Science Society

Welcome to another insightful episode, where today we have the pleasure of hosting Dr. Grinter, a leading authority on bacterial metabolism. Dr. Grinter will illuminate his latest research unraveling the process and mechanisms of atmospheric H2 oxidation in aerobic bacteria, a process with significant global implications, from regulating the composition of the atmosphere to driving primary production in extreme environments.

Dr. Grinter provides an in-depth explanation of his research on the Mycobacterium smegmatis hydrogenase Huc, a highly efficient oxygen-insensitive enzyme. His research team's success in determining the cryo-electron microscopy structure of this enzyme offers key insights into its function.

One of the most fascinating discoveries is the enzyme's unique capability to use narrow hydrophobic gas channels to selectively bind atmospheric H2 over O2 and the role of 3 [3Fe–4S] clusters in making atmospheric H2 oxidation energetically feasible. Further, he elaborates on how Huc couples the oxidation of atmospheric H2 to the hydrogenation of the respiratory electron carrier menaquinone.

Dr. Grinter delves into the intriguing octameric structure of the Huc catalytic subunits and its role in transporting and reducing menaquinone far from the membrane. His research uncovers a unique mode of energy coupling dependent on long-range quinone transport.

Join us in this enlightening episode to better understand the biogeochemically and ecologically critical process of atmospheric H2 oxidation. Dr. Grinter's research paves the way for the development of catalysts that oxidize H2 in ambient air, offering far-reaching implications for our understanding of bacterial metabolism and the broader field of biochemistry.

Grinter, R., Kropp, A., Venugopal, H. et al. Structural basis for bacterial energy extraction from atmospheric hydrogen. Nature 615, 541–547 (2023). https://doi.org/10.1038/s41586-023-05781-7

In this episode, we welcome Dr. Rusca, an expert in environmental and social sciences, to discuss the social-environmental implications of climate change-induced droughts in urban areas of Southern Africa.

Dr. Rusca draws upon the theoretical insights from critical social sciences to build a scenario predicting the impacts of an unprecedented drought in Maputo. This city epitomizes the highly uneven development and differential vulnerability found across urban areas in Southern Africa. She takes us through a comparative analysis, drawing lessons from Cape Town's experience during the 2015-2017 drought, which was locally unprecedented in Southern Africa.

Dr. Rusca elucidates her findings that future droughts in Southern Africa are likely to further polarize urban inequalities, lead to localized public health crises, and undo the progress made in water access. The conversation navigates the complex intersection of climate change, social power dynamics, and economic visions, highlighting how these factors shape societal responses to droughts.

This discussion is not just a prediction of the challenging times to come but a call to action. Dr. Rusca stresses that climate policies must acknowledge and address these inequalities, with a focus on developing equitable water distribution and conservation measures. This will be crucial to ensuring sustainable and inclusive adaptation to future droughts.

Join us for this enlightening episode as Dr. Rusca gives us a profound understanding of the intricate relationship between climate change, urban development, and social inequities. Tune in for a critical discussion on the future of Southern African cities in the face of intensifying droughts.

Unprecedented droughts are expected to exacerbate urban inequalities in Southern Africa https://www.nature.com/articles/s41558-022-01546-8

Maria Rusca (She/her)

Lecturer in Global Development

School of Environment, Education, and Development

University of Manchester

In today's episode, we are thrilled to welcome Molly Burkmar (Ph.D. student at the University of Portsmouth), a researcher in cosmology. Molly Burkmar takes us on an in-depth exploration into the dynamics of Friedmann-Lemaître-Robertson-Walker (FLRW) cosmologies consisting of dark matter, radiation, and dark energy with a quadratic equation of state.

Molly Burkmar focuses her analysis on non-singular bouncing and cyclic cosmologies, casting a spotlight on the potential for closed models to always have a bounce under any initial conditions. With a careful examination of the range of dynamical behaviors admitted by the system, she identifies a unique class of closed models that admit a non-singular bounce, characterized by early- and late-time accelerated expansion connected by a decelerating phase.

Our conversation delves into the conditions under which these bouncing models become relevant, exploring the necessary presence of dark matter and radiation at a specific energy scale, requiring a period such as reheating. Molly Burkmar further investigates the effects of imposing an upper limit on dark matter and radiation energy densities.

The episode continues with a consideration of potential parameter values for the dark energy component that could explain the discrepancy between the observed value of the cosmological constant (Λ) and theoretical estimates.

Despite finding that the remaining models do not allow for an early- and late-time accelerated expansion connected by a decelerating period, Dr. Burkmar's qualitative analysis sets the stage for constructing more realistic models with realistic quantitative behavior.

Join us for this fascinating episode as we delve into the enigmatic world of dark matter, dark energy, and the cosmic forces that shape our universe.

