241 research outputs found
New genus of the tribe Ceutorhynchini (Coleoptera: Curculionidae) from the late Oligocene of Enspel, southwestern Germany, with a remark on the role of weevils in the ancient food web
The new weevil genus Igneonasus gen. nov. (type species: I. rudolphi sp. nov.) of the tribe
Ceutorhynchini (Curculionidae: Conoderinae: Ceutorhynchitae) is described
from the late Oligocene of Fossillagerstätte Enspel, Germany. The new
genus differs from the similar genus Stenocarus Thomson, 1859 in the anterior margin
of the pronotum, which is not raised, a pronotum without tubercles on the
sides, and a femur without teeth. This weevil is the largest representative
of this supertribe and the first fossil Curculionidae species described from
the paleolake Enspel. In this ancient ecosystem, weevils were at least sometimes
an important food resource for the cyprinid fish Palaeorutilus enspelensis.</p
RISnet: A Domain-Knowledge Driven Neural Network Architecture for RIS Optimization with Mutual Coupling and Partial CSI
Multiple access techniques are cornerstones of wireless communications. Their
performance depends on the channel properties, which can be improved by
reconfigurable intelligent surfaces (RISs). In this work, we jointly optimize
MA precoding at the base station (BS) and RIS configuration. We tackle
difficulties of mutual coupling between RIS elements, scalability to more than
1000 RIS elements, and channel estimation. We first derive an RIS-assisted
channel model considering mutual coupling, then propose an unsupervised machine
learning (ML) approach to optimize the RIS. In particular, we design a
dedicated neural network (NN) architecture RISnet with good scalability and
desired symmetry. Moreover, we combine ML-enabled RIS configuration and
analytical precoding at BS since there exist analytical precoding schemes.
Furthermore, we propose another variant of RISnet, which requires the channel
state information (CSI) of a small portion of RIS elements (in this work, 16
out of 1296 elements) if the channel comprises a few specular propagation
paths. More generally, this work is an early contribution to combine ML
technique and domain knowledge in communication for NN architecture design.
Compared to generic ML, the problem-specific ML can achieve higher performance,
lower complexity and symmetry.Comment: 13 pages, 16 figure
Quantitative insights into the cyanobacterial cell economy
© Zavřel et al. Phototrophic microorganisms are promising resources for green biotechnology. Compared to heterotrophic microorganisms, however, the cellular economy of phototrophic growth is still insufficiently understood. We provide a quantitative analysis of light-limited, light-saturated, and light-inhibited growth of the cyanobacterium Synechocystis sp. PCC 6803 using a reproducible cultivation setup. We report key physiological parameters, including growth rate, cell size, and photosynthetic activity over a wide range of light intensities. Intracellular proteins were quantified to monitor proteome allocation as a function of growth rate. Among other physiological acclimations, we identify an upregulation of the translational machinery and downregulation of light harvesting components with increasing light intensity and growth rate. The resulting growth laws are discussed in the context of a coarse-grained model of phototrophic growth and available data obtained by a comprehensive literature search. Our insights into quantitative aspects of cyanobacterial acclimations to different growth rates have implications to understand and optimize photosynthetic productivity
Fungi hijack a ubiquitous plant apoplastic endoglucanase to release a ROS scavenging beta-glucan decasaccharide to subvert immune responses
Plant pathogenic and beneficial fungi have evolved several strategies to evade immunity and cope with host-derived hydrolytic enzymes and oxidative stress in the apoplast, the extracellular space of plant tissues. Fungal hyphae are surrounded by an inner insoluble cell wall layer and an outer soluble extracellular polysaccharide (EPS) matrix. Here, we show by proteomics and glycomics that these two layers have distinct protein and carbohydrate signatures, and hence likely have different biological functions. The barley (Hordeum vulgare) β-1,3-endoglucanase HvBGLUII, which belongs to the widely distributed apoplastic glycoside hydrolase 17 family (GH17), releases a conserved β-1,3;1,6-glucan decasaccharide (β-GD) from the EPS matrices of fungi with different lifestyles and taxonomic positions. This low molecular weight β-GD does not activate plant immunity, is resilient to further enzymatic hydrolysis by β-1,3-endoglucanases due to the presence of three β-1,6-linked glucose branches and can scavenge reactive oxygen species. Exogenous application of β-GD leads to enhanced fungal colonization in barley, confirming its role in the fungal counter-defensive strategy to subvert host immunity. Our data highlight the hitherto undescribed capacity of this often-overlooked EPS matrix from plant-associated fungi to act as an outer protective barrier important for fungal accommodation within the hostile environment at the apoplastic plant–microbe interface
CuCo2S4 deposited on TiO2: Controlling the pH Value Boosts Photocatalytic Hydrogen Evolution
Metallic spinel‐type CuCo2S4 nanoparticles were deposited on nanocrystalline TiO2 (P25®), forming heterostructure nanocomposites. The nanocomposites were characterized in detail by X‐ray powder diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM), nitrogen sorption (BET) and UV/Vis spectroscopy. Variation of the CuCo2S4:TiO2 ratio to an optimum value generated a catalyst which shows a very high photocatalytic H2 production rate at neutral pH of 32.3 µmol/h (0.72 mL h–1), which is much larger than for pure TiO2 (traces of H2). The catalyst exhibits an extraordinary long‐term stability and after 70 h irradiation time about 2 mmol H2 were generated. An increased light absorption and an efficient charge separation for the sample with the optimal CuCo2S4:TiO2 ratio is most probably responsible for the high catalytic activity
