Spatial Buffering Research Articles

Random forest and spatial cross-validation performance in predicting species abundance distributions

Random forests (RF) have been widely used to predict spatial variables. Several studies have shown that spatial cross-validation (CV) methods consistently cause RF to yield larger prediction errors compared to standard CV methods. This study examined the impact of species characteristics and data features on the performance of the standard RF and spatial CV approaches for predicting species abundance distribution. It compared the standard 5-fold CV, design-based validation, and three different spatial CV methods, such as spatial buffering, environmental blocking, and spatial blocking. Validation samples were randomly selected for design-based validation without replacement. We evaluated their predictive performance (accuracy and discrimination metrics) using artificial species abundance data generated by a linear function of a constant term (β0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta _0$$\\end{document}) and a random error term following a zero-mean Gaussian process with a covariance matrix determined by an exponential correlation function. The model was tuned over multiple simulations to consider different mean levels of species abundance, spatial autocorrelation variation, and species detection probability. Here we found that the standard RF had poor predictive performance when spatial autocorrelation was high and the species probability of detection was low. Design-based validation and standard K-fold CV were found to be the most effective strategies for evaluating RF performance compared to spatial CV methods, even in the presence of high spatial autocorrelation and imperfect detection for random samples. For weakly or moderately clustered samples, they yielded good modelling efficiency but overestimated RF’s predictive power, while they overestimated modelling efficiency, predictive power, and accuracy for strongly clustered samples with high spatial autocorrelation. Globally, the checkerboard pattern in the allocation of blocks to folds in blocked spatial CV was found to be the most effective CV approach for clustered samples, whatever the degree of clustering, spatial autocorrelation, or species abundance class. The checkerboard pattern in spatial CV was found to be the best method for random or systematic samples with spatial autocorrelation, but less effective than non-spatial CV approaches. Failing to take data features into account when validating models can lead to unrealistic predictions of species abundance and related parameters and, therefore, incorrect interpretations of patterns and conclusions. Further research should explore the benefits of using blocked spatial K-fold CV with checkerboard assignment of blocks to folds for clustered samples with high spatial autocorrelation.

Revisiting the 2023 wildfire season in Canada

The area burned by wildfires in Canada in 2023 is unprecedented in historical records. To help ensure the safety of communities and support the mobilization of firefighting resources, rapid detection of areas affected by wildfires is required. Satellite data are ideally suited to provide near real-time wildfire information over large areas. At the same time, clouds, smoke, and haze can obscure the collection of observations from sensors typically used for mapping purposes. Established methods using coarse spatial resolution satellites (e.g., MODIS, VIIRS) rely upon the combination of daily revisit to enable the rapid and reliable detection of large active fires, in full or in part, and the application of modeling (including spatial buffering) to infer additional, yet still obscured, areas. While timely, these initial maps of wildfire-impacted areas do not capture small fires (those smaller than 200 ha) and, importantly, are not intended to differentiate unburned areas within fire perimeters. To address these limitations, we used data from Sentinel-2A and -2B, and Landsat-8 and -9, which form a virtual constellation of four satellites to revisit and map burned area in Canada's forested ecosystems for the 2023 fire season. Availing upon the high temporal data density and using the Tracking Intra- and Inter-year Change algorithm (TIIC), an aggregate seasonal mapping of wildfires resulted in a total area affected by wildfires in 2023 of 12.74 Mha. Within this total area, 9.51 Mha of treed land cover was impacted. Shrubs and wetlands comprised most of the remaining non-treed area that was burned. Using a 2022 map of aboveground treed biomass (AGB), approximately 0.649 Pg of AGB was impacted by 2023 wildfires, representing an 11-fold increase in AGB impacts relative to a long-term annual average of treed AGB loss. Differences between the estimate of total burned area reported herein and the total burned area indicated by the Natural Resources Canada (NRCan) Fire M3 hotspot fire perimeters (18.64 Mha) were analyzed. Overall, estimates of burned area differed by 5.9 Mha, including over 1.13 Mha of water identified as burned within the NRCan perimeters. Differences in land cover and AGB impacts between the two products were also investigated and quantified. TIIC enables the near-continuous capture of areas impacted by fire through the fire season, allowing for within-year refinement of total burned area, rapid interrogation of land cover types impacted, and estimation of associated biomass consequences.

