Periodic Firing Research Articles

Analysis of the meteorological situation during period of forest fires and smoke-blanketing monitoring in Siberia in 2019

Analysis of the meteorological situation during period of forest fires and smoke-blanketing monitoring in Siberia in 2019

Development of advanced intumescent flame-retardant binder for fire rated timber door

Intumescent flame-retardant binder (IFRB) offers a great advancement for the most efficient utilization of a wide variety of passive fire safety system at the recent development. This article highlights the fire-resistance and thermal properties of the IFRB using Bunsen burner and thermogravimetric analysis. The five IFRB formulations were mixed with vermiculite and perlite for the fabrication of fire-resistant timber door prototypes. Additionally, the fire rated door prototypes were compared under 2 hours fire test. The prototype (P2), with a low density of 637 kg/m3 showed the superlative fire-resistance rating performance, resulting in temperature reduction by up to 58.9 °C, as compared with that of prototype (P1). Significantly, an innovative fire rated timber door prototype with the addition of formulating intumescent binder has verified to be effective in stopping fires and maintaining its integrity by surviving a fire resistance period of 2 hours.

Identifying Possible Climate Change Signals Using Meteorological Parameters in Short-Term Fire Weather Variability for Russian Boreal Forest in the Republic of Sakha (Yakutia)

The Boreal forest is a terrestrial ecosystem highly vulnerable to the impacts of short-term climate and weather variabilities. Detecting abrupt, rapid climate-induced changes in fire weather and related changes in fire seasonality can provide important insights to assessing impacts of climate change on forestry. This paper, taking the Sakha Republic of Russia as study area, aims to suggest an approach for detecting signals indicating climate-induced changes in fire weather to express recent fire weather variability by using short-term ranks of major meteorological parameters such as air temperature and atmospheric precipitation. Climate data from the “Global Summary of the Day Product” of NOAA (the United States National Oceanic and Atmospheric Administration) for 1996 to 2018 were used to investigate meteorological parameters that drive fire activity. The detection of the climate change signals is made through a 4-step analysis. First, we used descriptive statistics to grasp monthly, annual, seasonal and peak fire period characteristics of fire weather. Then we computed historical normals for WMO reference period, 1961-1990, and the most recent 30-year period for comparison with the current means. The variability of fire weather is analyzed using standard deviation, coefficient of variation, percentage departures from historical normals, percentage departures from the mean, and precipitation concentration index. Inconsistency and abrupt changes in the evolution of fire weather are assessed using homogeneity analysis whilst a Mann-Kendall test is used to detect significant trends in the time series. The results indicate a significant increase of temperature during spring and fall months, which extends the fire season and potentially contributes to increase of burned areas. We again detected a significant rainfall shortage in September which extended the fire season. Furthermore, this study suggests a new approach in statistical methods appropriate for the detection of climate change signals on fire weather variability using short-term climate ranks and evaluation of its impact on fire seasonality and activity.

Mid- and late Holocene vegetation, climate and fire dynamics in the Serra do Itatiaia, Rio de Janeiro State, southeastern Brazil

We present a high-resolution pollen and charcoal record from the 350-cm Agulhas Negras (AN) sediment core from the Serra do Itatiaia, Itatiaia National Park, located at 2410 m altitude in Rio de Janeiro State, southeastern (SE) Brazil. Diverse campos de altitude (high elevation grassland) with small areas of montane forest and periodic fires dominated the landscape during the period of the last 7430 cal yr BP. Montane forest expanded after 4870 cal yr BP, reflecting a transition to wetter late Holocene climatic conditions. Araucaria angustifolia was rare in the Serra do Itatiaia and is evidenced only after 4200 cal yr BP. Fires may have markedly reduced montane forest cover between 4450 and 4000 cal yr BP. Continuous expansion of montane forest under moister conditions and the general absence of fire after 1960 cal yr BP was interrupted by a local fire event at about 530 cal yr BP. Increased fires may have limited montane forest expansion under the wet climatic conditions of the last 600 years. During this period Araucaria angustifolia became more frequent in the montane forest. Further paleoecological work is necessary to better document the natural and human-influenced relationships between climate, vegetation and fire in the high mountain vegetation of SE Brazil.

