The study of high energy cosmic rays is a diversified field of observational and phenomenological physics addressing questions ranging from shock acceleration of charged particles in various astrophysical objects, via transport properties through galactic and extragalactic space, to questions of dark matter, and even to those of particle physics beyond the Standard Model including processes taking place in the earliest moments of our Universe. After decades of mostly independent evolution of nuclear, particle and high energy cosmic ray physics we find ourselves entering a symbiotic era of these fields of research. Some examples of interrelations will be given from the perspective of modern Particle-Astrophysics and new major experiments will briefly be sketched.
We review open questions and prospects for progress in ultrahigh-energy cosmicray (UHECR) research, based on a series of discussions that took place during the “The High-Energy Universe: Gamma-Ray, Neutrino, and Cosmic-ray Astronomy” MIAPP workshop in 2018.Specifically, we overview open questions on the origin of the bulk of UHECRs, the UHECR mass composition, the origin of the end of the cosmic-ray spectrum, the transition from Galactic to extragalactic cosmic-rays, the effect of magnetic fields on thetrajectories of UHECRs, anisotropy expectations for specific astrophysical scenarios, hadronicinteractions, and prospects for discovering neutral particles as well as new physics at ultrahighenergies. We also briefly overview upcoming and proposed UHECR experiments and discusstheir projected science reach.
Abstract Ocean circulations are essential for global climate, redistributing heat and water across ocean basins. The Andaman Sea (AS), a key semi‐enclosed sea connecting to the Bay of Bengal, has lacked sufficient observational data to understand its intermediate circulation. Based on advanced reanalysis data sets, for the first time, we here report a very interesting natural phenomenon, that is, the basin‐wide intermediate circulation of the AS changes its direction twice yearly between cyclonic and anticyclonic, somewhat like a YOYO being played by a kid. A further insightful analysis based on numerical experiments demonstrates that it is the Kelvin waves propagating from the equatorial Indian Ocean that drive basin‐wide intermediate circulation with a semi‐annual cycle under the constraint law of the potential vorticity conservation. This finding highlights the critical role of equatorial Kelvin waves in driving the AS intermediate circulation, advancing our understanding of circulation dynamics in a marginal sea like the AS.
This study proposes an infrared-to-rain (IR2Rain) model to enhance the accuracy of the geostationary (GEO) weather satellite Geo-Kompsat-2A (GK-2A) rain rate (RR) product. The IR2Rain model is built upon a conditional generative adversarial network, taking GK-2A brightness temperatures as inputs and Integrated MultisatellitE Retrievals for Global Precipitation Measurement (IMERG) Final RRs as target values. To address the distinct physical characteristics and ranges of the input and target datasets, IR2Rain employs preprocessing for normalization and postprocessing for denormalization. The IR2Rain model is developed and validated using the paired input and output datasets collected between September 2019 and December 2022, encompassing a broad region across Asia and Oceania. This study compares the performance of IR2Rain-derived RRs against IMERG RR, GK-2A RR, and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network dynamic infrared (IR) rain rate-now products. The results demonstrated a probability of detection of 0.607, a critical success index of 0.482, a root-mean-square error of 0.759 mm/h, and a correlation coefficient of 0.671. By combining the high temporal resolution of GEO satellite observations with the reliability of IMERG Final data, the IR2Rain model produces a robust near-real-time IMERG-like precipitation product. Despite smoothing effects and the tendency to underestimate intense rainfall, IR2Rain improves the performance relative to RR products based on the same GK-2A IR data, mitigates the latency encountered in IMERG data generation, and provides timely and accurate precipitation information on intensity and distribution. These products are particularly valuable for operational weather forecasting and public end users in Asia and Oceania, supporting disaster preparedness and hydrological applications.
Sinesipho Ngamile, Sinesipho Ngamile, Mahlatse Kganyago
et al.
IntroductionWater quality assessment is essential for monitoring and managing freshwater resources, particularly in ecologically and culturally significant areas like the Cradle of Humankind World Heritage Site (COHWHS). This study aimed to predict and map the spatio-temporal patterns of both optically and non-optically active water quality parameters within small inland water bodies located in the COHWHS.MethodsHigh-resolution Sentinel-2 Multispectral Instrument (MSI) satellite data and two random forest models (Model 1 [consisting of sensitive spectral bands] and Model 2 [consisting of spectral bands + indices]) were used alongside In-situ measurements of chlorophyll-a, suspended solids, dissolved oxygen (DO), pH, Temperature, and electrical conductivity (EC) were integrated to establish empirical relationships and assess spatial variability across high-flow and low-flow conditions.ResultsThe results indicated that DO could be predicted with the highest accuracy under low-flow conditions, followed by EC. Specifically, Model 2 achieved an R2 of 0.88 and an RMSE of 1.37 for DO, while Model 1 achieved an R2 of 0.63 and an RMSE of 291.48 for EC. For optically active parameters, suspended solids showed the highest prediction accuracy under high-flow conditions using Model 2 (R2p = 0.55; RMSE = 118.19). Due to the over-pixelation of other smaller water bodies within the COHWHS in Sentinel-2 imagery, Cradlemoon Lake was selected to show distinct seasonal (high- and low-flow) and spatial variations in optically and non-optically active water quality parameters.DiscussionVariations in the results were influenced by runoff dynamics and upstream pollution: lower Temperatures and suspended solids under low-flow conditions increased DO concentrations, whereas higher suspended solid concentrations under high-flow conditions likely reduced light penetration, resulting in lower spectral reflectance and chlorophyll-a levels. These findings highlight the potential of Sentinel-2 MSI data and machine learning models for monitoring dynamic water quality variations in freshwater ecosystems.
