Rate Of Spread Research Articles

Background Prevailing American wildland fire modelling systems fail to predict fire growth in urban areas due to the absence of burnable urban fuels. Aims This research aims to identify fuel models that optimise fire spread in urban areas relative to a hypothetical fire spread model derived from observations of recent urban fires. Methods A target Rate of Spread (RoS) is derived from observations of seven urban conflagrations to anchor the model to absolute RoS. Exhaustive parameter sweeps are used to identify combinations of fuel variables that result in optimal performance. Key results The target RoS is 0.81 km/h. Parameter sweeps converge on unique sets of fuel parameters including (1) BU0, an unconstrained custom fuel model; (2) BU1, a custom fuel model that operates within the constraints of current US modelling systems; and (3) Anderson Fuel Model 9, a best-performing standard fuel model. Conclusions & implications Although this approach stretches current modelling systems beyond their intended design, the resultant fuel models provide a necessary stopgap for emergency management until urban-specific fire spread models find their way into operational use.

Gangue slurry pumping backfill offers a cost-effective and environmentally sound solution for coal mine solid waste disposal. Addressing the poor pumpability of pure gangue slurry, this study applied the Talbot gradation theory to a non-cemented gangue system by designing various particle size gradations and water-solid ratios (W/S). Through tests on rheological properties, slump, spread, and bleeding rate, the optimal proportion for pumpability of pure gangue slurry (PGS) within the scope of this study was determined. Tests were conducted on rheology, slump, spread flow, and bleeding rate to determine the optimal mix proportion for pumpability. The results show that: The slurry in this study demonstrates a strong correlation with the characteristics of a Bingham fluid. Its yield stress increases significantly as the W/S decreases. At a gradation index (n) of 0.4, particle packing is densest, resulting in the lowest yield stress. Slump and spread flow decrease with a lower W/S. They initially increase and then decrease as the gradation index increases, with optimal fluidity observed at n = 0.4. Bleeding rate increases with a higher gradation index but decreases with a lower W/S. Comprehensive optimization determined the optimal mix proportion as gradation index n = 0.4 and W/S of 0.18. At this ratio: Yield stress = 144.25 Pa, Slump = 255 mm, Spread flow = 60.1 cm, Bleeding rate = 2.21%. This meets the pumping requirements (Slump > 180 mm, Bleeding rate < 3%). The research results provide important experimental value for the practical pipeline transportation of PGS and the reduction in pumping friction resistance.

Background Wind speed is one of the major parameters that affect fire rate of spread and heat transfer in propagating bushfires. Aims Laboratory-scale experiments and physics-based simulations are used to derive a correlation between wind speed and convective heating and cooling of surface fuels in bushfire scenarios. Methods A low-speed wind tunnel was designed and built to conduct fire spread experiments using Excelsior fuel on a level test bed, with a packing ratio 0.03 and a moisture content of 10%. The wind speed was varied between 0 and 3.3 m s−1. Heat flux gauges and the retroreflective shadowgraph (RS) technique were used simultaneously to measure and visualise convective heat transfer. Simulations were conducted using the Fire Dynamics Simulator (FDS) to replicate the experimental study, enabling a detailed exploration of heat transfer modelling within the FDS framework. Key results The relationship between convective heat transfer and factors such as wind speed, flame angle, flame length and distance from the flame front was analysed and derived. Implications The results of this analysis reveal the mechanism of local convective heat transfer to downstream vegetation.

