Firing Phase Research Articles

CFD-based analysis of deviations between thermocouple measurements and local gas temperatures during the cooling phase of compartment fires

Data from thermocouple (TC) measurements play a pivotal role in fire safety science and engineering studies. It is well-known that there are deviations from the actual local gas temperature and many studies have led to the development of correction factors. The present study focuses on these deviations inside compartments through a systematic series of CFD simulations, performed with Fire Dynamics Simulator (FDS), version 6.8.0. A canonical cubic box is used as geometry. This allows for the demonstration of the impact of the presence of smoke, with variable optical thickness, on the TC data as retrieved from FDS. Significant differences are observed between TC measurements and local gas temperatures. Corrections as developed for TC measurements in open atmospheres cannot be readily applied in compartment configurations, where smoke properties change both spatially and temporally.

Empirical study on the influence of initial relative humidity on wood crib fire behavior in compartment under varied natural ventilation conditions

This empirical study investigates the influence of initial relative humidity (RH) variations (35 % and 95 %) on key fire behavior parameters, specifically focusing on the fully developed stage, occurrences of flashover, and the temperature of the upper gas layer. Wooden cribs weighing 10 kg–40 kg are used as fuel in a compartment with three openings to establish different natural ventilation conditions. The experimental findings reveal that increasing the initial RH within the chamber leads to a delay in the onset of the fire growth phase. Furthermore, it induces two noticeable effects on the fully developed fire stage: a reduction in its duration by up to 50 % and a delay in its initiation by at least 30 s. While heightened initial RH does not prevent flashover, it effectively postpones its occurrence by a minimum of 40 s. Experiments with maximum fuel loads demonstrate negligible effects of increased RH on the maximum temperature, even under varying ventilation conditions. Conversely, lower fuel loads exhibit a significant decline in temperature with rising humidity, notably from 626 °C to 474 °C. The quantitative and qualitative insights derived from this study have considerable potential to inform the development of more effective fire suppression strategies in enclosed compartments.

Enhancing Mechanical Properties of Clay Brick by Using Stone Powder

Abstract Hundreds of studies have been written in the last several decades on the advantages of using stone powder as a raw material in the production of fired clay bricks. The durability and long-term behavior of the finished product, however, have received very little attention in the literature. Clay bricks are generally fired at high temperatures in developing countries, which reduces the mechanical performance of the bricks. This is especially evident in extreme environmental settings where weathering leads to significant damage. The evaluation of concrete waste (stone powder) used to make fired clay bricks is the main topic of this study. There are two sections: the first evaluates how adding stone powder to clay bricks improves their physical characteristics such absorption, efflorescence, density, and firing shrinkage. The impact of stone powder on the mechanical characteristics of specimens of burned clay bricks, such as compressive and flexural strengths, is covered in the second section. The percentages of stone powder in the clay bricks are 0 %, 5 %, 10 %, 15 %, and 20%. While the ratio of dry soil to water content remains is 0.3. In this work three fire phases are used untel to the maximum temperature is reached. The first one is 300 °C, the second phase is 600 °C, and 900 °C for the third phase. The water absorption of specimens decreased as the quantity of stone powder increased, and efflorescence also decreased, according to the results for the physical attributes. The density does, however, somewhat rise with the amount of stone powder. Additionally, when the amount of stone powder was increased, the experimental results indicated that firing shrinkage decreased. Mechanically considered, clay brick specimens with 20% more stone powder showed stronger compressive flexural capabilities.

Numerical analysis of fire-exposed reinforced concrete sections for assessing post-heating axial and flexural capacity

