@article{11584, abstract = {Observations show that star-forming galaxies reside on a tight 3D plane between mass, gas-phase metallicity, and star formation rate (SFR), which can be explained by the interplay between metal-poor gas inflows, SFR and outflows. However, different metals are released on different time-scales, which may affect the slope of this relation. Here, we use central, star-forming galaxies with Mstar = 109.0–10.5 M⊙ from the EAGLE hydrodynamical simulation to examine 3D relations between mass, SFR, and chemical enrichment using absolute and relative C, N, O, and Fe abundances. We show that the scatter is smaller when gas-phase α-enhancement is used rather than metallicity. A similar plane also exists for stellar α-enhancement, implying that present-day specific SFRs are correlated with long time-scale star formation histories. Between z = 0 and 1, the α-enhancement plane is even more insensitive to redshift than the plane using metallicity. However, it evolves at z > 1 due to lagging iron yields. At fixed mass, galaxies with higher SFRs have star formation histories shifted towards late times, are more α-enhanced, and this α-enhancement increases with redshift as observed. These findings suggest that relations between physical properties inferred from observations may be affected by systematic variations in α-enhancements.}, author = {Matthee, Jorryt J and Schaye, Joop}, issn = {1745-3933}, journal = {Monthly Notices of the Royal Astronomical Society: Letters}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, galaxies: abundances, galaxies: evolution, galaxies: formation, galaxies: star formation}, number = {1}, pages = {L34 -- L39}, publisher = {Oxford University Press}, title = {{Star-forming galaxies are predicted to lie on a fundamental plane of mass, star formation rate, and α-enhancement}}, doi = {10.1093/mnrasl/sly093}, volume = {479}, year = {2018}, } @article{11618, abstract = {Asteroseismology provides global stellar parameters such as masses, radii, or surface gravities using mean global seismic parameters and effective temperature for thousands of low-mass stars (0.8 M⊙ < M < 3 M⊙). This methodology has been successfully applied to stars in which acoustic modes excited by turbulent convection are measured. Other methods such as the Flicker technique can also be used to determine stellar surface gravities, but only works for log g above 2.5 dex. In this work, we present a new metric called FliPer (Flicker in spectral power density, in opposition to the standard Flicker measurement which is computed in the time domain); it is able to extend the range for which reliable surface gravities can be obtained (0.1 < log g < 4.6 dex) without performing any seismic analysis for stars brighter than Kp < 14. FliPer takes into account the average variability of a star measured in the power density spectrum in a given range of frequencies. However, FliPer values calculated on several ranges of frequency are required to better characterize a star. Using a large set of asteroseismic targets it is possible to calibrate the behavior of surface gravity with FliPer through machine learning. This calibration made with a random forest regressor covers a wide range of surface gravities from main-sequence stars to subgiants and red giants, with very small uncertainties from 0.04 to 0.1 dex. FliPer values can be inserted in automatic global seismic pipelines to either give an estimation of the stellar surface gravity or to assess the quality of the seismic results by detecting any outliers in the obtained νmax values. FliPer also constrains the surface gravities of main-sequence dwarfs using only long-cadence data for which the Nyquist frequency is too low to measure the acoustic-mode properties.}, author = {Bugnet, Lisa Annabelle and García, R. A. and Davies, G. R. and Mathur, S. and Corsaro, E. and Hall, O. J. and Rendle, B. M.}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, asteroseismology / methods, data analysis / stars, oscillations}, publisher = {EDP Sciences}, title = {{FliPer: A global measure of power density to estimate surface gravities of main-sequence solar-like stars and red giants}}, doi = {10.1051/0004-6361/201833106}, volume = {620}, year = {2018}, } @article{11619, abstract = {We report on the confirmation and mass determination of π Men c, the first transiting planet discovered by NASA’s TESS space mission. π Men is a naked-eye (V = 5.65 mag), quiet G0 V star that was previously known to host a sub-stellar companion (π Men b) on a longperiod (Porb = 2091 days), eccentric (e = 0.64) orbit. Using TESS time-series photometry, combined with Gaia data, published UCLES at AAT Doppler