@article{19828, abstract = {We describe an optical method to directly measure the position-dependent thermal diffusivity of reflective single crystal samples across a broad range of temperatures for condensed matter physics research. Two laser beams are used, one as a source to locally modulate the sample temperature, and the other as a probe of sample reflectivity, which is a function of the modulated temperature. Thermal diffusivity is obtained from the phase delay between source and probe signals. We combine this technique with a microscope setup in an optical cryostat, in which the sample is placed on a three-axis piezo-stage, allowing for spatially resolved measurements. Furthermore, we demonstrate experimentally and mathematically that isotropic in-plane diffusivity can be obtained when overlapping the two laser beams instead of separating them in the traditional way, which further enhances the spatial resolution to a micron scale, especially valuable when studying inhomogeneous or multidomain samples. We discuss in detail the experimental conditions under which this technique is valuable and demonstrate its performance on two stoichiometric bilayer ruthenates: Sr3Ru2O7 and Ca3Ru2O7. The spatial resolution allowed us to study the diffusivity in single domains of the latter, and we uncovered a temperature-dependent in-plane diffusivity anisotropy. Finally, we used the enhanced spatial resolution enabled by overlapping the two beams to measure the temperature-dependent diffusivity of Ti-doped Ca3Ru2O7, which exhibits a metal–insulator transition. We observed large variations of transition temperature over the same sample, originating from doping inhomogeneity and pointing to the power of spatially resolved techniques in accessing inherent properties.}, author = {Sun, F. and Mishra, S. and McGuinness, P. H. and Filipiak, Z. H. and Marković, I. and Sokolov, D. A. and Kikugawa, N. and Orenstein, J. W. and Hartnoll, S. A. and Mackenzie, A. P. and Sunko, Veronika}, issn = {1089-7623}, journal = {Review of Scientific Instruments}, number = {4}, publisher = {AIP Publishing}, title = {{A spatially resolved optical method to measure thermal diffusivity}}, doi = {10.1063/5.0098800}, volume = {94}, year = {2023}, } @inbook{19983, abstract = {The sinkless orientation problem plays a key role in understanding the foundations of distributed computing. The problem can be used to separate two fundamental models of distributed graph algorithms, LOCAL and SLOCAL: the locality of sinkless orientation is Ω(log n) in the deterministic LOCAL model and O(log log n) in the deterministic SLOCAL model. Both of these results are known by prior work, but here we give new simple, self-contained proofs for them.}, author = {Balliu, Alkida and Korhonen, Janne and Kuhn, Fabian and Lievonen, Henrik and Olivetti, Dennis and Pai, Shreyas and Paz, Ami and Rybicki, Joel and Schmid, Stefan and Studený, Jan and Suomela, Jukka and Uitto, Jara}, booktitle = {Symposium on Simplicity in Algorithms}, location = {Florence, Italy}, pages = {175--191}, publisher = {2023 Society for Industrial and Applied Mathematics}, title = {{Sinkless Orientation Made Simple}}, doi = {10.1137/1.9781611977585.ch17}, year = {2023}, } @inproceedings{19985, abstract = {We consider a natural problem dealing with weighted packet selection across a rechargeable link, which e.g., finds applications in cryptocurrency networks. The capacity of a link (u, v) is determined by how much nodes u and v allocate for this link. Specifically, the input is a finite ordered sequence of packets that arrive in both directions along a link. Given (u, v) and a packet of weight x going from u to v, node u can either accept or reject the packet. If u accepts the packet, the capacity on link (u, v) decreases by x. Correspondingly, v’s capacity on (u, v) increases by x. If a node rejects the packet, this will entail a cost affinely linear in the weight of the packet. A link is “rechargeable” in the sense that the total capacity of the link has to remain constant, but the allocation of capacity at the ends of the link can depend arbitrarily on the nodes’ decisions. The goal is to minimise the sum of the capacity injected into the link and the cost of rejecting packets. We show that the problem is NP-hard, but can be approximated efficiently with a ratio of (1 + E) . (1 + square3) for some arbitrary E>0.