IST Austria: PubRep (Institute of Science and Technology)
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Lattice distortion leads to glassy thermal transport in crystalline Cs3Bi2I6Cl3
No full textThe glassy thermal conductivities observed in crystalline inorganic perovskites such as Cs3Bi2I6Cl3 are perplexing and lacking theoretical explanations. Here, we first experimentally measure its thermal transport behavior from 20 to 300 K, after synthesizing Cs3Bi2I6Cl3 single crystals. Using path-integral molecular dynamics simulations driven by machine learning potentials, we reveal that Cs3Bi2I6Cl3 has large lattice distortions at low temperatures, which may be related to the large atomic size mismatch. Employing the Wigner formulation of thermal transport, we reproduce theexperimental thermal conductivities based on lattice-distorted structures. This studythus provides a framework for predicting and understanding glassy thermal transportin materials with strong lattice disorder
DebDaB: A database of supraglacial debris thickness and physical properties
No full textRocky debris covers around 7.3 % of the global glacier area, influencing ice melt rates and the surface mass balance of glaciers, making the dynamics and hydrology of debris-covered glaciers distinct from those of clean-ice glaciers. Accurate representation of debris in models is challenging, as measurements of the physical properties and thickness of the supraglacial debris layer are scarce. Here, we compile a database of measured and reported bulk physical properties and layer thicknesses of supraglacial debris that we call the supraglacial Debris Database (DebDaB) and that is open to community submissions. The majority of the database (90 %) is compiled from 172 sources in the literature, and the remaining 10 % was previously unpublished. DebDaB contains 8741 data entries for supraglacial debris layer thickness, of which 1770 entries also include sub-debris ablation rates, 179 thermal conductivity of debris, 160 aerodynamic surface roughness length, 79 debris albedo, 59 debris emissivity, and 37 debris porosity. The data are distributed over 84 glaciers in 13 regions in the Global Terrestrial Network for Glaciers. We show regional differences in the distribution of debris thickness measurements in DebDaB and fit simplified Østrem curves to 19 glaciers with sufficient debris thickness and ablation data. The data in DebDaB can be used for energy balance, melt, and surface mass balance studies by incorporating site-specific debris properties or for evaluation of remote sensing estimates of debris thickness and surface roughness. They can also help future field campaigns on debris-covered glaciers by identifying observation gaps. DebDaB's uneven spatial coverage points to sampling biases in community efforts to observe debris-covered glaciers, with some regions (e.g. central Europe and South Asia) well-sampled but others having gaps with prevalent debris (e.g. the Andes and Alaska). Debris thickness measurements are mostly concentrated at lower elevations, leaving higher-elevation debris-covered areas undersampled and suggesting that our knowledge of debris properties might not be representative of all elevations. The aims of DebDaB, as an openly available dataset, are to evolve over time, to be updated, and to add to community submissions as new data on supraglacial properties become available. The data described in this paper can be accessed from Zenodo at https://doi.org/10.5281/zenodo.14224835 (Groeneveld et al., 2025)
Temporal and spatial coordination of DNA segregation and cell division in an archaeon
No full textCells must coordinate DNA segregation with cytokinesis to ensure that each daughter cell inherits a complete genome. Here, we explore how DNA segregation and division are mechanistically coupled in archaeal relatives of eukaryotes, which lack Cyclin-dependent kinase (CDK)/Cyclins. Using live cell imaging, we first describe the series of sequential changes in DNA organization that accompany cell division in Sulfolobus, which computational modeling shows likely aid genome segregation. Through a perturbation analysis we identify a regulatory checkpoint which ensures that the compaction of the genome into two spatially segregated nucleoids only occurs once cells have assembled a division ring—which also defines the axis of DNA segregation. Finally, we show that DNA compaction and segregation depend, in part, on a ParA homologue, SegA, and its partner SegB, whose absence leads to bridging DNA. Taken together, these data show how regulatory checkpoints like those operating in eukaryotes aid high-fidelity division in an archaeon
Charging dynamics of electric double-layer nanocapacitors in mean field
No full textAn electric double-layer capacitor (EDLC) stores energy by modulating the spatial distribution of ions in the electrolytic solution that it contains. We determine the mean-field timescales for planar EDLC relaxation to equilibrium after a potential difference is applied. We tackle first the fully symmetric case, where positive and negative ionic species have the same valence and diffusivity, and then the general, more complex, asymmetric case. Depending on the applied voltage and salt concentration, different regimes appear, revealing a remarkably rich phenomenology relevant for nanocapacitors
Maximum Betti numbers of Čech complexes
No full textThe Upper Bound Theorem for convex polytopes implies that the p-th Betti number of the Čech complex of any set of N points in ℝ^d and any radius satisfies β_p = O(N^m), with m = min{p+1, ⌈d/2⌉}. We construct sets in even and odd dimensions, which prove that this upper bound is asymptotically tight. For example, we describe a set of N = 2(n+1) points in ℝ³ and two radii such that the first Betti number of the Čech complex at one radius is (n+1)² - 1, and the second Betti number of the Čech complex at the other radius is n²
Role of cAMP in TIR1/AFB auxin signaling: Open issues
No full textThe canonical mechanism by which the phytohormone auxin regulates transcription has been one of the cornerstones of plant signaling. The recent unexpected discovery of cyclic AMP (cAMP) as a second messenger in this pathway has revised its foundations while leaving many open questions and gaps in our understanding; these will be discussed in this forum article
The miniW domain directs polarized membrane localization of non-canonical PINs in Marchantia polymorpha
No full textThis study demonstrates that Marchantia non-canonical PINs are predominantly localized to the plasma membrane, with MpPINX and MpPINW exhibiting asymmetric distribution.