This study evaluated the impact of incorporating taro flour (Colocasia esculenta) into wheat-based biscuit formulations, focusing on nutritional, phytochemical, rheological, technological, and organoleptic characteristics. Four distinct types of biscuits were formulated with 0% (CC), 10% (TWC1), 20% (TWC2), and 30% (TWC3) taro. The results indicate that taro flour (TF) has a higher moisture, ash, and gallic acid content, as well as significant mineral richness, particularly in potassium, magnesium, and calcium, compared to wheat flour (WF). It has been shown that the gradual incorporation of TF (10 to 30%) into composite flours improves the bioavailability of certain micronutrients and polyphenols, while maintaining a harmonious balance with the flavonoids characteristic of wheat, such as quercetin. The evaluation of antioxidant activity indicates a higher value for TF (50.71%) compared to WF (36.53%), with a significant increase in activity observed in enriched cookies (58.92% for TWC3 vs. 31.36% for CC). In addition, the incorporation of taro flour modifies the technological properties of the cookies, resulting in a decrease in thickness and baking yield, as well as an increase in diameter and spread rate. This modification may result in a crisper texture. However, a high substitution rate (30%) resulted in a decrease in dough stability and baking yield due to a reduction in gluten and a change in dough structure. In terms of antinutritional profile, partially replacing wheat flour with taro flour significantly reduces phytic acid content, while moderately increasing oxalate content. Sensory analysis of different types of cookies indicated that moderate substitution levels (10%) tended to improve or maintain sensory quality, while higher substitution levels (20% and 30%) tended to reduce overall acceptability. Linear correlations showed a positive relationship between antioxidant activity and polyphenols and minerals, but a negative relationship with proteins and specific technological properties. In summary, the incorporation of taro flour into cookie formulations represents a promising strategy for improving the nutritional value and functional potential of baked goods without compromising their technological quality. These results confirm the value of taro as a functional ingredient that can contribute to the development of healthy foods.

Background The spread of canyon fire often involves sudden acceleration, which is related to eruptive fire. Aims The purpose of the study is to explore the pattern of fire line evolution and rate of spread (ROS) with topographic conditions in canyon fire, and to clarify the critical conditions for and mechanism of eruptive fire. Methods A systematic experimental study on canyon fire was conducted by igniting dead pine needles with a point ignition. Key results Four different types of fire line contours were identified under different topographic conditions. When the central slope angle α ≥ 15°, the direction of the fire head gradually deviates from the line of maximum slope and moves to the center line, and this deviation increases with α. Accordingly, ROS along the center line also exhibits dynamic characteristics, and ROS increases with α and the lateral slope angle δ. The critical conditions for eruptive fire are α = 27.5° and δ = 20°. Conclusions When eruptive fire occurs, there is significant convective heating ahead of the fire front. This strong convective heating is the basic mechanism for eruptive fire in canyons. Implications Our results may provide a theoretical basis to assist fire commanders to make decisions.

We study the growth order of the maximal displacement of branching symmetric α-stable processes. We assume that the branching rate measure μ belongs to the Kato class and μ has a compact support on R d . We show that the maximal displacement exponentially grows and its order is determined by the index α and the spectral bottom of the corresponding Schrödinger-type operator.

BACKGROUND: One of the common and unfavorable complications in patients with long-term diabetes mellitus (DM) is diabetic foot syndrome (DFS). The type of pathogen plays a key role in the course of the infectious process, its severity, the nature of tissue damage, the rate of spread and the outcome of the disease. Improving the rationality and efficacy of antibiotic therapy (ABT) in patients with SDS infection is currently an important practical task, both to improve patient outcomes and to prevent the spread of antibiotic resistance (ABR).AIM: To study the species diversity and ABR profile of etiologic agents of lower extremity infections in patients with SDS.MATERIALS AND METHODS: Retrospective descriptive clinical and epidemiologic study. The analysis of 83 cases of hospitalization of patients with SDS in City Clinical Hospital №3 named after B.I.Alperovich (Tomsk) in 2023–2024 was carried out. 118 isolates — microorganisms identified in patients from wound discharge were studied.RESULTS: The structure of pathogens was represented by Gram-negative (67,8%), Gram-positive (29,7%) flora and fungi (2,5%). In the species structure, the predominant role belonged to S. aureus (20,3 %), K. pneumoniae (17,8%), P. aeruginosa (13,6%), E. coli (8,5%) and P. mirabilis (8,5%). K. pneumoniae lost sensitivity to ampicillin and significantly decreased sensitivity to amoxicillin/clavulanic acid. The frequency of ABR of K. pneumoniae and E. coli to fluoroquinolones was often higher than to drugs from the group of cephalosporins. At the same time, pathogens demonstrated good sensitivity to carbapenems and aminoglycosides. The ABR of S. aureus strains to erythromycin was 25,0%, 12,5% of isolates were insensitive to oxacillin.CONCLUSION: Gram-negative etiologic agents are characterized by an unfavorable sensitivity profile mainly to cephalosporins and fluoroquinolones. The etiologic share of MRSA accounts for 12,5% of SDS-associated infections. The data obtained have important clinical significance in the optimization of empirical ABT of infections in diabetic foot patients.

