Frequency Of Events Research Articles

Late Events Occurring After 5Years in Pediatric Rhabdomyosarcoma: A Report From the Children's Oncology Group.

Rhabdomyosarcoma is the most common pediatric soft tissue sarcoma, and 5-year overall survival exceeds 70%. With more long-term survivors, it is critical to understand the frequency of late events, including recurrence, second malignant neoplasm, and death, occurring 5years after diagnosis, and the variables associated with these events. We report late events in patients enrolled on Intergroup Rhabdomyosarcoma Study Group and Children's Oncology Group trials from 1997 to 2013 including D9602, D9803, D9802, ARST0331, ARST0431, ARST0531, and ARST08P1. A late event occurred in 2.9% of 5-year event-free survivors supporting guidelines to limit surveillance for these events to 5years from diagnosis.

Efficacy and Safety of Weekly Calcifediol Formulations (75 and 100 µg) in Subjects with Vitamin D Deficiency: A Phase II/III Randomised Trial

Background/Objective: Optimal vitamin D levels are required for bone health and proper functionality of the nervous, musculoskeletal and immune systems. The objective of this study was to assess the efficacy and safety profiles of new weekly calcifediol formulations with the potential to improve adherence and outcome. Methods: A Phase II-III, double-blind, randomized, multicentre trial (EudraCT 2020-001099-14 and NCT04735926). Subjects were randomized 2:2:1 to calcifediol 75 µg, 100 µg and placebo. 25(OH)D levels were measured at 4, 16, 24, 32 and 52 weeks. The main outcome was the percentage of subjects who achieved a response defined as 25(OH)D levels ≥20 ng/mL and/or ≥30 ng/mL at week 16. Results: 398 subjects (51.1 ± 15.96 years, 74.2% females, 98.7% Caucasian) with plasma 25(OH)D levels between 10 and 20 ng/mL were randomized. A total of 376 subjects completed 16 weeks of treatment, and 355 subjects completed the study. Six patients withdrew due to an adverse event, all unrelated to treatment. At week 16, 93.6% and 74.4% of subjects receiving calcifediol 75 µg achieved response levels of ≥20 ng/mL and ≥30 ng/mL, respectively. The calcifediol 100 µg group showed 98.7% and 89.9% of responders for ≥20 ng/mL and ≥30 ng/mL, respectively. Both calcifediol groups showed superiority over placebo at each response level at all time points analyzed (p < 0.0001). Calcifediol treatments increased 25(OH)D levels from baseline to week 24 and remained stable thereafter. The frequency of treatment-emergent adverse events was balanced between groups. Conclusions: New weekly calcifediol 75 and 100 µg formulations showed an effective and sustained response with a good long-term safety profile.

Climate Change Impacts on Agricultural Systems Mitigation and Adaptation Strategies: A Review

Climate change poses a substantial threat to global agricultural systems, impacting crop yields, livestock productivity, and resource availability through rising temperatures, altered precipitation patterns, and increased frequency of extreme weather events. This review synthesizes current understanding of climate change impacts on agriculture and explores strategies for mitigating greenhouse gas (GHG) emissions while enhancing system resilience through adaptation. Mitigation approaches, such as conservation agriculture, agroforestry, and improved nutrient and livestock management, show significant potential to reduce emissions and increase carbon sequestration. However, economic, technological, and institutional barriers such as high implementation costs, limited access to finance, and inadequate policy support restrict their adoption. Adaptation strategies, including crop diversification, advanced water management, and climate-resilient technologies, are critical for sustaining agricultural productivity in variable climates. Synergies between mitigation and adaptation, such as integrating trees into croplands, can provide co-benefits, but trade-offs arise when resource competition occurs or land is diverted from food production to carbon sequestration. The review highlights the need for interdisciplinary research, robust data infrastructure, and tailored policies to bridge knowledge and resource gaps, particularly in vulnerable regions. Successful implementation requires coordinated efforts across stakeholders, supported by enabling policy frameworks that incentivize sustainable practices and align with global climate goals. Future research should prioritize understanding the long-term impacts of integrated strategies, enhancing monitoring systems, and fostering inclusive approaches that consider local contexts and socio-economic conditions. Addressing these challenges holistically will be crucial to building resilient agricultural systems capable of maintaining food security and supporting livelihoods in the face of accelerating climate change.

