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Saprotrophic-mycorrhizal divide in stable isotope composition throughout the whole fungus: From mycelium to hymenophore
No full textMycorrhizal and saprotrophic macromycetes contribute strongly to the carbon and nitrogen cycles of forest ecosystems, often studied by tracing stable isotope composition of carbon and nitrogen. The phenomenon of the saprotrophic-mycorrhizal divide highlights the difference in the stable isotope composition of fruiting bodies of mycorrhizal and saprotrophic fungi. Much less is known about the isotopic composition of the mycelium, which plays an important role in the formation of the soil organic matter and fuels the fungal trophic channel in soil food webs. In this study, we assessed whether the saprotrophic-mycorrhizal divide in the natural δ13С and δ15N values can be traced throughout entire fungal organisms. This hypothesis was tested using 16 species of ectomycorrhizal and six species of saprotrophic basidiomycetous fungi. We showed that not only fruiting bodies, but also the mycelium of ectomycorrhizal and saprotrophic fungi differs in the δ13C and δ15N values. In both ectomycorrhizal and saprotrophic fungi, the δ13C and δ15N values increased from mycelium to hymenophores and correlated positively with the total N content in the corresponding tissues. The differences between ectomycorrhizal and saprotrophic mycelium can be used to reconstruct the fungal-driven belowground carbon and nitrogen allocation, and the contribution of saprotrophic and mycorrhizal fungi to soil food webs
Scales
No full textWe introduce the notions of scale for sets and measures on metric space by generalizing the usual notions of dimension. Several versions of scales are introduced such as Hausdorff, packing, box, local and quantization. They are defined for different growth, allowing a refined study of infinite dimensional spaces. We prove general theorems comparing the different versions of scales. They are applied to describe geometries of ergodic decompositions, of the Wiener measure and from functional spaces. The first application solves a problem of Berger on the notions of emergence (2020); the second lies in the geometry of the Wiener measure and extends the work of Dereich–Lifshits (2005); the last refines Kolmogorov–Tikhomirov (1958) study on finitely differentiable functions
Hardware-optimal quantum algorithms
No full textQuantum hardware is inherently fragile and noisy. We find that the accuracy of traditional quantum error correction algorithms can be improved depending on the hardware. Given different hardware specifications, we automatically synthesize hardware-optimal algorithms for parity correction, qubit resetting, and GHZ (Greenberger–Horne–Zeilinger) state preparation. Using stochastic techniques from computer science, our method presents a computational tool to compute exact accuracy guarantees and synthesize optimal algorithms that are often different from traditional ones. We also show that improvements can be gained with respect to the Qiskit transpiler as we compute the hardware-optimal qubit mapping for the GHZ state-preparation problem
Optimal sums of three cubes in Fq[t]
No full textWe use the circle method to prove that a density 1 of elements in Fq[t] are representable as a sum of three cubes of essentially minimal degree from Fq[t], assuming the Ratios Conjecture and that char(Fq)>3. Roughly speaking, to do so, we upgrade an order of magnitude result to a full asymptotic formula that was conjectured by Hooley in the number field setting
RUBIES: A complete census of the bright and red distant universe with JWST/NIRSpec
No full textWe present the Red Unknowns: Bright Infrared Extragalactic Survey (RUBIES) providing JWST/NIRSpec spectroscopy of red sources selected across ∼150 arcmin2 from public JWST/NIRCam imaging in the UDS and EGS fields. The novel observing strategy of RUBIES offers a well-quantified selection function. The survey has been optimised to reach high (>70%) spectroscopic completeness for bright and red (F150W−F444W>2) sources that are very rare. To place these rare sources in context, we simultaneously observed a reference sample of the 23 using only the G395M disperser. The RUBIES data reveal a highly diverse population of red sources that span a broad redshift range (zspec∼1−9), with photometric redshift scatter and an outlier fraction that are three times higher than for similarly bright sources that are less red. This diversity is not apparent from the photometric spectral energy distributions (SEDs). Only spectroscopy reveals that the SEDs encompass a mixture of galaxies with dust-obscured star formation, extreme line emission, a lack of star formation indicating early quenching, and luminous active galactic nuclei. As a first demonstration of our broader selection function we compared the stellar masses and rest-frame U−V colours of the red sources and our reference sample. We find that the red sources are typically more massive (M*∼1010−11.5 M⊙) across all redshifts. However, we also find that the most massive systems span a wide range in U−V colour. We describe our data reduction procedure and data quality, and we publicly release the reduced RUBIES data and vetted spectroscopic redshifts of the first half of the survey through the DAWN JWST Archive