Abstract Background Timely information on wildfire burn severity is critical to assess and mitigate potential post-fire impacts on soils, vegetation, and hillslope stability. Tracking individual fire spread and intensity using satellite active fire data provides a pathway to near real-time (NRT) information. Here, we generated a large database (n = 2177) of wildfire events in the western United States (U.S.) between 2012 and 2021 using active fire detections from the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the Suomi National Polar-orbiting Partnership (SNPP) satellite and the Fire Events Data Suite (FEDS) algorithm to track large fire growth every 12 h. We integrated fire tracking data with final fire perimeters and burn severity data from the Monitoring Trends in Burn Severity (MTBS) program to evaluate the relationship between burn severity and fire behavior metrics derived from the fire tracking approach, including the rate of fire spread and average fire radiative power (FRP) of fire detections for each 12-h growth increment. Results When stratified by vegetation type, FRP and rate of spread metrics were positively correlated with classified burn severity for each 12-h growth increment, highlighting the potential to rapidly identify areas of high and low severity burning. In forests, integrated measures of FRP over the fire lifetime captured persistent flaming and smoldering that compensated for initial differences between AM (01:30) and PM (13:30) fire detections. Predictive modeling of these relationships based on multiple fire behavior indicators and vegetation type from the LANDFIRE program yielded an accuracy of 78% for the separation of unburned/low and moderate/high burn severity classes. Conclusions These results demonstrate the ability to capture within-fire differences in burn severity using NRT indicators from fire tracking to assist with emergency management and disaster preparedness for post-fire hazards, such as landslides, debris flows, or changes in stream flow and water quality. As VIIRS data are available within minutes of each satellite overpass in the U.S., rapid estimates of burn severity based on fire tracking can be made days or weeks before a large wildfire is fully contained.

Fire serves as management tool in protected areas in savanna ecosystems, particularly for biodiversity conservation and tourism purposes. However, selecting the appropriate burning periods that align with management objectives remains a major challenge for managers. For fire spreading, taking into account soil and fuel moisture levels, which vary throughout the season, is essential. This study aimed to identify the moisture content controlling fire spread and to determine its critical threshold. Through monthly experimental burnings on 90 plots in Comoé National Park’s savanna ecosystems, we measured soil and fuel moisture contents throughout a complete dry season spanning from October 2023 to March 2024. The results showed that soil moisture (p ˂ 0.001) and fuel moisture (p ˂ 0.001) decreased as the season progressed. Regarding fire spread, the rate of spread increased when soil moisture (p ˂ 0.001) and fuel moisture (p ˂ 0.001) decreased. On the other hand, the distance traveled by flames that was indicating continuous fire spread, was exclusively influenced by fuel moisture content (p ˂ 0.001). Fire spreading risk mapping revealed the fuel moisture critical threshold of 30.35 ± 2.35% from December. Above this threshold, fuel moisture limits fire spread by its dominant influence. But below it, the probability of continuous fire spread was high and almost certain, because fuel moisture ceases to be a limiting factor. This quantitative threshold provides park managers with an objective tool for timing prescribed burns according to specific fire management objectives.

Mathematical and computational models play a crucial role in understanding the epidemiology of economically important plant disease outbreaks, and in evaluating the effectiveness of surveillance and disease management measures. A case in point is Xylella fastidiosa, one of the world's most deadly plant pathogens. Since its European discovery in olives in Puglia, Italy in 2013, there remain key knowledge gaps that undermine landscape-scale containment efforts of the outbreak, most notably concerning the year of introduction, the rate of spread, dispersal mechanisms and control efficacy. To address this, we developed a spatially explicit simulation model for the outbreak spreading among olive groves coupled to a simulation of the real surveillance and containment measures. We used Approximate Bayesian Computation to fit the model to surveillance and remote-sensing infection data, comparing the fits for three alternative dispersal mechanisms (isotropic, wind and road). The model accurately explained the rate and spatiotemporal pattern of the outbreak and found weak support for the wind dispersal model over the isotropic model. It suggests that the bacterium may have been introduced as early as 2003 (95% CI [2000, 2009]), earlier than previous estimates and congruent with anecdotal evidence. The isotropic model estimates the pathogen is spreading at 5.7 km y-1 (95% CI [5.4-5.9]) under containment measures, down from 7.2 km y-1 (95% CI [6.9-7.5]) without containment measures. Our estimate of an approximately 10-year lag between introduction and detection highlights the need for stronger biosecurity and surveillance for earlier detection of emerging plant pathogens. The outputs from simulations without any disease management also suggest that while containment measures have caused some slowing of X. fastidiosa spread, stronger measures will be required to contain the outbreak fully.

