Probabilistic Inverse Method for Source Localization Applied to ETEX and the 2017 Case of Ru-106 including Analyses of Sensitivity to Measurement Data

In recent years, cases of unexplained, elevated levels of radioactive particles have demonstrated an increasing need for efficient and robust source localization methods. In this study, a Bayesian method for source localization is developed and applied to two cases. First, the method is validated against the European tracer experiment (ETEX) and then applied to the still unaccounted for release of Ru-106 in the fall of 2017. The ETEX dataset, however, differs significantly from the Ru-106 dataset with regard to time resolution and the distance from the release site to the nearest measurements. Therefore, sensitivity analyses are conducted in order to test the method’s sensitivity to these parameters. The analyses show that the resulting source localization depends on both the observed temporal resolution and the existence of sampling stations close to the source. However, the method is robust, in the sense that reducing the amount of information in the dataset merely reduces the accuracy, and hence, none of the results are contradictory. When applied to the Ru-106 case, the results indicate that the Southern Ural region is the most plausible release area, and, as hypothesized by other studies, that the Mayak nuclear facility is the most likely release location.

Automated snow avalanche release area delineation in data sparse, remote, and forested regions

Potential avalanche release area (PRA) modelling is critical for generating automated avalanche terrain maps which provide low-cost large scale spatial representations of snow avalanche hazard for both infrastructure planning and recreational applications. Current methods are not applicable in mountainous terrain where high-resolution elevation models are unavailable and do not include an efficient method to account for avalanche release in forested terrain. This research focuses on expanding an existing PRA model to better incorporate forested terrain using satellite imagery and presents a novel approach for validating the model using local expertise, thereby broadening its application to numerous mountain ranges worldwide. The study area of this research is a remote portion of the Columbia Mountains in southeastern British Columbia, Canada which has no pre-existing high-resolution spatial data sets. Our research documents an open source workflow to generate high-resolution DEM and forest land cover data sets using optical satellite data processing. We validate the PRA model by collecting a polygon dataset of observed potential release areas from local guides, using a method which accounts for the uncertainty of human recollection and variability of avalanche release. The validation dataset allows us to perform a quantitative analysis of the PRA model accuracy and optimize the PRA model input parameters to the snowpack and terrain characteristics of our study area. Compared to the original PRA model our implementation of forested terrain and local optimization improved the percentage of validation polygons accurately modelled by 11.7 percentage points and reduced the number of validation polygons that were underestimated by 14.8 percentage points. Our methods demonstrate substantial improvement in the performance of the PRA model in forested terrain and provide means to generate the requisite input datasets and validation data to apply and evaluate the PRA model in vastly more mountainous regions worldwide than was previously possible.

Evaluation on Bali Mynah (Leucopsar rothschildi Stresemann, 1912) population, result of release process 1998-2015 in Bali Barat National Park, Indonesia

Hernowo JB, Haquesta S. 2021. Evaluation on Bali Mynah (Leucopsar rothschildi Stresemann, 1912) population, result of release process 1998-2015 in Bali Barat National Park, Indonesia. Biodiversitas 22: 2699-2710. The release of Bali Mynah (Leucopsar rothschildi Stresemann, 1912) is an attempt to return the bird population to its natural habitat to increase the number of Bali Mynah populations in nature. Bali Mynah population release results that can grow, but slow rate, so that indicates to review technical and management evaluation of Bali Mynah release. The study aims to evaluate the development of the population, the factors that affect population numbers and habitat for the results of releasing Bali Mynah, as well as the security factor. The research was conducted and focused on the Breeding Centre of Bali Mynah (BCBM) in Tegal Bunder, Teluk Brumbun, Teluk Kotal, Tanjung Gelap, and Pos Lampu Merah of Bali Barat National Park (BBNP), Indonesia from May to June 2015. The method of data collection is direct observation, measurement (population with concentration method), interview in relation to management of the bird, and literature. Data analysis was done by calculating the score of the assessment and the animal welfare. The result shows that the Bali Mynah population in Breeding Centre of Bali Mynah in Tegal Bunder has been categorized as good (analyzed from the animal welfare and assessment of the Bali Mynah with a score of 76.53 and 4.32 respectively). Bali Mynah population in the release area is well developed. The BM population has shown survival supported by an abundance of food and water availability, but the movement is still limited (500 m-1000 m) from the release areas.

Asynchronous glutamate exocytosis is enhanced in low release probability synapses and is widely dispersed across the active zone.

The balance between fast synchronous and delayed asynchronous release of neurotransmitters has a major role in defining computational properties of neuronal synapses and regulation of neuronal network activity. However, how it is tuned at the single synapse level remains poorly understood. Here, using the fluorescent glutamate sensor SF-iGluSnFR, we image quantal vesicular release in tens to hundreds of individual synaptic outputs from single pyramidal cells with 4 millisecond temporal and 75 nm spatial resolution. We find that the ratio between synchronous and asynchronous synaptic vesicle exocytosis varies extensively among synapses supplied by the same axon, and that and that synchronicity of release is reduced at low release probability synapses. We further demonstrate that asynchronous exocytosis sites are more widely distributed within the release area than synchronous sites. Together, our results reveal a universal relationship between the two major functional properties of synapses – the timing and the probability of neurotransmitter release.

