@article{7931, abstract = {In the course of sample preparation for Next Generation Sequencing (NGS), DNA is fragmented by various methods. Fragmentation shows a persistent bias with regard to the cleavage rates of various dinucleotides. With the exception of CpG dinucleotides the previously described biases were consistent with results of the DNA cleavage in solution. Here we computed cleavage rates of all dinucleotides including the methylated CpG and unmethylated CpG dinucleotides using data of the Whole Genome Sequencing datasets of the 1000 Genomes project. We found that the cleavage rate of CpG is significantly higher for the methylated CpG dinucleotides. Using this information, we developed a classifier for distinguishing cancer and healthy tissues based on their CpG islands statuses of the fragmentation. A simple Support Vector Machine classifier based on this algorithm shows an accuracy of 84%. The proposed method allows the detection of epigenetic markers purely based on mechanochemical DNA fragmentation, which can be detected by a simple analysis of the NGS sequencing data.}, author = {Uroshlev, Leonid A. and Abdullaev, Eldar T. and Umarova, Iren R. and Il’Icheva, Irina A. and Panchenko, Larisa A. and Polozov, Robert V. and Kondrashov, Fyodor and Nechipurenko, Yury D. and Grokhovsky, Sergei L.}, issn = {20452322}, journal = {Scientific Reports}, publisher = {Springer Nature}, title = {{A method for identification of the methylation level of CpG islands from NGS data}}, doi = {10.1038/s41598-020-65406-1}, volume = {10}, year = {2020}, } @article{7932, abstract = {Pulsating flows through tubular geometries are laminar provided that velocities are moderate. This in particular is also believed to apply to cardiovascular flows where inertial forces are typically too low to sustain turbulence. On the other hand, flow instabilities and fluctuating shear stresses are held responsible for a variety of cardiovascular diseases. Here we report a nonlinear instability mechanism for pulsating pipe flow that gives rise to bursts of turbulence at low flow rates. Geometrical distortions of small, yet finite, amplitude are found to excite a state consisting of helical vortices during flow deceleration. The resulting flow pattern grows rapidly in magnitude, breaks down into turbulence, and eventually returns to laminar when the flow accelerates. This scenario causes shear stress fluctuations and flow reversal during each pulsation cycle. Such unsteady conditions can adversely affect blood vessels and have been shown to promote inflammation and dysfunction of the shear stress-sensitive endothelial cell layer.}, author = {Xu, Duo and Varshney, Atul and Ma, Xingyu and Song, Baofang and Riedl, Michael and Avila, Marc and Hof, Björn}, issn = {10916490}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {21}, pages = {11233--11239}, publisher = {National Academy of Sciences}, title = {{Nonlinear hydrodynamic instability and turbulence in pulsatile flow}}, doi = {10.1073/pnas.1913716117}, volume = {117}, year = {2020}, } @article{7933, abstract = {We study a mobile quantum impurity, possessing internal rotational degrees of freedom, confined to a ring in the presence of a many-particle bosonic bath. By considering the recently introduced rotating polaron problem, we define the Hamiltonian and examine the energy spectrum. The weak-coupling regime is studied by means of a variational ansatz in the truncated Fock space. The corresponding spectrum indicates that there emerges a coupling between the internal and orbital angular momenta of the impurity as a consequence of the phonon exchange. We interpret the coupling as a phonon-mediated spin-orbit coupling and quantify it by using a correlation function between the internal and the orbital angular momentum operators. The strong-coupling regime is investigated within the Pekar approach, and it is shown that the correlation function of the ground state shows a kink at a critical coupling, that is explained by a sharp transition from the noninteracting state to the states that exhibit strong interaction with the surroundings. The results might find applications in such fields as spintronics or topological insulators where spin-orbit coupling is of crucial importance.