measurements, and archival HARPS at ESO-3.6m radial velocities, we found that π Men c is a close-in planet with an orbital period of Porb = 6.27 days, a mass of Mc = 4.52 ± 0.81 M⊕, and a radius of Rc = 2.06 ± 0.03 R⊕. Based on the planet’s orbital period and size, π Men c is a super-Earth located at, or close to, the radius gap, while its mass and bulk density suggest it may have held on to a significant atmosphere. Because of the brightness of the host star, this system is highly suitable for a wide range of further studies to characterize the planetary atmosphere and dynamical properties. We also performed an asteroseismic analysis of the TESS data and detected a hint of power excess consistent with the seismic values expected for this star, although this result depends on the photometric aperture used to extract the light curve. This marginal detection is expected from pre-launch simulations hinting at the asteroseismic potential of the TESS mission for longer, multi-sector observations and/or for more evolved bright stars.}, author = {Gandolfi, D. and Barragán, O. and Livingston, J. H. and Fridlund, M. and Justesen, A. B. and Redfield, S. and Fossati, L. and Mathur, S. and Grziwa, S. and Cabrera, J. and García, R. A. and Persson, C. M. and Van Eylen, V. and Hatzes, A. P. and Hidalgo, D. and Albrecht, S. and Bugnet, Lisa Annabelle and Cochran, W. D. and Csizmadia, Sz. and Deeg, H. and Eigmüller, Ph. and Endl, M. and Erikson, A. and Esposito, M. and Guenther, E. and Korth, J. and Luque, R. and Montañes Rodríguez, P. and Nespral, D. and Nowak, G. and Pätzold, M. and Prieto-Arranz, J.}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, planetary systems / planets and satellites, detection / planets and satellites, fundamental parameters / planets and satellites, terrestrial planets / stars, fundamental parameters}, publisher = {EDP Sciences}, title = {{TESS’s first planet: A super-Earth transiting the naked-eye star π Mensae}}, doi = {10.1051/0004-6361/201834289}, volume = {619}, year = {2018}, } @article{11620, abstract = {We report the discovery and characterization of HD 89345b (K2-234b; EPIC 248777106b), a Saturn-sized planet orbiting a slightly evolved star. HD 89345 is a bright star (V = 9.3 mag) observed by the K2 mission with 1 min time sampling. It exhibits solar-like oscillations. We conducted asteroseismology to determine the parameters of the star, finding the mass and radius to be 1.12+0.04−0.01M⊙ and 1.657+0.020−0.004R⊙⁠, respectively. The star appears to have recently left the main sequence, based on the inferred age, 9.4+0.4−1.3Gyr⁠, and the non-detection of mixed modes. The star hosts a ‘warm Saturn’ (P = 11.8 d, Rp = 6.86 ± 0.14 R⊕). Radial-velocity follow-up observations performed with the FIbre-fed Echelle Spectrograph, HARPS, and HARPS-N spectrographs show that the planet has a mass of 35.7 ± 3.3 M⊕. The data also show that the planet’s orbit is eccentric (e ≈ 0.2). An investigation of the rotational splitting of the oscillation frequencies of the star yields no conclusive evidence on the stellar inclination angle. We further obtained Rossiter–McLaughlin observations, which result in a broad posterior of the stellar obliquity. The planet seems to confirm to the same patterns that have been observed for other sub-Saturns regarding planet mass and multiplicity, orbital eccentricity, and stellar metallicity.}, author = {Van Eylen, V and Dai, F and Mathur, S and Gandolfi, D and Albrecht, S and Fridlund, M and García, R A and Guenther, E and Hjorth, M and Justesen, A B and Livingston, J and Lund, M N and Pérez Hernández, F and Prieto-Arranz, J and Regulo, C and Bugnet, Lisa Annabelle and Everett, M E and Hirano, T and Nespral, D and Nowak, G and Palle, E and Silva Aguirre, V and Trifonov, T and Winn, J N and Barragán, O and Beck, P G and Chaplin, W J and Cochran, W D and Csizmadia, S and Deeg, H and Endl, M and Heeren, P and Grziwa, S and Hatzes, A P and Hidalgo, D and Korth, J and Mathis, S and Montañes Rodriguez, P and Narita, N and Patzold, M and Persson, C M and Rodler, F and Smith, A M S}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, keywords = {Space and Planetary Science, Astronomy and Astrophysics, asteroseismology, planets and satellites: composition, planets and satellites: formation, planets and satellites: fundamental parameters}, number = {4}, pages = {4866--4880}, publisher = {Oxford University Press}, title = {{HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2}}, doi = {10.1093/mnras/sty1390}, volume = {478}, year = {2018}, } @unpublished{11631, abstract = {The recently launched NASA Transiting Exoplanet Survey Satellite (TESS) mission is going to collect lightcurves for a few hundred