@article{17945, abstract = {We perform temperature dependent conductance measurements on sub-nanometer sized single molecules bound to gold electrodes using a scanning tunneling microscope-based break junction technique in Ultra-High Vacuum (UHV). We find a threefold increase in the conductance of amine-terminated conjugated molecules when the temperature increases from 4 K to 300 K in UHV. Furthermore, the conductance measured at 300 K in UHV is consistent with solution-based measurements under ambient conditions where the transport mechanism corresponds to off-resonant electron tunneling across the molecule. Our measurements indicate that at 300 K, conductance is largely independent of pressure or solvent around the junction. In addition, our data unambiguously show that temperature can affect the tunneling conductance of single molecule-metal junctions. We show that the structure of the metal electrodes that form in these junctions varies systematically with temperature, and hypothesize that this changing structure of the interface alters electron tunneling probability and propose a mechanism to explain our findings.}, author = {Kamenetska, M. and Widawsky, J. R. and Dell’Angela, M. and Frei, M. and Venkataraman, Latha}, issn = {1089-7690}, journal = {The Journal of Chemical Physics}, number = {9}, publisher = {AIP Publishing}, title = {{Temperature dependent tunneling conductance of single molecule junctions}}, doi = {10.1063/1.4973318}, volume = {146}, year = {2017}, } @article{17947, abstract = {We investigate light-induced conductance enhancement in single-molecule junctions via photon-assisted transport and hot-electron transport. Using 4,4′-bipyridine bound to Au electrodes as a prototypical single-molecule junction, we report a 20–40% enhancement in conductance under illumination with 980 nm wavelength radiation. We probe the effects of subtle changes in the transmission function on light-enhanced current and show that discrete variations in the binding geometry result in a 10% change in enhancement. Importantly, we prove theoretically that the steady-state behavior of photon-assisted transport and hot-electron transport is identical but that hot-electron transport is the dominant mechanism for optically induced conductance enhancement in single-molecule junctions when the wavelength used is absorbed by the electrodes and the hot-electron relaxation time is long. We confirm this experimentally by performing polarization-dependent conductance measurements of illuminated 4,4′-bipyridine junctions. Finally, we perform lock-in type measurements of optical current and conclude that currents due to laser-induced thermal expansion mask optical currents. This work provides a robust experimental framework for studying mechanisms of light-enhanced transport in single-molecule junctions and offers tools for tuning the performance of organic optoelectronic devices by analyzing detailed transport properties of the molecules involved.}, author = {Fung, E-Dean and Adak, Olgun and Lovat, Giacomo and Scarabelli, Diego and Venkataraman, Latha}, issn = {1530-6992}, journal = {Nano Letters}, number = {2}, pages = {1255--1261}, publisher = {American Chemical Society}, title = {{Too hot for photon-assisted transport: Hot-electrons dominate conductance enhancement in illuminated single-molecule junctions}}, doi = {10.1021/acs.nanolett.6b05091}, volume = {17}, year = {2017}, } @article{17949, abstract = {Single-molecule electronic devices provide researchers with an unprecedented ability to relate novel physical phenomena to molecular chemical structures. Typically, conjugated aromatic molecular backbones are relied upon to create electronic devices, where the aromaticity of the building blocks is used to enhance conductivity. We capitalize on the classical physical organic chemistry concept of Hückel antiaromaticity by demonstrating a single-molecule switch that exhibits low conductance in the neutral state and, upon electrochemical oxidation, reversibly switches to an antiaromatic high-conducting structure. We form single-molecule devices using the scanning tunneling microscope–based break-junction technique and observe an on/off ratio of ~70 for a thiophenylidene derivative that switches to an antiaromatic state with 6-4-6-π electrons. Through supporting nuclear magnetic resonance measurements, we show that the doubly oxidized core has antiaromatic character and we use density functional theory calculations to rationalize the origin of the high-conductance state for the oxidized single-molecule junction. Together, our work demonstrates how the concept of antiaromaticity can be exploited to create single-molecule devices that are highly conducting.