Pinus sylvestris L. var. cretacea Kalen. In The ”Kreidova Flora” Branch of Ukrainian Steppe Nature Reserve: Current State and Conservation Measures

The "Kreidova Flora" (Cretaceous Flora) branch of Ukrainian Steppe Nature Reserve was created in 1988 to protect unique cretaceous vegetation, including pine forests on chalk. The Standing Committee of the Berne Convention in 2018 added these forests to the list of endangered habitats as “G3.4G Pinus sylvestris forest on chalk in the steppe zone“. For the last 40 years, the area covered with pine trees has doubled, but there are threats of invasive plants, periodical fires and other losses as a result of military actions since 2014. Satellite remote sensing data (Landsat archive) were used to analyze the distribution patterns and disturbances over 40-year period. The assessment of the stability and risks in this habitat shows its rareness, narrow prevalence, poor reproduction, very high (R> 83%) danger of destruction, and strong sensitivity to the environmental changes. Special set of monitoring and conservation measures are considered to provide successful protection of the habitat as a part of Emerald network.

Early life exposure to coal mine fire and tobacco smoke affect subclinical vascular function

ObjectiveTo evaluate whether vascular health in young children was associated with exposure to a 6-week episode of coal mine fire smoke or environmental tobacco smoke (ETS) in a retrospective cohort...

Coherent signature of warming-induced extreme sub-continental boreal wildfire activity 4800 and 1100 years BP

Climate changes are expected to progressively increase extreme wildfire frequency in forests. Finding past analogs for periods of extreme biomass burning would provide valuable insights regarding what the effects of warming might be for tree species distribution, ecosystem integrity, atmospheric greenhouse gas balance, and human safety. Here, we used a network of 42 lake-sediment charcoal records across a ∼2000 km transect in eastern boreal North America to infer widespread periods of wildfire activity in association with past climate conditions. The reconstructed fluctuations in biomass burning are broadly consistent with variations in ethane concentration in Greenland polar ice cores. Biomass burning fluctuations also significantly co-varied with Greenland temperatures estimated from ice cores, at least for the past 6000 years. Our retrospective analysis of past fire activity allowed us to identify two fire periods centered around 4800 and 1100 BP, coinciding with large-scale warming in northern latitudes and having respectively affected an estimated ∼71% and ∼57% of the study area. These two periods co-occurred with widespread decreases in mean fire-return intervals. The two periods are likely the best analogs for what could be anticipated in terms of impacts of fire on ecosystem services provided by these forests in coming decades.

Statistical Estimation of Forest Fire Precaution Periods

In order to maximize the efficiency of the limited resources for fire-fighting and prevention, it is important to set a forest fire precaution period by considering the temporal characteristics of forest fire occurrence and spread. In this study, the forest fire precaution periods were suggested based on statistical analysis of the national fire statistics data from 1991 to 2018. Multiple, ridge, and Lasso regression analyses were applied to identify the monthly (or 10 days) linear trend of fire occurrences, while k-means cluster analysis was used to select the precaution period. The fire occurrences in January, June, August and November have increased significantly over time, whilst those in March, April and May remained high without fluctuation over this period. The results suggest the extension of the fire precaution period in South Korea from 5 months (Spring: February 1 to May 15, Autumn: November 1 to December 15) to 8 months from mid-October to mid-June. This results from this study are expected to serve as statistical evidence for readjustment of forest fire precaution period in South Korea.

Моніторинг ландшафтних пожеж Транскордонної Рамсарської території «Ольмани-Переброди» за даними дистанційного зондування Землі

Зміни клімату, землекористування та зростання відвідуваності лісів населенням зумовили суттєве загострення проблеми охорони лісів від пожеж, зокрема на заповідних та суміжних територіях. Транскордонна Рамсарська територія «Ольмани-Переброди», в яку входить Рівненський природний заповідник, характеризується високим рівнем ландшафтного та біологічного різноманіття за рахунок видів птахів, тварин і рослин, які знаходяться під загрозою зникнення, тому задача охорони таких територій від пожеж є однією з пріоритетних. Зважаючи на те, що в останні роки на території України почастішали випадки великих лісових пожеж, слід бути готовим до можливих випадків таких пожеж і на території Рівненського природного заповідника, до якого входить українська частина Транскордонної Рамсарської території. У статті наводиться аналіз динаміки пожеж, які відбулися в природних ландшафтах Транскордонної Рамсарської території «Ольмани-Переброди» упродовж 2006–2016 рр., на основі даних дистанційного зондування Землі. Отримані результати щодо часового та просторового розподілу пожеж на досліджуваній території за багаторічний період дозволять у майбутньому спрогнозувати ймовірність виникнення та поширення пожеж.