million of stars and we expect to increase the number of pulsating stars to analyze compared to the few thousand stars observed by the CoRoT, Kepler and K2 missions. However, most of the TESS targets have not yet been properly classified and characterized. In order to improve the analysis of the TESS data, it is crucial to determine the type of stellar pulsations in a timely manner. We propose an automatic method to classify stars attending to their pulsation properties, in particular, to identify solar-like pulsators among all TESS targets. It relies on the use of the global amount of power contained in the power spectrum (already known as the FliPer method) as a key parameter, along with the effective temperature, to feed into a machine learning classifier. Our study, based on TESS simulated datasets, shows that we are able to classify pulsators with a 98% accuracy.}, author = {Bugnet, Lisa Annabelle and García, R. A. and Davies, G. R. and Mathur, S. and Hall, O. J. and Rendle, B. M.}, booktitle = {arXiv}, keywords = {asteroseismology - methods, data analysis - stars, oscillations}, title = {{FliPer: Classifying TESS pulsating stars}}, doi = {10.48550/arXiv.1811.12140}, year = {2018}, } @article{11657, abstract = {The minimum cut problem for an undirected edge-weighted graph asks us to divide its set of nodes into two blocks while minimizing the weight sum of the cut edges. Here, we introduce a linear-time algorithm to compute near-minimum cuts. Our algorithm is based on cluster contraction using label propagation and Padberg and Rinaldi’s contraction heuristics [SIAM Review, 1991]. We give both sequential and shared-memory parallel implementations of our algorithm. Extensive experiments on both real-world and generated instances show that our algorithm finds the optimal cut on nearly all instances significantly faster than other state-of-the-art exact algorithms, and our error rate is lower than that of other heuristic algorithms. In addition, our parallel algorithm runs a factor 7.5× faster on average when using 32 threads. To further speed up computations, we also give a version of our algorithm that performs random edge contractions as preprocessing. This version achieves a lower running time and better parallel scalability at the expense of a higher error rate.}, author = {Henzinger, Monika H and Noe, Alexander and Schulz, Christian and Strash, Darren}, issn = {1084-6654}, journal = {ACM Journal of Experimental Algorithmics}, keywords = {Theoretical Computer Science}, pages = {1--22}, publisher = {Association for Computing Machinery}, title = {{Practical minimum cut algorithms}}, doi = {10.1145/3274662}, volume = {23}, year = {2018}, } @article{11664, abstract = {We present a deterministic incremental algorithm for exactly maintaining the size of a minimum cut with O(log3 n log log2 n) amortized time per edge insertion and O(1) query time. This result partially answers an open question posed by Thorup (2007). It also stays in sharp contrast to a polynomial conditional lower bound for the fully dynamic weighted minimum cut problem. Our algorithm is obtained by combining a sparsification technique of Kawarabayashi and Thorup (2015) or its recent improvement by Henzinger, Rao, and Wang (2017), and an exact incremental algorithm of Henzinger (1997). We also study space-efficient incremental algorithms for the minimum cut problem. Concretely, we show that there exists an O(nlog n/ε2) space Monte Carlo algorithm that can process a stream of edge insertions starting from an empty graph, and with high probability, the algorithm maintains a (1+ε)-approximation to the minimum cut. The algorithm has O((α (n) log3 n)/ε 2) amortized update time and constant query time, where α (n) stands for the inverse of Ackermann function.}, author = {Goranci, Gramoz and Henzinger, Monika H and Thorup, Mikkel}, issn = {1549-6333}, journal = {ACM Transactions on Algorithms}, number = {2}, publisher = {Association for Computing Machinery}, title = {{Incremental exact min-cut in polylogarithmic amortized update time}}, doi = {10.1145/3174803}, volume = {14}, year = {2018}, } @article{11667, abstract = {The focus of classic mechanism design has been on truthful direct-revelation mechanisms. In the context of combinatorial auctions, the truthful direct-revelation mechanism that maximizes social welfare is the Vickrey-Clarke-Groves mechanism. For many valuation spaces, computing the allocation and payments of the VCG mechanism, however, is a computationally hard problem. We thus study the performance of the VCG mechanism when bidders are forced to choose bids from a subspace of the valuation space for which the VCG outcome can be computed efficiently. We prove improved upper bounds on the welfare loss for restrictions to additive bids and upper and lower bounds for restrictions to non-additive bids. These bounds show that increased expressiveness can give rise to additional equilibria of poorer efficiency.