}, author = {Maslov, Mikhail and Lemeshko, Mikhail and Yakaboylu, Enderalp}, issn = {24699969}, journal = {Physical Review B}, number = {18}, publisher = {American Physical Society}, title = {{Synthetic spin-orbit coupling mediated by a bosonic environment}}, doi = {10.1103/PhysRevB.101.184104}, volume = {101}, year = {2020}, } @inproceedings{7936, abstract = {State-of-the-art detection systems are generally evaluated on their ability to exhaustively retrieve objects densely distributed in the image, across a wide variety of appearances and semantic categories. Orthogonal to this, many real-life object detection applications, for example in remote sensing, instead require dealing with large images that contain only a few small objects of a single class, scattered heterogeneously across the space. In addition, they are often subject to strict computational constraints, such as limited battery capacity and computing power.To tackle these more practical scenarios, we propose a novel flexible detection scheme that efficiently adapts to variable object sizes and densities: We rely on a sequence of detection stages, each of which has the ability to predict groups of objects as well as individuals. Similar to a detection cascade, this multi-stage architecture spares computational effort by discarding large irrelevant regions of the image early during the detection process. The ability to group objects provides further computational and memory savings, as it allows working with lower image resolutions in early stages, where groups are more easily detected than individuals, as they are more salient. We report experimental results on two aerial image datasets, and show that the proposed method is as accurate yet computationally more efficient than standard single-shot detectors, consistently across three different backbone architectures.}, author = {Royer, Amélie and Lampert, Christoph}, booktitle = {IEEE Winter Conference on Applications of Computer Vision}, isbn = {9781728165530}, location = { Snowmass Village, CO, United States}, publisher = {IEEE}, title = {{Localizing grouped instances for efficient detection in low-resource scenarios}}, doi = {10.1109/WACV45572.2020.9093288}, year = {2020}, } @inproceedings{7937, abstract = {Fine-tuning is a popular way of exploiting knowledge contained in a pre-trained convolutional network for a new visual recognition task. However, the orthogonal setting of transferring knowledge from a pretrained network to a visually different yet semantically close source is rarely considered: This commonly happens with real-life data, which is not necessarily as clean as the training source (noise, geometric transformations, different modalities, etc.).To tackle such scenarios, we introduce a new, generalized form of fine-tuning, called flex-tuning, in which any individual unit (e.g. layer) of a network can be tuned, and the most promising one is chosen automatically. In order to make the method appealing for practical use, we propose two lightweight and faster selection procedures that prove to be good approximations in practice. We study these selection criteria empirically across a variety of domain shifts and data scarcity scenarios, and show that fine-tuning individual units, despite its simplicity, yields very good results as an adaptation technique. As it turns out, in contrast to common practice, rather than the last fully-connected unit it is best to tune an intermediate or early one in many domain- shift scenarios, which is accurately detected by flex-tuning.}, author = {Royer, Amélie and Lampert, Christoph}, booktitle = {2020 IEEE Winter Conference on Applications of Computer Vision}, isbn = {9781728165530}, location = {Snowmass Village, CO, United States}, publisher = {IEEE}, title = {{A flexible selection scheme for minimum-effort transfer learning}}, doi = {10.1109/WACV45572.2020.9093635}, year = {2020}, } @article{7940, abstract = {We prove that the Yangian associated to an untwisted symmetric affine Kac–Moody Lie algebra is isomorphic to the Drinfeld double of a shuffle algebra. The latter is constructed in [YZ14] as an algebraic formalism of cohomological Hall algebras. As a consequence, we obtain the Poincare–Birkhoff–Witt (PBW) theorem for this class of affine Yangians. Another independent proof of the PBW theorem is given recently by Guay, Regelskis, and Wendlandt [GRW18].