Using the Nasopalatine Canal for Enhanced Distribution in Severely Atrophic Maxilla With Immediate Loading of Zygomatic Implants: An 8-Year Retrospective Cohort Study.

This study presents retrospective 8-year clinical performance data from a patient cohort treated with immediately loaded maxillary full prostheses supported by zygomatic implants combined with implants placed in the nasopalatine canal, as a treatment for severely resorbed edentulous ridges. A retrospective analysis was conducted on data of maxillary edentulous patients with severe bone atrophy. All of them received zygomatic implants in combination with an implant placed in the nasopalatine foramen and an immediately loaded fixed temporary prosthesis in the first 24 hours. The frequency of major and minor adverse events was presented according to the time of occurrence. Fifteen patients were included in the study, without cases of implant loss or sensitivity in the nasopalatine region were observed up to 8 years. Only 1 major complication was observed, whereas minor complications were more frequent. In conclusion, this 8-year follow-up study demonstrated that the nasopalatine canal can be considered a viable implant site, with no major risks, to improve biomechanics by enabling a polygonal distribution in severely atrophic maxillae treated with zygomatic implants and immediate loading.

Impacts of changing weather patterns on the dynamics of water pollutants in agricultural catchments: Insights from 11-year high temporal resolution data analysis

Widespread and long-term shifts in weather patterns are contributing to further degradation of surface water quality. This challenge caused by the increasing frequency of extreme weather events requires appropriate adaptation of current mitigation strategies. But to confirm the need to redesign such strategies, an understanding of the impacts of increasing weather extremes on pollutant losses in different catchment types is required. With this in view, this study investigated the impact of changing weather patterns on the inter-seasonal and inter-annual dynamics of nutrient losses in six agricultural catchments in Ireland over 11 years. The high temporal resolution data (10-min) from these intensively managed catchments represented different characteristics and management practices. Mann-Kendall Trend Analysis and Generalised Additive Models were used to study nutrient concentration trends, and to investigate the significance of water discharge, precipitation, potential evapotranspiration, soil moisture deficit, air temperature, and soil temperature on the losses of nutrients, respectively. The analysis of historical data revealed changes in the trends of daily average nitrate (NO3-N), phosphorus (P), and suspended sediment (SS) concentrations in association with significant increasing trends in air temperature, soil temperature, and precipitation across the same month over 11 years of monitoring. While discharge was significantly contributing to the concentrations of NO3-N, P, and SS across different catchments, air and soil temperature were significantly correlated to NO3-N losses, and precipitation was the major contributor to regulating P (total P and total reactive P) concentrations. In short, air temperature, soil temperature, soil moisture deficit, and precipitation were the main climatic drivers regulating the nutrient concentrations while the soil chemistry and drainage status were the non-climatically related drivers. The results revealed that the extent of the impact of climatic drivers depends on catchment characteristics. Therefore, expanding the application of this type of study would facilitate better understanding of current and future challenges to water management and provision of climate-resilient mitigation strategies for different catchment typologies.

Mechanical fatigue in microtubules

Mechanical failure of biological nanostructures due to sustained force application has been studied in great detail. In contrast, fatigue failure arising from repeated application of subcritical stresses has received little attention despite its prominent role in engineering and potentially biology. Here, paclitaxel-stabilized microtubules are up to 256 times bent into sinusoidal shapes of varying wavelength and the frequency of breaking events are observed. These experiments allow the calculation of fatigue life parameters for microtubules. Repeated buckling due to 12.5% compression–equal to the compression level experienced by microtubules in contracting cardiomyocytes – results in failure after in average 5 million cycles, whereas at 20.0% compression failure occurs after in average one thousand cycles. The fatigue strength (Basquin) exponent B is estimated as − 0.054±0.009.