}, author = {Dütting, Paul and Henzinger, Monika H and Starnberger, Martin}, issn = {2167-8383}, journal = {ACM Transactions on Economics and Computation}, keywords = {Theory of computation, Algorithmic game theory and mechanism design, Applied computing, Economics, Simplified mechanisms, Combinatorial auctions with item bidding, Price of anarchy}, number = {2}, publisher = {Association for Computing Machinery}, title = {{Valuation compressions in VCG-based combinatorial auctions}}, doi = {10.1145/3232860}, volume = {6}, year = {2018}, } @article{11757, abstract = {We develop a dynamic version of the primal-dual method for optimization problems, and apply it to obtain the following results. (1) For the dynamic set-cover problem, we maintain an O ( f 2)-approximately optimal solution in O ( f · log(m + n)) amortized update time, where f is the maximum “frequency” of an element, n is the number of sets, and m is the maximum number of elements in the universe at any point in time. (2) For the dynamic b-matching problem, we maintain an O (1)-approximately optimal solution in O (log3 n) amortized update time, where n is the number of nodes in the graph.}, author = {Bhattacharya, Sayan and Henzinger, Monika H and Italiano, Giuseppe}, issn = {0890-5401}, journal = {Information and Computation}, number = {08}, pages = {219--239}, publisher = {Elsevier}, title = {{Dynamic algorithms via the primal-dual method}}, doi = {10.1016/j.ic.2018.02.005}, volume = {261}, year = {2018}, } @article{11768, abstract = {In the decremental single-source shortest paths (SSSP) problem, we want to maintain the distances between a given source node s and every other node in an n-node m-edge graph G undergoing edge deletions. While its static counterpart can be solved in near-linear time, this decremental problem is much more challenging even in the undirected unweighted case. In this case, the classic O(mn) total update time of Even and Shiloach [16] has been the fastest known algorithm for three decades. At the cost of a (1+ϵ)-approximation factor, the running time was recently improved to n2+o(1) by Bernstein and Roditty [9]. In this article, we bring the running time down to near-linear: We give a (1+ϵ)-approximation algorithm with m1+o(1) expected total update time, thus obtaining near-linear time. Moreover, we obtain m1+o(1) log W time for the weighted case, where the edge weights are integers from 1 to W. The only prior work on weighted graphs in o(mn) time is the mn0.9 + o(1)-time algorithm by Henzinger et al. [18, 19], which works for directed graphs with quasi-polynomial edge weights. The expected running time bound of our algorithm holds against an oblivious adversary. In contrast to the previous results, which rely on maintaining a sparse emulator, our algorithm relies on maintaining a so-called sparse (h, ϵ)-hop set introduced by Cohen [12] in the PRAM literature. An (h, ϵ)-hop set of a graph G=(V, E) is a set F of weighted edges such that the distance between any pair of nodes in G can be (1+ϵ)-approximated by their h-hop distance (given by a path containing at most h edges) on G′=(V, E ∪ F). Our algorithm can maintain an (no(1), ϵ)-hop set of near-linear size in near-linear time under edge deletions. It is the first of its kind to the best of our knowledge. To maintain approximate distances using this hop set, we extend the monotone Even-Shiloach tree of Henzinger et al. [20] and combine it with the bounded-hop SSSP technique of Bernstein [4, 5] and Mądry [27]. These two new tools might be of independent interest.}, author = {Henzinger, Monika H and Krinninger, Sebastian and Nanongkai, Danupon}, issn = {1557-735X}, journal = {Journal of the ACM}, number = {6}, pages = {1--40}, publisher = {Association for Computing Machinery}, title = {{Decremental single-source shortest paths on undirected graphs in near-linear total update time}}, doi = {10.1145/3218657}, volume = {65}, year = {2018}, } @inproceedings{11827, abstract = {We study the metric facility location problem with client insertions and deletions. This setting differs from the classic dynamic facility location problem, where the set of clients remains the same, but the metric space can change over time. We show a deterministic algorithm that maintains a constant factor approximation to the optimal solution in worst-case time O~(2^{O(kappa^2)}) per client insertion or deletion in metric spaces while answering queries about the cost in O(1) time, where kappa denotes the doubling dimension of the metric. For metric spaces with bounded doubling dimension, the update time is polylogarithmic in the parameters of the problem.