Institute of Cosmology and Gravitation (University of Portsmouth), researching bouncing cosmologies: Bouncing cosmology from nonlinear dark energy with two cosmological constants https://arxiv.org/abs/2302.03710

Welcome to another enlightening episode where today we're joined by Dr. Yang Bai, who challenges the prevailing assumption in exoplanetary science. In an unconventional proposition, Dr. Bai suggests that some exoplanets could be comprised of dark matter, a hypothesis leading to the concept of "dark exoplanets."

Throughout the episode, Dr. Bai explores various methods to detect these hypothesized dark exoplanets. From the mass-radius relation to spectroscopy, missing transit, and transit light curve methods, we delve into the exciting and innovative techniques that could uncover these celestial bodies.

Our focus turns to the transit light curve method, as Dr. Bai details how this approach can differentiate between partially transparent dark exoplanets and fully opaque ordinary exoplanets. Drawing from both observed exoplanet data and dark exoplanet mock data; we'll explore how this method could potentially reveal the existence of dark exoplanets.

Interestingly, Dr. Bai's analysis suggests that with current telescope sensitivities, dark exoplanets with a large radius (above around 10% of the star radius) and a small optical depth (below around one) could be identified.

Join us on this intriguing journey into the unseen world of dark exoplanets as we explore the boundaries of our knowledge of the cosmos and challenge the very assumptions that have guided our understanding of the universe.

https://doi.org/10.48550/arXiv.2303.12129

Welcome to another episode where we dive into the undercurrents of our world's oceans. Today, we're joined by Dr. Galloway, who will share fascinating insights into the ecosystem dynamics of the North American west coast.

Recently, a collapse in predatory sunflower sea star (Pycnopodia helianthoides) populations due to Sea Star Wasting Disease (SSWD) has coincided with an explosive proliferation of sea urchin barrens, leading to a concerning decrease in kelp forests. Dr. Galloway's research tackles the potential role that recovering Pycnopodia populations could play in kelp forest regeneration by consuming nutritionally poor purple sea urchins (Strongylocentrotus purpuratus) typical of barrens.

Dr. Galloway's experiments reveal that Pycnopodia consume an average of 0.68 S. purpuratus per day, and interestingly, they seem unable to chemically distinguish between starved and fed urchins. They even demonstrate higher predation rates on starved urchins due to shorter handling times.

By using a model and sensitivity analysis, Dr. Galloway shows that even minor recoveries in Pycnopodia populations could lead to a reduction in sea urchin densities consistent with kelp-urchin coexistence. These findings emphasize the vital role of Pycnopodia in regulating purple sea urchin populations and maintaining healthy kelp forests through top-down control.

Join us as we explore the fascinating world of marine ecosystems, and learn how the recovery of predatory sunflower sea stars could be a key step towards restoring kelp forests at ecologically significant scales. Whether through natural means or human-assisted reintroductions, the return of this important predator might be the ray of hope these underwater forests need.

Sunflower sea star predation on urchins can facilitate kelp forest recovery https://doi.org/10.1098/rspb.2022.1897

In this engaging episode, Dr. Olguín delves deep into the intricate connection between cardiac metabolism and heart failure, focusing on the crucial role of the enzyme lysine demethylase 8 (Kdm8). Dr. Olguín's groundbreaking research suggests that Kdm8 ensures the smooth functioning of the mitochondrial gene network by suppressing the gene Tbx15, thereby preventing dilated cardiomyopathy, a condition that can lead to lethal heart failure. Through their work on mice, the research team found that a lack of Kdm8 increases a certain type of protein modification which activates Tbx15, subsequently leading to a drop in target genes within the NAD+ pathway before the onset of dilated cardiomyopathy. Furthermore, the team discovered that NAD+ supplementation could prevent dilated cardiomyopathy in Kdm8-deficient mice. Remarkably, KDM8 was found to be downregulated in human hearts afflicted by dilated cardiomyopathy. Higher TBX15 expression was found in a subgroup of these hearts, which were also strongly marked by the downregulation of genes encoding mitochondrial proteins. This in-depth discussion with Dr. Olguín not only reveals how KDM8 regulates TBX15 to maintain cardiac metabolism but also opens up a wider conversation on how the epigenetic dysregulation of metabolic gene networks might initiate deterioration of the myocardium, potentially underlying the heterogeneity of dilated cardiomyopathy. This episode is a must-listen for anyone interested in cutting-edge research on heart disease and the complex interplay between genetics, epigenetics, and metabolism.