Spatial Analysis of Environmental Factors in the Dengue Hemorrhagic Fever Incident at Soe City District

Introduction: In 2022, there was a large increase in cases resulting in extraordinary events cases in the TTS district with the number 226 cases. Half of the percentage of outbreak cases that occurred in Soe City with a number of cases is 134 cases. Spatial analysis can be used to see patterns of disease distribution in certain areas.Methods: This research is a type of descriptive research with a case study approach. This descriptive research was carried out using a survey method where there was no intervention on variables but simply observing natural phenomena or looking for relationships between these phenomena and other variables.Results: The research of dengue case data is divided into univariate analysis and spatial analysis, for example, classification, buffering and Moran index. Environmental factors in the form of the existence and condition of water reservoirs with dengue fever incidents can be seen in data related to the number of water reservoirs used by the community which are left open and the number is >3, making it easier for mosquitoes to breed. In the Spatial Classification Analysis, Nonohonis Village has the highest level of risk, but Autocorrelation Analysis states that the Oekefan area has larger cluster points than Nonohonis Village. Furthermore, environmental factors include the existence and condition of dug wells. at a depth of ≤15m with open conditions makes it easier for mosquitoes to breed. Apart from that, based on the buffer data above, it can be seen that at a radius of <100m it is 3 times larger than a radius of 100 to 300m and 2.7 times larger than a radius of 300m to 500m. Environmental factors include the existence and condition of waste water drainage channels (SPAL) with dengue fever incidents. Based on the buffer data above, it can be seen that at a radius of <100m it is 0.6 times greater than the radius from 100 to 300m and 0.8 times greater than the radius from 300m to 500m.Conclusion: It is necessary to control mosquito breeding in water reservoirs and dug wells through education regarding malaria risk factors in Soe City.

Mathematical Psychiatry: On Cortical Spreading Depression-A Review.

The concept of migraine with aura (MwA) is a widespread condition that can affect up to 30% of migraine patients and manifests itself as a temporary visual illusion followed by a prolonged headache. It was initially pitched as a neurological disease, and observed that the spread of accompanying electrophysiological waves as part of the condition, which came to be known as cortical spreading depression (CSD). A strong theoretical basis for a link between MwA and CSD has eventually led to knowledge of the dynamics between the pair. In addition to experiment-based observations, mathematical models make an important contribution towards a numerical means of expressing codependent neural-scale manifestations. This provides alternate means of understanding and observing the phenomena while helping to visualize the links between the variables and their magnitude in contributing towards the emanation and dynamic pulsing of the condition. A number of biophysical mechanisms are believed to contribute to the MwA-CSD, spanning ion diffusion, ionic currents of membranes, osmosis, spatial buffering, neurotransmission, gap junctions, metabolic pumping, and synapse connections. As part of this review study, the various mathematical models for the description of the condition are expressed, reviewed, and contrasted, all of which vary in their depth, perspective, and level of information presented. Subsequent to this, the review looked into links between electrophysiological data-driven manifestations from measurements such as EEG and fMRI. While concluding remarks forged a structured pathway in the area on sub-themes that need to be investigated in order to strengthen and robustify the existing models, they include an accounting for inter-personal variability in models, sex and hormonal factors, and age groups, i.e., pediatrics vs. adults.

