Experimental study of heat release rate and pulsation frequency of non-axisymmetric fires

Background Subjective tinnitus is an auditory perception occurring without an external sound source. The medial geniculate body (MGB) plays a critical role in tinnitus pathology. The order of this study is to investigate whether mid-infrared (MIR) modulation of the MGB can mitigate tinnitus-like behavior in mice. Methods RNA sequencing was employed to analyze and compare gene expression levels in the MGB of mice with tinnitus to those of control mice. Golgi staining and transmission electron microscopy were used to confirm alterations in the structural plasticity of neurons. The whole-cell patch-clamp technique was applied to assess changes in neuronal functional plasticity. MIR optical fibers were employed to modulate MGB neuronal activity. Molecular dynamics simulations were performed to investigate the regulatory effect of MIR on hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channel function. Results The results of this study illustrates that MIR modulation reversed the abnormal electrophysiological properties of neurons associated with tinnitus-like behavior. Furthermore, molecular dynamics simulations revealed that MIR regulates HCN channel function, reducing the increased firing frequency of MGB neurons in tinnitus mice. Conclusions MIR intervention may alleviate the abnormal increase in neuronal firing frequency in the MGB of tinnitus mice by modulating HCN channel function. This regulatory mechanism involves influencing the secondary structure of HCN channels, enhancing hyperpolarization-activated current amplitude, and restoring reduced amplitudes observed in tinnitus mice.

Co-exposure to fentanyl, a mu-opioid receptor (MOR) agonist, and xylazine, a pan-α2- adrenoceptor (α2AR) agonist, results in deleterious interactions thought to ensue from the augmentation of the negative consequences of fentanyl by xylazine. Ex vivo striatal slice electrophysiology was used to investigate the effects of fentanyl (100 nM) and xylazine (10 μM) co-exposure on dopamine type 2 receptor (D2) expressing dorsolateral medium spiny neurons (MSN)s. While the acute application of either fentanyl or xylazine caused some decreases in D2 MSN firing rates at greater stimulus currents, co-exposure dysregulated D2 MSN excitability- resulting in paradoxical increases in excitability at lower stimulating currents, a more robust decrease in firing frequencies at higher stimulus currents, and overall increases in the initial momentary frequency of action potentials. The pan-opioid receptor and selective α2A-AR antagonists, naloxone (10 μM) and BRL 44408 (1 μM), respectively, assessed the contributions of these receptor types. BRL 44408 and naloxone each partially negated the interactive effects of fentanyl and xylazine co-exposure suggesting the involvement of α2A-ARs and MORs. Our findings underscore the unique consequences and complex nature of opioid and non-opioid receptor interactions in mediating the combined effects of fentanyl and xylazine in the striatum, which may contribute to the enhancement of fentanyl's reinforcing properties and underlie reported neurological complications including postural abnormalities and dystonia seen with opioid use disorder.

The bud bank of perennial grasses is a key aspect of their reproduction and longevity in frequently burned ecosystems. We investigated how fire intensity and time since fire affected fire-stimulated flowering and bud activity of wiregrass (Aristida beyrichiana), a foundational bunchgrass in south-eastern US pine savannas. We manipulated fuels and monitored fire temperatures in plants during an experimental fire. We tested effects of plant size and fire intensity on flowering stem production and proportions of active and dead buds. We compared active, dead and total buds from plants in the experimental burn with those in stands burned one and 2 years ago, and described the species' bud morphology and anatomy. The duration above 60 °C had a marginally significant negative effect on the number of flowering stems per plant. This effect was less than the significant positive correlation of flowering stem number with plant size. Fire intensity did not affect the proportions of dead and active buds 5 months after fire. There were significant differences in proportions of active, dead and dormant buds 1 year after fire, and the total number of buds decreased with time since fire. Plants had an average of one bud per tiller, and mean bud depth was 3 cm. Perennial bud banks are a substantial source of regenerative biomass for plants in fire-prone savannas. For fire-stimulated flowering species, frequent fires are likely important for maintaining large bud banks that supply both vegetative and flowering structures. A focus on belowground structures should shed light on long-term ecosystem dynamics in fire-prone ecosystems.