Decadal trends and climatic influences on flash droughts and flash floods in Indian cities

Flash droughts/floods are extreme weather phenomena that are expected to become increasingly frequent and severe with the changing climate. Flash droughts result from a rapid decline in soil moisture, while flash floods occur due to a high extreme rainfall intensity over a short duration. This study analyzes the ERA5 reanalysis data (hourly temperature, soil moisture, and precipitation) from 1992 to 2022 to assess flash drought/flood attribute variations across fourteen Indian cities. Flash drought events are identified based on specific conditions using the obtained Soil Moisture Index (SMI) values. At the same time, we propose a novel approach to attribute flash floods by setting thresholds for precipitation and soil moisture.This study examines the frequency and trends of flash drought and flood events across India's various Köppen-Geiger climatic zones from 1992 to 2022. Jaipur and Dehradun show a statistically significant decrease in flash drought events with magnitudes of −0.0833 events/year and −0.0769 events/year, respectively. Conversely, Hyderabad exhibits a highly significant increase in flash flood events with a magnitude of 1.1851 events/year. Similarly, Bengaluru, Varanasi, and Vishakhapatnam also show substantial increases in flash flood events. These findings underscore the impact of climate change on flash droughts/floods, highlighting the necessity for sustainable strategies.

Agronomic adaptations to heat stress: Sowing summer crops earlier

CONTEXTSummer crops are exposed to heat and drought stresses at critical stages during and after flowering, and their intensity and frequency are likely to increase with climate change. Agronomic stress avoidance offers the opportunity to temporally separate critical crop stages from heat and drought events. However, it might require sowing cold-sensitive summer crops earlier into colder than recommended soil temperatures. There is a need to understand how cold is too cold to sow summer crops early in late winter as well as what are the yield benefits and risks. OBJECTIVEHere, we quantify the likely benefits and trade-offs of sowing sorghum, a summer cereal, earlier to adapt to the increased frequency and intensity of heat and water stresses during flowering and grain filling. METHODSTwo years of multi-environment (n=32) genotype by management trials were conducted across the main sorghum growing regions of Australia. Environments (E) consisted of the combination of years, sites, three times of sowing (early, spring, and summer), and the use of supplementary irrigation. At each E a factorial combination of four plant populations (M) and eight commercial sorghum hybrids (G) were sown with three replications. Crop growth and yield components were measured, and the APSIM model was used to simulate all trials and treatments to quantify risks and derive insights into functional relationships between simulated and measured environmental covariates, and measured crop traits. RESULTSThe tested hybrids showed small differences in cold tolerance during crop establishment. Across the tested environments, the G×M combinations produced up to 60% variation in treatment yields across environment yields, which varied between <0.5 to about 10t ha-1; this translated into a ~5.5-fold variation in water use efficiency. Significant G×E and M×E interactions were observed for grain yield components. No G×M or G×E×M interactions were observed on yield or yield components. Early sowing was associated with a reduced risk of heat stress and water use transfer from vegetative to reproductive stages. Early sowing in late winter or early spring resulted in no significant yield gain or loss when all sites and years were included in the analysis. However, early sowing yielded between 1-2 t ha-1 more when the hottest sites and years were considered separately. This resulted from both the avoidance of heat stresses and milder or no terminal drought stresses. CONCLUSIONSEarly sowing of sorghum can reduce the likelihood of heat stresses around flowering as well as the likelihood of terminal drought stresses. Advantages include reduced yield losses in the hottest years and a transfer of water use to grain filling stages, resulting in increased grain yield and improved grain quality parameters. IMPLICATIONSEarly sowing, an agronomic adaptation, offers the opportunity to quickly adapt to the increase in the frequency and intensity of extreme hot events during critical crop stages. However, for the practice to be de-risked, there is a need to increase cold and chilling tolerance in sorghum and/or identify interventions that enhance seed germination and seedling vigour when the crop is sown early into cold soils.

Frequency of androgenic cutaneous adverse events associated with levonorgestrel intrauterine devices: an analysis of the Food and Drug Administration Adverse Events Reporting System database.

Frequency of androgenic cutaneous adverse events associated with levonorgestrel intrauterine devices: an analysis of the Food and Drug Administration Adverse Events Reporting System database.