}, author = {Yin, Xiaodong and Zang, Yaping and Zhu, Liangliang and Low, Jonathan Z. and Liu, Zhen-Fei and Cui, Jing and Neaton, Jeffrey B. and Venkataraman, Latha and Campos, Luis M.}, issn = {2375-2548}, journal = {Science Advances}, number = {10}, publisher = {American Association for the Advancement of Science}, title = {{A reversible single-molecule switch based on activated antiaromaticity}}, doi = {10.1126/sciadv.aao2615}, volume = {3}, year = {2017}, } @article{17950, abstract = {Whilst most studies in single-molecule electronics involve components first synthesized ex situ, there is also great potential in exploiting chemical transformations to prepare devices in situ. Here, as a first step towards this goal, we conduct reversible reactions on monolayers to make and break covalent bonds between alkanes of different lengths, then measure the conductance of these molecules connected between electrodes using the scanning tunneling microscopy-based break junction (STM-BJ) method. In doing so, we develop the critical methodology required for assembling and disassembling surface-bound single-molecule circuits. We identify effective reaction conditions for surface-bound reagents, and importantly demonstrate that the electronic characteristics of wires created in situ agree with those created ex situ. Finally, we show that the STM-BJ technique is unique in its ability to definitively probe surface reaction yields both on a local (∼50 nm2) and pseudo-global (≥10 mm2) level. This investigation thus highlights a route to the construction and integration of more complex, and ultimately functional, surface-based single-molecule circuitry, as well as advancing a methodology that facilitates studies beyond the reach of traditional ex situ synthetic approaches.}, author = {Inkpen, Michael S. and Leroux, Yann R. and Hapiot, Philippe and Campos, Luis M. and Venkataraman, Latha}, issn = {2041-6539}, journal = {Chemical Science}, number = {6}, pages = {4340--4346}, publisher = {Royal Society of Chemistry}, title = {{Reversible on-surface wiring of resistive circuits}}, doi = {10.1039/c7sc00599g}, volume = {8}, year = {2017}, } @article{17951, abstract = {Thiophene-1,1-dioxide (TDO) oligomers have fascinating electronic properties. We previously used thermopower measurements to show that a change in charge carrier from hole to electron occurs with increasing length of TDO oligomers when single-molecule junctions are formed between gold electrodes. In this article, we show for the first time that the dominant conducting orbitals for thiophene/TDO oligomers of fixed length can be tuned by altering the strength of the electron acceptors incorporated into the backbone. We use the scanning tunneling microscope break-junction (STM-BJ) technique and apply a recently developed method to determine the dominant transport channel in single-molecule junctions formed with these systems. Through these measurements, we find that increasing the electron affinity of thiophene derivatives, within a family of pentamers, changes the polarity of the charge carriers systematically from holes to electrons, with some systems even showing mid-gap transport characteristics.}, author = {Low, Jonathan Z. and Capozzi, Brian and Cui, Jing and Wei, Sujun and Venkataraman, Latha and Campos, Luis M.}, issn = {2041-6539}, journal = {Chemical Science}, number = {4}, pages = {3254--3259}, publisher = {Royal Society of Chemistry}, title = {{Tuning the polarity of charge carriers using electron deficient thiophenes}}, doi = {10.1039/c6sc05283e}, volume = {8}, year = {2017}, } @article{18198, abstract = {Higgs and Goldstone modes are collective excitations of the amplitude and phase of an order parameter that is related to the breaking of a continuous symmetry. We directly studied these modes in a supersolid quantum gas created by coupling a Bose-Einstein condensate to two optical cavities, whose field amplitudes form the real and imaginary parts of a U(1)-symmetric order parameter. Monitoring the cavity fields in real time allowed us to observe the dynamics of the associated Higgs and Goldstone modes and revealed their amplitude and phase nature. We used a spectroscopic method to measure their frequencies, and we gave a tunable mass to the Goldstone mode by exploring the crossover between continuous and discrete symmetry. Our experiments link spectroscopic measurements to the theoretical concept of Higgs and Goldstone modes.