TY - CONF AB - Adversarial training is an effective method to train deep learning models that are resilient to norm-bounded perturbations, with the cost of nominal performance drop. While adversarial training appears to enhance the robustness and safety of a deep model deployed in open-world decision-critical applications, counterintuitively, it induces undesired behaviors in robot learning settings. In this paper, we show theoretically and experimentally that neural controllers obtained via adversarial training are subjected to three types of defects, namely transient, systematic, and conditional errors. We first generalize adversarial training to a safety-domain optimization scheme allowing for more generic specifications. We then prove that such a learning process tends to cause certain error profiles. We support our theoretical results by a thorough experimental safety analysis in a robot-learning task. Our results suggest that adversarial training is not yet ready for robot learning. AU - Lechner, Mathias AU - Hasani, Ramin AU - Grosu, Radu AU - Rus, Daniela AU - Henzinger, Thomas A ID - 10666 SN - 1050-4729 T2 - 2021 IEEE International Conference on Robotics and Automation TI - Adversarial training is not ready for robot learning ER - TY - JOUR AB - In this paper, we investigate the distribution of the maximum of partial sums of families of m -periodic complex-valued functions satisfying certain conditions. We obtain precise uniform estimates for the distribution function of this maximum in a near-optimal range. Our results apply to partial sums of Kloosterman sums and other families of ℓ -adic trace functions, and are as strong as those obtained by Bober, Goldmakher, Granville and Koukoulopoulos for character sums. In particular, we improve on the recent work of the third author for Birch sums. However, unlike character sums, we are able to construct families of m -periodic complex-valued functions which satisfy our conditions, but for which the Pólya–Vinogradov inequality is sharp. AU - Autissier, Pascal AU - Bonolis, Dante AU - Lamzouri, Youness ID - 10711 IS - 7 JF - Compositio Mathematica KW - Algebra and Number Theory SN - 0010-437X TI - The distribution of the maximum of partial sums of Kloosterman sums and other trace functions VL - 157 ER - TY - JOUR AB - Thermoelectric materials are engines that convert heat into an electrical current. Intuitively, the efficiency of this process depends on how many electrons (charge carriers) can move and how easily they do so, how much energy those moving electrons transport, and how easily the temperature gradient is maintained. In terms of material properties, an excellent thermoelectric material requires a high electrical conductivity σ, a high Seebeck coefficient S (a measure of the induced thermoelectric voltage as a function of temperature gradient), and a low thermal conductivity κ. The challenge is that these three properties are strongly interrelated in a conflicting manner (1). On page 722 of this issue, Roychowdhury et al. (2) have found a way to partially break these ties in silver antimony telluride (AgSbTe2) with the addition of cadmium (Cd) cations, which increase the ordering in this inherently disordered thermoelectric material. AU - Liu, Yu AU - Ibáñez, Maria ID - 10809 IS - 6530 JF - Science KW - multidisciplinary SN - 0036-8075 TI - Tidying up the mess VL - 371 ER - TY - JOUR AB - The cost-effective conversion of low-grade heat into electricity using thermoelectric devices requires developing alternative materials and material processing technologies able to reduce the currently high device manufacturing costs. In this direction, thermoelectric materials that do not rely on rare or toxic elements such as tellurium or lead need to be produced using high-throughput technologies not involving high temperatures and long processes. Bi2Se3 is an obvious possible Te-free alternative to Bi2Te3 for ambient temperature thermoelectric applications, but its performance is still low for practical applications, and additional efforts toward finding proper dopants are required. Here, we report a scalable method to produce Bi2Se3 nanosheets at low synthesis temperatures. We studied the influence of different dopants on the thermoelectric properties of this material. Among the elements tested, we demonstrated that Sn doping resulted in the best performance. Sn incorporation resulted in a significant improvement to the Bi2Se3 Seebeck coefficient and a reduction in the thermal conductivity in the direction of the hot-press axis, resulting in an overall 60% improvement in the thermoelectric figure of merit of Bi2Se3. AU - Li, Mengyao AU - Zhang, Yu AU - Zhang, Ting AU - Zuo, Yong AU - Xiao, Ke AU - Arbiol, Jordi AU - Llorca, Jordi AU - Liu, Yu AU - Cabot, Andreu ID - 10858 IS - 7 JF - Nanomaterials KW - General Materials Science KW - General Chemical Engineering SN - 2079-4991 TI - Enhanced thermoelectric performance of n-type Bi2Se3 nanosheets through Sn doping VL - 11 ER - TY - JOUR AB - Hematopoietic-specific protein 1 (Hem1) is an essential subunit of the WAVE regulatory complex (WRC) in immune cells. WRC is crucial for Arp2/3 complex activation and the protrusion of branched actin filament networks. Moreover, Hem1 loss of function in immune cells causes autoimmune diseases in humans. Here, we show that genetic removal of Hem1 in macrophages diminishes frequency and efficacy of phagocytosis as well as phagocytic cup formation in addition to defects in lamellipodial protrusion and migration. Moreover, Hem1-null macrophages displayed strong defects in cell adhesion despite unaltered podosome formation and concomitant extracellular matrix degradation. Specifically, dynamics of both adhesion and de-adhesion as well as concomitant phosphorylation of paxillin and focal adhesion kinase (FAK) were significantly compromised. Accordingly, disruption of WRC function in non-hematopoietic cells coincided with both defects in adhesion turnover and altered FAK and paxillin phosphorylation. Consistently, platelets exhibited reduced adhesion and diminished integrin αIIbβ3 activation upon WRC removal. Interestingly, adhesion phenotypes, but not lamellipodia formation, were partially rescued by small molecule activation of FAK. A full rescue of the phenotype, including lamellipodia formation, required not only the presence of WRCs but also their binding to and activation by Rac. Collectively, our results uncover that WRC impacts on integrin-dependent processes in a FAK-dependent manner, controlling formation and dismantling of adhesions, relevant for properly grabbing onto extracellular surfaces and particles during cell edge expansion, like in migration or phagocytosis. AU - Stahnke, Stephanie AU - Döring, Hermann AU - Kusch, Charly AU - de Gorter, David J.J. AU - Dütting, Sebastian AU - Guledani, Aleks AU - Pleines, Irina AU - Schnoor, Michael AU - Sixt, Michael K AU - Geffers, Robert AU - Rohde, Manfred AU - Müsken, Mathias AU - Kage, Frieda AU - Steffen, Anika AU - Faix, Jan AU - Nieswandt, Bernhard AU - Rottner, Klemens AU - Stradal, Theresia E.B. ID - 10834 IS - 10 JF - Current Biology KW - General Agricultural and Biological Sciences KW - General Biochemistry KW - Genetics and Molecular Biology SN - 0960-9822 TI - Loss of Hem1 disrupts macrophage function and impacts migration, phagocytosis, and integrin-mediated adhesion VL - 31 ER -