Phosphorus Spatial Variation and Environmental Buffering Capacity of Mountainous River Bars

Phosphorus Spatial Variation and Environmental Buffering Capacity of Mountainous River Bars

Oxidative stress targets Kir2.1 channel in a model of aging neuroglia

Oxidative stress (OS) has a main role in the pathogenesis of central nervous system disorders. In this regard, epilepsy is a highly prevalent serious brain disease and its prevalence increases with age. Strikingly, about 50% of all epilepsy cases diagnosed in elderly patients (>65 years) are idiopathic. Metabolic changes, including the production of reactive oxygen species (ROS), are regarded to as possible mechanism involved in epileptogenesis. The neuronal glia plays a crucial role in epilepsy by controlling neuronal hyperexcitability. One of the key roles of glial cells is the spatial buffering of extracellular K+ ions that are released by excited neurons and transported through glial inwardly rectifying potassium (Kir) channels from extracellular regions of high K+ to those of low K+ to inhibit epileptogenesis. Among experimental OS‐related aging models, long‐term (24 hours) exposure to D‐Galactose (D‐Gal, 100 mM) is considered the most similar to natural aging. In the present study, we investigated the effect of D‐Gal‐induced aging on Kir channel activity in glioblastoma U87‐MG cells. Screening of all fifteen Kir isoforms revealed that the predominant transcript corresponds to Kir2.1, with minor contribution of Kir4.1. D‐Galactose had no obvious cytotoxicity, but strongly promoted OS, namely increased lipoperoxidation levels and decreased the membrane protein sulfhydryl group abundance. Interestingly, D‐Gal exposure was associated with a decrease of inwardly rectifying K+ currents sensitive to ML‐133, a specific inhibitor of Kir2.1 channels. Our findings reveal a novel Kir2.1 channel modulation that is likely to occur in OS. We suggest that inhibition of Kir2.1 channels in glia cells may alter extracellular K+ buffering and contribute to OS‐related neuronal hyperexcitability and epileptogenesis during aging.

A cloud-based toolbox for the versatile environmental annotation of biodiversity data.

A vast range of research applications in biodiversity sciences requires integrating primary species, genetic, or ecosystem data with other environmental data. This integration requires a consideration of the spatial and temporal scale appropriate for the data and processes in question. But a versatile and scale flexible environmental annotation of biodiversity data remains constrained by technical hurdles. Existing tools have streamlined the intersection of occurrence records with gridded environmental data but have remained limited in their ability to address a range of spatial and temporal grains, especially for large datasets. We present the Spatiotemporal Observation Annotation Tool (STOAT), a cloud-based toolbox for flexible biodiversity-environment annotations. STOAT is optimized for large biodiversity datasets and allows user-specified spatial and temporal resolution and buffering in support of environmental characterizations that account for the uncertainty and scale of data and of relevant processes. The tool offers these services for a growing set of near global, remotely sensed, or modeled environmental data, including Landsat, MODIS, EarthEnv, and CHELSA. STOAT includes a user-friendly, web-based dashboard that provides tools for annotation task management and result visualization, linked to Map of Life, and a dedicated R package (rstoat) for programmatic access. We demonstrate STOAT functionality with several examples that illustrate phenological variation and spatial and temporal scale dependence of environmental characteristics of birds at a continental scale. We expect STOAT to facilitate broader exploration and assessment of the scale dependence of observations and processes in ecology.

General Synthesis of Multiple‐Cores@Multiple‐Shells Hollow Composites and Their Application to Lithium‐Ion Batteries

AbstractRational nanostructure design has proved fruitful in addressing the bottlenecks of diverse fields. Especially hollow multi‐shelled structures (HoMS) have stood out due to their temporal–spatial ordering mass transfer and buffering effect. Localizing multiple cores in a HoMS is highly desired, which could endow it with more fascinating properties. However, such a structure has been barely reported due to the highly challenging fabrication. Here, we develop a controllable synthesis strategy to realize such a structure, which is applicable for diverse cores and shells. Additionally, cores and shells could be tuned to be homogeneous or heterogeneous, with the core and shell number well controlled. In situ TEM analysis verifies that the inner shell confines the expansion orientation of cores, while the outer shell maintains a stable interface. In addition to energy storage, such structure is also promising for multi‐drug co‐delivery and sequential responsive release as well as tandem catalysis applications.