Ahmed, A., et al. KDM8 epigenetically controls cardiac metabolism to prevent initiation of dilated cardiomyopathy. Nat Cardiovasc Res 2, 174–191 (2023). https://doi.org/10.1038/s44161-023-00214-0

In this podcast episode, Dr. Cassak delves into the exploration of energy conversion in weakly collisional and collisionless plasmas that are typically far from local thermodynamic equilibrium (LTE). He challenges the standard approach of focusing solely on changes in internal energy and density, advocating for consideration of higher-order moments of the phase space density for systems not in LTE. Through particle-in-cell simulations of collisionless magnetic reconnection, Dr. Cassak unveils that energy conversion associated with higher-order moments can have a significant local impact. These insights could illuminate a myriad of plasma environments, including reconnection, turbulence, shocks, and wave-particle interactions in heliospheric, planetary, and astrophysical plasmas.

Weakly Collisional Plasmas, Collisionless Plasmas, Local Thermodynamic Equilibrium, Energy Conversion, Higher-Order Moments, Phase Space Density, Particle-in-Cell Simulations, Collisionless Magnetic Reconnection, Plasma Settings, Reconnection, Turbulence, Shocks, Wave-Particle Interactions, Heliospheric Plasmas, Planetary Plasmas, Astrophysical Plasmas.

Quantifying Energy Conversion in Higher-Order Phase Space Density Moments in Plasmas Paul A. Cassak, et al Phys. Rev. Lett. 2023 https://doi.org/10.1103/PhysRevLett.130.085201

In this podcast episode, Dr. Man Ho Chan presents his intriguing research that provides evidence for the existence of dark matter density spikes around stellar-mass black holes, specifically A0620-00 and XTE J1118+480. His team's work challenges the long-held notion that dark matter forms a density spike around a black hole, which until now lacked solid observational evidence. Their findings, based on the study of abnormally fast orbital decays in these binaries due to the dynamical friction between dark matter and companion stars, point towards the possible existence of dark matter density spikes. This episode underscores the importance of analyzing observational data from nearby black hole X-ray binaries as a promising avenue for further revealing the elusive nature of dark matter.

Dark Matter, Density Spikes, Black Holes, Stellar-Mass Black Holes, Orbital Decays, Dynamical Friction, Companion Stars, Stellar Heating Model, X-ray Binaries, A0620-00, XTE J1118+480.

Indirect Evidence for Dark Matter Density Spikes around Stellar-mass Black Holes DOI 10.3847/2041-8213/acaafa possible indirect evidence that dark matter forms a density spike around a black hole.

Join us for an insightful conversation with Dr. Sandra Stojić, Dr. Vanja Topić, and Prof. Zoltan Nadasdy as they delve into the fascinating world of time perception and its evolution from early childhood to adulthood. In this episode, they discuss their research on how individuals across different age groups attribute varying meanings to time when comparing durations. They explain their experiment, which involved comparing the durations of "eventful" and "uneventful" videos using hand gestures and observing the divergence in perception across pre-kindergarteners, school-age children, and adults. As the findings reveal, our understanding and interpretation of time evolve significantly as we grow, shedding light on the complex interplay of cognitive development and temporal perception. Whether you are a student of psychology, a cognitive science enthusiast, or just curious about the intricacies of the human mind, this episode promises to offer you valuable insights.

Key Words: Time Perception, Cognitive Development, Temporal Bias, Event Density, Observer-Independent Time, Heuristics, Temporal Duration, Pre-Kindergarteners, School-Age Children, Adults, Experimental Psychology.

Stojić, S., Topić, V. & Nadasdy, Z. Children and adults rely on different heuristics for estimation of durations. Sci Rep 13, 1077 (2023). https://doi.org/10.1038/s41598-023-27419-4

In this intriguing episode, we welcome Dr. Efstathiou to discuss his pivotal research on endoplasmic reticulum (ER) homeostasis. The conversation focuses on the endoplasmic reticulum's role in coordinating mRNA translation and processing of secreted and endomembrane proteins. It further explores the mechanisms by which the ER-associated degradation (ERAD) and ER-associated RNA silencing (ERAS) pathways, identified through a genetic screen in Caenorhabditis elegans, interact to preserve ER health and functionality. Dr. Efstathiou explains how these pathways' simultaneous inactivation can lead to increased ER stress, reduced protein quality control, and impaired intestinal integrity. If you're interested in cell biology, molecular genetics or want to understand the intricate workings of our cells better, this episode promises to deliver enlightening insights.

Endoplasmic Reticulum, ERAD, ERAS, RNA Interference, Protein Quality Control, Caenorhabditis elegans, Argonaute Protein, RNA Turnover, ER Stress, Intestinal Integrity.

Efstathiou, S., Ottens, F., Schütter, LS. et al. ER-associated RNA silencing promotes ER quality control. Nat Cell Biol 24, 1714–1725 (2022). https://doi.org/10.1038/s41556-022-01025-4