The use of seismic ground particle motion for snow avalanche release area identification

<p>Knowledge of the snow avalanche release area is key information in snow avalanche studies. However, it is not easy to obtain from a remote location. The study of the seismic vibrations produced in the initial stages of the snow avalanche, makes possible to identify their origin and to link them to the starting area of the snow avalanche. We developed a methodology for this purpose, applied to seismic data acquired from a 3D seismic station (2Hz eigenfrequency) placed at Cavern A in Vallée de la Sionne experimental site (VDLS, WSL-SLF), deployed in 2013 by UB-RISKNAT. This is the closest position to the snow avalanche release areas, at 700 m to the farthest point. We focus on spontaneous triggered snow avalanches to achieve better signal-to-noise ratio and to be more realistic on its application.</p><p>For the isolation of the Signal Onset (SON) section of seismic data, which corresponds to those vibrations produced by the initial stage of the snow avalanche, we use the STA/LTA ratios and seismic signal amplitude, common methodologies in seismology. The STA/LTA is used for the identification of the first vibrations produced by the movement of the snow mass and the seismic signal amplitude thresholds for the identification of the end of the SON section -when the snow avalanche front reaches the seismic sensor position-. The 3D seismic data [ZNE components] of the SON section were processed in time windows. The study of polarization of the particle motion to obtain the direction of the back-azimuth of the signal (Vidale, 1986; Jurckevicks, 1988) was carried out for each time window of the seismic signal. The accumulation of back-azimuth directions for the entire SON section is related to the origin of the vibrations and, by extension, to the snow avalanche release area.</p><p>The entire algorithm has been automated. In its application on all the trigger activations at VDLS since 2015 until 2020, it was achieved a success rate of 78% on snow avalanche release area identification. In addition, we defined an algorithm based on STA/LTA ratio to select the snow avalanches from other seismic events, used with a success rate of 95%.</p><p>We present the application of our method in a case study, a large spontaneous snow avalanche released on 16th February 2018 at VDLS. The snow avalanche had two main release areas, clearly identified in photos of the site. The two developed fronts can be recognized in the seismic data. The directions to the release areas from Cavern A position can be identified using the presented method. Also, more interpretations can be done on the downhill snow avalanche path.</p>

Geospatial Analysis and Simulation of Glacial Avalanche Hazard in Hunza River Basin

Glacial avalanche hazard poses threat to human lives and damage settlements / infrastructures in alpine glaciers mountainous regions. A gigantic ice plus rock avalanche destroyed Gyari military camp in Siachen sector on April 2012 and buried 139 personals. The study focuses on geospatial analysis and simulation of Shishper glacial avalanche of Hunza basin. To simulate the potential glacial avalanche hazard to Hassan Abad settlements, an empirical process based Glacier Avalanche Model; Rapid Access Mass Movement Simulation (RAMMS) is utilized. The model encompasses avalanche release area and height for the execution of simulation. The model output of Shishper glacial avalanche resulted; a max pressure of 450 Kpa, max velocity of 40 m/s, and the max flow height of 80m, while the resulted surge extent output was 2500m. The potential hazardous Shishper glacial avalanche remains a continuous hazard to Hassan Abad of Hunza valley including Karakoram Highway and Frontier Works Organization (FWO) camp. The study has resulted in identifying the Upper Indus Bain (UIB) being more prone to glacial avalanche hazards because of host factors in general and the anthropogenic factor in particular.

Initiation and flow conditions of contemporary flows in Martian gullies

<p>Understanding the initial and flow conditions of contemporary flows in Martian gullies, generally believed to be triggered and fluidized by CO<sub>2</sub> sublimation, is crucial for deciphering climate conditions needed to trigger and sustain them. We employ the RAMMS (RApid Mass Movement Simulation) debris flow and avalanche model to back-calculate initial and flow conditions of recent flows in three gullies in Hale crater. We infer minimum release depths of 1.0–1.5 m and initial release volumes of 100–200 m<sup>3</sup>. Entrainment leads to final flow volumes that are 2.5–5.5 times larger than initially released, and entrainment is found necessary to match the observed flow deposits. Simulated mean cross-channel flow velocities decrease from 3–4 m s<sup>-1</sup> to ~1 m s<sup>-1</sup> from release area to flow terminus, while flow depths generally decrease from 0.5–1 m to 0.1–0.2 m. The mean cross-channel erosion depth and deposition thicknesses are _0.1–0.3 m. Back-calculated dry-Coulomb friction ranges from 0.1 to 0.25 and viscous turbulent friction between 100–200 m s<sup>-2</sup>, which are values similar to those of granular debris flows on Earth. These results suggest that recent flows in gullies are fluidized to a similar degree as are granular debris flows on Earth. Using a novel model for mass-flow fluidization by CO<sub>2</sub> sublimation we are able to show that under Martian atmospheric conditions very small volumetric fractions of CO<sub>2</sub> of ~1% within mass flows may indeed yield sufficiently large gas fluxes to cause fluidization and enhance flow mobility.</p>