A tridomain model for potassium clearance in optic nerve of Necturus

Complex fluids flow in complex ways in complex structures. Transport of water and various organic and inorganic molecules in the central nervous system are important in a wide range of biological and medical processes. However, the exact driving mechanisms are often not known. In this work, we investigate flows induced by action potentials in an optic nerve as a prototype of the central nervous system. Different from traditional fluid dynamics problems, flows in biological tissues such as the central nervous system are coupled with ion transport. They are driven by osmosis created by concentration gradient of ionic solutions, which in turn influence the transport of ions. Our mathematical model is based on the known structural and biophysical properties of the experimental system used by the Harvard group Orkand et al. Asymptotic analysis and numerical computation show the significant role of water in convective ion transport. The full model (including water) and the electrodiffusion model (excluding water) are compared in detail to reveal an interesting interplay between water and ion transport. In the full model, convection due to water flow dominates inside the glial domain. This water flow in the glia contributes significantly to the spatial buffering of potassium in the extracellular space. Convection in the extracellular domain does not contribute significantly to spatial buffering. Electrodiffusion is the dominant mechanism for flows confined to the extracellular domain.

Study Of The Making Of Land Value Zone Map Based On The Market Price To Update Land Value In Central Government Areas ( Case Study: Mejayan Sub-District, Madiun Regency)

Based on Government Regulation number 3 of 2019 concerning an amendment to regulation number 52 of 2010, the Government of Madiun Regency relocates of the capital city of Madiun Regency from the Madiun City area to Caruban City located in the Mejayan SubDistrict. With the relocation of the capital city of Madiun Regency in the Mejayan Sub-District, the region is increasingly strategic with developments. Development in this region, triggering influence on changes in land values. This study aims to make of land value zone map in the Mejayan Sub-District, to update land value information in Mejayan Sub-District using a comparative market approach and the final process of this study to analyze the effect of distance of public facilities on land values in the sorrounding area, using spatial buffering analysis. The results show that the highest average indication value (NIR) in the C4 zone is IDR 3.597.668 / m2 and the lowest average indication value (NIR) in the A8 zone is IDR 134.950 / m2 and Spatial buffering analysis on land value zone map, The results showed that the zone located at a radius of 1 kilometer from public facilities, namely the Central Government Office Area of Madiun Regency and the Caruban Railway Station had higher land values than the zone within a radius of 2 kilometers and a radius of 3 kilometers. As for the results of spatial buffering from the Gemblung Traditional Market, it appears that the zone located at a radius of 3 kilometers from the market results has a higher land value than the zone within a radius of 1 kilometer and a radius of 2 kilometers because at a radius of 3 kilometers it has better accessibility. Other factors that affect land value are accessibility, land position, and type of land use.

Optic nerve microcirculation: Fluid flow and electrodiffusion

Complex fluids flow in complex ways in complex structures. Transport of water and various organic and inorganic molecules in the central nervous system (CNS) are important in a wide range of biological and medical processes [C. Nicholson and S. Hrabětová, “Brain extracellular space: The final frontier of neuroscience,” Biophys. J. 113(10), 2133 (2017)]. However, the exact driving mechanisms are often not known. In this paper, we investigate flows induced by action potentials in an optic nerve as a prototype of the CNS. Different from traditional fluid dynamics problems, flows in biological tissues such as the CNS are coupled with ion transport. It is driven by osmosis created by the concentration gradient of ionic solutions, which in turn influence the transport of ions. Our mathematical model is based on the known structural and biophysical properties of the experimental system used by the Harvard group [R. K. Orkand, J. G. Nicholls, and S. W. Kuffler, “Effect of nerve impulses on the membrane potential of glial cells in the central nervous system of amphibia,” J. Neurophysiol. 29(4), 788 (1966)]. Asymptotic analysis and numerical computation show the significant role of water in convective ion transport. The full model (including water) and the electrodiffusion model (excluding water) are compared in detail to reveal an interesting interplay between water and ion transport. In the full model, convection due to water flow dominates inside the glial domain. This water flow in the glia contributes significantly to the spatial buffering of potassium in the extracellular space. Convection in the extracellular domain does not contribute significantly to spatial buffering. Electrodiffusion is the dominant mechanism for flows confined to the extracellular domain.