Exploring climate stabilisation at different global warming levels in ACCESS-ESM-1.5

Abstract. Under the Paris Agreement, signatory nations aim to keep global warming well below 2 °C above pre-industrial levels and preferably below 1.5 °C. This implicitly requires achieving net-zero or net-negative greenhouse gas emissions to ensure long-term global temperature stabilisation or reduction. Despite this requirement, there have been few analyses of stabilised climates, and there is a lack of model experiments to address our need for understanding the implications of the Paris Agreement. Here, we describe a new set of experiments using the Australian Community Climate and Earth System Simulator Earth system model (ACCESS-ESM-1.5) that enables the analysis of climate evolution under net-zero emissions, and we present initial results. Seven 1000-year-long simulations were run with global temperatures stabilising at levels in line with the Paris Agreement and at a range of higher global warming levels (GWLs). We provide an overview of the experimental design and use these simulations to demonstrate the consequences of delayed attainment of global net-zero carbon dioxide emissions. We show that there are substantial differences between transient and stabilising climate states and differences in stabilisation between GWLs. As the climate stabilises under net-zero emissions, we identify significant and robust changes in temperature and precipitation patterns including continued Southern Ocean warming and changes in regional precipitation trends. Changes under net-zero emissions differ greatly between regions, including contrasting trajectories of sea ice extent between the Arctic and Antarctic. We also examine the El Niño–Southern Oscillation (ENSO) and find evidence of reduced amplitude and frequency of ENSO events under climate stabilisation relative to projections under transient warming. An analysis at specific GWLs shows that significant regional changes continue for centuries after emission cessation and that these changes are stronger at higher GWLs. Our findings suggest substantial long-term climate changes are possible even under net-zero emission pathways. These simulations are available for use in the community and will hopefully motivate further experiments and analyses based on other Earth system models.

Dampak Perubahan Iklim terhadap Keanekaragaman Hayati: Literature Review

Climate change is one of the biggest challenges faced by ecosystems and biodiversity worldwide. This research examines climate change's impact on biodiversity through a comprehensive literature review. By collecting and analyzing various previous studies, this research identifies patterns of change in flora and fauna species in response to changing climate variables, such as temperature, rainfall, and the frequency of extreme weather events. Literature results show that many species experience changes in distribution, behavior and reproductive timing, which have the potential to disrupt ecosystem interactions and damage ecological balance. This research also discusses the impact of climate change on natural habitats and the conservation efforts needed to protect biodiversity. These findings highlight the urgency of taking effective mitigation and adaptation measures to maintain biodiversity amidst the increasing challenges of climate change.

Nuclear Energy's Role in Sustainability and Environmental Protection in India

The world today stands at a critical juncture, grappling with the profound and far-reaching impacts of climate change. The increasing frequency of extreme weather events, rising sea levels, and deteriorating ecosystems only serve to underscore the urgency of transitioning to a low-carbon economy. Governments across the globe are intensifying their climate policies, striving to meet the ambitious goals set forth in international agreements such as the Paris Agreement. Central to these efforts is the systematic decarbonization of national energy mixes [1], where nations are increasingly turning to green and clean technologies to power their economies and ensure sustainable electrification. In this global race to mitigate climate change, renewable energy sources like wind, solar, and hydropower are often highlighted as the vanguards of a sustainable future [2]. However, the challenge lies not only in generating sufficient clean energy but also in ensuring a reliable and continuous supply that can meet the growing demands of an energy-hungry world.

Nuclear Energy's Role in Sustainability and Environmental Protection in India

The world today stands at a critical juncture, grappling with the profound and far-reaching impacts of climate change. The increasing frequency of extreme weather events, rising sea levels, and deteriorating ecosystems only serve to underscore the urgency of transitioning to a low-carbon economy. Governments across the globe are intensifying their climate policies, striving to meet the ambitious goals set forth in international agreements such as the Paris Agreement. Central to these efforts is the systematic decarbonization of national energy mixes [1], where nations are increasingly turning to green and clean technologies to power their economies and ensure sustainable electrification. In this global race to mitigate climate change, renewable energy sources like wind, solar, and hydropower are often highlighted as the vanguards of a sustainable future [2]. However, the challenge lies not only in generating sufficient clean energy but also in ensuring a reliable and continuous supply that can meet the growing demands of an energy-hungry world.