}, author = {Goranci, Gramoz and Henzinger, Monika H and Leniowski, Dariusz}, booktitle = {26th Annual European Symposium on Algorithms}, isbn = {9783959770811}, issn = {1868-8969}, location = {Helsinki, Finland}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{A tree structure for dynamic facility location}}, doi = {10.4230/LIPICS.ESA.2018.39}, volume = {112}, year = {2018}, } @inproceedings{11828, abstract = {We consider the problem of dynamically maintaining (approximate) all-pairs effective resistances in separable graphs, which are those that admit an n^{c}-separator theorem for some c<1. We give a fully dynamic algorithm that maintains (1+epsilon)-approximations of the all-pairs effective resistances of an n-vertex graph G undergoing edge insertions and deletions with O~(sqrt{n}/epsilon^2) worst-case update time and O~(sqrt{n}/epsilon^2) worst-case query time, if G is guaranteed to be sqrt{n}-separable (i.e., it is taken from a class satisfying a sqrt{n}-separator theorem) and its separator can be computed in O~(n) time. Our algorithm is built upon a dynamic algorithm for maintaining approximate Schur complement that approximately preserves pairwise effective resistances among a set of terminals for separable graphs, which might be of independent interest. We complement our result by proving that for any two fixed vertices s and t, no incremental or decremental algorithm can maintain the s-t effective resistance for sqrt{n}-separable graphs with worst-case update time O(n^{1/2-delta}) and query time O(n^{1-delta}) for any delta>0, unless the Online Matrix Vector Multiplication (OMv) conjecture is false. We further show that for general graphs, no incremental or decremental algorithm can maintain the s-t effective resistance problem with worst-case update time O(n^{1-delta}) and query-time O(n^{2-delta}) for any delta >0, unless the OMv conjecture is false.}, author = {Goranci, Gramoz and Henzinger, Monika H and Peng, Pan}, booktitle = {26th Annual European Symposium on Algorithms}, isbn = {9783959770811}, issn = {1868-8969}, location = {Helsinki, Finland}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Dynamic effective resistances and approximate schur complement on separable graphs}}, doi = {10.4230/LIPICS.ESA.2018.40}, volume = {112}, year = {2018}, } @inproceedings{11872, abstract = {We design fast dynamic algorithms for proper vertex and edge colorings in a graph undergoing edge insertions and deletions. In the static setting, there are simple linear time algorithms for (Δ + 1)- vertex coloring and (2Δ – 1)-edge coloring in a graph with maximum degree Δ. It is natural to ask if we can efficiently maintain such colorings in the dynamic setting as well. We get the following three results. (1) We present a randomized algorithm which maintains a (Δ + 1)-vertex coloring with O(log Δ) expected amortized update time. (2) We present a deterministic algorithm which maintains a (1 + o(1)Δ-vertex coloring with O(polylog Δ) amortized update time. (3) We present a simple, deterministic algorithm which maintains a (2Δ – 1)-edge coloring with O(log Δ) worst-case update time. This improves the recent O(Δ)-edge coloring algorithm with worst-case update time [4].}, author = {Bhattacharya, Sayan and Chakrabarty, Deeparnab and Henzinger, Monika H and Nanongkai, Danupon}, booktitle = {29th Annual ACM-SIAM Symposium on Discrete Algorithms}, location = {New Orleans, LA, United States}, pages = {1 -- 20}, publisher = {Society for Industrial and Applied Mathematics}, title = {{Dynamic algorithms for graph coloring}}, doi = {10.1137/1.9781611975031.1}, year = {2018}, } @inproceedings{11882, abstract = {The minimum cut problem for an undirected edge-weighted graph asks us to divide its set of nodes into two blocks while minimizing the weight sum of the cut edges. Here, we introduce a linear-time algorithm to compute near-minimum cuts. Our algorithm is based on cluster contraction using label propagation and Padberg and Rinaldi's contraction heuristics [SIAM Review, 1991]. We give both sequential and shared-memory parallel implementations of our algorithm. Extensive experiments on both real-world and generated instances show that our algorithm finds the optimal cut on nearly all instances significantly faster than other state-of-the-art exact algorithms, and our error rate is lower than that of other heuristic algorithms. In addition, our parallel algorithm shows good scalability.