Neuromodulation of Astrocytic K+ Clearance.

Potassium homeostasis is fundamental for brain function. Therefore, effective removal of excessive K+ from the synaptic cleft during neuronal activity is paramount. Astrocytes play a key role in K+ clearance from the extracellular milieu using various mechanisms, including uptake via Kir channels and the Na+-K+ ATPase, and spatial buffering through the astrocytic gap-junction coupled network. Recently we showed that alterations in the concentrations of extracellular potassium ([K+]o) or impairments of the astrocytic clearance mechanism affect the resonance and oscillatory behavior of both the individual and networks of neurons. These results indicate that astrocytes have the potential to modulate neuronal network activity, however, the cellular effectors that may affect the astrocytic K+ clearance process are still unknown. In this study, we have investigated the impact of neuromodulators, which are known to mediate changes in network oscillatory behavior, on the astrocytic clearance process. Our results suggest that while some neuromodulators (5-HT; NA) might affect astrocytic spatial buffering via gap-junctions, others (DA; Histamine) primarily affect the uptake mechanism via Kir channels. These results suggest that neuromodulators can affect network oscillatory activity through parallel activation of both neurons and astrocytes, establishing a synergistic mechanism to maximize the synchronous network activity.

Neocortical in vivo focal and spreading potassium responses and the influence of astrocytic gap junctional coupling

Raised extracellular potassium ion (K+) concentration is associated with several disorders including migraine, stroke, neurotrauma and epilepsy. K+ spatial buffering is a well-known mechanism for extracellular K+ regulation/distribution. Astrocytic gap junction-mediated buffering is a controversial candidate for K+ spatial buffering. To further investigate the existence of a K+ spatial buffering and to assess the involvement of astrocytic gap junctional coupling in K+ redistribution, we hypothesized that neocortical K+ and concomitant spreading depolarization (SD)-like responses are controlled by powerful local K+ buffering mechanisms and that K+ buffering/redistribution occurs partially through gap junctional coupling. Herein, we show, in vivo, that a threshold amount of focally applied KCl is required to trigger local and/or distal K+ responses, accompanied by a SD-like response. This observation indicates the presence of powerful local K+ buffering which mediates a rapid return of extracellular K+ to the baseline. Application of gap junctional blockers, carbenoxolone and Gap27, partially modulated the amplitude and shape of the K+ response and noticeably decreased the velocity of the spreading K+ and SD-like responses. Opening of gap junctions by trimethylamine, slightly decreased the amplitude of the K+ response and markedly increased the velocity of redistribution of K+ and SD-like events. We conclude that spreading K+ responses reflect powerful local K+ buffering mechanisms which are partially modulated by gap junctional communication. Gap junctional coupling mainly affected the velocity of the K+ and SD-like responses.

Validation of presence-only models for conservation planning and the application to whales in a multiple-use marine park.

Identification of species’ Biologically Important Areas (BIAs) is fundamental to conservation planning and species distribution models (SDMs) are a powerful tool commonly used to do this. Presence‐only data are increasingly being used to develop SDMs to aid the conservation decision‐making process. The application of presence‐only SDMs for marine species’ is particularly attractive due to often logistical and economic costs of obtaining systematic species’ distribution data. However, robust model validation is important for conservation management applications that require accurate and reliable species’ occurrence data (e.g., spatially explicit risk assessments). This is commonly done using a random subset of the data and less commonly with fully independent test data. Here, we apply a spatial block cross‐validation (CV) approach to validate a MaxEnt presence‐only model using independent presence/absence survey data for a highly mobile, marine species (humpback whale, Megaptera novaengliae) in the Great Barrier Reef (GBR). A MaxEnt model was developed using opportunistic whale sightings (2003–2007) and then used to identify areas differing in habitat suitability (low, medium, high) to conduct a systematic, line‐transect, aerial survey (2012) and derive a density surface model. A spatial block CV buffering strategy was used to validate the MaxEnt model, using the opportunistic sightings as training data and independent aerial survey sightings data as test data. Moderate performance measures indicate MaxEnt was reliable in identifying the distribution patterns of a mobile whale species on their breeding ground, indicated by areas of high density aligned to areas of high habitat suitability. Furthermore, we demonstrate that MaxEnt models can be useful and cost‐effective for designing a sampling scheme to undertake systematic surveys that significantly reduces sampling effort. In this study, higher quality information on whale reproductive class (calf vs. non‐calf groups) was obtained that the presence‐only data lacked, while sampling only 18% of the GBR World Heritage Area. The validation approach using fully independent data provides greater confidence in the MaxEnt model, which indicates significant overlap with the main breeding ground of humpback whales and the inner shipping route. This is important when evaluating presence‐only models within certain conservation management applications, such as spatial risk assessments.