}, author = {Schmid, Stefan and Svoboda, Jakub and Yeo, Michelle X}, booktitle = {30th International Colloquium on Structural Information and Communication Complexity}, isbn = {9783031327322}, issn = {1611-3349}, location = {Alcalá de Henares, Spain}, pages = {576--594}, publisher = {Springer Nature}, title = {{Weighted acket selection for rechargeable links in cryptocurrency networks: Complexity and approximation}}, doi = {10.1007/978-3-031-32733-9_26}, volume = {13892}, year = {2023}, } @unpublished{20572, abstract = {We present an elementary non-recursive formula for the multivariate moments of the Dirichlet distribution on the standard simplex, in terms of the pattern inventory of the moments' exponents. We obtain analog formulas for the multivariate moments of the Dirichlet-Ferguson and Gamma measures. We further introduce a polychromatic analogue of Ewens sampling formula on colored integer partitions, discuss its relation with suitable extensions of Hoppe's urn model and of the Chinese restaurant process, and prove that it satisfies an adapted notion of consistency in the sense of Kingman.}, author = {Dello Schiavo, Lorenzo and Quattrocchi, Filippo}, booktitle = {arXiv}, keywords = {Dirichlet distribution, Ewens sampling formula, Hoppe urn model, colored partitions}, title = {{Multivariate Dirichlet moments and a polychromatic Ewens sampling formula}}, doi = {10.48550/arXiv.2309.11292}, year = {2023}, } @unpublished{20624, abstract = {We describe a sequence of smooth quotients of the Deligne-Mumford moduli space ${\mathbb R}\overline{\mathcal M}_{0,\ell+1}$ of real rational curves with $\ell\!+\!1$ conjugate pairs of marked points that terminates at ${\mathbb R}\overline{\mathcal M}_{0,\ell}\!\times\!{\mathbb C}{\mathbb P}^1$. This produces an analogue of Keel's blowup construction of the Deligne-Mumford moduli spaces $\overline{\mathcal M}_{\ell+1}$ of rational curves with $\ell\!+\!1$ marked points, but with an explicit description of the intermediate spaces and the blowups of three different types. The same framework readily adapts to the real moduli spaces with real points. In a sequel, we use this inductive construction of ${\mathbb R}\overline{\mathcal M}_{0,\ell+1}$ to completely determine the rational (co)homology ring of ${\mathbb R}\overline{\mathcal M}_{0,\ell}$.}, author = {Chen, Xujia and Zinger, Aleksey}, booktitle = {arXiv}, title = {{Blowdowns of the Deligne-Mumford spaces of real rational curves}}, doi = {10.48550/ARXIV.2305.08811}, year = {2023}, } @unpublished{20625, abstract = {It is a long-established and heavily-used fact that the integral cohomology ring of the Deligne-Mumford moduli space of (complex) rational curves is the polynomial ring on the boundary divisors modulo the ideal generated by the obvious geometric relations between them. We show that the rational cohomology ring of the Deligne-Mumford moduli space of real rational curves with conjugate marked points only is the polynomial ring on certain (``complex") boundary divisors and real boundary hypersurfaces modulo the ideal generated by the obvious geometric relations between them and the geometric relation in positive dimension and codimension identified in a previous paper.}, author = {Chen, Xujia and Georgieva, Penka and Zinger, Aleksey}, booktitle = {arXiv}, title = {{The cohomology ring of the Deligne-Mumford moduli space of real rational curves with conjugate marked points}}, doi = {10.48550/ARXIV.2305.08798}, year = {2023}, } @unpublished{20626, abstract = {Kontsevich's characteristic classes are invariants of framed smooth fiber bundles with homology sphere fibers. It was shown by Watanabe that they can be used to distinguish smooth $S^4$-bundles that are all trivial as topological fiber bundles. In this article we show that this ability of Kontsevich's classes is a manifestation of the following principle: the ``real blow-up'' construction on a smooth manifold essentially depends on its smooth structure and thus, given a smooth manifold (or smooth fiber bundle) $M$, the topological invariants of spaces constructed from $M$ by real blow-ups could potentially differentiate smooth structures on $M$. The main theorem says that Kontsevich's characteristic classes of a smooth framed bundle $π$ are determined by the topology of the 2-point configuration space bundle of $π$ and framing data.