PurposeThis study investigates the impact of the fire decay phase on structural damage using the sectional analysis method. The primary objective of this work is to forecast the non-dimensional capacity parameters for the axial and flexural load-carrying capacity of reinforced concrete (RC) sections for heating and the subsequent post-heating phase (decay phase) of the fire.Design/methodology/approachThe sectional analysis method is used to determine the moment and axial capacities. The findings of sectional analysis and heat transfer for the heating stage are initially validated, and the analysis subsequently proceeds to determine the load capacity during the fire’s heating and decay phases by appropriately incorporating non-dimensional sectional and material parameters. The numerical analysis includes four fire curves with different cooling rates and steel percentages.FindingsThe study’s findings indicate that the rate at which the cooling process occurs after undergoing heating substantially impacts the axial and flexural capacity. The maximum degradation in axial and flexural capacity occurred in the range of 15–20% for cooling rates of 3 °C/min and 5 °C/min as compared to the capacity obtained at 120 min of heating for all steel percentages. As the fire cooling rate reduced to 1 °C/min, the highest deterioration in axial and flexural capacity reached 48–50% and 42–46%, respectively, in the post-heating stage.Research limitations/implicationsThe established non-dimensional parameters for axial and flexural capacity are limited to the analysed section in the study owing to the thermal profile, however, this can be modified depending on the section geometry and fire scenario.Practical implicationsThe study primarily focusses on the degradation of axial and flexural capacity at various time intervals during the entire fire exposure, including heating and cooling. The findings obtained showed that following the completion of the fire’s heating phase, the structural capacity continued to decrease over the subsequent post-heating period. It is recommended that structural members' fire resistance designs encompass both the heating and cooling phases of a fire. Since the capacity degradation varies with fire duration, the conventional method is inadequate to design the load capacity for appropriate fire safety. Therefore, it is essential to adopt a performance-based approach while designing structural elements' capacity for the desired fire resistance rating. The proposed technique of using non-dimensional parameters will effectively support predicting the load capacity for required fire resistance.Originality/valueThe fire-resistant requirements for reinforced concrete structures are generally established based on standard fire exposure conditions, which account for the fire growth phase. However, it is important to note that concrete structures can experience internal damage over time during the decay phase of fires, which can be quantitatively determined using the proposed non-dimensional parameter approach.

Tensile Tests for Material Characterisation of High- and Ultra-High-Strength Steels S690QL and S960QL under Natural Fire Conditions

The mechanical material behavior of mild steels is reversible in the cooling phase of natural fires, which is proven by experimental evidence. For the material behavior of high-strength steels during cooling, no results are yet available. The paper provides the first comprehensive test program on the constitutive material behavior of high-strength steels S690QL and S960QL as well as mild steel S355 J2 + N in the case of natural fires. It is elaborated that the mechanical material behavior of high-strength steels in the cooling phase differs from the behavior in the heating phase and is not reversible due to phase changes of the microstructure. A constitutive material model for structural fire design purposes is developed on the basis of experimental data and the soundness and reliability of the model are proven by a statistical study that systematically evaluates the deviation of the model prediction from the test data.

Hippocampome.org 2.0 is a knowledge base enabling data-driven spiking neural network simulations of rodent hippocampal circuits.

Hippocampome.org is a mature open-access knowledge base of the rodent hippocampal formation focusing on neuron types and their properties. Previously, Hippocampome.org v1.0 established a foundational classification system identifying 122 hippocampal neuron types based on their axonal and dendritic morphologies, main neurotransmitter, membrane biophysics, and molecular expression (Wheeler et al., 2015). Releases v1.1 through v1.12 furthered the aggregation of literature-mined data, including among others neuron counts, spiking patterns, synaptic physiology, in vivo firing phases, and connection probabilities. Those additional properties increased the online information content of this public resource over 100-fold, enabling numerous independent discoveries by the scientific community. Hippocampome.org v2.0, introduced here, besides incorporating over 50 new neuron types, now recenters its focus on extending the functionality to build real-scale, biologically detailed, data-driven computational simulations. In all cases, the freely downloadable model parameters are directly linked to the specific peer-reviewed empirical evidence from which they were derived. Possible research applications include quantitative, multiscale analyses of circuit connectivity and spiking neural network simulations of activity dynamics. These advances can help generate precise, experimentally testable hypotheses and shed light on the neural mechanisms underlying associative memory and spatial navigation.

Hippocampome.org 2.0 is a knowledge base enabling data-driven spiking neural network simulations of rodent hippocampal circuits

Hippocampome.org is a mature open-access knowledge base of the rodent hippocampal formation focusing on neuron types and their properties. Previously, Hippocampome.org v1.0 established a foundational classification system identifying 122 hippocampal neuron types based on their axonal and dendritic morphologies, main neurotransmitter, membrane biophysics, and molecular expression (Wheeler et al., 2015). Releases v1.1 through v1.12 furthered the aggregation of literature-mined data, including among others neuron counts, spiking patterns, synaptic physiology, in vivo firing phases, and connection probabilities. Those additional properties increased the online information content of this public resource over 100-fold, enabling numerous independent discoveries by the scientific community. Hippocampome.org v2.0, introduced here, besides incorporating over 50 new neuron types, now recenters its focus on extending the functionality to build real-scale, biologically detailed, data-driven computational simulations. In all cases, the freely downloadable model parameters are directly linked to the specific peer-reviewed empirical evidence from which they were derived. Possible research applications include quantitative, multiscale analyses of circuit connectivity and spiking neural network simulations of activity dynamics. These advances can help generate precise, experimentally testable hypotheses and shed light on the neural mechanisms underlying associative memory and spatial navigation.

