@article{9006,
abstract = {Cytoplasm is a gel-like crowded environment composed of various macromolecules, organelles, cytoskeletal networks, and cytosol. The structure of the cytoplasm is highly organized and heterogeneous due to the crowding of its constituents and their effective compartmentalization. In such an environment, the diffusive dynamics of the molecules are restricted, an effect that is further amplified by clustering and anchoring of molecules. Despite the crowded nature of the cytoplasm at the microscopic scale, large-scale reorganization of the cytoplasm is essential for important cellular functions, such as cell division and polarization. How such mesoscale reorganization of the cytoplasm is achieved, especially for large cells such as oocytes or syncytial tissues that can span hundreds of micrometers in size, is only beginning to be understood. In this review, we will discuss recent advances in elucidating the molecular, cellular, and biophysical mechanisms by which the cytoskeleton drives cytoplasmic reorganization across different scales, structures, and species.},
author = {Shamipour, Shayan and Caballero Mancebo, Silvia and Heisenberg, Carl-Philipp J},
issn = {18781551},
journal = {Developmental Cell},
number = {2},
pages = {P213--226},
publisher = {Elsevier},
title = {{Cytoplasm's got moves}},
doi = {10.1016/j.devcel.2020.12.002},
volume = {56},
year = {2021},
}
@article{9769,
abstract = {A few years ago, flow equations were introduced as a technique for calculating the ground-state energies of cold Bose gases with and without impurities. In this paper, we extend this approach to compute observables other than the energy. As an example, we calculate the densities, and phase fluctuations of one-dimensional Bose gases with one and two impurities. For a single mobile impurity, we use flow equations to validate the mean-field results obtained upon the Lee-Low-Pines transformation. We show that the mean-field approximation is accurate for all values of the boson-impurity interaction strength as long as the phase coherence length is much larger than the healing length of the condensate. For two static impurities, we calculate impurity-impurity interactions induced by the Bose gas. We find that leading order perturbation theory fails when boson-impurity interactions are stronger than boson-boson interactions. The mean-field approximation reproduces the flow equation results for all values of the boson-impurity interaction strength as long as boson-boson interactions are weak.},
author = {Brauneis, Fabian and Hammer, Hans-Werner and Lemeshko, Mikhail and Volosniev, Artem},
issn = {2542-4653},
journal = {SciPost Physics},
number = {1},
publisher = {SciPost},
title = {{Impurities in a one-dimensional Bose gas: The flow equation approach}},
doi = {10.21468/scipostphys.11.1.008},
volume = {11},
year = {2021},
}
@inproceedings{9825,
abstract = {The dual attack has long been considered a relevant attack on lattice-based cryptographic schemes relying on the hardness of learning with errors (LWE) and its structured variants. As solving LWE corresponds to finding a nearest point on a lattice, one may naturally wonder how efficient this dual approach is for solving more general closest vector problems, such as the classical closest vector problem (CVP), the variants bounded distance decoding (BDD) and approximate CVP, and preprocessing versions of these problems. While primal, sieving-based solutions to these problems (with preprocessing) were recently studied in a series of works on approximate Voronoi cells [Laa16b, DLdW19, Laa20, DLvW20], for the dual attack no such overview exists, especially for problems with preprocessing. With one of the take-away messages of the approximate Voronoi cell line of work being that primal attacks work well for approximate CVP(P) but scale poorly for BDD(P), one may further wonder if the dual attack suffers the same drawbacks, or if it is perhaps a better solution when trying to solve BDD(P).
In this work we provide an overview of cost estimates for dual algorithms for solving these “classical” closest lattice vector problems. Heuristically we expect to solve the search version of average-case CVPP in time and space 20.293𝑑+𝑜(𝑑) in the single-target model. The distinguishing version of average-case CVPP, where we wish to distinguish between random targets and targets planted at distance (say) 0.99⋅𝑔𝑑 from the lattice, has the same complexity in the single-target model, but can be solved in time and space 20.195𝑑+𝑜(𝑑) in the multi-target setting, when given a large number of targets from either target distribution. This suggests an inequivalence between distinguishing and searching, as we do not expect a similar improvement in the multi-target setting to hold for search-CVPP. We analyze three slightly different decoders, both for distinguishing and searching, and experimentally obtain concrete cost estimates for the dual attack in dimensions 50 to 80, which confirm our heuristic assumptions, and show that the hidden order terms in the asymptotic estimates are quite small.