}, author = {Yang, Yaping and Zhao, Gufang}, issn = {1531586X}, journal = {Transformation Groups}, pages = {1371--1385}, publisher = {Springer Nature}, title = {{The PBW theorem for affine Yangians}}, doi = {10.1007/s00031-020-09572-6}, volume = {25}, year = {2020}, } @article{7942, abstract = {An understanding of the missing antinodal electronic excitations in the pseudogap state is essential for uncovering the physics of the underdoped cuprate high-temperature superconductors1,2,3,4,5,6. The majority of high-temperature experiments performed thus far, however, have been unable to discern whether the antinodal states are rendered unobservable due to their damping or whether they vanish due to their gapping7,8,9,10,11,12,13,14,15,16,17,18. Here, we distinguish between these two scenarios by using quantum oscillations to examine whether the small Fermi surface pocket, found to occupy only 2% of the Brillouin zone in the underdoped cuprates19,20,21,22,23,24, exists in isolation against a majority of completely gapped density of states spanning the antinodes, or whether it is thermodynamically coupled to a background of ungapped antinodal states. We find that quantum oscillations associated with the small Fermi surface pocket exhibit a signature sawtooth waveform characteristic of an isolated two-dimensional Fermi surface pocket25,26,27,28,29,30,31,32. This finding reveals that the antinodal states are destroyed by a hard gap that extends over the majority of the Brillouin zone, placing strong constraints on a drastic underlying origin of quasiparticle disappearance over almost the entire Brillouin zone in the pseudogap regime7,8,9,10,11,12,13,14,15,16,17,18.}, author = {Hartstein, Máté and Hsu, Yu Te and Modic, Kimberly A and Porras, Juan and Loew, Toshinao and Tacon, Matthieu Le and Zuo, Huakun and Wang, Jinhua and Zhu, Zengwei and Chan, Mun K. and Mcdonald, Ross D. and Lonzarich, Gilbert G. and Keimer, Bernhard and Sebastian, Suchitra E. and Harrison, Neil}, issn = {17452481}, journal = {Nature Physics}, pages = {841--847}, publisher = {Springer Nature}, title = {{Hard antinodal gap revealed by quantum oscillations in the pseudogap regime of underdoped high-Tc superconductors}}, doi = {10.1038/s41567-020-0910-0}, volume = {16}, year = {2020}, } @phdthesis{7944, abstract = {This thesis considers two examples of reconfiguration problems: flipping edges in edge-labelled triangulations of planar point sets and swapping labelled tokens placed on vertices of a graph. In both cases the studied structures – all the triangulations of a given point set or all token placements on a given graph – can be thought of as vertices of the so-called reconfiguration graph, in which two vertices are adjacent if the corresponding structures differ by a single elementary operation – by a flip of a diagonal in a triangulation or by a swap of tokens on adjacent vertices, respectively. We study the reconfiguration of one instance of a structure into another via (shortest) paths in the reconfiguration graph. For triangulations of point sets in which each edge has a unique label and a flip transfers the label from the removed edge to the new edge, we prove a polynomial-time testable condition, called the Orbit Theorem, that characterizes when two triangulations of the same point set lie in the same connected component of the reconfiguration graph. The condition was first conjectured by Bose, Lubiw, Pathak and Verdonschot. We additionally provide a polynomial time algorithm that computes a reconfiguring flip sequence, if it exists. Our proof of the Orbit Theorem uses topological properties of a certain high-dimensional cell complex that has the usual reconfiguration graph as its 1-skeleton. In the context of token swapping on a tree graph, we make partial progress on the problem of finding shortest reconfiguration sequences. We disprove the so-called Happy Leaf Conjecture and demonstrate the importance of swapping tokens that are already placed at the correct vertices. We also prove that a generalization of the problem to weighted coloured token swapping is NP-hard on trees but solvable in polynomial time on paths and stars.}, author = {Masárová, Zuzana}, isbn = {978-3-99078-005-3}, issn = {2663-337X}, keywords = {reconfiguration, reconfiguration graph, triangulations, flip, constrained triangulations, shellability, piecewise-linear balls, token swapping, trees, coloured weighted token swapping}, pages = {160}, publisher = {Institute of Science and Technology Austria}, title = {{Reconfiguration problems}}, doi = {10.15479/AT:ISTA:7944}, year = {2020}, } @article{7948, abstract = {In agricultural systems, nitrate is the main source of nitrogen available for plants. Besides its role as a nutrient, nitrate has been shown to act as a signal molecule for plant growth, development and stress responses. In Arabidopsis, the NRT1.1 nitrate