}, author = {Leonard, Julian and Morales, Andrea and Zupancic, Philip and Donner, Tobias and Esslinger, Tilman}, issn = {1095-9203}, journal = {Science}, number = {6369}, pages = {1415--1418}, publisher = {American Association for the Advancement of Science}, title = {{Monitoring and manipulating Higgs and Goldstone modes in a supersolid quantum gas}}, doi = {10.1126/science.aan2608}, volume = {358}, year = {2017}, } @article{18199, abstract = {The concept of a supersolid state combines the crystallization of a many-body system with dissipationless flow of the atoms from which it is built. This quantum phase requires the breaking of two continuous symmetries: the phase invariance of a superfluid and the continuous translational invariance to form the crystal1,2. Despite having been proposed for helium almost 50 years ago3,4, experimental verification of supersolidity remains elusive5,6. A variant with only discrete translational symmetry breaking on a preimposed lattice structure—the ‘lattice supersolid’7—has been realized, based on self-organization of a Bose–Einstein condensate8,9. However, lattice supersolids do not feature the continuous ground-state degeneracy that characterizes the supersolid state as originally proposed. Here we report the realization of a supersolid with continuous translational symmetry breaking along one direction in a quantum gas. The continuous symmetry that is broken emerges from two discrete spatial symmetries by symmetrically coupling a Bose–Einstein condensate to the modes of two optical cavities. We establish the phase coherence of the supersolid and find a high ground-state degeneracy by measuring the crystal position over many realizations through the light fields that leak from the cavities. These light fields are also used to monitor the position fluctuations in real time. Our concept provides a route to creating and studying glassy many-body systems with controllably lifted ground-state degeneracies, such as supersolids in the presence of disorder.}, author = {Leonard, Julian and Morales, Andrea and Zupancic, Philip and Esslinger, Tilman and Donner, Tobias}, issn = {0028-0836}, journal = {Nature}, number = {7643}, pages = {87--90}, publisher = {Springer Science and Business Media LLC}, title = {{Supersolid formation in a quantum gas breaking a continuous translational symmetry}}, doi = {10.1038/nature21067}, volume = {543}, year = {2017}, } @inproceedings{18286, abstract = {We introduce a new framework for learning dense correspondence between deformable 3D shapes. Existing learning based approaches model shape correspondence as a labelling problem, where each point of a query shape receives a label identifying a point on some reference domain; the correspondence is then constructed a posteriori by composing the label predictions of two input shapes. We propose a paradigm shift and design a structured prediction model in the space of functional maps, linear operators that provide a compact representation of the correspondence. We model the learning process via a deep residual network which takes dense descriptor fields defined on two shapes as input, and outputs a soft map between the two given objects. The resulting correspondence is shown to be accurate on several challenging benchmarks comprising multiple categories, synthetic models, real scans with acquisition artifacts, topological noise, and partiality.}, author = {Litany, Or and Remez, Tal and Rodola, Emanuele and Bronstein, Alexander and Bronstein, Michael}, booktitle = {2017 IEEE International Conference on Computer Vision (ICCV)}, issn = {9781538610329}, publisher = {IEEE}, title = {{Deep functional maps: Structured prediction for dense shape correspondence}}, doi = {10.1109/iccv.2017.603}, volume = {31}, year = {2017}, } @inproceedings{18287, abstract = {Many algorithms for the computation of correspondences between deformable shapes rely on some variant of nearest neighbor matching in a descriptor space. Such are, for example, various point-wise correspondence recovery algorithms used as a post-processing stage in the functional correspondence framework. Such frequently used techniques implicitly make restrictive assumptions (e.g., nearisometry) on the considered shapes and in practice suffer from lack of accuracy and result in poor surjectivity. We propose an alternative recovery technique capable of guaranteeing a bijective correspondence and producing significantly higher accuracy and smoothness. Unlike other methods our approach does not depend on the assumption that the analyzed shapes are isometric. We derive the proposed method from the statistical framework of kernel density estimation and demonstrate its performance on several challenging deformable 3D shape matching datasets.