Neuropathic pain represents a critical challenge in medical research and clinical practice. Enhanced peripheral nerve activity and spinal dorsal horn neuronal firing are thought to contribute to the nociceptive hypersensitivities that are observed in chronic pain conditions, including those modeled by partial sciatic nerve ligation (PSNL). However, the detailed in vivo neuronal response dynamics and underlying mechanisms in the PSNL model remain to be fully clarified. To better understand these mechanisms, we evaluated dorsal root ganglion (DRG) and spinal dorsal horn neuronal activity in the PSNL model using in vivo approaches. Von Frey testing revealed sustained mechanical allodynia in PSNL animals; withdrawal thresholds were significantly reduced up to day 14 post-surgery. Immunohistochemistry revealed a stimulation-dependent increase in phosphorylated extracellular signal-regulated kinase (pERK)-positive neurons in the DRG, thereby indicating heightened peripheral nerve activity. Additionally, electrophysiological recordings demonstrated the enhanced firing of spinal dorsal horn neurons in response to the same stimuli. Notably, DRG pERK expression changes correlated with spinal neuronal firing frequency. Together, these findings suggest that peripheral nerve activity drives spinal neuronal sensitization, thus elucidating both pain mechanisms in the PSNL model and activity-dependent signaling in neuropathic pain.

Abstract. Forest fires are significantly influenced by climatic extremes, with variability in temperature and precipitation creating conducive conditions. India's diverse biogeographic zones, from tropical deciduous to montane ecosystems, display distinct fire regimes shaped by ecological, topographical, and climatic factors. This study investigates monthly climate indices across India's biogeographic zones experiencing extremely high forest fire frequencies (2003-2022). Four biogeographical provinces, representing subdivisions of larger biogeographical zones: North East Hill, North West Himalaya, Western Ghats, and Eastern Highlands were analysed using standardized indices recommended by the Expert Team on Climate Change Detection and Indices ETCCDI: Monthly Maximum Temperature (TXx), Monthly Minimum Temperature (TNx), Consecutive Wet Days (CWD), and Consecutive Dry Days (CDD). Results indicate distinct climatic patterns between February and June. The North East Hill region shows moderate dry conditions peaking in March, decreasing sharply due to pre-monsoon rainfall, with temperatures peaking (32-33 °C) in April. North West Himalaya experiences consistent dry periods (13-14 days), maximum temperatures in May (35-37 °C), and notable night-time warming. The Western Ghats experience extended dry spells and peak temperatures (45-47 °C in April), transitioning quickly with monsoon onset in June. The Eastern Highlands exhibit peak dryness in March and temperature extremes (43 °C) in April. These climatic transitions from dry-hot conditions to monsoon-driven rainfall significantly modulate seasonal forest fire risks. Understanding these patterns is crucial for developing adaptive, region-specific fire management strategies.

Abstract. Wildfires are fundamental ecological processes that shape terrestrial ecosystems and influence atmospheric dynamics. This study presents a global assessment of fire frequency, intensity, and burned extent over a 24-year period (2001-2024) using multi-source satellite observations. Spatio-temporal variability of forest fire activity and the critical role of seasonality in modulating fire behaviour has been captured in a grid of 0.25°. Our results reveal clear regional and hemispheric patterns wherein southern and central Africa, northern Australia, and parts of South America consistently exhibit the highest fire activity, with strong spatial and seasonal variability. In contrast, the Northern Hemisphere remains relatively stable, with lower fire occurrence and limited changes over time, aside from modest seasonal fluctuations in certain regions. Seasonal dynamics are especially pronounced in the tropics, reflecting variations in climatic drivers and fuel availability. To explore interactions among fire parameters, we conduct grid-level correlation analyses, revealing strong positive associations among frequency, intensity, and extent in tropical and subtropical regions. These relationships weaken or decouple in temperate and boreal zones, highlighting the influence of seasonal climate and vegetation dynamics. Building on these insights, clustering-based classification was used to delineate global fire regimes based on the combined behavior of the three parameters. The resulting maps reveal distinct spatial configurations and temporal evolution, with dynamic regime shifts across much of the Southern Hemisphere and comparatively stable regimes in the north.