Water Reservoir Placement Methodology for Forest Firefighting: A Case Study of Valparaíso, Chile

Climate change has a significant impact on generating forest fires. These fires damage property, interrupt productive processes, reduce employment sources, and generate direct economic losses. Also, fires contribute to climate change, resulting in a negative cycle. Therefore, the effective management of forest fires is of vital importance. This research focuses on the combat and mitigation phase of forest fires, with special emphasis on using helicopters to transport water from nearby reservoirs to the fire site. The location of these reservoirs is key since a greater distance traveled by helicopter means a longer delay in water transport, which favors the spread of the fire. For this reason, this research proposes an optimization model to determine the optimal location of these reservoirs in a territory. The proposed model is illustrated with a case study of the region of Valparaiso, demonstrating its usefulness for management and decision making when locating reservoirs for firefighting.

Pathological neurons generate ripples at the UP-DOWN transition disrupting information transfer.

To confirm and investigate why pathological high-frequency oscillations (pHFOs), including ripples (80-200 Hz) and fast ripples (200-600 Hz), are generated during the UP-DOWN transition of the slow wave and if information transmission mediated by ripple temporal coupling is disrupted in the seizure-onset zone (SOZ). We isolated 217 total units from 175.95 intracranial electroencephalography (iEEG) contact-hours of synchronized macro- and microelectrode recordings from 6 patients. Sleep slow oscillation (.1-2 Hz) epochs were identified in the iEEG recording. iEEG HFOs that occurred superimposed on the slow wave were transformed to phasors and adjusted by the phase of maximum firing in nearby units (i.e., maximum UP). We tested whether, in the SOZ, HFOs and associated action potentials (APs) occur more often at the UP-DOWN transition. We also examined ripple temporal correlations using cross-correlograms. At the group level in the SOZ, HFO and HFO-associated AP probability was highest during the UP-DOWN transition of slow wave excitability (p < < .001). In the non-SOZ, HFO and HFO-associated AP was highest during the DOWN-UP transition (p < < .001). At the unit level in the SOZ, 15.6% and 20% of units exhibited more robust firing during ripples (Cohen's d = .11-.83) and fast ripples (d = .36-.90) at the UP-DOWN transition (p < .05 f.d.r. corrected), respectively. By comparison, also in the SOZ, 6.6% (d = .14-.30) and 8.5% (d = .33-.41) of units had significantly less firing during ripples and fast ripples at the UP-DOWN transition, respectively. Additional data shows that ripple and fast ripple temporal correlations, involving global slow waves, between the hippocampus, entorhinal cortex, and parahippocampal gyrus were reduced by >50% in the SOZ compared to the non-SOZ (N = 3). The UP-DOWN transition of slow wave excitability facilitates the activation of pathological neurons to generate pHFOs. Ripple temporal correlations across brain regions may be important in memory consolidation and are disrupted in the SOZ, perhaps by pHFO generation.

Phase Synchronization and Dynamic Behavior of a Novel Small Heterogeneous Coupled Network

Studying the firing dynamics and phase synchronization behavior of heterogeneous coupled networks helps us understand the mechanism of human brain activity. In this study, we propose a novel small heterogeneous coupled network in which the 2D Hopfield neural network (HNN) and the 2D Hindmarsh–Rose (HR) neuron are coupled through a locally active memristor. The simulation results show that the network exhibits complex dynamic behavior and is different from the usual phase synchronization. More specifically, the membrane potential of the 2D HR neuron exhibits five stable firing modes as the coupling parameter k1 changes. In addition, it is found that in the local region of k1, the number of spikes in bursting firing increases with the increase in k1. More interestingly, the network gradually changes from synchronous to asynchronous during the increase in the coupling parameter k1 but suddenly becomes synchronous around the coupling parameter k1 = 1.96. As far as we know, this abnormal synchronization behavior is different from the existing findings. This research is inspired by the fact that the episodic synchronous abnormal firing of excitatory neurons in the hippocampus of the brain can lead to diseases such as epilepsy. This helps us further understand the mechanism of brain activity and build bionic systems. Finally, we design the simulation circuit of the network and implement it on an STM32 microcontroller.