transceptor represses lateral root (LR) development at low nitrate availability by promoting auxin basipetal transport out of the LR primordia (LRPs). In addition, our present study shows that NRT1.1 acts as a negative regulator of the TAR2 auxin biosynthetic gene expression in the root stele. This is expected to repress local auxin biosynthesis and thus to reduce acropetal auxin supply to the LRPs. Moreover, NRT1.1 also negatively affects expression of the LAX3 auxin influx carrier, thus preventing cell wall remodeling required for overlying tissues separation during LRP emergence. Both NRT1.1-mediated repression of TAR2 and LAX3 are suppressed at high nitrate availability, resulting in the nitrate induction of TAR2 and LAX3 expression that is required for optimal stimulation of LR development by nitrate. Altogether, our results indicate that the NRT1.1 transceptor coordinately controls several crucial auxin-associated processes required for LRP development, and as a consequence that NRT1.1 plays a much more integrated role than previously anticipated in regulating the nitrate response of root system architecture.}, author = {Maghiaoui, A and Bouguyon, E and Cuesta, Candela and Perrine-Walker, F and Alcon, C and Krouk, G and Benková, Eva and Nacry, P and Gojon, A and Bach, L}, issn = {1460-2431}, journal = {Journal of Experimental Botany}, number = {15}, pages = {4480--4494}, publisher = {Oxford University Press}, title = {{The Arabidopsis NRT1.1 transceptor coordinately controls auxin biosynthesis and transport to regulate root branching in response to nitrate}}, doi = {10.1093/jxb/eraa242}, volume = {71}, year = {2020}, } @article{7949, abstract = {Peptides derived from non-functional precursors play important roles in various developmental processes, but also in (a)biotic stress signaling. Our (phospho)proteome-wide analyses of C-terminally encoded peptide 5 (CEP5)-mediated changes revealed an impact on abiotic stress-related processes. Drought has a dramatic impact on plant growth, development and reproduction, and the plant hormone auxin plays a role in drought responses. Our genetic, physiological, biochemical and pharmacological results demonstrated that CEP5-mediated signaling is relevant for osmotic and drought stress tolerance in Arabidopsis, and that CEP5 specifically counteracts auxin effects. Specifically, we found that CEP5 signaling stabilizes AUX/IAA transcriptional repressors, suggesting the existence of a novel peptide-dependent control mechanism that tunes auxin signaling. These observations align with the recently described role of AUX/IAAs in stress tolerance and provide a novel role for CEP5 in osmotic and drought stress tolerance.}, author = {Smith, S and Zhu, S and Joos, L and Roberts, I and Nikonorova, N and Vu, LD and Stes, E and Cho, H and Larrieu, A and Xuan, W and Goodall, B and van de Cotte, B and Waite, JM and Rigal, A and R Harborough, SR and Persiau, G and Vanneste, S and Kirschner, GK and Vandermarliere, E and Martens, L and Stahl, Y and Audenaert, D and Friml, Jiří and Felix, G and Simon, R and Bennett, M and Bishopp, A and De Jaeger, G and Ljung, K and Kepinski, S and Robert, S and Nemhauser, J and Hwang, I and Gevaert, K and Beeckman, T and De Smet, I}, issn = {1535-9484}, journal = {Molecular & Cellular Proteomics}, number = {8}, pages = {1248--1262}, publisher = {American Society for Biochemistry and Molecular Biology}, title = {{The CEP5 peptide promotes abiotic stress tolerance, as revealed by quantitative proteomics, and attenuates the AUX/IAA equilibrium in Arabidopsis}}, doi = {10.1074/mcp.ra119.001826}, volume = {19}, year = {2020}, } @inproceedings{7952, abstract = {Isomanifolds are the generalization of isosurfaces to arbitrary dimension and codimension, i.e. manifolds defined as the zero set of some multivariate vector-valued smooth function f: ℝ^d → ℝ^(d-n). A natural (and efficient) way to approximate an isomanifold is to consider its Piecewise-Linear (PL) approximation based on a triangulation 𝒯 of the ambient space ℝ^d. In this paper, we give conditions under which the PL-approximation of an isomanifold is topologically equivalent to the isomanifold. The conditions are easy to satisfy in the sense that they can always be met by taking a sufficiently fine triangulation 𝒯. This contrasts with previous results on the triangulation of manifolds where, in arbitrary dimensions, delicate perturbations are needed to guarantee topological correctness, which leads to strong limitations in practice. We