}, author = {Chen, Xujia}, booktitle = {arXiv}, title = {{Kontsevich's characteristic classes as topological invariants of configuration space bundles}}, doi = {10.48550/ARXIV.2302.03021}, year = {2023}, } @article{20759, abstract = {Recent advances in single-atom insertion reactions have opened up new synthetic approaches for molecular diversification. Developing innovative strategies to directly transform biologically relevant molecules, without any prefunctionalization, is key to further expanding the scope and utility of such transformations. Herein, the direct access to quinazolines and pyrimidines from the corresponding unprotected 1H-indoles and 1H-pyrroles is reported, relying on the implementation of lithium bis(trimethylsilyl)amide (LiHMDS) as a novel nitrogen atom source in combination with commercially available hypervalent iodine reagents. Further application of this strategy in late-stage settings demonstrates its potential in lead structure diversification campaigns.}, author = {Reisenbauer, Julia and Paschke, Ann-Sophie K. and Krizic, Jelena and Botlik, Bence B. and Finkelstein, Patrick and Morandi, Bill}, issn = {1523-7052}, journal = {Organic Letters}, number = {47}, pages = {8419--8423}, publisher = {American Chemical Society}, title = {{Direct access to quinazolines and pyrimidines from unprotected indoles and pyrroles through nitrogen atom insertion}}, doi = {10.1021/acs.orglett.3c03264}, volume = {25}, year = {2023}, } @article{20760, abstract = {The implementation of HCN-free transfer hydrocyanation reactions on laboratory scales has recently been achieved by using HCN donor reagents under nickel- and Lewis acid co-catalysis. More recently, malononitrile-based HCN donor reagents were shown to undergo the C(sp3)–CN bond activation by the nickel catalyst in the absence of Lewis acids. However, there is a lack of detailed mechanistic understanding of the challenging C(sp3)–CN bond cleavage step. In this work, in-depth kinetic and computational studies using alkynes as substrates were used to elucidate the overall reaction mechanism of this transfer hydrocyanation, with a particular focus on the activation of the C(sp3)–CN bond to generate the active H–Ni–CN transfer hydrocyanation catalyst. Comparisons of experimentally and computationally derived 13C kinetic isotope effect data support a direct oxidative addition mechanism of the nickel catalyst into the C(sp3)–CN bond facilitated by the coordination of the second nitrile group to the nickel catalyst.}, author = {Reisenbauer, Julia and Finkelstein, Patrick and Ebert, Marc-Olivier and Morandi, Bill}, issn = {2155-5435}, journal = {ACS Catalysis}, number = {17}, pages = {11548--11555}, publisher = {American Chemical Society}, title = {{Mechanistic investigation of the nickel-catalyzed transfer hydrocyanation of alkynes}}, doi = {10.1021/acscatal.3c02977}, volume = {13}, year = {2023}, } @article{20761, abstract = {We report a convenient protocol for a nitrogen atom insertion into indenes to afford isoquinolines. The reaction uses a combination of commercially available phenyliodine(III) diacetate (PIDA) and ammonium carbamate as the nitrogen source to furnish a wide range of isoquinolines. Various substitution patterns and commonly used functional groups are well tolerated. The operational simplicity renders this protocol broadly applicable and has been successfully extended towards the direct interconversion of cyclopentadienes into the corresponding pyridines. Furthermore, this strategy enables the facile synthesis of 15N labelled isoquinolines, using 15NH4Cl as a commercial 15N source.