Mesoscale eddies, oceanic gyres about 100 kilometers in diameter, are ubiquitous features of the global ocean and play a vital role in marine ecosystems. Eddies, which form in biologically productive coastal upwelling regions, are important transporters of carbon and nutrients. These eddies trap water masses and migrate into the open ocean, where productivity is comparatively low. As such, they have a significant influence on the nutrient and carbon cycles within the ocean.
Siberia, a province located in Russia, is a significant geographical region playing a crucial role in the world's carbon cycle. With its vast forests, wetlands, and permafrost regions (permanently frozen grounds), Siberia stores a considerable amount of carbon on a global scale. But climate change is rapidly altering Siberia's landscape, shifting its vegetative distribution and accelerating the permafrost thaw.
As climate change continues to accelerate at an alarming pace, innovative and scalable solutions are more critical than ever. This week, the American Society for Microbiology (ASM) and the International Union for Microbiological Societies (IUMS) released "Microbial Solutions for Climate Change," a report developed by their scientific advisory group (SAG) of global experts.
Along with nitrogen and carbon, phosphorus is an essential element for life on Earth. It is a central component of molecules such as DNA and RNA, which serve to transmit and store genetic information, and ATP (adenosine triphosphate), which cells need to produce energy.
The monsoon rains have long remained the lifeblood of India, providing the lion's share of the water used for drinking and irrigation. The yearly arrival of the rains, which quenches the thirst of the harsh summers, is caused by the movement of cloud bands from the equator towards the north.
Author(s): Zhen-Ke Dou, Chong Lv, Yousef I. Salamin, Nan Zhang, Feng Wan, Zhong-Feng Xu, and Jian-Xing Li
Compact spin-polarized positron accelerators play a major role in promoting significant positron application research, which typically require high acceleration gradients and polarization degrees, both of which, however, are still greatly challenging. Here, we put forward a spin-polarized positron a…
[Phys. Rev. E 111, 035209] Published Tue Mar 25, 2025
SummaryExtreme value statistics (EVS) is commonly used to model rare, extreme events such as natural disasters. This study proposes a method that integrates EVS and Bayesian estimation to enable the early forecasting of aftershock-induced ground shaking. The method is applied to continuous seismograms recorded immediately after a large earthquake. The proposed method is based on several key assumptions: the Gutenberg–Richter (G–R) and Omori–Utsu laws, as well as the proportionality between earthquake magnitude and the logarithmic maximum amplitude. Based on these assumptions, two metrics were computed at each seismic station: the exceedance probability of the maximum amplitude (EPMA) and the number of threshold value exceedances (EPNUM). While EPMA follows a long-tailed Fréchet distribution, with uncertainty spanning at least an order of magnitude, EPNUM follows a short-tailed Poisson distribution, with uncertainty typically varying by a factor of two. The performance of the proposed method was evaluated across three different types of aftershock sequences in Japan. The practical forecasting capability was demonstrated within 1 hour of the mainshock and was effective up to 7 days. Compared to conventional methods that rely on incomplete earthquake catalogues, the proposed approach demonstrated faster and more robust results. While the median forecast of maximum amplitude tended to be overestimated, possibly due to the potential nonlinear relationship between magnitude and logarithmic maximum amplitude, the forecast for the number of felt earthquakes did not show such bias. Because the proposed method is based on single-station processing, it can be applied in regions without a dense seismograph network or real-time earthquake monitoring system, as long as continuous ground motion data is available at the target site.
SummaryThe interpretation of subsurface resistivity structures in volcanic areas remains challenging and requires the selection of the most plausible configuration from various geological features that affect the resistivity measurements. A comprehensive physical study of the rocks in the target area is essential for accurate interpretation. A magnetotelluric (MT) survey conducted in the southeast flank of Mt. Ontake volcano detected several kilometres of low resistivity below 30 Ωm. However, the interpretation of resistivity anomalies remains to be verified; borehole data have been used to resolve this problem. In this study, geological, fracture, temperature, and resistivity structures obtained from borehole investigations were analysed using rock physical methods, and core samples were subjected to physical property measurements and microscopic observations. The geology observed in the borehole was sedimentary rock with a porosity of less than a few percent, except for the surface volcanic breccia and some intrusive granites. The borehole wall was poorly fractured. The groundwater temperature in the borehole was aligned with the standard geothermal gradient, 40 °C at a depth of 800 m. These results indicate the absence of a hydrothermal reservoir at the site. In contrast, the core samples contained pyrite-filled microfractures. All the samples had poor porosity and contained a small amount of clay minerals but showed uniformly lower resistivity values than expected for similar porosity. Some samples exhibited robust induced polarization effects. The pyrite contents of the samples were low. A pseudo-high-frequency conductivity model test using electrostatic field analysis on a numerical model of microfractured rock properties reproduced the low resistivity observed in the borehole investigation and MT survey. The specifically low resistivity values observed were appropriately reproduced. The findings of this study indicate that pyrite filling the microfractures can be a major contributor to the low resistivity below 1 Ωm in the study area and suggest that it is necessary to consider the network of microscale veins formed by conductive sulfide minerals, mainly pyrite, for the interpretation of subsurface resistivity in geothermal areas.