Fire control systems in forest reserves: An assessment of three forest districts in the Northern region, Ghana

Forest fires may have beneficial effects ecologically, but can also be damaging to the overall health and diversity of flora and fauna and may also result in loss of farm produce and livelihood base of local communities living around the forest reserves. In order to minimize damage from fires to the forest vegetation, information on frequency, timing and control of fire events is needed for decision making at the district and regional management levels of the Forestry Commission. However, not much of such information exists, particularly for northern Ghana. Therefore, this research sought to ascertain occurrences of forest fires and how they are controlled in three (3) Forest Districts in the northern region of Ghana namely: the Tamale, Yendi and Walewale Forest Districts. Respondents comprised staff of Ghana Forestry commission, members of fringe communities and personnel from the Ghana National Fire Service. A mixed method research design involving structured interview schedule, in-depth interviews and quantitative review of secondary data was employed for data collection. Quantitative data was analyzed using descriptive statistics such as frequencies and percentages while qualitative data was analyzed using simple narratives. The study revealed that detection by smoke was the dominant means of detecting fires within the forest reserves. December and January were the months with the most fire occurrences and periods between 2 and 4 h and greater than 8 h were the dominant timeframes within which fires were controlled. Inadequate firefighting equipment and lack of effective cooperation between regulatory institutions and community members were identified as major constraints to effective control of forest fires. Active collaboration between regulatory agencies and members of fringe communities among others are recommended for effective control of wildfires in forest reserves in northern region of Ghana.

Investigation of the relationship between burned areas and climate factors in large forest fires in theÇanakkaleregion.

Fires pose a serious threat to the forests that lay on the western and southern coastline of Turkey that start with North Aegean coasts and end with the provincial boundaries of Hatay. Çanakkale, a western province of Turkey, is located in the North Aegean boundary and its topography (Dardanelles Strait), climate, and vegetation cover combine to form an inviting recipe to forest fires. Although the province is located in a transitional zone in terms of climate and vegetation, each year it witnesses highly dry and hot fire seasons. Thus, large forest fires occur periodically. In this research, the relationship between the large periodic fires (larger than 100 ha) and the climate data was investigated, with a particular focus on the most severe 8 fire seasons from 1969 to 2007. We established that there is a relationship between 1977, 1985, and 1986 fire seasons and the climate data for the corresponding periods. The remaining 5 seasons in which conflagrations occurred were also found to coincide with the days with high daily severity indices (DSR). These are 1969, 1977, 1985, 1987, and 2008. Additionally, 2008 was determined as the year with the highest fire risk, followed by year 1969.

Preparation of Intumescent Fire Protective Coating for Fire Rated Timber Door

Intumescent flame-retardant coating (IFRC) provides a protective barrier to heat and mass transfer for the most efficient utilization of a wide variety of passive fire protection systems at the recent development. This article highlights the fire-resistance, physical, chemical, mechanical, and thermal properties of the IFRC using a Bunsen burner, furnace, Scanning Electron Microscope, freeze-thaw stability test, Instron Micro Tester, and thermogravimetric analysis (TGA) test. The five IFRC formulations were mixed with vermiculite and perlite for the fabrication of fire-resistant timber door prototypes in this research project. Additionally, the best fire-resistance performance of the fire-rated door prototype was selected and compared with a commercial prototype under the fire endurance test. An inventive fire-rated door prototype (P2), with a low density of 636.45 kg/m3, showed an outstanding fire-resistance rating performance, resulting in temperature reduction by up to 54.9 °C, as compared with that of the commercial prototype. Significantly, a novel fire-rated timber door prototype with the addition of formulating intumescent coating has proven to be efficient in preventing fires and maintaining its integrity by surviving a fire resistance period of 2 h.

Disaster Management in Wetland Settlement at Ogan Komering ILIR Regency, South Sumatera

Ogan Komering Ilir (OKI) Regency is part of the South Sumatra Province whose area is prone to flooding and fire. As for the tropical region, OKI also has two extreme seasons between the rainy and dry seasons. In the dry season is a prone period of forest and land fires, while in the raining season, its prone to flooding. This study aimed to conduct Disaster Management in Wetland Settlements at Ogan Komering Ilir Regency. The method was using qualitative study design with six informant that consist of six local community and two key informant from worker of Badan Penanggulangan Bencana Daerah and Dinas Kesehatan OKI. The result showed that disaster management was classified into four phase. First, the phase of prevention and mitigation that analyzed socialization efforts conducted in OKI were distribution of leaflets and posters. Then, phase of disaster preparedness showed preparedness program in OKI has not been implemented optimally. In disaster emergency response phase discovered no specific procedure in disaster management. Moreover, the phase of disaster recovery indicated that collaborative efforts with multi-sector stakeholders have been conducted. It can be concluded to prepare Disaster Response Village Programs in Ogan Komering Ilir.