}, author = {Finkelstein, Patrick and Reisenbauer, Julia and Botlik, Bence B. and Green, Ori and Florin, Andri and Morandi, Bill}, issn = {2041-6539}, journal = {Chemical Science}, number = {11}, pages = {2954--2959}, publisher = {Royal Society of Chemistry}, title = {{Nitrogen atom insertion into indenes to access isoquinolines}}, doi = {10.1039/d2sc06952k}, volume = {14}, year = {2023}, } @article{20762, abstract = {A metal-free deaminative coupling of non-prefunctionalised benzylamines and arylboronic acids is reported. In this operationally simple reaction, a primary amine in benzylamine is converted into a good leaving group in situ using inexpensive and commercially available isoamyl nitrite as a nitrosating reagent. Lewis-acidic arylboronic acids are shown to replace mineral acids such as HCl or HBF4 that are conventionally used in the preparation of aryl diazonium salts. This unlocked the formation of the corresponding diarylmethanes by forging a new C–C bond in good yields. }, author = {Sirvinskaite, Giedre and Reisenbauer, Julia and Morandi, Bill}, issn = {2041-6539}, journal = {Chemical Science}, number = {7}, pages = {1709--1714}, publisher = {Royal Society of Chemistry}, title = {{Deaminative coupling of benzylamines and arylboronic acids}}, doi = {10.1039/d2sc06055h}, volume = {14}, year = {2023}, } @article{18942, abstract = {Photosynthesis is among the first processes negatively affected by environmental cues and its performance directly determines plant cell fitness and ultimately crop yield. Primarily sites of photosynthesis, chloroplasts are unique sites also for the biosynthesis of precursors of the growth regulator auxin and for sensing environmental stress, but their role in intracellular auxin homeostasis, vital for plant growth and survival in changing environments, remains poorly understood. Here, we identified two ATP-binding cassette (ABC) subfamily B transporters, ABCB28 and ABCB29, which export auxin across the chloroplast envelope to the cytosol in a concerted action in vivo. Moreover, we provide evidence for an auxin biosynthesis pathway in Arabidopsis thaliana chloroplasts. The overexpression of ABCB28 and ABCB29 influenced stomatal regulation and resulted in significantly improved water use efficiency and survival rates during salt and drought stresses. Our results suggest that chloroplast auxin production and transport contribute to stomata regulation for conserving water upon salt stress. ABCB28 and ABCB29 integrate photosynthesis and auxin signals and as such hold great potential to improve the adaptation potential of crops to environmental cues.}, author = {Tamizhselvan, Prashanth and Madhavan, Sharmila and Constan-Aguilar, Christian and Elrefaay, Eman Ryad and Liu, Jie and Pěnčík, Aleš and Novák, Ondřej and Cairó, Albert and Hrtyan, Mónika and Geisler, Markus and Tognetti, Vanesa Beatriz}, issn = {2223-7747}, journal = {Plants}, number = {1}, publisher = {MDPI}, title = {{Chloroplast auxin efflux mediated by ABCB28 and ABCB29 fine-tunes salt and drought stress responses in Arabidopsis}}, doi = {10.3390/plants13010007}, volume = {13}, year = {2023}, } @article{18959, abstract = {This workshop continues a series of workshops whose current format originated in 1981 under then-organizers Moser and Zehnder, and whose latest iteration took place in July 2023. The general goal of this series of workshops is to discuss the latest developments in the field of dynamical systems, broadly construed, and its connections with neighboring areas of mathematics such as differential geometry, partial differential equations, and more recently contact and symplectic geometry. We continued this tradition, bringing in new participants working in areas of dynamical systems and its connections with other areas of mathematics that are currently highly active and/or showing great promise for future development. Key focus areas for the 2023 workshop include spectral rigidity for planar domains, chaotic and oscillatory motions in celestial mechanics, conformal symplectic dynamics, and relations between dynamics.he workshop by the grant DMS-2230648, “US Junior Oberwolfach Fellows”.