further give a bound on the Fréchet distance between the original isomanifold and its PL-approximation. Finally we show analogous results for the PL-approximation of an isomanifold with boundary. }, author = {Boissonnat, Jean-Daniel and Wintraecken, Mathijs}, booktitle = {36th International Symposium on Computational Geometry}, isbn = {978-3-95977-143-6}, issn = {1868-8969}, location = {Zürich, Switzerland}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{The topological correctness of PL-approximations of isomanifolds}}, doi = {10.4230/LIPIcs.SoCG.2020.20}, volume = {164}, year = {2020}, } @inproceedings{7955, abstract = {Simple stochastic games are turn-based 2½-player games with a reachability objective. The basic question asks whether one player can ensure reaching a given target with at least a given probability. A natural extension is games with a conjunction of such conditions as objective. Despite a plethora of recent results on the analysis of systems with multiple objectives, the decidability of this basic problem remains open. In this paper, we present an algorithm approximating the Pareto frontier of the achievable values to a given precision. Moreover, it is an anytime algorithm, meaning it can be stopped at any time returning the current approximation and its error bound.}, author = {Ashok, Pranav and Chatterjee, Krishnendu and Kretinsky, Jan and Weininger, Maximilian and Winkler, Tobias}, booktitle = {Proceedings of the 35th Annual ACM/IEEE Symposium on Logic in Computer Science }, isbn = {9781450371049}, location = {Saarbrücken, Germany}, pages = {102--115}, publisher = {Association for Computing Machinery}, title = {{Approximating values of generalized-reachability stochastic games}}, doi = {10.1145/3373718.3394761}, year = {2020}, } @article{7956, abstract = {When short-range attractions are combined with long-range repulsions in colloidal particle systems, complex microphases can emerge. Here, we study a system of isotropic particles, which can form lamellar structures or a disordered fluid phase when temperature is varied. We show that, at equilibrium, the lamellar structure crystallizes, while out of equilibrium, the system forms a variety of structures at different shear rates and temperatures above melting. The shear-induced ordering is analyzed by means of principal component analysis and artificial neural networks, which are applied to data of reduced dimensionality. Our results reveal the possibility of inducing ordering by shear, potentially providing a feasible route to the fabrication of ordered lamellar structures from isotropic particles.}, author = {Pȩkalski, J. and Rzadkowski, Wojciech and Panagiotopoulos, A. Z.}, issn = {10897690}, journal = {The Journal of chemical physics}, number = {20}, publisher = {AIP Publishing}, title = {{Shear-induced ordering in systems with competing interactions: A machine learning study}}, doi = {10.1063/5.0005194}, volume = {152}, year = {2020}, } @article{7957, abstract = {Neurodevelopmental disorders (NDDs) are a class of disorders affecting brain development and function and are characterized by wide genetic and clinical variability. In this review, we discuss the multiple factors that influence the clinical presentation of NDDs, with particular attention to gene vulnerability, mutational load, and the two-hit model. Despite the complex architecture of mutational events associated with NDDs, the various proteins involved appear to converge on common pathways, such as synaptic plasticity/function, chromatin remodelers and the mammalian target of rapamycin (mTOR) pathway. A thorough understanding of the mechanisms behind these pathways will hopefully lead to the identification of candidates that could be targeted for treatment approaches.}, author = {Parenti, Ilaria and Garcia Rabaneda, Luis E and Schön, Hanna and Novarino, Gaia}, issn = {1878108X}, journal = {Trends in Neurosciences}, number = {8}, pages = {608--621}, publisher = {Elsevier}, title = {{Neurodevelopmental disorders: From genetics to functional pathways}}, doi = {10.1016/j.tins.2020.05.004}, volume = {43}, year = {2020}, } @article{7960, abstract = {Let A={A1,…,An} be a family of sets in the plane. For 0≤i2b be integers. We prove that if each k-wise or (k+1)-wise intersection of sets from A has at most b path-connected components, which all are open, then fk+1=0 implies fk≤cfk−1 for some positive constant c depending only on b and k. These results also extend to two-dimensional compact surfaces.