Forest fires cause major environmental and socio-economic impacts, with the greatest risk for people occurring in the wildland-urban interface (WUI). In Ibero-Atlantic landscapes, where dispersed settlements are expanding into wildlands and vegetation is encroaching on populated areas, both the frequency and severity of WUI fires are rising sharply. The objective of this study was to develop a new methodological approach to assess fire risk in the WUI of Ibero-Atlantic heterogeneous landscapes under the assumption that fire impacts on population entities may occur by direct or indirect exposure to different types of vegetation. Based on landscape configuration analysis, expert knowledge of fire behaviour across vegetation types and on-site observations of fire impact on buildings and other infrastructures, we developed a multi-ring system around different types of population entities to characterize pre-fire vegetation patterns and fire severity across zones of influence (rings) within the WUI. The relationships between vegetation and severity (estimated with the Relativized Burn Ratio –RBR– spectral index derived from Sentinel-2 satellite imagery) were evaluated using multivariate linear regression models, with a backward stepwise procedure, at two levels: WUI and ring. This framework was tested in the large forest fire of Foyedo (Asturias, NW Spain) that affected more than 10,000 ha in the spring of 2023. Vegetation changed across the WUI, reflecting a land-use gradient from more managed vegetation near settlements to less managed and more natural types in outer zones, with fire severity increasing outward. The main drivers of fire severity at WUI level were vegetation type and vertical complexity. At ring level, the pattern was similar, with the percentage of heathlands and shrublands being the best predictor of fire severity in all rings. In the outermost ring, pine and eucalyptus plantations were also directly related to fire severity. Our findings underscore the need to develop spatially complex analytical frameworks accounting for different exposures across the WUI in order to guide effective vegetation management for forest fire prevention in the Atlantic landscapes of the Iberian Peninsula.

Wildfires increasingly threaten Mediterranean landscapes, particularly in regions like Attica, Greece, where urban sprawl, agricultural abandonment, and climatic conditions heighten the risk at the Wildland–Urban Interface (WUI). The Mediterranean basin, recognized as one of the global wildfire “hotspots”, has witnessed a steady increase in both fire severity, frequency, and burned area during the last four decades, a trend amplified by urban sprawl and agricultural land abandonment. This study represents the first integrated, region-wide mapping of the WUI and associated wildfire risk in Attica, the most densely urbanized area in Greece and one of the most fire-exposed metropolitan regions in Southern Europe, utilizing advanced techniques such as Earth Observation and GIS analysis. For this purpose, various geospatial datasets were coupled, including Copernicus High Resolution Layers, multi-decadal Landsat fire history archive, UCR-STAR building footprints, and CORINE Land Cover, among others. The research delineated WUI zones into 40 interface and intermix categories, revealing that WUI encompasses 26.29% of Attica, predominantly in shrub-dominated areas. An analysis of fire frequency history from 1983 to 2023 indicated that approximately 102,366 hectares have been affected by wildfires. Risk assessments indicate that moderate hazard zones are most prevalent, covering 36.85% of the region, while approximately 25% of Attica is classified as moderate, high, or very high susceptibility zones. The integrated risk map indicates that 37.74% of Attica is situated in high- and very high-risk zones, principally concentrated in peri-urban areas. These findings underscore Attica’s designation as one of the most fire-prone metropolitan regions in Southern Europe and offer a viable methodology for enhancing land-use planning, fuel management, and civil protection efforts.

Understanding the historical variability in the disturbance dynamics of the most important defoliator in eastern Canada, the spruce budworm (SBW), throughout its range will be paramount in anticipating potential changes associated with current climate change. There is growing concerns that black spruce-dominated forests may become increasingly affected by more frequent and severe outbreaks with warmer spring temperatures. Therefore, in this study, we used lepidopteran scales, a novel paleo-proxy found in lake sediments, to reconstruct periods of large spruce budworm populations (LSBP) along a latitudinal gradient and examined the relationship between large population event frequency relative to geographic location over the course of the Holocene in eastern Canada. The synchronous increase in LSBP event frequency in the four lakes observed around 5500 cal. yr BP culminating in maximum event frequency likely resulted from a combination of the northward migration of balsam fir, and low fire frequency. Although favorable Holocene climate conditions appear to have allowed for the expansion of the spruce budworm’s range into more northerly black spruce-dominated stands, event frequency remained low suggesting that the most suitable area for the SBW appears to be in more southern balsamfir-dominated stands.

