion beam milling and cryo-electron tomography experiments. Their adaptable design allows for the generation of specialized grid holders customized to a large variety of applications.}, author = {Schur, Florian KM}, publisher = {Institute of Science and Technology Austria}, title = {{STL-files for 3D-printed grid holders described in Fäßler F, Zens B, et al.; 3D printed cell culture grid holders for improved cellular specimen preparation in cryo-electron microscopy}}, doi = {10.15479/AT:ISTA:14592}, year = {2020}, } @article{14694, abstract = {We study the unique solution m of the Dyson equation \( -m(z)^{-1} = z\1 - a + S[m(z)] \) on a von Neumann algebra A with the constraint Imm≥0. Here, z lies in the complex upper half-plane, a is a self-adjoint element of A and S is a positivity-preserving linear operator on A. We show that m is the Stieltjes transform of a compactly supported A-valued measure on R. Under suitable assumptions, we establish that this measure has a uniformly 1/3-Hölder continuous density with respect to the Lebesgue measure, which is supported on finitely many intervals, called bands. In fact, the density is analytic inside the bands with a square-root growth at the edges and internal cubic root cusps whenever the gap between two bands vanishes. The shape of these singularities is universal and no other singularity may occur. We give a precise asymptotic description of m near the singular points. These asymptotics generalize the analysis at the regular edges given in the companion paper on the Tracy-Widom universality for the edge eigenvalue statistics for correlated random matrices [the first author et al., Ann. Probab. 48, No. 2, 963--1001 (2020; Zbl 1434.60017)] and they play a key role in the proof of the Pearcey universality at the cusp for Wigner-type matrices [G. Cipolloni et al., Pure Appl. Anal. 1, No. 4, 615--707 (2019; Zbl 07142203); the second author et al., Commun. Math. Phys. 378, No. 2, 1203--1278 (2020; Zbl 07236118)]. We also extend the finite dimensional band mass formula from [the first author et al., loc. cit.] to the von Neumann algebra setting by showing that the spectral mass of the bands is topologically rigid under deformations and we conclude that these masses are quantized in some important cases.}, author = {Alt, Johannes and Erdös, László and Krüger, Torben H}, issn = {1431-0643}, journal = {Documenta Mathematica}, keywords = {General Mathematics}, pages = {1421--1539}, publisher = {EMS Press}, title = {{The Dyson equation with linear self-energy: Spectral bands, edges and cusps}}, doi = {10.4171/dm/780}, volume = {25}, year = {2020}, } @article{14891, abstract = {We give the first mathematically rigorous justification of the local density approximation in density functional theory. We provide a quantitative estimate on the difference between the grand-canonical Levy–Lieb energy of a given density (the lowest possible energy of all quantum states having this density) and the integral over the uniform electron gas energy of this density. The error involves gradient terms and justifies the use of the local density approximation in the situation where the density is very flat on sufficiently large regions in space.}, author = {Lewin, Mathieu and Lieb, Elliott H. and Seiringer, Robert}, issn = {2578-5885}, journal = {Pure and Applied Analysis}, number = {1}, pages = {35--73}, publisher = {Mathematical Sciences Publishers}, title = {{ The local density approximation in density functional theory}}, doi = {10.2140/paa.2020.2.35}, volume = {2}, year = {2020}, } @article{15036, abstract = {The assembly of a septin filament requires that homologous monomers must distinguish between one another in establishing appropriate interfaces with their neighbors. To understand this phenomenon at the molecular level, we present the first four crystal structures of heterodimeric septin complexes. We describe in detail the two distinct types of G-interface present within the octameric particles, which must polymerize to form filaments. These are formed between SEPT2 and SEPT6 and between SEPT7 and SEPT3, and their description permits an understanding of the structural basis for the selectivity necessary for correct filament assembly. By replacing SEPT6 by SEPT8 or SEPT11, it is possible to rationalize Kinoshita's postulate, which predicts the exchangeability of septins from within a subgroup. Switches I and II, which in classical small GTPases provide a mechanism for nucleotide-dependent conformational change, have been repurposed in septins to play a fundamental role in molecular recognition. Specifically, it is switch I which holds the key to discriminating between the two different G-interfaces. Moreover, residues which are characteristic for a given subgroup play subtle, but pivotal, roles in guaranteeing that the correct interfaces are formed.}, author = {Rosa, Higor Vinícius Dias and Leonardo, Diego Antonio and Brognara, Gabriel and Brandão-Neto, José and D'Muniz Pereira, Humberto and Araújo, Ana Paula Ulian and Garratt, Richard Charles}, issn = {0022-2836}, journal = {Journal of Molecular Biology}, keywords = {Molecular Biology, Structural Biology}, number = {21}, pages = {5784--5801}, publisher = {Elsevier}, title = {{Molecular recognition at septin interfaces: The switches hold the key}}, doi = {10.1016/j.jmb.2020.09.001}, volume = {432}, year = {2020}, } @article{15037, abstract = {Protein abundance and localization at the plasma membrane (PM) shapes plant development and mediates adaptation to changing environmental conditions. It is regulated by ubiquitination, a post-translational modification crucial for the proper sorting of endocytosed PM proteins to the vacuole for subsequent degradation. To understand the significance and the variety of roles played by this reversible modification, the function of ubiquitin receptors, which translate the ubiquitin signature into a cellular response, needs to be elucidated. In this study, we show that TOL (TOM1-like) proteins function in plants as multivalent ubiquitin receptors, governing ubiquitinated cargo delivery to the vacuole via the conserved Endosomal Sorting Complex Required for Transport (ESCRT) pathway. TOL2 and TOL6 interact with components of the ESCRT machinery and bind to K63-linked ubiquitin via two tandemly arranged conserved ubiquitin-binding domains. Mutation of these domains results not only in a loss of ubiquitin binding but also altered localization, abolishing TOL6 ubiquitin receptor activity. Function and localization of TOL6 is itself regulated by ubiquitination, whereby TOL6 ubiquitination potentially modulates degradation of PM-localized cargoes, assisting in the fine-tuning of the delicate interplay between protein recycling and downregulation. Taken together, our findings demonstrate the function and regulation of a ubiquitin receptor that mediates vacuolar degradation of PM proteins in higher plants.}, author = {Moulinier-Anzola, Jeanette and Schwihla, Maximilian and De-Araújo, Lucinda and Artner, Christina and Jörg, Lisa and Konstantinova, Nataliia and Luschnig, Christian and Korbei, Barbara}, issn = {1674-2052}, journal = {Molecular Plant}, keywords = {Plant Science, Molecular Biology}, number = {5}, pages = {717--731}, publisher = {Elsevier}, title = {{TOLs function as ubiquitin receptors in the early steps of the ESCRT pathway in higher plants}}, doi = {10.1016/j.molp.2020.02.012}, volume = {13}, 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}, } @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}, }