}, author = {Kalai, Gil and Patakova, Zuzana}, issn = {14320444}, journal = {Discrete and Computational Geometry}, pages = {304--323}, publisher = {Springer Nature}, title = {{Intersection patterns of planar sets}}, doi = {10.1007/s00454-020-00205-z}, volume = {64}, year = {2020}, } @article{7962, abstract = {A string graph is the intersection graph of a family of continuous arcs in the plane. The intersection graph of a family of plane convex sets is a string graph, but not all string graphs can be obtained in this way. We prove the following structure theorem conjectured by Janson and Uzzell: The vertex set of almost all string graphs on n vertices can be partitioned into five cliques such that some pair of them is not connected by any edge (n→∞). We also show that every graph with the above property is an intersection graph of plane convex sets. As a corollary, we obtain that almost all string graphs on n vertices are intersection graphs of plane convex sets.}, author = {Pach, János and Reed, Bruce and Yuditsky, Yelena}, issn = {14320444}, journal = {Discrete and Computational Geometry}, number = {4}, pages = {888--917}, publisher = {Springer Nature}, title = {{Almost all string graphs are intersection graphs of plane convex sets}}, doi = {10.1007/s00454-020-00213-z}, volume = {63}, year = {2020}, } @inproceedings{7966, abstract = {For 1≤m≤n, we consider a natural m-out-of-n multi-instance scenario for a public-key encryption (PKE) scheme. An adversary, given n independent instances of PKE, wins if he breaks at least m out of the n instances. In this work, we are interested in the scaling factor of PKE schemes, SF, which measures how well the difficulty of breaking m out of the n instances scales in m. That is, a scaling factor SF=ℓ indicates that breaking m out of n instances is at least ℓ times more difficult than breaking one single instance. A PKE scheme with small scaling factor hence provides an ideal target for mass surveillance. In fact, the Logjam attack (CCS 2015) implicitly exploited, among other things, an almost constant scaling factor of ElGamal over finite fields (with shared group parameters). For Hashed ElGamal over elliptic curves, we use the generic group model to argue that the scaling factor depends on the scheme's granularity. In low granularity, meaning each public key contains its independent group parameter, the scheme has optimal scaling factor SF=m; In medium and high granularity, meaning all public keys share the same group parameter, the scheme still has a reasonable scaling factor SF=√m. Our findings underline that instantiating ElGamal over elliptic curves should be preferred to finite fields in a multi-instance scenario. As our main technical contribution, we derive new generic-group lower bounds of Ω(√(mp)) on the difficulty of solving both the m-out-of-n Gap Discrete Logarithm and the m-out-of-n Gap Computational Diffie-Hellman problem over groups of prime order p, extending a recent result by Yun (EUROCRYPT 2015). We establish the lower bound by studying the hardness of a related computational problem which we call the search-by-hypersurface problem.}, author = {Auerbach, Benedikt and Giacon, Federico and Kiltz, Eike}, booktitle = {Advances in Cryptology – EUROCRYPT 2020}, isbn = {9783030457266}, issn = {1611-3349}, pages = {475--506}, publisher = {Springer Nature}, title = {{Everybody’s a target: Scalability in public-key encryption}}, doi = {10.1007/978-3-030-45727-3_16}, volume = {12107}, year = {2020}, } @article{7968, abstract = {Organic materials are known to feature long spin-diffusion times, originating in a generally small spin–orbit coupling observed in these systems. From that perspective, chiral molecules acting as efficient spin selectors pose a puzzle that attracted a lot of attention in recent years. Here, we revisit the physical origins of chiral-induced spin selectivity (CISS) and propose a simple analytic minimal model to describe it. The model treats a chiral molecule as an anisotropic wire with molecular dipole moments aligned arbitrarily with respect to the wire’s axes and is therefore quite general. Importantly, it shows that the helical structure of the molecule is not necessary to observe CISS and other chiral nonhelical molecules can also be considered as potential candidates for the CISS effect. We also show that the suggested simple model captures the main characteristics of CISS observed in the experiment, without the need for additional constraints employed in the previous studies. The results pave the way for understanding other related physical phenomena where the CISS effect plays an essential role.