Indonesia is an area that is vulnerable to various disasters, one of which is residential fires. Banjarmasin City has the highest population density and fire frequency in South Kalimantan. Alalak Tengah Urban Village is the urban village with the highest area of slums in North Banjarmasin Sub-district. Slums are often accompanied by a decline in the quality and facilities of settlements, making them areas that allow settlement fires to occur. Mapping vulnerability levels is necessary for disaster risk management. This research uses qualitative analysis based on Geographic Information System (GIS). The parameters used in this study are the density of residential buildings, type of residential buildings, settlement layout pattern, distance from water source location, distance from fire extinguisher location, distance from main road, and width of driveway. The research shows that the level of physical fire vulnerability in Alalak Tengah Village is divided into three levels with a low vulnerability level of 8.2 Ha, a medium vulnerability level of 11.7 Ha, and a high vulnerability level of 16.4 Ha. The high vulnerability level dominates with areas that have limited access, with dense settlements, and flammable building materials. The results of the physical vulnerability map of residential fires are reliable, with map accuracy test results ≥80%.

Metabolic syndrome is a recognized risk factor linked to hypertension, yet the beneficial role of natriuretic peptides (NPs) in this context remains debated. In this study, we established a high-fructose drinking-induced hypertension (HFD-HTN) model in male and female rats. Blood pressure (BP) and baroreceptor sensitivity (BRS) were evaluated, and gene/protein expressions of NP and their receptors were assessed by qRT-PCR and Western blot in the nodose ganglia (NG) and nucleus tractus solitarius (NTS). Our results demonstrated that the elevated systolic BP observed in both sexes of HFD-HTN rats was significantly reduced following NP administration (1.0 μg/g/day, tail vein). Impaired BRS was also ameliorated by NP treatment; the downregulation of NPRA/NPRB and upregulation of NPRC in NG/NTS were reversed. Interestingly, the expression of NR1/GluR2/GluR3 was markedly downregulated in NG but exhibited an inverse pattern in NTS, both of which were normalized by NP treatment. Patch-clamp recordings revealed that NP (100 nM) markedly shortened action potential duration with accelerated repolarization and increased firing frequency of repetitive discharge (FFRD) in C-type NG neurons of both sexes. Notably, the stimulus current required to elicit similar FFRD was significantly lower in female rats/dogs, consistent with their higher BRS. These findings provide new insights into the beneficial role of NPs in neurocontrol of BP regulation and hypertension via modulation of baroreflex afferent function.

It has well been documented that sex-related difference in the prevalence of migraine is widely accepted with more commonly seen in female patients. Although trigeminal ganglion (TG) neurons are the key players in the etiology of migraine, the underlying pathophysiology remains under debate so far. Myelinated Ah-type TG neurons were identified by the waveform characters of action potential (AP) conjugated with pharmacological validation using whole-cell patch techniques. The results showed that AP duration and current derivative for repolarization were markedly increased by 3 μM Yoda1 along with the increased firing frequency of repetitive discharge that could be abolished by 3 μM GsMTx4. Although Yoda1 concentration-dependently increased the peaks of Ca2+ currents, the blocker for Ca2+ channel ω-Conotoxin did not alter the AP waveform characters and discharge profiles, whereas Yoda1-mediated changes in AP waveform trajectory and repetitive discharge could be completely reversed by1.0 μM Iberiotoxin, a selective KCa1.1 blocker, suggesting that Piezo1-induced Ca2+ influx can activate KCa1.1 via presumably channel coupling. Additionally, Ah-type TG neurons functionally expressed Nav1.9/Nav1.8 in all tested neurons and their peaks were significantly increased by 3 μM Yoda1 and completely blocked by 3 μM GsMTx4. These datasets have demonstrated Piezo1-mediated neuroexcitation of female-specific subpopulation of myelinated Ah-type TG neurons due at least to the coupling between N-type Ca2+ channel and KCa1.1 and functional upregulation of Nav1.9, which uncovers an additional insights for higher incidence of migraine in woman.

