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From Patches to Processes:Linking Grazing, Facilitation, and Trait Variation in a Grazed Salt Marsh
No full textThis thesis investigated how plants, grazers, and the environment interact to shape vegetation patches and intraspecific plant traits. The research was conducted on the cattle-grazed and non-grazed salt marsh of the island Schiermonnikoog (the Netherlands) where visible patches of the grazer-defended rush Juncus maritimus and grazer-intolerant grass Elytrigia atherica occur. First, a conceptual framework was developed to describe cyclical vegetation patch dynamics in rangeland systems. This framework integrates theories of cyclical succession, self-organization, and multi-trophic feedbacks, proposing a four-phase cycle of patch initiation, establishment, expansion, and degeneration driven by interactions among grazer-defended and grazer-intolerant plants, large grazers, and bioturbation by soil fauna. Second, a transplant experiment assessed how plant-plant interactions between J. maritimus and E. atherica vary with grazing, abiotic stress, and E. atherica ecotype differentiation. The experiment found that survival and growth of E. atherica were strongly impacted by J. maritimus patches, grazing and inundation, with E. atherica ecotype playing no significant role. Third, an observational study examined how grazing, inundation stress, and plant interactions interactively influence structural and reproductive trait variation of E. atherica. Patches of J. maritimus buffered E. atherica against grazers and inundation stress. However, in the non-grazed salt marsh, the plant-plant interactions shifted towards competition, particularly under low inundation stress. Overall, this thesis demonstrated that vegetation patchiness and intraspecific plant trait variation emerge from context-dependent interactions among grazers, environmental stress, and plant-plant interactions, with implications for our understanding of vegetation structure and rangeland management
Timing of Cardiovascular and Kidney Benefits With Finerenone in Heart Failure and Chronic Kidney Disease With Type 2 Diabetes
No full textIonic glass formers show an inverted relation between fragility and non-exponential alpha-relaxation
No full textSupercooled liquids undergo a rapid change in dynamics as they are cooled to their glass transition temperature and turn from a flowing liquid into an amorphous solid. Depending on how steeply the viscosity changes with temperature around the glass transition, glass formers are classified as strong or fragile. An empirical relation exists between the fragility of the liquid and the non-exponentiality of its α-relaxation. However, the microscopic origins of this correlation remain unclear and its generality has been debated. Here, we demonstrate that this relationship is inverted in organic materials with ionic interactions. We introduce a class of materials consisting of highly charged hydrophobic polymers cross-linked via moderated ionic interactions, and show that these combine a strong glass transition with an unusually stretched mechanical relaxation spectrum. By surveying a large variety of ionic liquids, polymerized ionic liquids, and ionomers, we show that all these charged materials follow a trend between fragility and non-exponential relaxation that is opposite to that of non-charged materials. This finding suggests a special role of long-ranged ionic interactions in vitrification and opens up a route toward developing new materials that combine the processability of strong glass formers with the mechanical dissipation of polymers.</p
Measuring the stellar-to-halo mass relation at ∼10<sup>10</sup> solar masses, using forthcoming space-based imaging of galaxy–galaxy strong lenses
No full textThe stellar-to-halo mass relation (SHMR) is central to understanding the co-evolution of galaxies and their host dark matter haloes, yet it remains weakly constrained for dwarf galaxies owing to their faintness, especially beyond the Local Group. Strong gravitational lensing offers a unique probe of the SHMR at subgalactic scales and cosmological distances, as the masses of subhaloes within the main lens can be inferred from the perturbations they imprint on lensed images. Anticipating the discovery of ∼105 galaxy–galaxy strong lenses by forthcoming facilities such as Euclid, we perform an end-to-end simulation to forecast Euclid’s constraints on the SHMR at the halo mass scale of ∼1010, M⊙. We generate mock Euclid Visible Camera images of lens systems hosting a fiducial 3 × 1010, M⊙ subhalo and vary its properties to assess the robustness of mass inference. We find that Euclid’s angular resolution cannot break the intrinsic mass–concentration degeneracy of subhaloes, nor deblend the light of satellite galaxies (when present) associated with them, leading to biased inferred halo masses. These limitations can be overcome with high-resolution follow-up imaging from facilities such as the Hubble Space Telescope, enabling accurate halo-mass measurements.We forecast that a statistical sample of ∼100 such systems, combining lensing-derived halo masses with stellar masses from photometric spectral energy distribution fitting, can constrain the SHMR at dwarf-galaxy scales with a precision of ∼0.05 dex in halo mass and ∼0.03 dex in stellar mass, enabling powerful tests of galaxy formation theories.</p
Effect Modification of Trimethylamine N-Oxide and Lipoprotein Insulin Resistance with Post-Transplantation Diabetes After Liver Transplant
No full textPost-transplant diabetes mellitus (PTDM) is a common complication after liver transplantation. Trimethylamine N-oxide (TMAO), a microbiota-derived metabolite, has been linked to insulin resistance, but epidemiological findings on type 2 diabetes remain inconsistent. The Lipoprotein Insulin Resistance (LP-IR) score is a nuclear magnetic resonance (NMR)-derived marker of insulin resistance, yet its role in PTDM and interaction with TMAO are unknown. Three hundred sixty-seven (367) liver transplant recipients (LTRs) from the TransplantLines cohort were studied. Baseline TMAO and LP-IR score were quantified by NMR spectroscopy. Incident PTDM was defined by international criteria. Associations were tested using logistic regression and Cox proportional regression analysis. Effect modification was tested with interaction terms. Thirty-one out of 246 LTRs at risk developed PTDM after a median follow-up of 7.1 years. Higher TMAO (OR 2.14, p = 0.015) and LP-IR score (OR 1.66, p = 0.015) were associated with increased PTDM risk after adjustment for eGFR and immunosuppressant use. A positive interaction was present ( p = 0.029) with risk amplification when both biomarkers were elevated. TMAO's association with PTDM was strongest at high LP-IR (90th percentile; OR 3.20, p = 0.005), and LP-IR's association was strongest at high TMAO (90th percentile; OR 2.56, p = 0.002). Time-to-event analysis confirmed these findings. The independent and positive interaction of TMAO and LP-IR with PTDM in LTRs would suggest a pro-diabetic action of TMAO that depends on insulin resistance. </p