Scaling behaviors and self-organized criticality of two-dimensional small-world neural networks

It is widely believed that the brains of human beings work at or near the state of self-organized criticality (SOC). In the present work, we investigate two-dimensional small-world neural networks (2D SWNN) with Bak–Sneppen (BS)-type neurons as their nodes. By taking threshold firing and refractory period as the key features of neurons in the simulations, a few power laws are obtained for suitable range of parameters. The SOC characterized by the power-law distribution of avalanche sizes as well as 1∕f noise emerges in the present model. Moreover, a set of scaling relations are found to exhibit criticality. The exponent for the power spectrum of all return time is α=0.71, which is comparable with what were found in medical experiments.

Fire Scars Negatively Affect Hydraulic Conductivity in White Oak (Quercus alba)

Fire management is increasingly used to manage forest stand structure and dynamics. Relatively intense fires can injure the tree stem and induce fire scar formation, affecting subsequent tree growth and wood quality. Here, we consider the physiological effects of fire scarring in white oak. Potential hydraulic conductivity, estimated from the mean vessel area and vessel number, was determined for growth rings formed before, during, and after the year of injury. We measured vessel anatomy using the ROXAS image analysis tool on the cross-sections of 14 white oaks of various ages with fire scars originating in different years through the late 19th and early 20th century. We found that the mean vessel area and potential hydraulic conductivity were significantly reduced for the year of and the year immediately following fire injury. After this two-year period, mean vessel area returned to levels present in wood formed prior to the injury. Age when scarred, radius from the pith when scarred, scar height above ground, and percentage of circumference scarred did not explain the degree to which potential hydraulic conductivity was lost in the fire scar year compared to the year prior. Overall, the magnitude of reduction in potential hydraulic conductivity was small but significant. An earlier study on the same cross-sections verified no reductions in radial growth after fire injury. Thus, it is likely that the conductance of older rings is adequate to sustain conductance. Nonetheless, we recommend further investigation, in particular, the ability to predict how tree size, age, position along a slope, and other variables may influence the degree of wounding and possible losses of potential hydraulic conductivity after the fire. Information like this for white oak and other common tree species may help elucidate the physiological impacts fire injuries have on trees existing in forest stands with periodic fire.

Periodic firings in neurons with external sinusoidal applied current

The distinct qualitative behavior exhibited by neuron at externally applied current stimuli is well known in the Hodgkin-Huxley model (HH model). The resting state and periodic firings in neuron correspond to solutions of the HH model having stable fixed points and unstable fixed point (periodic solutions through Hopf bifurcation points). The one-parameter bifurcation with respect to externally applied current stimuli suggests a periodic window between two stable fixed point solutions in the HH model. The externally applied sinusoidal current stimuli generate periodic firings at very low current and a large periodic region is observed. The generations of limit cycles and possible chaotic behavior in the HH model is explored through numerical simulations extensively.

Platinum/Graphene Oxide Coated Microfabricated Arrays for Multinucleus Neural Activities Detection in the Rat Models of Parkinson's Disease Treated by Apomorphine.

Apomorphine (APO) is often used to treat Parkinson's disease (PD) while the mechanism in PD treatment remains unclear. In this study, a four-shank microelectrode array (MEA) was fabricated to monitor cortex (two shorter shanks) and caudate putamen (CPU) (two longer shanks) signals simultaneously. The dopamine (DA) concentration and neural spike firing in the bilateral targets were recorded in the unilateral 6-OHDA PD rats treated by APO. Electroplating platinum black and reduced graphene oxide nanocomposites onto the electrode surface significantly improved their performance with higher sensitivity, selectivity, and linearity and lower impedance. The DA level and neural spike firing rate were regulated to the normal level. On the lesioned side, the mean DA concentration increased, and the firing rate decreased significantly in the cortex and CPU. Synchronous spike oscillation and typical periodic firing appeared on the lesioned side but were significantly reduced after APO treatment. This represents a substantial contribution to PD treatment and effective recovery of movement. The nanotechnology-enhanced MEA biosensing interface provides an elaborate platform for detecting neuron activities and helps to reveal the abnormal signals between neurons.