The study of cosmic phase transitions are of central interest in modern cosmology. In the standard model of cosmology the Universe begins in a very hot state, right after at the end of inflation via the process of reheating/preheating, and cools to its present temperature as the Universe expands. Both new and existing physics at any scale can be responsible for catalyzing either first, second or cross over phase transition, which could be either thermal or non-thermal with a potential observable imprints. Thus this field prompts a rich dialogue between gravity, particle physics and cosmology. It is all but certain that at least two cosmic phase transitions have occurred—the electroweak and the QCD phase transitions. The focus of this review will be primarily on phase transitions above such scales, We review different types of phase transitions that can appear in our cosmic history, and their applications and experimental signatures in particular in the context of exciting gravitational waves, which could be potentially be constrained by LIGO/VIRGO, Kagra, LISA, and Decigo.
Abstract Earth's vegetation has been increasing over the past decades, altering water and energy cycles by changing evapotranspiration (ET). Greening, caused by climatic and anthropogenic factors, has high rates in High Mountain Asia (HMA). Here we focus on two HMA basins (the Yangtze and the Ganges‐Brahmaputra) to contrast the impacts of climate‐ and human‐induced greening on ET. Though the rate of greening is similar in both basins, anthropogenic influences lead to dissimilar responses in ET. In the Yangtze, climate‐induced greening increases ET, with the increase in moisture being high enough to meet the ET demand. In the Ganges‐Brahmaputra, irrigation‐induced greening does not alter annual ET, only pre‐monsoon ET increases. The dry season declines in water storage due to pumping decrease ET, while laboriously meeting the demand. This study provides a representative example of the contrasting influences of climate induced and anthropogenic driven processes on the seasonality of ET.
In the realm of real-time spaceborne synthetic aperture radar (SAR) imaging, the accurate and swift phase factors calculation (PFC) holds significant importance. This article introduces an innovative advanced RISC machines (ARM) field-programmable gate array (FPGA) hybrid acceleration technique designed to expedite the phase factor computation process of SAR imaging. By combing the strengths of ARM and FPGA, our approach achieves optimal performance. The proposed methodology strategically allocates the initial and intermediate calculations to ARM, while delegating the intricate exponential functions to FPGA. By incorporating a parallel four-channel coordinated rotation digital computer (CORDIC) structure and redundancy-based fault tolerant modules with error correction codes, the protection of soft errors is realized and the reliability is improved. By utilizing a modified three-tiered reconfigurable processing elements exchange network for fault tolerant CORDIC processors, the acceleration of computing time is realized and hardware overhead is reduced. A comprehensive prototype verification illustrates the method's efficacy for PFC in spaceborne SAR imaging. The evaluation of computational time and resource utilization unveils ARM's suitability for the initial two levels, while the complexities and precision of the third level warrant FPGA computing acceleration. Overall, this research advances a novel ARM-FPGA hybrid strategy that elevates phase factor computation in spaceborne SAR imaging, opening up avenues for efficient and dependable radar imaging applications.
Xianfeng Liu, Philippe Ciais, David Makowski
et al.
Abstract Rice quality, which is intricately connected to market value and human nutrition, is sensitive to weather conditions. However, the relative importance of the different climatic factors is poorly understood, and the impact of climate change on rice quality has been little studied on a large scale. Here, using more than 35 years of rice quality data, we present the first effort to determine the key climate variables driving rice quality in China and Japan. Results show a significant decline in high quality rice rate (HRR, an indicator of rice quality), mainly driven by warm nighttime temperatures when they exceed a critical threshold estimated at 18°C and 12°C in China and Japan, respectively. Climate projections suggest a continuing decreasing trend in HRR under moderate and high emission scenarios by 2100. These findings emphasize the importance of breeding new heat tolerant cultivars to maintain stable rice quality in the future.