Programmed meiotic errors facilitate dichotomous sperm production in the silkworm, <i>Bombyx mori.</i>
No full textThe goal of meiosis is typically to produce haploid gametes (eggs or sperm). Failure to do so is catastrophic for fertility. However, Lepidopteran (moths and butterflies) males produce two sperm morphs: nucleated (eupyrene) sperm and anucleated (apyrene) sperm, both of which are essential for fertilization. The meiotic differences in the two types of spermatogenesis are unclear, and our knowledge of the molecular differences between eupyrene and apyrene spermatogenesis is extremely limited in all systems. The only factor identified as being required for apyrene spermatogenesis is Sex-lethal ( Sxl). Here, we show through cytological analysis of meiotic events that there are several key differences in the genesis of apyrene and eupyrene sperm. Specifically, during meiosis I, apyrene spermatocytes fail to decondense and pair their chromosomes during meiotic prophase I. Telomeres fail to localize to the nuclear periphery, and full-length synaptonemal complex does not form. We also find evidence of an abnormal second cell division during apyrene meiosis. RNA sequencing of both eupyrene- and apyrene-producing testes reveals distinct changes in transcriptional programs, including down-regulation of a myriad of cell division genes during apyrene meiosis. By comparing wildtype and Sxl-knockout apyrene testes, we found that Sxl is not required for regulating the expression of the cell division genes but instead may play a role in blocking hormone signaling from altering testis cell identity. Together, our findings reveal significant insights into two converging molecular pathways that promote the formation of dimorphic sperm in Lepidoptera. </p
Neurophysiological correlates of passive movements are speed- and type-dependent
No full textPurposeThe supraspinal involvement in the control of passive movements remains elusive. Previous studies provided electromyographic evidence for speed and –type dependent changes in muscle activity. Based on mechanoreceptor properties, their age-related changes and the somatotopically organized connections between sensory and motor systems, this study aimed to provide electrophysiological evidence for the involvement of frontal cortex inhibition and corticomotor interactions in the control of passive movements.MethodsTwenty healthy younger and older adults performed passive elbow flexion and extension movements at three metronome-based speeds (20, 60, and 100 beats per minute) in continuous and discontinuous fashion. The continuous condition included movements with no inter-movement pauses and the discontinuous conditions with pauses between flexion–extension transitions. The order of movement speeds increased progressively to prevent carryover effects in hypothesized resistance to passive movements from higher to lower speeds. In all conditions, electro-encephalographic and electromyographic data were acquired. Alpha power and beta corticomuscular coherence were used to quantify frontal cortex inhibition and brain-muscle connectivity, respectively.ResultsFrontal cortex inhibition decreased (p = 0.036) and brain-muscle connectivity increased (p < 0.001) with increasing movement speeds. In addition, frontal cortex inhibition was 17% higher in the discontinuous condition as compared to the continuous condition (p = 0.005) while corticomuscular coherence was 25.9% higher in the continuous vs. the discontinuous condition (p < 0.001). These effects were independent of age.ConclusionFrontal cortex inhibition and brain-muscle interactions depend on passive movement speed and -type. The current data may provide insights into the processes underlying pathological muscle tone during passive movements
Letter regarding “DNA damage and cancer risk in endovascular operators exposed to occupational radiation”
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Bruno:Backpropagation Running Undersampled for Novel device Optimization
No full textRecent efforts to improve the efficiency of neuromorphic and machine learning systems have centred on developing of specialised hardware for neural networks. These systems typically feature architectures that go beyond the von Neumann model employed in general-purpose hardware such as GPUs, offering potential efficiency and performance gains. However, neural networks developed for specialised hardware must consider its specific characteristics. This requires novel training algorithms and accurate hardware models, since they cannot be abstracted as a general-purpose computing platform. In this work, we present a bottom-up approach to training neural networks for hardware-based spiking neurons and synapses, built using ferroelectric capacitors (FeCAPs) and resistive random-access memories (RRAMs), respectively. Unlike the common approach of designing hardware to fit abstract neuron or synapse models, we start with compact models of the physical device to model the computational primitives. Based on these models, we have developed a training algorithm (BRUNO) that can reliably train the networks, even when applying hardware limitations, such as stochasticity or low bit precision. We analyse and compare BRUNO with Backpropagation Through Time. We test it on different spatio-temporal datasets. First on a music prediction dataset, where a network composed of ferroelectric leaky integrate-and-fire (FeLIF) neurons is used to predict at each time step the next musical note that should be played. The second dataset consists on the classification of the Braille letters using a network composed of quantised RRAM synapses and FeLIF neurons. The performance of this network is then compared with that of networks composed of LIF neurons. Experimental results show the potential advantages of using BRUNO by reducing the time and memory required to detect spatio-temporal patterns with quantised synapses