}, author = {Vestner, Matthias and Litman, Roee and Rodola, Emanuele and Bronstein, Alexander and Cremers, Daniel}, booktitle = {2017 IEEE Conference on Computer Vision and Pattern Recognition (CVPR)}, isbn = {9781538604588}, issn = {1063-6919}, location = {Honolulu, HI, United States}, pages = {6681 -- 6690}, publisher = {IEEE}, title = {{Product manifold filter: Non-rigid shape correspondence via kernel density estimation in the product space}}, doi = {10.1109/cvpr.2017.707}, year = {2017}, } @inproceedings{18288, abstract = {The increasing demand for high image quality in mobile devices brings forth the need for better computational enhancement techniques, and image denoising in particular. To this end, we propose a new fully convolutional deep neural network architecture which is simple yet powerful and achieves state-of-the-art performance for additive Gaussian noise removal. Furthermore, we claim that the personal photo-collections can usually be categorized into a small set of semantic classes. However simple, this observation has not been exploited in image denoising until now. We show that a significant boost in performance of up to 0.4dB PSNR can be achieved by making our network class-aware, namely, by fine-tuning it for images belonging to a specific semantic class. Relying on the hugely successful existing image classifiers, this research advocates for using a class-aware approach in all image enhancement tasks.}, author = {Remez, Tal and Litany, Or and Giryes, Raja and Bronstein, Alexander}, booktitle = {2017 International Conference on Sampling Theory and Applications (SampTA)}, location = {Tallinn, Estonia}, publisher = {IEEE}, title = {{Deep class-aware image denoising}}, doi = {10.1109/sampta.2017.8024474}, year = {2017}, } @inproceedings{18329, abstract = {Multidimensional Scaling (MDS) is one of the most popular methods for dimensionality reduction and visualization of high dimensional data. Apart from these tasks, it also found applications in the field of geometry processing for the analysis and reconstruction of non-rigid shapes. In this regard, MDS can be thought of as a shape from metric algorithm, consisting of finding a configuration of points in the Euclidean space that realize, as isometrically as possible, some given distance structure. In the present work we cast the least squares variant of MDS (LS-MDS) in the spectral domain. This uncovers a multiresolution property of distance scaling which speeds up the optimization by a significant amount, while producing comparable, and sometimes even better, embeddings.}, author = {Boyarski, Amit and Bronstein, Alexander and Bronstein, Michael M.}, booktitle = {International Conference on Scale Space and Variational Methods in Computer Vision}, isbn = {9783319587707}, issn = {1611-3349}, location = {Kolding, Denmark}, pages = {681--693}, publisher = {Springer Nature}, title = {{Subspace least squares multidimensional scaling}}, doi = {10.1007/978-3-319-58771-4_54}, volume = {10302}, year = {2017}, } @inproceedings{18330, abstract = {With increasingly sophisticated Diffusion Weighted MRI acquisition methods and modeling techniques, very large sets of streamlines (fibers) are presently generated per imaged brain. These reconstructions of white matter architecture, which are important for human brain research and pre-surgical planning, require a large amount of storage and are often unwieldy and difficult to manipulate and analyze. This work proposes a novel continuous parsimonious framework in which signals are sparsely represented in a dictionary with continuous atoms. The significant innovation in our new methodology is the ability to train such continuous dictionaries, unlike previous approaches that either used pre-fixed continuous transforms or training with finite atoms. This leads to an innovative fiber representation method, which uses Continuous Dictionary Learning to sparsely code each fiber with high accuracy. This method is tested on numerous tractograms produced from the Human Connectome Project data and achieves state-of-the-art performances in compression ratio and reconstruction error.