A Synoptic Scale Perspective of Solar Forcing on Extreme Precipitation and Floods Over Europe During Summer

AbstractThe relationship between total solar irradiance (TSI) forcing and summer extreme precipitation and flood frequency over western Europe is investigated from a synoptic‐scale perspective, with a focus on the role of Rossby wave packets (RWPs). Utilizing observational, model, and proxy data, we reveal a significant increase in RWP frequency along a zonal band centered around 50°N, extending from North America to western Europe, during periods of low TSI. This anomaly in RWP frequency is consistent with a significant increase in the frequency of extreme precipitation events recorded over western Europe. Sensitivity experiments conducted with a state‐of‐the‐art chemistry‐climate model corroborate our findings based on observational data. Additionally, a flood record from western Europe demonstrates a significant increase in flood frequency during low TSI years, a relationship that persists across timescales. We argue that the frequency patterns associated with TSI forcing presented in this study are robust and, therefore, valuable for estimating the frequency of extreme precipitation events over western Europe under various solar irradiance scenarios. Moreover, our findings indicate that the North Atlantic sector is more responsive to changes in solar forcing during the boreal summer than previously thought, with this effect manifesting primarily on synoptic timescales rather than the long‐term climatological mean.

Extreme events and ichthyofauna: case report of a neotropical river

The increasing frequency and intensity of extreme weather events and their impact on aquatic ecosystems and fish species is concerning. This manuscript reports and analyzes two events, a drought in 2019 and a flood in 2024, providing valuable insights into the consequences of these events. The rescue of 269 individuals of 19 fish species during the 2019 drought highlights the significant impact of the extreme conditions on the ichthyofauna. Rising temperatures, isolation, and habitat fragmentation must have posed severe challenges for the fish species during this period. On the other hand, the observation of 53 dead individuals of 5 species during the 2024 flood indicates the detrimental effects of this event on the fish population. The association of mortality and dispersal of several species with the existing dam further underscores the complexity of the challenges faced by fish during extreme flood events. The correlation between rainfall, river regime, and the impact of land use and occupation provides an important context for understanding the dynamics of these extreme events. The low rainfall during the 2019 drought and the gradual increase in rainfall between 2022 and 2024 leading to the flood demonstrate the significant role of precipitation patterns in shaping the outcomes for fish species. Additionally, the analysis of land use and occupation, particularly the substantial increase in urbanization in the drainage basin over the last 30 years, highlights the human-induced factors contributing to the stress on aquatic ecosystems. Both extreme floods and droughts have significant implications for fish species. Extreme floods can alter riverbeds, cause direct mortality, and disrupt isolated populations, while extreme droughts can lead to fish kills, and habitat fragmentation, and exacerbate environmental stressors. This analysis emphasizes the urgent need for comprehensive measures to mitigate the impact of extreme weather events on aquatic ecosystems and fish species. Addressing factors such as land use and occupation, water management, and climate change adaptation strategies is crucial for promoting the resilience of fish populations in the face of ongoing environmental challenges. Keywords: drought, Ipanema National Forest, rainfall.

UAVs as a Tool for Optimizing Boat-Supported Flood Evacuation Operations

The frequency and intensity of flood events are increasing year by year as a result of climate change. This poses significant threats to human settlements and adversely affects biodiversity, agriculture, and infrastructure. One of the most prominent and traditional flood evacuation approaches is through the use of boats. Nonetheless, serious challenges exist with respect to determining the optimal deployment locations, routes, and timing. Given research advances in the Unmanned Aerial Vehicles (UAVs) sector—and their ability to offer real-time data and aerial monitoring services—we argue that their applications could help enhance boat-supported flood evacuation operations. In this opinion piece, we explore new opportunities for disaster management and underscore the advantages of integrating UAVs into flood evacuation methodologies, including areas of rapid field assessment, optimal route planning, and improved coordination between rescue boats. Notwithstanding the potential of UAVs, we emphasize several gaps to be explored in terms of large-scale data management/processing, regulatory limitations, and technological know-how. Furthermore, we provide recommendations for bolstering boat deployment protocols, disaster preparedness training programs, policy frameworks, and emergency response systems, which could maximize their efficacy in flood evacuation scenarios.

Integration of SPEI and machine learning for assessing the characteristics of drought in the middle ganga plain, an agro-climatic region of India.