}, author = {Ghazaryan, Areg and Paltiel, Yossi and Lemeshko, Mikhail}, issn = {1932-7455}, journal = {The Journal of Physical Chemistry C}, number = {21}, pages = {11716--11721}, publisher = {American Chemical Society}, title = {{Analytic model of chiral-induced spin selectivity}}, doi = {10.1021/acs.jpcc.0c02584}, volume = {124}, year = {2020}, } @article{7971, abstract = {Multilayer graphene lattices allow for an additional tunability of the band structure by the strong perpendicular electric field. In particular, the emergence of the new multiple Dirac points in ABA stacked trilayer graphene subject to strong transverse electric fields was proposed theoretically and confirmed experimentally. These new Dirac points dubbed “gullies” emerge from the interplay between strong electric field and trigonal warping. In this work, we first characterize the properties of new emergent Dirac points and show that the electric field can be used to tune the distance between gullies in the momentum space. We demonstrate that the band structure has multiple Lifshitz transitions and higher-order singularity of “monkey saddle” type. Following the characterization of the band structure, we consider the spectrum of Landau levels and structure of their wave functions. In the limit of strong electric fields when gullies are well separated in momentum space, they give rise to triply degenerate Landau levels. In the second part of this work, we investigate how degeneracy between three gully Landau levels is lifted in the presence of interactions. Within the Hartree-Fock approximation we show that the symmetry breaking state interpolates between the fully gully polarized state that breaks C3 symmetry at high displacement field and the gully symmetric state when the electric field is decreased. The discontinuous transition between these two states is driven by enhanced intergully tunneling and exchange. We conclude by outlining specific experimental predictions for the existence of such a symmetry-breaking state.}, author = {Rao, Peng and Serbyn, Maksym}, issn = {2469-9969}, journal = {Physical Review B}, number = {24}, publisher = {American Physical Society}, title = {{Gully quantum Hall ferromagnetism in biased trilayer graphene}}, doi = {10.1103/physrevb.101.245411}, volume = {101}, year = {2020}, } @article{7985, abstract = {The goal of limiting global warming to 1.5 °C requires a drastic reduction in CO2 emissions across many sectors of the world economy. Batteries are vital to this endeavor, whether used in electric vehicles, to store renewable electricity, or in aviation. Present lithium-ion technologies are preparing the public for this inevitable change, but their maximum theoretical specific capacity presents a limitation. Their high cost is another concern for commercial viability. Metal–air batteries have the highest theoretical energy density of all possible secondary battery technologies and could yield step changes in energy storage, if their practical difficulties could be overcome. The scope of this review is to provide an objective, comprehensive, and authoritative assessment of the intensive work invested in nonaqueous rechargeable metal–air batteries over the past few years, which identified the key problems and guides directions to solve them. We focus primarily on the challenges and outlook for Li–O2 cells but include Na–O2, K–O2, and Mg–O2 cells for comparison. Our review highlights the interdisciplinary nature of this field that involves a combination of materials chemistry, electrochemistry, computation, microscopy, spectroscopy, and surface science. The mechanisms of O2 reduction and evolution are considered in the light of recent findings, along with developments in positive and negative electrodes, electrolytes, electrocatalysis on surfaces and in solution, and the degradative effect of singlet oxygen, which is typically formed in Li–O2 cells.}, author = {Kwak, WJ and Sharon, D and Xia, C and Kim, H and Johnson, LR and Bruce, PG and Nazar, LF and Sun, YK and Frimer, AA and Noked, M and Freunberger, Stefan Alexander and Aurbach, D}, issn = {1520-6890}, journal = {Chemical Reviews}, number = {14}, pages = {6626--6683}, publisher = {American Chemical Society}, title = {{Lithium-oxygen batteries and related systems: Potential, status, and future}}, doi = {10.1021/acs.chemrev.9b00609}, volume = {120}, year = {2020}, }