The article considers the problem of fire hazard of transformer equipment, which is a key element of the energy infrastructure and determines the stability and reliability of power supply in industrial and urban networks. Transformer fires are accompanied by significant material losses, disruptions in the functioning of the power system and pose a threat to the life and health of people. The relevance of the study is due to the increase in the frequency of emergencies in conditions of military operations, wear and tear of electrical equipment and an increase in the load on the power grid, which requires a comprehensive analysis of statistical data and the construction of fire hazard assessment models. The article systematizes and processes the arrays of statistical information on fires that occurred on transformers. The dynamics of changes in the frequency of fires in recent years is analyzed, the most common causes of ignition and factors affecting the spread of fire are identified. Special attention is paid to the correlations between the technical condition of the equipment, operating conditions and the intensity of fire risks. Based on the generalized data, statistical models of hazard assessment are built, which allow predicting the probability of fires depending on the group of risk factors. The scientific novelty of the work lies in the application of a comprehensive approach to the analysis of statistical arrays, which combines classical data processing methods with elements of risk-oriented analysis. This allowed us to identify priority areas for minimizing danger, in particular, increasing the reliability of transformer diagnostics, modernizing fire protection systems and forming a basis for further mathematical modeling of risks. The practical significance of the results obtained lies in the possibility of using the proposed approaches to assess the fire hazard of transformers, developing preventive measures and optimizing the system of technogenic safety of energy infrastructure based on statistical data.

The mechanisms underlying the generation and termination of epileptic discharges remain incompletely understood. This study investigates the role of KCa3.1 (KCNN4) channels in modulating epileptiform activity in the deep layers of the entorhinal cortex using two in vitro models: short-lasting late recurrent discharges (LRDs) and prolonged tonic-clonic seizure-like events (SLEs). Whole-cell patch-clamp recordings in rodent brain slices revealed that blocking KCa3.1 channels with TRAM-34 increased neuronal excitability and firing frequency, enabling sustained firing at higher depolarizing currents. In the LRD model, TRAM-34 had no effect on the frequency or duration of spontaneously generated LRDs, likely due to the low intrinsic expression of KCa3.1 channels in the entorhinal cortex. However, NS-309, a positive modulator of KCa3.1 and SK channels, reduced LRD duration, while TRAM-34 prolonged LRDs induced by extracellular stimulation. In the SLE model, TRAM-34 increased SLE frequency and enhanced glutamatergic activity at SLE onset, indicating a more pronounced role of KCa3.1 channels during intense epileptiform activity. To address the function of KCa3.1 channels in glutamatergic neurons, we specifically overexpressed KCNN4 in these cells using a viral vector. Although overexpression did not abolish LRD generation, its duration and magnitude were significantly reduced, mirroring the effects of NS-309. These results demonstrate that the contribution of KCa3.1 channels to epileptiform activity depends on its temporal pattern, with minimal influence on short LRDs but greater effects on robust glutamatergic activity at SLE onset. Thus, KCa3.1 upregulation provides feedback mechanisms for the premature termination of epileptiform discharges, suggesting KCa3.1 channels as potential therapeutic targets.

Psychosocial stress in women is a major public health concern, yet the intergenerational mechanisms linking maternal premating stress to offspring neuropsychiatric vulnerability remain incompletely understood. Here, female mice were exposed to chronic unpredictable mild stress (CUMS) prior to mating, and offspring were assessed for neurodevelopment, adult behavior, and multi-omics profiles. Premating stress induced neurodevelopmental delays and sexually dimorphic adult phenotypes: female offspring exhibited hyperactivity and social deficits, whereas male offspring displayed anxiety. Cerebellum cytokine levels were reduced in a sex-dependent manner. Maternal stress shifted offspring gut microbiota (GM) composition, with p_Proteobacteria as core taxa in females and p_Firmicutes in males, exhibiting sex-dependent and inverse shifts in microbial network connectivity. Male offspring showed marked metabolic alterations and enhanced maternal-offspring metabolic concordance. Integrated analyses of GM, metabolites, and cerebellum profiles identified sexually dimorphic network correlations, further supported by human data demonstrating maternal stress-induced, sex-dependent GM network remodeling. Lactoferrin (LF) intervention selectively rescued male anxiety but not female behavioral deficits, and in males specifically, reduced cerebellum pro-inflammatory cytokines, enhanced GM network connectivity, and enriched immune-related serum metabolic and cerebellum transcriptomic pathways. LF also suppressed Purkinje cell firing frequency in males and reinforced post-treatment connectivity across microbial, metabolic, and cerebellum transcriptional nodes. Collectively, these findings delineate a previously unrecognized sexually dimorphic neuro-microbiota-metabolic network underpinning intergenerational vulnerability and highlight microbiota-targeted modulation as a systems-level mechanistic framework for sex-specific prevention of maternal stress-associated neuropsychiatric disorders.