Our main take-away message is that the dual attack appears to mirror the approximate Voronoi cell line of work – whereas using approximate Voronoi cells works well for approximate CVP(P) but scales poorly for BDD(P), the dual approach scales well for BDD(P) instances but performs poorly on approximate CVP(P).},
author = {Laarhoven, Thijs and Walter, Michael},
booktitle = {Topics in Cryptology – CT-RSA 2021},
isbn = {9783030755386},
issn = {16113349},
location = {Virtual Event},
pages = {478--502},
publisher = {Springer Nature},
title = {{Dual lattice attacks for closest vector problems (with preprocessing)}},
doi = {10.1007/978-3-030-75539-3_20},
volume = {12704},
year = {2021},
}
@inproceedings{9826,
abstract = {Automated contract tracing aims at supporting manual contact tracing during pandemics by alerting users of encounters with infected people. There are currently many proposals for protocols (like the “decentralized” DP-3T and PACT or the “centralized” ROBERT and DESIRE) to be run on mobile phones, where the basic idea is to regularly broadcast (using low energy Bluetooth) some values, and at the same time store (a function of) incoming messages broadcasted by users in their proximity. In the existing proposals one can trigger false positives on a massive scale by an “inverse-Sybil” attack, where a large number of devices (malicious users or hacked phones) pretend to be the same user, such that later, just a single person needs to be diagnosed (and allowed to upload) to trigger an alert for all users who were in proximity to any of this large group of devices.
We propose the first protocols that do not succumb to such attacks assuming the devices involved in the attack do not constantly communicate, which we observe is a necessary assumption. The high level idea of the protocols is to derive the values to be broadcasted by a hash chain, so that two (or more) devices who want to launch an inverse-Sybil attack will not be able to connect their respective chains and thus only one of them will be able to upload. Our protocols also achieve security against replay, belated replay, and one of them even against relay attacks.},
author = {Auerbach, Benedikt and Chakraborty, Suvradip and Klein, Karen and Pascual Perez, Guillermo and Pietrzak, Krzysztof Z and Walter, Michael and Yeo, Michelle X},
booktitle = {Topics in Cryptology – CT-RSA 2021},
isbn = {9783030755386},
issn = {16113349},
location = {Virtual Event},
pages = {399--421},
publisher = {Springer Nature},
title = {{Inverse-Sybil attacks in automated contact tracing}},
doi = {10.1007/978-3-030-75539-3_17},
volume = {12704},
year = {2021},
}
@inproceedings{9823,
abstract = {Approximate agreement is one of the few variants of consensus that can be solved in a wait-free manner in asynchronous systems where processes communicate by reading and writing to shared memory. In this work, we consider a natural generalisation of approximate agreement on arbitrary undirected connected graphs. Each process is given a vertex of the graph as input and, if non-faulty, must output a vertex such that
all the outputs are within distance 1 of one another, and
each output value lies on a shortest path between two input values.
From prior work, it is known that there is no wait-free algorithm among 𝑛≥3 processes for this problem on any cycle of length 𝑐≥4 , by reduction from 2-set agreement (Castañeda et al. 2018).
In this work, we investigate the solvability and complexity of this task on general graphs. We give a new, direct proof of the impossibility of approximate agreement on cycles of length 𝑐≥4 , via a generalisation of Sperner’s Lemma to convex polygons. We also extend the reduction from 2-set agreement to a larger class of graphs, showing that approximate agreement on these graphs is unsolvable. On the positive side, we present a wait-free algorithm for a class of graphs that properly contains the class of chordal graphs.},
author = {Alistarh, Dan-Adrian and Ellen, Faith and Rybicki, Joel},
booktitle = {Structural Information and Communication Complexity},
isbn = {9783030795269},
issn = {16113349},
location = {Wrocław, Poland},
pages = {87--105},
publisher = {Springer Nature},
title = {{Wait-free approximate agreement on graphs}},
doi = {10.1007/978-3-030-79527-6_6},
volume = {12810},
year = {2021},
}