N eutrinos are among the most abundant particles in the Universe, but they rarely interact with matter: trillions pass through us every second, but most of us will never have even a single one interact with the matter in our bodies. Nonetheless, scientists can study these particles using high-intensity neutrino sources and detectors that are large enough to overcome the rarity of neutrino interactions. In this way, neutrinos have been observed from the Sun, from cosmic-ray interactions in the atmosphere, from Earth’s interior, from supernovae and other astrophysical objects, and from artificial sources such as nuclear reactors and particle accelerators in which a beam of particles hits a fixed target. But
Ecosystems offer a wide array of benefits to support human livelihoods and enhance the quality of life. Quantitative evaluation of ecosystem services (ESs) is crucial for achieving the goal of sustainable development. The Yellow River Basin has a large population, and there are contradictions and conflicts in ecological protection, resource utilization, and economic development, among which the downstream region is the most prominent. However, the ESs selected in the existing research are not comprehensive enough, and there are also few studies that further focus on the effects of urbanization on this basis. This article calculated seven types of ESs based on the InVEST model and related methods, and then constructed a composite ecosystem service index (CESI), and studied its spatiotemporal evolution and response to urbanization indicators through bivariate spatial autocorrelation and spatial metrological models. We found that from 1990 to 2020, the CESI fluctuated and decreased with time, with a significant positive spatial correlation but showed a weakening trend. There were differences in the evolution process of the spatial correlation between the CESI and population density, economic density, and land development degree, but ultimately the spatial correlation changed from positive to negative. In terms of spatial spillover effect, population density had a significant positive effect on the CESI, land development had a significant negative effect, and economic density had a weak spillover effect. This article provides a certain reference basis for governments at all levels to formulate relevant strategies for environmental protection and economic development.
Abstract Applications of cosmic-ray muons have grown in numbers in the last decades. This was possible thanks to the development of detectors and techniques employed in particle and nuclear physics. Indeed the first famous application, the scanning of the Chephren’s pyramid, was performed by L. W. Alvarez, that was a great expert in particle detectors and indeed was awarded a Nobel prize for his work on the hydrogen bubble chambers. After a first period in which the applications exploited mainly the absorption of the cosmic-ray muons when crossing a structure under investigation, more recently also the deflection of the muons has been used to design new applications. Nowadays more and more groups around the world are working on this research field. In the present review, after an introduction on cosmic-ray muons, the principles of the interaction of muons with matter will be briefly summarised. This description is important to classify the applications in three main categories: muon radiography, muon tomography and muon metrology. In the following, for each class, an overview of the basic ideas and a detailed description of the technologies will be presented along with a list of past and present applications.
We review the main experimental evidences on ultra high energy cosmic rays and their implications in the physics of these extremely energetic particles, also in connection with dark matter and cosmology. We discuss the basis of theoretical models aiming at explaining observations, highlighting the most relevant open questions in this fascinating field of research.
The effects of realistic, deep space radiation environments on neuronal function remain largely unexplored. In silico modeling studies of radiation-induced neuronal damage provide important quantitative information about physico-chemical processes that are not directly accessible through radiobiological experiments. Here, we present the first nano-scale computational analysis of broad-spectrum galactic cosmic ray irradiation in a realistic neuron geometry. We constructed thousands of in silico realizations of a CA1 pyramidal neuron, each with over 3500 stochastically generated dendritic spines. We simulated the entire 33 ion-energy beam spectrum currently in use at the NASA Space Radiation Laboratory galactic cosmic ray simulator (GCRSim) using the TOol for PArticle Simulation (TOPAS) and TOPAS-nBio Monte Carlo-based track structure simulation toolkits. We then assessed the resulting nano-scale dosimetry, physics processes, and fluence patterns. Additional comparisons were made to a simplified 6 ion-energy spectrum (SimGCRSim) also used in NASA experiments. For a neuronal absorbed dose of 0.5 Gy GCRSim, we report an average of 250 ± 10 ionizations per micrometer of dendritic length, and an additional 50 ± 10, 7 ± 2, and 4 ± 2 ionizations per mushroom, thin, and stubby spine, respectively. We show that neuronal energy deposition by proton and α -particle tracks declines approximately hyperbolically with increasing primary particle energy at mission-relevant energies. We demonstrate an inverted exponential relationship between dendritic segment irradiation probability and neuronal absorbed dose for each ion-energy beam. We also find that there are no significant differences in the average physical responses between the GCRSim and SimGCRSim spectra. To our knowledge, this is the first nano-scale simulation study of a realistic neuron geometry using the GCRSim and SimGCRSim spectra. These results may be used as inputs to theoretical models, aid in the interpretation of experimental results, and help guide future study designs.
The physics content of the QGSJET-III Monte Carlo generator of high energy hadronic collisions is discussed. New theoretical approaches implemented in QGSJET-III are addressed in some detail and a comparison to alternative treatments of other cosmic ray interaction models is performed. Calculated characteristics of cosmic ray-induced extensive air showers are presented and differences between the respective results of QGSJET-III and other models are analyzed. In particular, it is demonstrated that those differences are partly caused by severe deficiencies of the other interaction models.
Appearance of cosmic strings in the early Universe is a common manifestation of new physics typically linked to some high energy scale. In this paper, we discuss a different situation, where a model underlying cosmic string formation is approximately scale free. String tension is naturally related to the square of the temperature of the hot primordial plasma in such a setting, and hence decreases with (cosmic) time. With gravitational backreaction neglected, the dynamics of these melting strings in an expanding Universe is equivalent to the dynamics of constant tension strings in a Minkowski spacetime. We provide an estimate for the emission of gravitational waves from string loops. Contrary to the standard case, the resulting spectrum is markedly non-flat and has a characteristic falloff at frequencies below the peak one. The peak frequency is defined by the underlying model and lies in the range accessible by the future detectors for very weak couplings involved.