}, author = {Henzinger, Monika H and Noe, Alexander and Schulz, Christian and Strash, Darren}, booktitle = {20th Workshop on Algorithm Engineering and Experiments}, location = {New Orleans, LA, United States}, pages = {48--61}, publisher = {Society for Industrial and Applied Mathematics}, title = {{Practical minimum cut algorithms}}, doi = {10.1137/1.9781611975055.5}, year = {2018}, } @article{11890, abstract = {We present the first deterministic data structures for maintaining approximate minimum vertex cover and maximum matching in a fully dynamic graph 𝐺=(𝑉,𝐸), with |𝑉|=𝑛 and |𝐸|=𝑚, in 𝑜(𝑚‾‾√) time per update. In particular, for minimum vertex cover, we provide deterministic data structures for maintaining a (2+𝜖) approximation in 𝑂(log𝑛/𝜖2) amortized time per update. For maximum matching, we show how to maintain a (3+𝜖) approximation in 𝑂(min(𝑛√/𝜖,𝑚1/3/𝜖2) amortized time per update and a (4+𝜖) approximation in 𝑂(𝑚1/3/𝜖2) worst-case time per update. Our data structure for fully dynamic minimum vertex cover is essentially near-optimal and settles an open problem by Onak and Rubinfeld [in 42nd ACM Symposium on Theory of Computing, Cambridge, MA, ACM, 2010, pp. 457--464].}, author = {Bhattacharya, Sayan and Henzinger, Monika H and Italiano, Giuseppe F.}, issn = {1095-7111}, journal = {SIAM Journal on Computing}, number = {3}, pages = {859--887}, publisher = {Society for Industrial & Applied Mathematics}, title = {{Deterministic fully dynamic data structures for vertex cover and matching}}, doi = {10.1137/140998925}, volume = {47}, year = {2018}, } @inproceedings{11911, abstract = {It is common knowledge that there is no single best strategy for graph clustering, which justifies a plethora of existing approaches. In this paper, we present a general memetic algorithm, VieClus, to tackle the graph clustering problem. This algorithm can be adapted to optimize different objective functions. A key component of our contribution are natural recombine operators that employ ensemble clusterings as well as multi-level techniques. Lastly, we combine these techniques with a scalable communication protocol, producing a system that is able to compute high-quality solutions in a short amount of time. We instantiate our scheme with local search for modularity and show that our algorithm successfully improves or reproduces all entries of the 10th DIMACS implementation challenge under consideration using a small amount of time.}, author = {Biedermann, Sonja and Henzinger, Monika H and Schulz, Christian and Schuster, Bernhard}, booktitle = {17th International Symposium on Experimental Algorithms}, isbn = {9783959770705}, issn = {1868-8969}, location = {L'Aquila, Italy}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Memetic graph clustering}}, doi = {10.4230/LIPICS.SEA.2018.3}, volume = {103}, year = {2018}, } @article{12, abstract = {Molding is a popular mass production method, in which the initial expenses for the mold are offset by the low per-unit production cost. However, the physical fabrication constraints of the molding technique commonly restrict the shape of moldable objects. For a complex shape, a decomposition of the object into moldable parts is a common strategy to address these constraints, with plastic model kits being a popular and illustrative example. However, conducting such a decomposition requires considerable expertise, and it depends on the technical aspects of the fabrication technique, as well as aesthetic considerations. We present an interactive technique to create such decompositions for two-piece molding, in which each part of the object is cast between two rigid mold pieces. Given the surface description of an object, we decompose its thin-shell equivalent into moldable parts by first performing a coarse decomposition and then utilizing an active contour model for the boundaries between individual parts. Formulated as an optimization problem, the movement of the contours is guided by an energy reflecting fabrication constraints to ensure the moldability of each part. Simultaneously, the user is provided with editing capabilities to enforce aesthetic guidelines. Our interactive interface provides control of the contour positions by allowing, for example, the alignment of part boundaries with object features. Our technique enables a novel workflow, as it empowers novice users to explore the design space, and it generates fabrication-ready two-piece molds that can be used either for casting or industrial injection molding of free-form objects.