Numerical Simulation for Mine Oblique Lane Fire Based on PDF Non-Premixed Combustion

ABSTRACT In the mine fire period, the smoke plume temperature, critical air velocity, back-flow layer and other fire parameters in the lanes are subjected to environmental factors such as lane dip angle and airflow conditions, coupled with uncertain evolution process. In view of this, a numerical simulation is performed for exploring the dynamic evolution law of fire possibly occurred in the mine. The ANSYS Fluent PDF non-premixed combustion model is applied to reveal the fire development in the lanes with different dip angles under different air velocity. The temperature distribution in the lanes and the evolution law of the fire back-flow layer are also analyzed. Here introduces the dimensionless number-Richardson number (Ri value) to determine the critical value of the development of the fire back-flow layer. The results show that there is a regular relationship of the spatiotemporal evolution properties of fire in the inclined lane with the two factors: dip angle, airflow velocity, According to this law, the calculation model of smoke back-flow layer length with respect to air velocity and inclination angle is established, and the critical air velocity prediction model under the condition of large inclination angle is revised. Based on the critical air velocity and critical angle, the critical value of the Richardson number is determined to be 91.6. When Ri is greater than 91.6, the fire back-flow layer appears, otherwise, it disappears. The findings provide certain clues to identifying the fire in the underground tunnel and predicting the fire development and smoke spread.

Between- and within-biome resistance and resilience at the fynbos-forest ecotone, South Africa

In the Greater Cape Floristic Region (GCFR) of South Africa, afrotemperate forest islands persist within a broader landscape of Mediterranean-type fynbos shrubland. The co-existence of these contrasting vegetation types in the same climate space suggests interactions between broad-scale climatic parameters and localised variables (notably local disturbance regimes and catchment hydrology). In this study, palaeoecological data from a fynbos-forest boundary were used to assess the effects of interactions between changes in climate, fire and land use on vegetation dynamics and biome resilience at millennial timescales. Fossil pollen, spores and charcoal were extracted from radiocarbon-dated sediment cores to provide proxies for vegetation, hydrology, large herbivore abundance and fire. Constrained hierarchical clustering (CONISS) was applied to the fossil data to identify distinct vegetation assemblages in the palaeoecological record, and to further elucidate ecosystem trajectories through time. Regional palaeoenvironmental data are also referred to in inferring local and regional environmental changes. We expected to find shifts between fynbos and forest alternate stable states associated with changes in fire and rainfall. More specifically, we anticipated fynbos expansion during drier periods and/or those with more fire, and forest expansion during wetter and/or less fire prone periods. However, the fossil pollen data reveal remarkable stability of the fynbos-forest ecotone over the past 3000 years, despite significant changes in climate, fire and land-use. We found resilience of fynbos was enhanced through internal dynamics, namely, a shift from grassy, fire-prone fynbos in warmer, less seasonal time periods with less summer drought stress, to proteoid fynbos with less frequent fire during times of greater summer drought stress. The emergent properties of the respective fynbos types offset physiological advantages to forest species afforded by changes in the fire-free interval and abundant abiotic resource supply, inhibiting invasion of the former biome by the latter. We suggest these mechanisms require further investigation.

Modulating grid cell scale and intrinsic frequencies via slow high-threshold conductances: A simplified model

Grid cells in the medial entorhinal cortex (MEC) have known spatial periodic firing fields which provide a metric for the representation of self-location and path planning. The hexagonal tessellation pattern of grid cells scales up progressively along the MEC’s layer II dorsal-to-ventral axis. This scaling gradient has been hypothesized to originate either from inter-population synaptic dynamics as postulated by attractor networks, or from projected theta frequency waves to different axis levels, as in oscillatory models. Alternatively, cellular dynamics and specifically slow high-threshold conductances have been proposed to have an impact on the grid cell scale. To test the hypothesis that intrinsic hyperpolarization-activated cation currents account for both the scaled gradient and the oscillatory frequencies observed along the dorsal-to-ventral axis, we have modeled and analyzed data from a population of grid cells simulated with spiking neurons interacting through low-dimensional attractor dynamics. We observed that the intrinsic neuronal membrane properties of simulated cells were sufficient to induce an increase in grid scale and potentiate differences in the membrane potential oscillatory frequency. Overall, our results suggest that the after-spike dynamics of cation currents may play a major role in determining the grid cells’ scale and that oscillatory frequencies are a consequence of intrinsic cellular properties that are specific to different levels of the dorsal-to-ventral axis in the MEC layer II.