}, author = {Alexandroni, Guy and Podolsky, Yana and Greenspan, Hayit and Remez, Tal and Litany, Or and Bronstein, Alexander and Giryes, Raja}, booktitle = {20th International Conference on Medical Image Computing and Computer-Assisted Intervention}, isbn = {9783319661810}, issn = {1611-3349}, location = {Quebec City, QC, Canada}, number = {Part 1}, pages = {566 -- 574}, publisher = {Springer Nature}, title = {{White matter fiber representation using continuous dictionary learning}}, doi = {10.1007/978-3-319-66182-7_65}, volume = {10433}, year = {2017}, } @article{18366, abstract = {We present ASIST, a technique for transforming point clouds by replacing objects with their semantically equivalent counterparts. Transformations of this kind have applications in virtual reality, repair of fused scans, and robotics. ASIST is based on a unified formulation of semantic labeling and object replacement; both result from minimizing a single objective. We present numerical tools for the efficient solution of this optimization problem. The method is experimentally assessed on new datasets of both synthetic and real point clouds, and is additionally compared to two recent works on object replacement on data from the corresponding papers.}, author = {Litany, Or and Remez, Tal and Freedman, Daniel and Shapira, Lior and Bronstein, Alexander and Gal, Ran}, issn = {1077-3142}, journal = {Computer Vision and Image Understanding}, pages = {284--299}, publisher = {Elsevier}, title = {{ASIST: Automatic semantically invariant scene transformation}}, doi = {10.1016/j.cviu.2016.08.002}, volume = {157}, year = {2017}, } @article{18372, abstract = {The sliding clamp, PCNA, plays a central role in DNA replication and repair. In the moving replication fork, PCNA is present at the leading strand and at each of the Okazaki fragments that are formed on the lagging strand. PCNA enhances the processivity of the replicative polymerases and provides a landing platform for other proteins and enzymes. The loading of the clamp onto DNA is performed by the Replication Factor C (RFC) complex, whereas its unloading can be carried out by an RFC-like complex containing Elg1. Mutations in ELG1 lead to DNA damage sensitivity and genome instability. To characterize the role of Elg1 in maintaining genomic integrity, we used homology modeling to generate a number of site-specific mutations in ELG1 that exhibit different PCNA unloading capabilities. We show that the sensitivity to DNA damaging agents and hyper-recombination of these alleles correlate with their ability to unload PCNA from the chromatin. Our results indicate that retention of modified and unmodified PCNA on the chromatin causes genomic instability. We also show, using purified proteins, that the Elg1 complex inhibits DNA synthesis by unloading SUMOylated PCNA from the DNA. Additionally, we find that mutations in ELG1 suppress the sensitivity of rad5Δ mutants to DNA damage by allowing trans-lesion synthesis to take place. Taken together, the data indicate that the Elg1–RLC complex plays an important role in the maintenance of genomic stability by unloading PCNA from the chromatin.}, author = {Shemesh, Keren and Sebesta, Marek and Pacesa, Martin and Sau, Soumitra and Bronstein, Alexander and Parnas, Oren and Liefshitz, Batia and Venclovas, Česlovas and Krejci, Lumir and Kupiec, Martin}, issn = {0305-1048}, journal = {Nucleic Acids Research}, number = {6}, pages = {3189 -- 3203}, publisher = {Oxford University Press (OUP)}, title = {{A structure-function analysis of the yeast Elg1 protein reveals the importance of PCNA unloading in genome stability maintenance}}, doi = {10.1093/nar/gkw1348}, volume = {45}, year = {2017}, } @inproceedings{18403, abstract = {Recent studies validated the feasibility of estimating heart rate from human faces in RGB video. However, test subjects are often recorded under controlled conditions, as illumination variations significantly affect the RGB-based heart rate estimation accuracy. Intel newly-announced low-cost RealSense 3D (RGBD) camera is becoming ubiquitous in laptops and mobile devices starting this year, opening the door to new and more robust computer vision. RealSense cameras produce RGB images with extra depth information inferred from a latent near-infrared (NIR) channel. In this paper, we experimentally demonstrate, for the first time, that heart rate can be reliably estimated from RealSense near-infrared images. This enables illumination invariant heart rate estimation, extending the heart rate from video feasibility to low-light applications, such as night driving. With the (coming) ubiquitous presence of RealSense devices, the proposed method not only utilizes its near-infrared channel, designed originally to be hidden from consumers; but also exploits the associated depth information for improved robustness to head pose.