Selenium Utilization by GPX4 Is Required to Prevent Hydroperoxide-Induced Ferroptosis
open24siSelenoproteins are rare proteins among all kingdoms of life containing the 21st amino acid, selenocysteine. Selenocysteine resembles cysteine, differing only by the substitution of selenium for sulfur. Yet the actual advantage of selenolate- versus thiolate-based catalysis has remained enigmatic, as most of the known selenoproteins also exist as cysteine-containing homologs. Here, we demonstrate that selenolate-based catalysis of the essential mammalian selenoprotein GPX4 is unexpectedly dispensable for normal embryogenesis. Yet the survival of a specific type of interneurons emerges to exclusively depend on selenocysteine-containing GPX4, thereby preventing fatal epileptic seizures. Mechanistically, selenocysteine utilization by GPX4 confers exquisite resistance to irreversible overoxidation as cells expressing a cysteine variant are highly sensitive toward peroxide-induced ferroptosis. Remarkably, concomitant deletion of all selenoproteins in Gpx4cys/cys cells revealed that selenoproteins are dispensable for cell viability provided partial GPX4 activity is retained. Conclusively, 200 years after its discovery, a specific and indispensable role for selenium is provided.openIngold, Irina; Berndt, Carsten; Schmitt, Sabine; Doll, Sebastian; Poschmann, Gereon; Buday, Katalin; Roveri, Antonella; Peng, Xiaoxiao; Porto Freitas, Florencio; Seibt, Tobias; Mehr, Lisa; Aichler, Michaela; Walch, Axel; Lamp, Daniel; Jastroch, Martin; Miyamoto, Sayuri; Wurst, Wolfgang; Ursini, Fulvio; Arnér, Elias S J; Fradejas-Villar, Noelia; Schweizer, Ulrich; Zischka, Hans; Friedmann Angeli, José Pedro; Conrad, MarcusIngold, Irina; Berndt, Carsten; Schmitt, Sabine; Doll, Sebastian; Poschmann, Gereon; Buday, Katalin; Roveri, Antonella; Peng, Xiaoxiao; Porto Freitas, Florencio; Seibt, Tobias; Mehr, Lisa; Aichler, Michaela; Walch, Axel; Lamp, Daniel; Jastroch, Martin; Miyamoto, Sayuri; Wurst, Wolfgang; Ursini, Fulvio; Arnér, Elias S J; Fradejas-Villar, Noelia; Schweizer, Ulrich; Zischka, Hans; Friedmann Angeli, José Pedro; Conrad, Marcu
A Comparison of Chi^2-Test and Mutual Information as Distinguisher for Side-Channel Analysis
Masking is known as the most widely studied countermeasure against side-channel analysis attacks.
Since a masked implementation is based on a certain number of shares (referred to as the order of masking), it still exhibits leakages at higher orders.
In order to exploit such leakages, higher-order statistical moments individually at each order need to be estimated reflecting the higher-order attacks.
Instead, Mutual Information Analysis (MIA) known for more than 10 years avoids such a moment-based analysis by considering the entire distribution for the key recovery.
Recently the -test has been proposed for leakage detection and as a distinguisher where also the whole distribution of the leakages is analyzed.
In this work, we compare these two schemes to examine their dependency.
Indeed, one of the goals of this research is to conclude whether one can outperform the other.
In addition to a theoretical comparison, we present two case studies and their corresponding practical evaluations.
Both case studies are masked hardware implementations; one is an FPGA-based realization of a threshold implementation of PRESENT, and the other is an AES implementation as a coprocessor on a commercial smart card
Shuffle and Mix: On the Diffusion of Randomness in Threshold Implementations of Keccak
Threshold Implementations are well-known as a provably firstorder secure Boolean masking scheme even in the presence of glitches. A precondition for their security proof is a uniform input distribution at each round function, which may require an injection of fresh randomness or an increase in the number of shares. However, it is unclear whether violating
the uniformity assumption causes exploitable leakage in practice. Recently, Daemen undertook a theoretical study of lossy mappings to extend the understanding of uniformity violations. We complement his work by entropy simulations and practical measurements of Keccak’s round function. Our findings shed light on the necessity of mixing operations in addition to bit-permutations in a cipher’s linear layer to propagate
randomness between S-boxes and prevent exploitable leakage. Finally, we argue that this result cannot be obtained by current simulation methods, further stressing the continued need for practical leakage measurements
Gene Expression Changes Associated with the Airway Wall Response to Injury
Understanding the way in which the airway heals in response to injury is fundamental to dissecting the mechanisms underlying airway disease pathology. As only limited data is available in relation to the in vivo characterisation of the molecular features of repair in the airway we sought to characterise the dynamic changes in gene expression that are associated with the early response to physical injury in the airway wall.We profiled gene expression changes in the airway wall using a large animal model of physical injury comprising bronchial brush biopsy in anaesthetised sheep. The experimental design featured sequential studies in the same animals over the course of a week and yielded data relating to the response at 6 hours, and 1, 3 and 7 days after injury. Notable features of the transcriptional response included the early and sustained preponderance of down-regulated genes associated with angiogenesis and immune cell activation, selection and differentiation. Later features of the response included the up-regulation of cell cycle genes at d1 and d3, and the latter pronounced up-regulation of extracellular matrix-related genes at d3 and d7.It is possible to follow the airway wall response to physical injury in the same animal over the course of time. Transcriptional changes featured coordinate expression of functionally related genes in a reproducible manner both within and between animals. This characterisation will provide a foundation against which to assess the perturbations that accompany airway disease pathologies of comparative relevance
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