Using Randomization in Self-organized Synchronization for Wireless Networks

The concept of pulse-coupled oscillators for self-organized synchronization has been applied to wireless systems. Putting theory into practice, however, faces certain obstacles, particularly in radio technologies that cannot implement pulses but use common messages for interactions between nodes. This raises the question of how to deal with interference between messages. We show that interference can disturb the synchronization process and propose low-complex, randomization-based techniques to address this issue. First, we demonstrate that randomly switching between two transmit power levels (without increasing the average power) can expedite synchronization. The high-power transmissions temporarily boost network connectivity with negligible impact on the average interference. Second, we reduce interference by blindly distributing the messages over the entire oscillator cycle. Instead of using a fixed oscillator phase at which the pulses are sent, each node chooses its own, randomly selected phase to send a synchronization message. This node-specific “fire phase” is contained in the message to permit others to compute the timing. Third, we suggest that such interference management can also be beneficial for other synchronization techniques and validate this claim using Glossy as an example. Our insights may contribute to feasible solutions for self-organized wireless synchronization. Further work is needed to gain a comprehensive understanding of the effects of randomization and to develop algorithms for the adaptability of local parameters.

Defining the fire decay and the cooling phase of post-flashover compartment fires

The current research study discusses and characterises the fire decay and cooling phase of post-flashover compartment fires, as they are often mixed up despite their important heat transfer differences. The two phases are defined according to the fire heat release rate time-history. The fire decay represents the phase in which the fire heat release rate decreases from the ventilation- or fuel-limited steady-state value of the fully-developed phase to fire extinguishment. This phase is highly influenced by the fuel characteristics, ranging from fast decays for hydrocarbon and liquid fuels to slow decays for charring cellulosic fuels (wood). Once the fuel is consumed, the compartment volume enters the cooling phase, where the cooling in the gas-phase and solid-phase happens with significantly different modes and characteristic times. The thermal boundary conditions at the structural elements are then defined according to physical characteristics and dynamics within the compartment. The research study also underlines how the existing performance-based methodologies lack explicit definitions of the decay and cooling phases and the corresponding thermal boundary conditions for the design of fire-safe structural elements under realistic fire conditions.

Theta oscillations as a substrate for medial prefrontal-hippocampal assembly interactions

The execution of cognitive functions requires coordinated circuit activity across different brain areas that involves the associated firing of neuronal assemblies. Here, we tested the circuit mechanism behind assembly interactions between the hippocampus and the medial prefrontal cortex (mPFC) of adult rats by recording neuronal populations during a rule-switching task. We identified functionally coupled CA1-mPFC cells that synchronized their activity beyond that expected from common spatial coding or oscillatory firing. When such cell pairs fired together, the mPFC cell strongly phase locked to CA1 theta oscillations and maintained consistent theta firing phases, independent of the theta timing of their CA1 counterpart. These functionally connected CA1-mPFC cells formed interconnected assemblies. While firing together with their CA1 assembly partners, mPFC cells fired along specific theta sequences. Our results suggest that upregulated theta oscillatory firing of mPFC cells can signal transient interactions with specific CA1 assemblies, thus enabling distributed computations.

Numerical analysis of the effects of fire with cooling phase on reinforced concrete members

Fire exposed structures may collapse during or after the fire decay phase, with risks for building occupants and firefighters; yet, understanding of the effects of the fire decay phase on structural loadbearing capacity remains limited. This paper describes a numerical investigation on the behavior of reinforced concrete columns, beams, and walls under natural fires including cooling down phases. Finite element models are benchmarked against experiments capturing the behavior during heating. The models are then used to simulate the structural response of the concrete members under fires with various cooling rates and load ratios. The analyses capture the irreversibility of material properties through tracing of the temperature history in the structure. The results show that temperatures and deformations continue increasing after the end of the fire heating phase. As a result, concrete columns, beams, and walls may fail during the cooling phase. Faster cooling rates reduce the likelihood of failure in cooling. For beams, failure can be inferred from the maximum reinforcement temperature reached throughout the fire, but for columns and walls a thermal–mechanical analysis of the member throughout the fire history is needed. A relationship is proposed to evaluate the burnout resistance from the fire resistance rating and cooling rate. The presented numerical method allows assessing the structural stability throughout a fire event, an important requirement for designing a fire resilient built environment.