}, author = {Chen, Jie and Chang, Zhuoqing and Qiu, Qiang and Li, Xiaobai and Sapiro, Guillermo and Bronstein, Alexander and Pietikainen, Matti}, booktitle = {2016 Sixth International Conference on Image Processing Theory, Tools and Applications (IPTA)}, isbn = {9781467389112}, issn = {2154-512X}, location = {Oulu, Finland}, publisher = {IEEE}, title = {{RealSense = real heart rate: Illumination invariant heart rate estimation from videos}}, doi = {10.1109/ipta.2016.7820970}, year = {2017}, } @article{18427, abstract = {We propose an efficient procedure for calculating partial dense intrinsic correspondence between deformable shapes performed entirely in the spectral domain. Our technique relies on the recently introduced partial functional maps formalism and on the joint approximate diagonalization (JAD) of the Laplace-Beltrami operators previously introduced for matching non-isometric shapes. We show that a variant of the JAD problem with an appropriately modified coupling term (surprisingly) allows to construct quasi-harmonic bases localized on the latent corresponding parts. This circumvents the need to explicitly compute the unknown parts by means of the cumbersome alternating minimization used in the previous approaches, and allows performing all the calculations in the spectral domain with constant complexity independent of the number of shape vertices. We provide an extensive evaluation of the proposed technique on standard non-rigid correspondence benchmarks and show state-of-the-art performance in various settings, including partiality and the presence of topological noise.}, author = {Litany, O. and Rodolà, E. and Bronstein, Alexander and Bronstein, M. M.}, issn = {1467-8659}, journal = {Computer Graphics Forum}, number = {2}, pages = {247--258}, publisher = {Wiley}, title = {{Fully spectral partial shape matching}}, doi = {10.1111/cgf.13123}, volume = {36}, year = {2017}, } @inproceedings{18435, abstract = {Notions of similarity and correspondence between geometric shapes and images are central to many tasks in geometry processing, computer vision, and computer graphics. The goal of this course is to familiarize the audience with a set of recent techniques that greatly facilitate the computation of mappings or correspondences between geometric datasets, such as 3D shapes or 2D images by formulating them as mappings between functions rather than points or triangles. Methods based on the functional map framework have recently led to state-of-the-art results in problems as diverse as non-rigid shape matching, image co-segmentation and even some aspects of tangent vector field design. One challenge in adopting these methods in practice, however, is that their exposition often assumes a significant amount of background in geometry processing, spectral methods and functional analysis, which can make it difficult to gain an intuition about their performance or about their applicability to real-life problems. In this course, we try to provide all the tools necessary to appreciate and use these techniques, while assuming very little background knowledge. We also give a unifying treatment of these techniques, which may be difficult to extract from the individual publications and, at the same time, hint at the generality of this point of view, which can help tackle many problems in the analysis and creation of visual content. This course is structured as a half day course. We will assume that the participants have knowledge of basic linear algebra and some knowledge of differential geometry, to the extent of being familiar with the concepts of a manifold and a tangent vector space. We will discuss in detail the functional approach to finding correspondences between non-rigid shapes, the design and analysis of tangent vector fields on surfaces, consistent map estimation in networks of shapes and applications to shape and image segmentation, shape variability analysis, and other areas.}, author = {Ovsjanikov, Maks and Corman, Etienne and Bronstein, Michael and Rodolà, Emanuele and Ben-Chen, Mirela and Guibas, Leonidas and Chazal, Frederic and Bronstein, Alexander}, booktitle = {ACM SIGGRAPH 2017 Courses}, isbn = {9781450350143}, location = {Los Angeles, CA, United States}, publisher = {ACM}, title = {{Computing and processing correspondences with functional maps}}, doi = {10.1145/3084873.3084877}, year = {2017}, } @article{1228, abstract = {Since 2006, reprogrammed cells have increasingly been used as a biomedical research technique in addition to neuro-psychiatric methods. These rapidly evolving techniques allow for the generation of neuronal sub-populations, and have sparked interest not only in monogenetic neuro-psychiatric diseases, but also in poly-genetic and poly-aetiological disorders such as schizophrenia (SCZ) and bipolar disorder (BPD). This review provides a summary of 19 