}, author = {Nakashima, Kazutaka and Auzinger, Thomas and Iarussi, Emmanuel and Zhang, Ran and Igarashi, Takeo and Bickel, Bernd}, journal = {ACM Transaction on Graphics}, number = {4}, publisher = {ACM}, title = {{CoreCavity: Interactive shell decomposition for fabrication with two-piece rigid molds}}, doi = {10.1145/3197517.3201341}, volume = {37}, year = {2018}, } @article{22, abstract = {Conventional ultra-high sensitivity detectors in the millimeter-wave range are usually cooled as their own thermal noise at room temperature would mask the weak received radiation. The need for cryogenic systems increases the cost and complexity of the instruments, hindering the development of, among others, airborne and space applications. In this work, the nonlinear parametric upconversion of millimeter-wave radiation to the optical domain inside high-quality (Q) lithium niobate whispering-gallery mode (WGM) resonators is proposed for ultra-low noise detection. We experimentally demonstrate coherent upconversion of millimeter-wave signals to a 1550 nm telecom carrier, with a photon conversion efficiency surpassing the state-of-the-art by 2 orders of magnitude. Moreover, a theoretical model shows that the thermal equilibrium of counterpropagating WGMs is broken by overcoupling the millimeter-wave WGM, effectively cooling the upconverted mode and allowing ultra-low noise detection. By theoretically estimating the sensitivity of a correlation radiometer based on the presented scheme, it is found that room-temperature radiometers with better sensitivity than state-of-the-art high-electron-mobility transistor (HEMT)-based radiometers can be designed. This detection paradigm can be used to develop room-temperature instrumentation for radio astronomy, earth observation, planetary missions, and imaging systems.}, author = {Botello, Gabriel and Sedlmeir, Florian and Rueda Sanchez, Alfredo R and Abdalmalak, Kerlos and Brown, Elliott and Leuchs, Gerd and Preu, Sascha and Segovia Vargas, Daniel and Strekalov, Dmitry and Munoz, Luis and Schwefel, Harald}, issn = {2334-2536}, journal = {Optica}, number = {10}, pages = {1210--1219}, title = {{Sensitivity limits of millimeter-wave photonic radiometers based on efficient electro-optic upconverters}}, doi = {10.1364/OPTICA.5.001210}, volume = {5}, year = {2018}, } @article{23, abstract = {The strong atomistic spin–orbit coupling of holes makes single-shot spin readout measurements difficult because it reduces the spin lifetimes. By integrating the charge sensor into a high bandwidth radio frequency reflectometry setup, we were able to demonstrate single-shot readout of a germanium quantum dot hole spin and measure the spin lifetime. Hole spin relaxation times of about 90 μs at 500 mT are reported, with a total readout visibility of about 70%. By analyzing separately the spin-to-charge conversion and charge readout fidelities, we have obtained insight into the processes limiting the visibilities of hole spins. The analyses suggest that high hole visibilities are feasible at realistic experimental conditions, underlying the potential of hole spins for the realization of viable qubit devices.}, author = {Vukušić, Lada and Kukucka, Josip and Watzinger, Hannes and Milem, Joshua M and Schäffler, Friedrich and Katsaros, Georgios}, issn = {1530-6984}, journal = {Nano Letters}, number = {11}, pages = {7141 -- 7145}, publisher = {American Chemical Society}, title = {{Single-shot readout of hole spins in Ge}}, doi = {10.1021/acs.nanolett.8b03217}, volume = {18}, year = {2018}, } @inproceedings{24, abstract = {Partially-observable Markov decision processes (POMDPs) with discounted-sum payoff are a standard framework to model a wide range of problems related to decision making under uncertainty. Traditionally, the goal has been to obtain policies that optimize the expectation of the discounted-sum payoff. A key drawback of the expectation measure is that even low probability events with extreme payoff can significantly affect the expectation, and thus the obtained policies are not necessarily risk-averse. An alternate approach is to optimize the probability that the payoff is above a certain threshold, which allows obtaining risk-averse policies, but ignores optimization of the expectation. We consider the expectation optimization with probabilistic guarantee (EOPG) problem, where the goal is to optimize the expectation ensuring that the payoff is above a given threshold with at least a specified probability. We present several results on the EOPG problem, including the first algorithm to solve it.}, author = {Chatterjee, Krishnendu and Elgyütt, Adrian and Novotny, Petr and Rouillé, Owen}, location = {Stockholm, Sweden}, pages = {4692 -- 4699}, publisher = {IJCAI}, title = {{Expectation optimization with probabilistic guarantees in POMDPs with discounted-sum objectives}}, doi = {10.24963/ijcai.2018/652}, volume = {2018}, year = {2018}, }