No evidence that acute clozapine administration alters CA1 phase precession in rats

Hippocampal phase precession, wherein there is a systematic shift in the phase of neural firing against the underlying theta activity, is proposed to play an important role in the sequencing of information in memory. Previous research shows that the starting phase of precession is more variable in rats following maternal immune activation (MIA), a known risk factor for schizophrenia. Since starting phase variability has the potential to disorganize the construction of sequences of information, we tested whether the atypical antipsychotic clozapine, which ameliorates some cognitive deficits in schizophrenia, alters this aspect of phase precession. Either saline or clozapine (5 mg/kg) was administered to rats and then CA1 place cell activity was recorded from the CA1 region of the hippocampus as the animals ran around a rectangular track for food reward. When compared to saline trials, acute administration of clozapine did not affect any place cell properties, including those related to phase precession, in either control or MIA animals. Clozapine did, however, produce a reduction in locomotion speed, indicating that its presence had some effect on behaviour. These results help to constrain explanations of phase precession mechanisms and their potential role in sequence learning deficits.

Investigation of Wastes Plastic and Glass to Enhance Physical - Mechanical Properties of Fired Clay Brick

Abstract Around the world, large amounts of plastic and glass waste have been collected. This work is given as a way to reduce this material. This paper aims to investigate how fired clay bricks' physical and mechanical properties are affected by plastic/glass (P/G) powder. It is used as a replacement for clay, varying the plastic/glass content 00/20, 05/15, 10/10, 15/05, and 20/00 weight %. The ratio of soil to water remains constant 0.3. The maximum temperature is presented after three fire phases. The temperatures are 300 °C for the first, 600 °C for the second, and 900 °C for the third. Results for the physical properties showed an increase in the water absorption of clay brick specimens as the plastic content increased; in addition, efflorescence was increased with plastic powder. However, the density and firing shrinkage decrease with plastic quantity. Also, the experimental results showed a decrease in water absorption and efflorescence when the glass powder was increased. While the density is higher when glass powder is 20 %. According to the findings on mechanical properties, clay brick samples with higher plastic powder content 20 % displayed a decrease in compressive strength and flexural bending strength, i. e. the mechanical properties (compressive and flexural strengths) are increased with the increased

Factors Affecting the Fire Safety Design of Photovoltaic Installations Under Performance-Based Regulations in Norway

The impact of Photovoltaic (PV) installations on the fire safety of buildings must be considered in all building projects where such energy systems are established. The holistic fire safety of the building largely depends on how the fire safety of the PV installation is considered by the different actors during the design and construction process. Research has therefore been undertaken to study how performance-based regulations in combination with the lack of national guidelines affect the overall fire safety considerations for PV installations in Norway. Four factors were found to govern to which extent PV installations are emphasised in the fire safety design phase: (1) whether the building was first of its kind as a pioneering building, (2) whether the building was built before or after the publication of the 2018 revision of the norm NEK 400, (3) The level of knowledge and experience of the fire safety consultant, which in turn affects the use of performance-based engineering tools and the level of detailing in the design and construction phases, and (4) The degree of integration in the building. The main goal of the study is to give an insight and a contribution to the development of in-depth knowledge on how fire safety design for PV installations on buildings is handled in Norway, which may also be relevant to other countries with similar performance-based regulations.

Car Fires in Multi-Story Parking Garages

Automated multi-story parking garages are modern alternatives to conventional parking structures to save space and volume in highly demanded parking regions in urban areas. The design of such structures has significant knowledge gaps in terms of fire safety. The purpose of this study is to estimate the horizontal and vertical fire spread between passenger cars in automated multi-story parking garages and provide fire safety design to minimize fire spread and possible structural collapse. The fire spread between cars is established by estimating irradiance heat flux of each car component. An 8-floor automated multi-story parking garage with 56 passenger car capacity is designed in accordance with European standards. The results show that steel parking pallets underneath cars reach extreme temperatures about 1000 ℃ in early phases of fire for Category III vehicle fire with 8 MW maximum heat release rate, which could cause structural failure. Without any fire protection on the structure, the fire spreads to the car above in 23 minutes, to the neighboring car in 37 minutes and beyond the elevator shaft to the other cars in 82 minutes. The proposed sprinkler layout eliminates fire spread within 5 minutes. The most efficient way of passive fire protection is to seal steel pallet, its rail system and beams on the elevator shaft with 5 cm gypsum-based fire protection boards.