The growing frequency of extreme weather, earthquakes, fires, and environmental hazards underscores the need for real-time monitoring and predictive management at the urban scale. Conventional three-dimensional spatial information systems, which rely on orthophotos and ground surveys, often suffer from computational inefficiency and data overload when processing large and heterogeneous datasets. To address these limitations, this study introduces a three-dimensional GeoHash-based geocoding algorithm designed for lightweight, real-time, and attribute-driven digital twin operations. The proposed method comprises five integrated steps: generation of 3D GeoHash grids using longitude, latitude, and altitude coordinates; integration with GIS-based urban 3D models; level optimization using the Shape Overlap Ratio (SOR) with a threshold of 0.90; representative object labeling through weighted volume ratios; and altitude correction using DEM interpolation. Validation using a testbed in Sillim-dong, Seoul (10.19 km2), demonstrated that the framework achieved approximately 9.8 times faster 3D modeling performance than conventional orthophoto-based methods, while maintaining complete object recognition accuracy. The results confirm that the 3D GeoHash framework provides a unified spatial key structure that enhances data interoperability across querying, visualization, and simulation. This approach offers a practical foundation for operational digital twins, supporting high-efficiency 3D mapping and predictive disaster management toward resilient and data-driven urban systems.

Disparities in wildfire regimes across China's borders: Policy-driven asymmetries in fire frequency, intensity and impact

Beta oscillations (13-30 Hz) of the local field potential are a hallmark of Parkinson's disease induced by dopamine deficiency, yet their underlying mechanism remains unclear. This study investigates the complex dynamics underlying beta oscillations of striatal medium spiny neurons in a theoretical model, where the conductance of the M-current (gM) is reduced to reflect dopamine deficiency. For an isolated neuron, codimension-1 and -2 bifurcations underlie excitability transition and the shift of phase response curves (PRCs) from Type 2 to Type 1. In a network with inhibitory coupling, interactions between synchronization regimes and firing frequency of individual neurons generate beta oscillations. Under weak coupling, anti-phase synchronization (AS) changes to global synchronization (GS) via a discontinuous phase transition with a bistable regime. Typical AS and GS are explained by the match between PRC types and inhibitory post-synaptic currents. In the AS, the network frequency is about twice the firing frequency of individual neurons at intermediate gM, resulting in beta network oscillations. As gM decreases further, neurons show higher firing frequencies, and GS replaces AS via a discontinuous transition, yielding beta oscillations with paradoxical frequency reduction. Under strong coupling, partial synchronization emerges instead of AS or GS, accompanied by a continuous transition. The partial synchronization induces beta oscillations across a wide parameter region, where the network frequency exceeds the low firing frequency of individual neurons. These nonlinear dynamics of single neurons and synchronization transitions in the network provide new insights into the generation and modulation of beta oscillations in Parkinson's disease.

The “sign-tracking” and “goal-tracking” model of individual variation in associative learning permits the identification of rats with different cue reactivity and predisposition to addiction-like behaviors. Certainly, compared with “goal-trackers” (GTs), “sign-trackers” (STs) show more susceptibility traits such as increased cue-induced “relapse” of drugs of abuse. Different cue- and reward-evoked patterns of activity in the nucleus accumbens (NAc) have been a hallmark of the ST/GT phenotype. However, it is unknown whether differences in the intrinsic neuronal properties of NAc medium spiny neurons (MSNs) in the core and shell subregions are also a physiological correlate of these phenotypes. We performed whole-cell slice electrophysiology in outbred male rats and found that STs exhibited the lowest excitability in the NAc core, with lower number of action potentials and firing frequency as well as a blunted voltage/current relationship curve in response to hyperpolarized potentials in both the NAc core and shell. Although firing properties of shell MSNs did not differ between STs and GTs, intermediate responders that engage in both behaviors showed greater excitability compared with both STs and GTs. These findings suggest that intrinsic excitability in the NAc may contribute to individual differences in the attribution of incentive salience.