Kir4.1 RNA Interference by In Utero Electroporation Fails to Affect Ictogenesis and Reveals a Possible role of Kir4.1 in Corticogenesis

Astrocyte dysfunction, and in particular impaired extracellular potassium spatial buffering, has been postulated to have a potential role in seizure susceptibility and ictogenesis. Inwardly rectifying potassium (Kir) channels, and specifically KIR4.1, have a predominant role in K+ homeostasis and their involvement in neuronal excitability control have been hypothesized. To avoid the severe side effects observed in Kir4.1 cKO, we studied the effects of Kir4.1 down-regulation in cortical astrocytes by using Kir4.1 RNA interference (RNAi) technique combined with in utero electroporation (IUE) at E16 and a piggyBac transposon system. Kir4.1 down-regulation was confirmed by immunohistochemistry and field fraction analysis. To investigate if Kir4.1 silencing affects 4AP–induced seizure threshold and extracellular potassium homeostasis, simultaneous in vitro field potential and extracellular K+ recordings were performed on somatosensory cortex slices obtained from rats electroporated with a piggyBac-Kir4.1-shRNA (Kir4.1−) and scrambled shRNA (Kir4.1Sc). Electrophysiological data revealed no significant differences in terms of seizure onset and seizure-induced extracellular K+ changes between Kir4.1− and Kir4.1Sc rats. Intriguingly, immunohistochemical analysis performed on slices studied with electrophysiology revealed a reduced number of neurons generated from radial glial cells in Kir4.1− rats.We conclude that focal down-regulation of Kir4.1 channel in cortical astrocytes by Kir4.1 RNAi technique combined with IUE is not effective in altering potassium homeostasis and seizure susceptibility. This technique revealed a possible role of Kir4.1 during corticogenesis.

Model of Efficient Buildings on Electrical Consumption towards Location in Simpang Lima Commercial Cluster

Compact city emerged as one of the concepts that opposed the concept of urban sprawl. Its primary objective relied on the greater densification of spatial use under the term called mix land-use to reduce energy consumption on mobility. Our article intended to delve into a study which relates electricity to Compact city. The focus is to quantitatively analyze the interdependence between Compact city and electricity efficiencies. Simpang Lima central business district (CBD) in Semarang city constituted the field study. This article employs positivistic approach that consists of cross-analyzing GIS-Nearest Neighbor analysis dedicated for spatial buffering analysis and ETAP technique devoted to calculating energy losses within the CBD cluster. Our findings imply such a primary hypothesis that the distribution of the buildings on a cluster thatcovered by the electricity supply from central substation positively affected the distribution efficiencies. A group of commercial building with minimum distance of 129.49 m among them in a cluster of 1,424.6 Ha poses an ability to save more than 0, 293%(11.411/Kwh) compared to another cluster. Thus, this research is a preliminary discussion that aims at enriching Compact city discussion by bringing forth the electricity sector as a considerable aspect.

Differential migration in Chesapeake Bay striped bass.