Fine particulate matter and gas emissions at different burn phases from household coal-fired heating stoves

Household coal burning contributes a large proportion of fine particulate matter (PM2.5), black carbon (BC), organic carbon (OC), and CO emissions in China. Previous lab or field investigations generally measured short-term emissions from heating coal stoves, and only covered the high power phase or the flaming combustion processes, and did not consider smoldering combustion condition, which does not provide full characterization of the actual conditions in most cases. In this study, we investigated air pollutant emissions during the different burn phases of seven types of coal burned in a typical household coal-fired heating stove in the lab with a hood sampling system. We proposed a method to estimate coal consumption at the different burn phases, and thus quantify emission factors (EFs) at different burn phases. The concentrations of CO2, CO, SO2, NOx, and PM2.5 fluctuated over 1 to 4 orders of magnitude during the whole burn cycle. The air pollutant concentration peaks, such as CO and PM2.5, were generally associated with coal addition. EFs of CO2, SO2, total water soluble inorganic ions (TWSIIs) followed the trend: high power phase > low power phase > banked fire phase. However, CO EFs followed the opposite trend, i.e., banked fire phase > low power phase > high power phase. EFs of NOx and EC in high power phase and low power phase were higher than those in banked fire phase. The variation in EFs of PM2.5 and OC in different burn phases across seven types of coal burned in this study is complicated. When using EFs from high power phase or flaming phase to represent EFs from the whole process, CO2, SO2, NOx, EC and TWSIIs emissions will be overestimated, CO emissions will be underestimated, PM2.5 and OC emissions may be overestimated or underestimated, depending on coal types.

Comparative Effects of Domain-Specific Human Monoclonal Antibodies Against LGI1 on Neuronal Excitability.

Autoantibodies to leucine-rich glioma inactivated protein 1 (LGI1) cause an autoimmune limbic encephalitis with frequent focal seizures and anterograde memory dysfunction. LGI1 is a neuronal secreted linker protein with 2 functional domains: the leucine-rich repeat (LRR) and epitempin (EPTP) regions. LGI1 autoantibodies are known to interfere with presynaptic function and neuronal excitability; however, their epitope-specific mechanisms are incompletely understood. We used patient-derived monoclonal autoantibodies (mAbs), which target either LRR or EPTP domains of LGI1 to investigate long-term antibody-induced alteration of neuronal function. LRR- and EPTP-specific effects were evaluated by patch-clamp recordings in cultured hippocampal neurons and compared with biophysical neuron modeling. Kv1.1 channel clustering at the axon initial segment (AIS) was quantified by immunocytochemistry and structured illumination microscopy techniques. Both EPTP and LRR domain-specific mAbs decreased the latency of first somatic action potential firing. However, only the LRR-specific mAbs increased the number of action potential firing together with enhanced initial instantaneous frequency and promoted spike-frequency adaptation, which were less pronounced after the EPTP mAb. This also led to an effective reduction in the slope of ramp-like depolarization in the subthreshold response, suggesting Kv1 channel dysfunction. A biophysical model of a hippocampal neuron corroborated experimental results and suggests that an isolated reduction of the conductance of Kv1-mediated K+ currents largely accounts for the antibody-induced alterations in the initial firing phase and spike-frequency adaptation. Furthermore, Kv1.1 channel density was spatially redistributed from the distal toward the proximal site of AIS under LRR mAb treatment and, to a lesser extant, under EPTP mAb. These findings indicate an epitope-specific pathophysiology of LGI1 autoantibodies. The pronounced neuronal hyperexcitability and SFA together with dropped slope of ramp-like depolarization after LRR-targeted interference suggest disruption of LGI1-dependent clustering of K+ channel complexes. Moreover, considering the effective triggering of action potentials at the distal AIS, the altered spatial distribution of Kv1.1 channel density may contribute to these effects through impairing neuronal control of action potential initiation and synaptic integration.