publications on reprogrammed adult somatic cells derived from patients with SCZ, and five publications using this technique in patients with BPD. As both disorders are complex and heterogeneous, there is a plurality of hypotheses to be tested in vitro. In SCZ, data on alterations of dopaminergic transmission in vitro are sparse, despite the great explanatory power of the so-called DA hypothesis of SCZ. Some findings correspond to perturbations of cell energy metabolism, and observations in reprogrammed cells suggest neuro-developmental alterations. Some studies also report on the efficacy of medicinal compounds to revert alterations observed in cellular models. However, due to the paucity of replication studies, no comprehensive conclusions can be drawn from studies using reprogrammed cells at the present time. In the future, findings from cell culture methods need to be integrated with clinical, epidemiological, pharmacological and imaging data in order to generate a more comprehensive picture of SCZ and BPD.}, author = {Sauerzopf, Ulrich and Sacco, Roberto and Novarino, Gaia and Niello, Marco and Weidenauer, Ana and Praschak Rieder, Nicole and Sitte, Harald and Willeit, Matthaeus}, journal = {European Journal of Neuroscience}, number = {1}, pages = {45 -- 57}, publisher = {Wiley-Blackwell}, title = {{Are reprogrammed cells a useful tool for studying dopamine dysfunction in psychotic disorders? A review of the current evidence}}, doi = {10.1111/ejn.13418}, volume = {45}, year = {2017}, } @article{123, abstract = {The Leidenfrost effect occurs when an object near a hot surface vaporizes rapidly enough to lift itself up and hover. Although well understood for liquids and stiff sublimable solids, nothing is known about the effect with materials whose stiffness lies between these extremes. Here we introduce a new phenomenon that occurs with vaporizable soft solids - the elastic Leidenfrost effect. By dropping hydrogel spheres onto hot surfaces we find that, rather than hovering, they energetically bounce several times their diameter for minutes at a time. With high-speed video during a single impact, we uncover high-frequency microscopic gap dynamics at the sphere/substrate interface. We show how these otherwise-hidden agitations constitute work cycles that harvest mechanical energy from the vapour and sustain the bouncing. Our findings suggest a new strategy for injecting mechanical energy into a widely used class of soft materials, with potential relevance to fields such as active matter, soft robotics and microfluidics.}, author = {Waitukaitis, Scott R and Zuiderwijk, Antal and Souslov, Anton and Coulais, Corentin and Van Hecke, Martin}, journal = {Nature Physics}, number = {11}, pages = {1095 -- 1099}, publisher = {Nature Publishing Group}, title = {{Coupling the Leidenfrost effect and elastic deformations to power sustained bouncing}}, doi = {10.1038/nphys4194}, volume = {13}, year = {2017}, } @inproceedings{12571, abstract = {We consider the problems of maintaining approximate maximum matching and minimum vertex cover in a dynamic graph. Starting with the seminal work of Onak and Rubinfeld [STOC 2010], this problem has received significant attention in recent years. Very recently, extending the framework of Baswana, Gupta and Sen [FOCS 2011], Solomon [FOCS 2016] gave a randomized 2-approximation dynamic algorithm for this problem that has amortized update time of O(1) with high probability. We consider the natural open question of derandomizing this result. We present a new deterministic fully dynamic algorithm that maintains a O(1)-approximate minimum vertex cover and maximum fractional matching, with an amortized update time of O(1). Previously, the best deterministic algorithm for this problem was due to Bhattacharya, Henzinger and Italiano [SODA 2015]; it had an approximation ratio of (2+ϵ) and an amortized update time of O(logn/ϵ2). Our result can be generalized to give a fully dynamic O(f3)-approximation algorithm with O(f2) amortized update time for the hypergraph vertex cover and fractional matching problems, where every hyperedge has at most f vertices.}, author = {Bhattacharya, Sayan and Chakrabarty, Deeparnab and Henzinger, Monika H}, booktitle = {19th International Conference on Integer Programming and Combinatorial Optimization}, isbn = {9783319592497}, issn = {0302-9743}, location = {Waterloo, ON, Canada}, pages = {86--98}, publisher = {Springer Nature}, title = {{Deterministic fully dynamic approximate vertex cover and fractional matching in O(1) amortized update time}}, doi = {10.1007/978-3-319-59250-3_8}, volume = {10328}, year = {2017}, }