Differential migration—increased migration propensity with increasing individual size—is common in migratory species. Like other forms of partial migration, it provides spatial buffering against regional differences in habitat quality and sources of mortality. We investigated differential migration and its consequences to survival and reproductive patterns in striped bass, a species with well-known plasticity in migration behaviors. A size-stratified sample of Potomac River (Chesapeake Bay) Morone saxatilis striped bass was implanted with acoustic transmitters and their subsequent coastal shelf migrations recorded over a 4-yr period by telemetry receivers throughout the Mid-Atlantic Bight and Southern New England. A generalized linear mixed model predicted that ≥ 50% of both males and females depart the Chesapeake Bay at large sizes >80 cm total length. Egressing striped bass exited through both the Chesapeake Bay mouth and Delaware Bay (via the Chesapeake and Delaware Canal), favoring the former. All large fish migrated to Massachusetts shelf waters and in subsequent years repeatedly returned to regions within Massachusetts and Cape Cod Bays. Within this dominant behavior, minority behaviors included straying, skipped spawning, and residency by large individuals (those expected to migrate). Analysis of the last day of transmission indicated that small resident striped bass experienced nearly 2-fold higher loss rates (70% yr-1) than coastal shelf emigrants (37% yr-1). The study confirmed expectations for a threshold size at emigration and different mortality levels between Chesapeake Bay (resident) and ocean (migratory) population contingents; and supported the central premise of the current assessment and management framework of a two-contingent population: smaller Chesapeake Bay residents and a larger ocean contingent. An improved understanding of differential migration thus affords an opportunity to specify stock assessments according to different population sub-components, and tailor reference points and control rules between regions and fishing stakeholder groups.

BUFFER ANALYSIS OF THE REACH OF PASSPORT ISSUING SERVICES USING GEOGRAPHIC INFORMATION SYSTEM (GIS) APPLICATIONS (CASE STUDY OF YOUR KUALANAN PASSPORT SERVICE UNIT)


 
 The government organizes public services in the immigration sector in terms of issuing passports through the Directorate General of Immigration which has the responsibility of carrying out immigration functions and determining service standards for each Technical Service Unit owned. In providing public services, the TPI Medan Special Class I Immigration Office is responsible for four districts and two cities covering Langkat Regency, Deli Serdang Regency, Serdang Bedagai Regency, Karo Regency, Medan City and Binjai City. With a large enough working area, it is necessary to establish an Office Work Unit or Passport Service Unit as an effective and efficient way to carry out immigration functions and to bring services closer to the public.
 The establishment of an Office Work Unit (UKK) and a Passport Service Unit (ULP) based on the workload of the Technical Implementing Unit is very broad so it is necessary to establish an Office Work Unit and Passport Service Unit to optimize immigration functions to the community. The aim is that every community can get the fulfillment of service needs in accordance with the laws and regulations governing the delivery of public services. In the framework of establishing an Office Work Unit (UKK) and Passport Service Unit (ULP), it is necessary to determine a strategic location and can be reached by the community so that it can achieve its maximum function.
 The Kualanamu Passport Service Unit is located in the Kualanamu Airport area, which is located in Beringin District. Therefore, this study aims to analyze strategic locations in determining the location of ULPs. In order to analyze the location and range of services, a spatial buffering analysis was carried out as well as theories that were considered relevant, such as the theory of Von Thunen, Weber and Christaller. From the spatial analysis process carried out, it can be seen that a strategic location in the formation of ULPs so that the range of services provided can meet the needs of the community.
 
 

Molecular mechanisms of K+ clearance and extracellular space shrinkage-Glia cells as the stars.