}, author = {Arnaud, Marie-Claude and Hutchings, Michael and Kaloshin, Vadim}, issn = {1660-8941}, journal = {Oberwolfach Reports}, number = {3}, pages = {1671--1730}, publisher = {EMS Press}, title = {{Dynamische Systeme}}, doi = {10.4171/owr/2023/30}, volume = {20}, year = {2023}, } @article{19053, abstract = {Building on previous works by Bilu, Chambert-Loir and Loeser, we study the asymptotic behaviour of the moduli space of sections of a given family over a smooth projective curve, assuming that the generic fiber is an equivariant compactification of a finite dimensional vector space. Working in a suitable Grothendieck ring of varieties, we show that the class of these moduli spaces converges, modulo an adequate normalisation, to a non-zero effective element, when the class of the sections goes arbitrary far from the boundary of the dual of the effective cone. The limit can be interpreted as a motivic Euler product in the sense of Bilu’s thesis. This result provides a positive answer to a motivic version of the Batyrev–Manin–Peyre conjectures in this particular setting.}, author = {Faisant, Loïs}, issn = {2191-0383}, journal = {Beiträge zur Algebra und Geometrie / Contributions to Algebra and Geometry}, number = {3}, pages = {783--850}, publisher = {Springer Nature}, title = {{Geometric Batyrev–Manin–Peyre for equivariant compactifications of additive groups}}, doi = {10.1007/s13366-022-00656-w}, volume = {64}, year = {2023}, } @misc{19308, abstract = {This Dataset contains the raw data from the following publication: "Optical and electronic signal stabilization of plasmonic fiber optic gate electrodes: towards improved real-time dual-mode biosensing" (DOI 10.3389/fphy.2023.1202132)}, author = {Hasler, Roger and Polt, Marie-Helene and Reiner-Rozman, Ciril and Fossati, Stefan and Lee, Seungho and Aspermair, Patrik and Kleber, Christoph and Ibáñez, Maria and Dostalek, Jakub and Knoll, Wolfgang}, publisher = {Zenodo}, title = {{Optical and electronic signal stabilization of plasmonic fiber optic gate electrodes: Towards improved real-time dual-mode biosensing}}, doi = {10.5281/ZENODO.7716920}, year = {2023}, } @article{19471, abstract = {Fasting initiates a multitude of adaptations to allow survival. Activation of the hypothalamic–pituitary–adrenal (HPA) axis and subsequent release of glucocorticoid hormones is a key response that mobilizes fuel stores to meet energy demands1,2,3,4,5. Despite the importance of the HPA axis response, the neural mechanisms that drive its activation during energy deficit are unknown. Here, we show that fasting-activated hypothalamic agouti-related peptide (AgRP)-expressing neurons trigger and are essential for fasting-induced HPA axis activation. AgRP neurons do so through projections to the paraventricular hypothalamus (PVH), where, in a mechanism not previously described for AgRP neurons, they presynaptically inhibit the terminals of tonically active GABAergic afferents from the bed nucleus of the stria terminalis (BNST) that otherwise restrain activity of corticotrophin-releasing hormone (CRH)-expressing neurons. This disinhibition of PVHCrh neurons requires γ-aminobutyric acid (GABA)/GABA-B receptor signalling and potently activates the HPA axis. Notably, stimulation of the HPA axis by AgRP neurons is independent of their induction of hunger, showing that these canonical ‘hunger neurons’ drive many distinctly different adaptations to the fasted state. Together, our findings identify the neural basis for fasting-induced HPA axis activation and uncover a unique means by which AgRP neurons activate downstream neurons: through presynaptic inhibition of GABAergic afferents. Given the potency of this disinhibition of tonically active BNST afferents, other activators of the HPA axis, such as psychological stress, may also work by reducing BNST inhibitory tone onto PVHCrh neurons.}, author = {Douglass, Amelia May Barnett and Resch, Jon M. and Madara, Joseph C. and Kucukdereli, Hakan and Yizhar, Ofer and Grama, Abhinav and Yamagata, Masahito and Yang, Zongfang and Lowell, Bradford B.