Publication date: 15 March 2025
Source: Advances in Space Research, Volume 75, Issue 6
Author(s): Sumanjit Chakraborty, Dibyendu Chakrabarty, Anil K. Yadav, Gopi K. Seemala
Publication date: 15 March 2025
Source: Advances in Space Research, Volume 75, Issue 6
Author(s): C. Cesaroni, M. Pezzopane, E. Zuccheretti, E. Pica, L. Spogli, D. Okoh, A. Pignalberi, J. Olwendo, L. Alfonsi, C. Marcocci, V. Romano, R. Imam, G. De Franceschi, B. Nava, J.B. Habarulema, G. Santilli, A. Di Cecco, J. Munzer
Publication date: 15 March 2025
Source: Advances in Space Research, Volume 75, Issue 6
Author(s): Maocai Wang, Cui Pei, Xiaoyu Chen, Guangming Dai, Zhiming Song, Lei Peng
Publication date: 15 March 2025
Source: Advances in Space Research, Volume 75, Issue 6
Author(s): Carynelisa Haspel, Yoav Yair
NASA research is revealing there's more to flowers than meets the human eye. A recent analysis of wildflowers in California shows how aircraft- and space-based instruments can use color to track seasonal flower cycles. The results suggest a potential new tool for farmers and natural-resource managers who rely on flowering plants.
Global heating over this millennium could exceed previous estimates due to carbon cycle feedback loops. This is the conclusion of a new study by the Potsdam Institute for Climate Impact Research (PIK). The analysis shows that achieving the Paris Agreement's aim of limiting global temperature rise to well below 2°C is only feasible under very low emission scenarios, and if climate sensitivity is lower than current best estimates. The paper is the first to make long-term projections over the next 1,000 years while accounting for currently established carbon cycle feedbacks, including methane.
Around 14,500 years ago, toward the end of the last ice age, melting continental ice sheets drove a sudden and cataclysmic sea level rise of up to 65 feet in just 500 years or less. Despite the scale of the event, known as Meltwater Pulse 1a, scientists still aren't sure which ice sheets were responsible for shedding all that water.
A pair of researchers at the University of Waterloo in Canada, working with a colleague from the Scripps Institution of Oceanography in the U.S., have created a model to visualize how water flows in Antarctica's Aurora Subglacial Basin and how it might flow in coming decades. In their paper published in the journal Nature Communications, Anna-Mireilla Hayden, Tyler Pelle and Christine Dow suggest that water flowing beneath the ice in the Antarctic today may not be reflective of how it might flow in the future.
Freshwater ecosystems require adequate oxygen levels to sustain aerobic life and maintain healthy biological communities. However, both long-term climate warming and the increasing frequency and intensity of short-term heat waves are significantly reducing surface dissolved oxygen (DO) levels in lakes worldwide, according to a study published in Science Advances.
Author(s): Qingbo Luo, Xin Liang, Chengliang Lin, Xinlian Zhang, Jianpeng Liu, Cheng Gao, Yong Hou, and Jianmin Yuan
In hot dense plasma, the interaction between charged particles leads to the ionization potential depression (IPD), which further affects the physical properties of plasma, such as opacity and equation of state. The experiment of IPD of solid-density Al plasma has indicated that present theoretical m…
[Phys. Rev. E 111, 035208] Published Mon Mar 24, 2025
Children are always asking "Why?" As they experience things for the first time, it's natural to want to find out more. But as children grow into adults, they often dismiss something new that challenges their experience and understanding.
SummaryThe intricate architecture of plant root systems is crucial for nutrient and water uptake, significantly influencing plant growth and productivity. Induced polarization (IP) is a promising non-destructive technique for analyzing plant roots in their natural conditions. This study introduces a novel theoretical and numerical model to explain the significant low-frequency polarization of plant root cells observed in previous experiments. Our approach addresses the limitations of existing models by incorporating geometric constraints and internal mechanisms of cell polarization, particularly focusing on interfacial polarization across the cell membrane. Through comprehensive simulations, we investigate various geometries and boundary conditions, demonstrating that densely packed root cells exhibit significant polarization signals within a measurable frequency range due to coupling effects. Our findings align with experimental observations, indicating that the peak frequency is highly sensitive to cell arrangement and membrane properties, while the maximum phase shift remains consistent. This model provides a robust framework for interpreting polarization signals in root systems, offering potential applications for in-situ characterization of plant roots and enhancing the understanding of root dynamics under different environmental conditions.