Neuronal signaling in the central nervous system (CNS) associates with release of K+ into the extracellular space resulting in transient increases in [K+ ]o . This elevated K+ is swiftly removed, in part, via uptake by neighboring glia cells. This process occurs in parallel to the [K+ ]o elevation and glia cells thus act as K+ sinks during the neuronal activity, while releasing it at the termination of the pulse. The molecular transport mechanisms governing this glial K+ absorption remain a point of debate. Passive distribution of K+ via Kir4.1-mediated spatial buffering of K+ has become a favorite within the glial field, although evidence for a quantitatively significant contribution from this ion channel to K+ clearance from the extracellular space is sparse. The Na+ /K+ -ATPase, but not the Na+ /K+ /Cl- cotransporter, NKCC1, shapes the activity-evoked K+ transient. The different isoform combinations of the Na+ /K+ -ATPase expressed in glia cells and neurons display different kinetic characteristics and are thereby distinctly geared toward their temporal and quantitative contribution to K+ clearance. The glia cell swelling occurring with the K+ transient was long assumed to be directly associated with K+ uptake and/or AQP4, although accumulating evidence suggests that they are not. Rather, activation of bicarbonate- and lactate transporters appear to lead to glial cell swelling via the activity-evoked alkaline transient, K+ -mediated glial depolarization, and metabolic demand. This review covers evidence, or lack thereof, accumulated over the last half century on the molecular mechanisms supporting activity-evoked K+ and extracellular space dynamics.

Abstract 2670: Spatial potassium buffering among clustered glioblastoma cells is proposed to enable survival scavenging of nutrients released by interior necrotic cells

Abstract Glioblastoma cells are known for surviving harsh environments and for forming secondary structures of Scherer (cell clusters around neurons/axons, blood vessels, regions of coagulative necrosis, & in the subpia). The astrocytic lineage of glioblastomas suggests recapitulation of astrocytic-type syncytia that buffer potassium released from neurons/axons. Here, multiple glioblastoma cell lines were stressed by nutrient withdrawal to observe cell behavior in view of their astrocytic lineage & known genome sequence of 1 cell line. Methods: Single cell suspensions of 4 glioblastoma cell lines (U87, LN229, T98G & A172) were added to a settling chamber (Neuro Probe, Gaithersburg, MD). After 0.5 hr of gradual nutrient withdrawal, slides (Diff Quik stain) were analyzed, 2 replicate wells per cell line. U87 cells with cytoplasmic vacuoles were quantified to indicate the degeneration in cell clusters. When vacuoles collectively had a diameter at least 1/3 of an ave. nuclear diameter in the same 100X microscopic field, the vacuolated cell was deemed +. Potassium ion channel genes potentially used by glioblastoma cells per the Online Mendelian Inheritance in Man (OMIM) database were checked in genome sequence results for U87 cells (Clark MJ, et al. PLoS Genet 2010 6(1): e10000832). Results: All glioblastoma cell lines displayed cell adherence & wrapping around single swollen, often heavily vacuolated degenerating cells of the same lineage after nutrient withdrawal. As clustered U87 cells (putative syncytia) increased in cell number, the number of constituent cells with vacuoles decreased (Pearson regressions, p=.04, p=.006) in 2 replicate wells. Whereas single cells were +, 72% and 51%, vacuolated cells fell to 18% and 11% in putative syncytia of over 20 cells in 100X microscopic fields across the width (7 mm) of each well. Thus, within increasing-sized putative syncytia, which offer increasing potassium buffering capacity, significantly fewer constituent cells displayed vacuoles. Presumably this was due to available nutrients from one to few necrotic cells in their midst during nutrient withdrawal. Potassium ion channeling within astrocytic-type syncytia, termed "spatial buffering" explains how viable glioblastoma cells adhere to degenerating cells despite high potassium levels. Genome sequencing of U87 cells revealed that only KCNMB2 & KCNJ16 of 47 potassium channeling genes pertinent to brain, were negatively affected by genetic defects. Functional losses of KCNMB2 as an enhancer for KCNMA1 (intact), and KCNJ16 as a co-assembler with other family members (intact), are unlikely to prevent potassium buffering. Preservation of nearly all potassium channeling genes in U87 suggests that maintenance of spatial buffering in astrocytic-type syncytia permits viable cells to surround necrotic cells and salvage released nutrients as a survival strategy. Citation Format: Marie Beckner. Spatial potassium buffering among clustered glioblastoma cells is proposed to enable survival scavenging of nutrients released by interior necrotic cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2670.