Prussian blue analogues as anode materials for battery applications: Complexities and horizons
No full textPrussian blue (PB) and Prussian blue analogues (PBAs) are a class of porous materials composed of transition metal cations, cyanide ligands, and alkali metal cations. Their ability to intercalate and deintercalate ions within their framework pores, coupled with the adaptability of their crystal structure to electrochemical changes, underpins their success in battery applications. PBAs with Fe or Co as the active site exhibit high redox potentials (vs SHE) and have been extensively explored as cathode materials, with well-documented chemistry, crystal structures, and electrochemical properties. In contrast, PBAs with Cr or Mn as the active site display lower redox potentials and remain significantly underexplored as anode materials. This gap has led to fewer reported compounds and a less comprehensive understanding of their structural and electrochemical behavior, leaving the field relatively opaque. In this perspective, we comprehensively analyze the challenges involved in producing and employing PBAs with low redox potentials as active battery materials. Conversely, we propose numerous horizons and ask fundamental questions that should pave the way for future research to advance the field
Quantum transport in the presence of a chiral molecular potential
No full textWe investigate quantum transport in a two-dimensional electron system coupled to a chiral molecular potential, demonstrating how molecular chirality and orientation affect charge and spin transport properties. We propose a minimal model for realizing true chiral symmetry breaking on a magnetized surface, with a crucial role played by the tilt angle of the molecular dipole with respect to the surface. For non-zero tilting, we show that the Hall response exhibits clear signatures of chirality-induced effects, in both charge- and spin-resolved observables. Concerning the former, tilted enantiomers produce asymmetric Hall conductances and, even more remarkably, the persistence of this feature in the absence of spin–orbit coupling (SOC) signals how the enantiospecific charge response results from electron scattering off the molecular potential. Concerning spin-resolved observables where SOC plays a relevant role, we reveal that chiral symmetry breaking is crucial in enabling spin-flipping processes
Solving robust Markov decision processes: Generic, reliable, efficient
No full textMarkov decision processes (MDP) are a well-established model for sequential decision-making in the presence of probabilities. In *robust* MDP (RMDP), every action is associated with an *uncertainty set* of probability distributions, modelling that transition probabilities are not known precisely. Based on the known theoretical connection to stochastic games, we provide a framework for solving RMDPs that is generic, reliable, and efficient. It is *generic* both with respect to the model, allowing for a wide range of uncertainty sets, including but not limited to intervals, L1- or L2-balls, and polytopes; and with respect to the objective, including long-run average reward, undiscounted total reward, and stochastic shortest path. It is *reliable*, as our approach not only converges in the limit, but provides precision guarantees at any time during the computation. It is *efficient* because -- in contrast to state-of-the-art approaches -- it avoids explicitly constructing the underlying stochastic game. Consequently, our prototype implementation outperforms existing tools by several orders of magnitude and can solve RMDPs with a million states in under a minute
Files for "Evolutionary repurposing of a DNA segregation machinery into a cytoskeletal system controlling cyanobacterial cell shape"
No full textOn the chromatic number of powers of subdivisions of graphs
No full textFor a given graph G=(V,E), we define its \emph{nth subdivision} as the graph obtained from G by replacing every edge by a path of length n. We also define the \emph{mth power} of G as the graph on vertex set V where we connect every pair of vertices at distance at most m in G. In this paper, we study the chromatic number of powers of subdivisions of graphs and resolve the case m=n asymptotically. In particular, our result confirms a conjecture of Mozafari-Nia and Iradmusa in the case m=n=3 in a strong sense