Universality classes in directed sandpile models

We perform large scale numerical simulations of a directed version of the two-state stochastic sandpile model. Numerical results show that this stochastic model defines a new universality class with respect to the Abelian directed sandpile. The physical origin of the different critical behavior has to be ascribed to the presence of multiple topplings in the stochastic model. These results provide new insights onto the long debated question of universality in abelian and stochastic sandpiles.Comment: 5 pages, RevTex, includes 9 EPS figures. Minor english corrections. One reference adde

Developing a Community Innovation Grant in Response to Increasing Rural Critical Incidents in Agricultural Mental Health and Wellbeing, Community Trauma, and Natural Disasters

Spink Area Support Network (SASN) is a skilled team of community volunteers that facilitate rural critical incident response services in an effort to prevent a critical incident and offer structured support during the aftermath. SASN was developed in response to identified gaps in rural critical incident response and risk reduction through prevention in Spink County, South Dakota. SASN utilizes a collaborative team approach to fill in gaps between first responder silos and establish community interventions by providing support and resources while utilizing critical incident stress management methods. SASN requires funding to maintain response resources, training, prevention education, and follow-up services. The capstone project will produce the requirements to apply for the Bush Foundation Community Innovation Grant as a partnership and funding source. The grant requires a strategic plan, needs assessment, data collection, evaluation, and sustainability plan. Some of the footwork such as the stakeholder engagement, board, strategic plan, and needs assessment was established in the pilot year, 2019-2020. The results analysis indicates the need for a network of skilled volunteers to mobilize during events of agricultural mental health and wellbeing crises, community trauma, and natural disasters. The subsequent data that was collected for this grant had similar findings with a special focus on COVID-19 response. Resources that were developed from the current analysis are an area resource directory, crisis and COVID-19 prevention resources, and the SASN Critical Response Team (SASN CRT) manual. With these resources and the strategic plan in place the grant was submitted with all requirements and awaiting award notice. Rural, frontier populations in South Dakota will benefit from grant funding for SASN to increase efficacy of rural critical incident response

The Effects of Weather on the Life Time of Wireless Sensor Networks Using FSO/RF Communication

The increased interest in long lasting wireless sensor networks motivates to use Free Space Optics (FSO) link along with radio frequency (RF) link for communication. Earlier results show that RF/FSO wireless sensor networks have life time twice as long as RF only wireless sensor networks. However, for terrestrial applications, the effect of weather conditions such as fog, rain or snow on optical wireless communication link is major concern, that should be taken into account in the performance analysis. In this paper, life time performance of hybrid wireless sensor networks is compared to wireless sensor networks using RF only for terrestrial applications and weather effects of fog, rain and snow. The results show that combined hybrid network with three threshold scheme can provide efficient power consumption of 6548 seconds, 2118 seconds and 360 seconds for measured fog, snow and rain events respectively resulting in approximately twice of the life time with only RF link

Corrections to scaling in the forest-fire model

We present a systematic study of corrections to scaling in the self-organized critical forest-fire model. The analysis of the steady-state condition for the density of trees allows us to pinpoint the presence of these corrections, which take the form of subdominant exponents modifying the standard finite-size scaling form. Applying an extended version of the moment analysis technique, we find the scaling region of the model and compute the first non-trivial corrections to scaling.Comment: RevTeX, 7 pages, 7 eps figure

Optimizing interpolation of shoot density data from a Posidonia oceanica seagrass bed

A case study on the optimization of Posidonia oceanica density interpolation, using a data set from a large meadow at Porto Conte Bay (NW Sardinia, Italy), is presented. Ordinary point kriging, cokriging and a weighted average based on inverse square distance were used to interpolate density data measured in 36 sampling stations. The results obtained from different methods were then compared by means of a leave-one-out cross-validation procedure. The scale at which interpolation was carried out was defined on the basis of the Hausdorff dimension of the variogram. Optimizing spatial scale and data points search strategy allowed obtaining more accurate density estimates independently of the interpolation method

Universality in sandpiles

We perform extensive numerical simulations of different versions of the sandpile model. We find that previous claims about universality classes are unfounded, since the method previously employed to analyze the data suffered a systematic bias. We identify the correct scaling behavior and conclude that sandpiles with stochastic and deterministic toppling rules belong to the same universality class.Comment: 4 pages, 4 ps figures; submitted to Phys. Rev.