A newly identified miniW domain within the MpPINW hydrophilic loop governs subcellular trafficking and asymmetric PM localization of non-canonical PINs in Marchantia
LNCS
No full textWe develop new attacks against the Evasive LWE family of assumptions, in both the public and private-coin regime. To the best of our knowledge, ours are the first attacks against Evasive LWE in the public-coin regime, for any instantiation from the family. Our attacks are summarized below.
Public-Coin Attacks.
1.The recent work by Hseih, Lin and Luo [17] constructed the first Attribute Based Encryption (ABE) for unbounded depth circuits by relying on the “circular” evasive LWE assumption. This assumption has been popularly considered as a safe, public-coin instance of Evasive LWE in contrast to its “private-coin” cousins (for instance, see [10, 11]).
We provide the first attack against this assumption, challenging the widely held belief that this is a public-coin assumption.
2. We demonstrate a counter-example against vanilla public-coin evasive LWE by Wee [26] in an unnatural parameter regime. Our attack crucially relies on the error in the pre-condition being larger than the error in the post-condition, necessitating a refinement of the assumption.
Private-Coin Attacks.
1. The recent work by Agrawal, Kumari and Yamada [2] constructed the first functional encryption scheme for pseudorandom functionalities (PRFE) and extended this to obfuscation for pseudorandom functionalities (PRIO) [4] by relying on private-coin evasive LWE. We provide a new attack against the assumption stated in the first posting of their work (subsequently refined to avoid these attacks).
2. The recent work by Branco et al. [8] (concurrently to [4]) provides a construction of obfuscation for pseudorandom functionalities by relying on private-coin evasive LWE. We provide a new attack against their stated assumption.
3. Branco et al. [8] showed that there exist contrived, “self-referential” classes of pseudorandom functionalities for which pseudorandom obfuscation cannot exist. We extend their techniques to develop an analogous result for pseudorandom functional encryption.
While Evasive LWE was developed to specifically avoid “zeroizing attacks”, our work shows that in certain settings, such attacks can still apply
Proximity labeling of DAF-16 FOXO highlights aging regulatory proteins
No full textInsulin/insulin-like growth factor signaling inhibits FOXO transcription factors to control development, homeostasis, and aging. Here, we use proximity labeling to identify proteins interacting with the C. elegans FOXO DAF-16. We show that in well-fed, unstressed animals harboring active insulin signaling, DAF-16 forms a complex with the PAR-1/MARK serine/threonine kinase, a key regulator of cell polarity. PAR-1 inhibits DAF-16 accumulation and promotes DAF-16 phosphorylation at S249, at a conserved motif that PAR-1/human MARK2 phosphorylates in vitro. DAF-2 insulin-like receptor signaling stimulates DAF-16 S249 phosphorylation, suggesting DAF-2 activates PAR-1. DAF-2 also promotes PAR-1 expression by inhibiting DAF-16. PAR-1 knockdown, or DAF-16 S249A, prolong lifespan, whereas phosphomimetic DAF-16 S249D suppresses the longevity of daf-2 mutants. At low insulin signaling, DAF-16 proximity labeling highlights transcription factors, chromatin regulators, and DNA repair proteins. One interactor, the zinc finger/homeobox protein ZFH-2/ZFHX3, forms a complex with DAF-16 and prolongs lifespan. Our work provides entry points for hypothesis-driven studies of FOXO function and longevity
Single-cell migration along and against confined haptotactic gradients
No full textHaptotaxis is the process of directed cell migration along gradients of extracellular matrix density and is central to morphogenesis, immune responses and cancer invasion. It is commonly assumed that cells respond to these gradients by migrating directionally towards the regions of highest ligand density. In contrast with this view, here we show that cells exposed to micropatterned fibronectin gradients exhibit a wide range of complex trajectories, including directed haptotactic migration up the gradient but also linear oscillations and circles with extended periods of migration down the gradient. To explain this behaviour, we developed a biophysical model of haptotactic cell migration based on a coarse-grained molecular clutch model coupled to persistent stochastic polarity dynamics. Although initial haptotactic migration is explained by the differential friction at the front and back of the cell, the observed complex trajectories over longer timescales arise from the interplay between differential friction, persistence and physical confinement. Overall, our study reveals that confinement and persistence modulate the ability of cells to sense and respond to haptotactic cues and provides a framework for understanding how cells navigate complex environments