Drought, as a natural and intricate climatic phenomenon, poses challenges with implications for both natural ecosystems and socioeconomic conditions. Evaluating the characteristics of drought is a significant endeavor aimed at mitigating its impact on society and individuals. This research paper explores the integration of the Standardized Precipitation Evapotranspiration Index (SPEI) and machine learning techniques for an assessment of drought characteristics in the Middle Ganga Plain, a crucial agro-climatic region in India. The study focuses on evaluating the frequency, intensity, magnitude, and recurrence interval of drought events. Various drought models, including Random Forest (RF), Artificial Neural Networks (ANN), and an ensemble model combining ANN and RF, were employed to analyze and predict drought patterns at different temporal scales (3-month, 6-month, and 12-month). The performance of these models was rigorously validated using key metrics such as precision, accuracy, proportion incorrectly classified, over-all area under the curve (AUC), mean absolute error (MAE), and root mean square error (RMSE). Furthermore, the research extends its application to delineating drought vulnerability zones by establishing demarcations for high and very high drought vulnerability areas for each model and temporal scale. Results indicate that the south-western part of the middle Ganga plain falls under the highly drought-vulnerable zone, which averagely covers 40% of the study region. The core and buffer regions of drought vulnerability have also been identified. The south-western part of the study area is identified as the core region of drought. Ground verification of the drought-vulnerable area has been done by using soil moisture meter. Validation metrics show that the ensemble model of ANN and RF exhibits the highest accuracy across all temporal scales. This research's findings can be applied to improve drought preparedness and water resource management in the Middle Ganga Plain. By identifying high-risk drought zones and utilizing accurate prediction models, policymakers and farmers can implement targeted mitigation strategies. This approach could enhance agricultural resilience, protect livelihoods, and optimize water allocation in this vital agro-climatic region.

Effect of Progressive Wetting on Permanent Deformation of Fouled Ballast under Cyclic Loading

Climate change in recent decades has increased the frequency and intensity of extreme rainfall events, causing varied moisture contents in the ballasted track, which greatly challenges railway operation and track maintenance. Currently, most research about permanent deformation of fouled ballast are under dry condition or with a moisture content in the individual tested sample, which could not fully represent varied moisture conditions in the field induced by varying rainfall intensities. In this paper, permanent deformation of field-sourced fouled ballast under progressive wetting condition was investigated using large-scale triaxial cyclic tests. The results indicate that, with progressively rising water contents (0% to 12%), the fouled ballast sample maintained their stability; however, the rate of permanent strain increases to a peak value before experiencing a slight decline, aligning with classified shakedown ranges. This observed phenomenon can be attributed to the interplay between wetting, densification, and interlocking under conditions of cyclic loading and progressive wetting, an aspect that existing research have not elaborated. To encapsulate the identified deformation characteristics, this study proposes and validates a new predictive model for the permanent deformation of fouled ballast, demonstrating high prediction accuracy for fouled ballast with varying water contents.

Spatio-temporal distribution of intensity and frequency of extreme temperature events over Nigeria

Spatio-temporal distribution of intensity and frequency of extreme temperature events over Nigeria

Running with the bulls

Context. Stars and planets form in regions of enhanced stellar density, subjecting protoplanetary discs to gravitational perturbations from neighbouring stars. Observations in the Taurus star-forming region have uncovered evidence of at least three recent, star-disc encounters that have truncated discs (HV/DO Tau, RW Aurigae, and UX Tau), raising questions about the frequency of such events. Aims. We aim to assess the probability of observing truncating star-disc encounters in Taurus. Methods. We generated a physically motivated dynamical model including binaries and a spatial-kinematic substructure to follow the historical dynamical evolution of the Taurus star-forming region. We used this model to track star-disc encounters and the resulting outer disc truncation over the lifetime of Taurus. Results. A quarter of discs are truncated below 30 au by dynamical encounters, but this truncation mostly occurs in binaries over the course of a few orbital periods, on a timescale ≲0.1 Myr. Nonetheless, some truncating encounters still occur up to the present age of Taurus. Strongly truncating encounters (ejecting ≳10 percent of the disc mass) occur at a rate ∼10 Myr−1, sufficient to explain the encounter between HV and DO Tau ∼0.1 Myr ago. If encounters that eject only ∼1 percent of the disc mass are responsible for RW Aurigae and UX Tau, then they are also expected with encounter rate Γenc ∼ 100–200 Myr−1. However, the observed sample of recent encounters is probably incomplete, since these examples occurred in systems that are not consistent with a random drawing from the mass function. One more observed example would statistically imply additional physics, such as replenishment of the outer disc material. Conclusions. The marginal consistency of the frequency of observed recent star-disc encounters with theoretical expectations underlines the value of future large surveys searching for external structures associated with recent encounters. The outcome of such a survey offers a highly constraining, novel probe of protoplanetary disc physics.