}, issn = {1476-4687}, journal = {Nature}, number = {7972}, pages = {154--162}, publisher = {Springer Nature}, title = {{Neural basis for fasting activation of the hypothalamic–pituitary–adrenal axis}}, doi = {10.1038/s41586-023-06358-0}, volume = {620}, year = {2023}, } @article{19487, abstract = {Fix a non-square integer 𝑘≠0. We show that the number of curves 𝐸𝐵:𝑦^2=𝑥^3+𝑘𝐵^2 containing an integral point, where B ranges over positive integers less than N, is bounded by ≪𝑘𝑁(log𝑁)−1/2+𝜖. In particular, this implies that the number of positive integers 𝐵≤𝑁 such that −3𝑘𝐵^2 is the discriminant of an elliptic curve over 𝑄 is o(N). The proof involves a discriminant-lowering procedure on integral binary cubic forms.}, author = {Chan, Yik Tung}, issn = {1432-1807}, journal = {Mathematische Annalen}, number = {3}, pages = {2275--2288}, publisher = {Springer Nature}, title = {{Integral points on cubic twists of Mordell curves}}, doi = {10.1007/s00208-023-02578-x}, volume = {388}, year = {2023}, } @inproceedings{14744, abstract = {Sharding distributed ledgers is a promising on-chain solution for scaling blockchains but lacks formal grounds, nurturing skepticism on whether such complex systems can scale blockchains securely. We fill this gap by introducing the first formal framework as well as a roadmap to robust sharding. In particular, we first define the properties sharded distributed ledgers should fulfill. We build upon and extend the Bitcoin backbone protocol by defining consistency and scalability. Consistency encompasses the need for atomic execution of cross-shard transactions to preserve safety, whereas scalability encapsulates the speedup a sharded system can gain in comparison to a non-sharded system. Using our model, we explore the limitations of sharding. We show that a sharded ledger with n participants cannot scale under a fully adaptive adversary, but it can scale up to m shards where n=c'm log m, under an epoch-adaptive adversary; the constant c' encompasses the trade-off between security and scalability. This is possible only if the sharded ledgers create succinct proofs of the valid state updates at every epoch. We leverage our results to identify the sufficient components for robust sharding, which we incorporate in a protocol abstraction termed Divide & Scale. To demonstrate the power of our framework, we analyze the most prominent sharded blockchains (Elastico, Monoxide, OmniLedger, RapidChain) and pinpoint where they fail to meet the desired properties.}, author = {Avarikioti, Zeta and Desjardins, Antoine and Kokoris Kogias, Eleftherios and Wattenhofer, Roger}, booktitle = {30th International Colloquium on Structural Information and Communication Complexity}, isbn = {9783031327322}, issn = {1611-3349}, location = {Alcalá de Henares, Spain}, pages = {199--245}, publisher = {Springer Nature}, title = {{Divide & Scale: Formalization and roadmap to robust sharding}}, doi = {10.1007/978-3-031-32733-9_10}, volume = {13892}, year = {2023}, } @inproceedings{14748, author = {Chen, Yi-Lu and Ly, Mickaël and Wojtan, Christopher J}, booktitle = {Proceedings of the ACM SIGGRAPH/Eurographics Symposium on Computer Animation}, isbn = {9798400702686}, location = {Los Angeles, CA, United States}, publisher = {Association for Computing Machinery}, title = {{Unified treatment of contact, friction and shock-propagation in rigid body animation}}, doi = {10.1145/3606037.3606836}, year = {2023}, } @article{14749, abstract = {We unveil a powerful method for the stabilization of laser injection locking based on sensing variations in the output beam ellipticity of an optically seeded laser. The effect arises due to an interference between the seeding beam and the injected laser output. We demonstrate the method for a commercial semiconductor laser without the need for any internal changes to the readily operational injection locked laser system that was used. The method can also be used to increase the mode-hop free tuning range of lasers, and has the potential to fill a void in the low-noise laser industry.}, author = {Mishra, Umang and Li, Vyacheslav and Wald, Sebastian and Agafonova, Sofya and Diorico, Fritz R and Hosten, Onur}, issn = {1539-4794}, journal = {Optics Letters}, keywords = {Atomic and Molecular Physics, and Optics}, number = {15}, pages = {3973--3976}, publisher = {Optica Publishing Group}, title = {{Monitoring and active stabilization of laser injection locking using beam ellipticity}}, doi = {10.1364/ol.495553}, volume = {48}, year = {2023}, }