Impact of ecology, subsistence, and climate on language spread rates

PremiseRainforests are usually too wet to burn, acting as natural barriers to fire spread and as refuges for biodiversity. However, climate change is increasing the risk of fire incursion into rainforests. Our capacity to manage these impacts is hindered by limited research on rainforest flammability.MethodsFallen leaf and litter bed samples were collected from cool temperate rainforest and eucalypt forest in Willi Willi and Werrikimbe National Parks, New South Wales, Australia. Litter bed flammability of 13 common temperate rainforest species was measured in the laboratory. The flammability of rainforest litter beds and fire‐prone eucalypt forest litter beds were compared for 0.07 m2 and 7.2 m2 beds. We also examined links between flammability and key structural and chemical leaf traits.ResultsRainforest species varied in their litter bed flammability; 64% of the species had lower flammability than litter comprising eucalypt leaves, which typically occur in more fire‐prone environments. Species with smaller leaves and less leaf cellulose were associated with lower flammability. Rainforest litter beds had slower flame spread rates, smaller flames, and less material consumed compared to eucalypt litter beds.ConclusionsFire characteristics in cool temperate rainforests will vary depending on the species composition of the litter bed, which depends on the litterfall composition of the rainforest stand. This study provides key insights into litter bed flammability in cool temperate rainforests in Australia, which will inform decisions on management of wildfires.

Predicting initial spread rate of continuous spill fires using machine learning

COVID-19, a perilous disease triggered by the SARS-CoV-2 virus, exhibits an unusually high spread rate through both direct and indirect physical contact. There are many ways to inspect the possibility of COVID-19 which may include but not limited to shortness of breath, fatigue, strict headaches, tastelessness, continuous chest pain, diarrhea and vomiting. In the present paper, the COVID-19 deterministic mathematical model with cost effectiveness strategies is considered and examined. The threshold quantity, assisting in establishing the existence and stability characteristics of equilibria, is computed by employing the next-generation matrix. The main objective of the present work is to use conditionally stable Euler and Runge-Kutta of order 4 (RK-4) schemes with the collaboration of unconditionally stable non-standard finite difference (NSFD) scheme to show the changing behavior of consistent SEIHR epidemic model. The Euler and RK-4 schemes are unable to precisely focus on the important aspects of the continuous model, resulting in numerical solutions that are not entirely analogous to the original model. However, the NSFD scheme provides a straightforward approach that demonstrates how discrete and continuous models behave appropriately and yield mathematically precise results. The NSFD system is a useful tool for tracking the spread of COVID-19 disease. For the NSFD scheme, different criteria and theories are employed to discuss the local and global stability of disease-free and endemic equilibria. Numerical simulations are provided to verify the theoretical findings and validate the dynamical aspects of the aforementioned schemes.

Abstract Invasive pests and pathogens cause immense damage globally, costing an estimated US$ 248 billion to the agricultural industry alone. Vehicles, such as farming and timber harvesting machinery and transportation trucks, can facilitate the rapid spread of biological invaders over distances far greater and more quickly than their natural dispersal ability. Understanding how frequent trips by these vehicles increase the spread of invasive agricultural and forestry pests can help inform effective biosecurity procedures before, during, or after an incursion. We used a case study of timber transport trucks in Aotearoa New Zealand to examine whether and how vehicles facilitate the spread of soil-borne pathogens between commercial forest plantations. Our results show that long-distance dispersal associated with truck movement facilitated the introduction of oomycete-like pathogens in 97% of forest sites within only one year, with pathogen loads within infected sites predicted at 84% of the sites’ carrying capacity. Implementing preventative management strategies to reduce the transportation of infected soil by logging trucks, however, can reduce the spread by up to 50% after one year and reduce the pathogen load within infested sites by more than three times. Mitigating other human-assisted dispersal pathways can also help reduce spread. Reducing movement of forest visitors not involved in forestry activities, for instance, by closing forest sites to the public, can help to further reduce spread in addition to management related to harvesting activities. These results highlight the benefits of preventative management strategies in reducing the spread rate of novel soil pathogens through a high-intensity commercial forestry network but show that pest spread is still likely even with significant investment.

Potential fire behavior varied significantly among tree species, directly influencing forest fire intensity and spread. To quantify these differences and evaluate species-specific fuel traits for fire management applications, this study conducted field surveys and sample collection in the Jin Dian Yuanbaoshan Forest Area, Kunming, Yunnan Province. Using a combustion bed experiment, we simulated the burning behavior of Acacia dealbata, Alnus nepalensis, and Pinus armandii under windless conditions, recording ignition time, extinction time, flame height, spread rate, and calculating fire intensity. Comparative analysis revealed: (1) Fire intensity ranking: P. armandii needles &gt; A. dealbata leaves &gt; P. armandii branches &gt; A. nepalensis leaves &gt; P. armandii bark &gt; A. dealbata branches &gt; A. nepalensis branches &gt; A. dealbata bark &gt; A. nepalensis bark; (2) The biological firebreaks composed of A. nepalensis and A. dealbata in Yuanbaoshan exhibited effective flame-retardant performance; (3) Coarse woody fuels negatively affected prescribed burning intensity and effectiveness. By quantifying fire behavior differences among these species, this study provides scientific support for fuel management and fire-resistant species selection in central Yunnan, while offering practical guidance for prescribed burning strategies in the Jin Dian Yuanbaoshan Forest Area.

Fanconi Anemia (FA) is a heritable syndrome characterized by DNA damage repair deficits, frequent malformations and a significantly elevated risk of bone marrow failure, leukemia, and mucosal head and neck squamous cell carcinomas (HNSCC). Hematopoietic stem cell gene therapy can prevent marrow failure and lower leukemia risk, but mucosal gene therapy to lower HNSCC risk remains untested. Major knowledge gaps include an incomplete understanding of how rapidly gene-corrected cellular lineages could spread through the oral epithelium, and which delivery parameters are critical for ensuring efficient gene correction. To answer these questions, we extended an agent-based model of the oral epithelium to include the delivery of gene correction in situ to FA cells and determine the competitive dynamics between cellular lineages with and without gene correction. We found that only gene-corrected lineages with substantial proliferative advantages (probability of resisting displacement out of the basal layer ) could spread on clinically relevant timelines, and that these lineages were initially at high risk of loss in the generations following correction. Delivering gene correction to many cells minimizes the risk of loss, while delivery to many distinct locations within a tissue maximizes the rate of spread. To determine the impact of mucosal gene therapy in preventing the clonal expansion of pre-cancerous mutations, we compared the expected burden of TP53 mutations in simulated tissue sections with and without gene correction. We found that when FA cells have elevated genome instability or a TP53-dependent proliferative advantage, gene correction can substantially reduce the accumulation of pro-tumorigenic mutations. This model illustrates the power of computational frameworks to identify critical determinants of therapeutic success to enable experimental optimization and support novel and effective gene therapy applications.

Nonlinear impacts of fuel load on rate of spread and residence time in forest surface fires

Impact of information dissemination and behavioural responses on epidemic dynamics: A multi-layer network analysis.

Recently, the fishery industry all over the world has been developing at a very fast rate, especially the soft-bodied animals. With the growing population of soft-bodied animals, the reproductive rate of Fasciola hepatica may increase significantly, and the incidence of infection and transmission of fascioliasis (a kind of zoonotic disease caused by Fasciola hepatica) will also increase significantly. This article will analyze the curve of fishery industry development around the world, combine the scholarly literature, and find out the relationship between the development of the fishery industry and the infection and spread of fascioliasis. According to the result, this article will give some advice to the fisheries sector and people about how to reduce the population and spread rate of Fasciola hepatica and take some preventive measures to protect themselves from fascioliasis. The analysis indicates that the rise of the aquatic products industry will intensify the reproduction, spread, and infection of liver flukes. People should frequently wash their hands, insist on eating cooked food, reduce the frequency of pets going out to forage, and limit the grazing areas for livestock in order to prevent infection with liver fluke disease.