A Practical Toolbox for Getting Started with mmWave FMCW Radar Sensors

In this paper, we sum up our experience gathered working with mmWave FMCW radar sensors for localization problems. We give a glimpse of the foundations of radar that is necessary to understand the benefit and advantages of this technology. Moreover, we introduce our open-source software toolbox pymmw based on Python for Texas Instruments IWR1443 ES2.0 EVM sensors to provide students and researchers easy access to those radar sensors. In doing so, one can jump right into sensing with mmWave FMCW radar from a practical point of view and start doing experiments and developing own applications. Finally, pymmw is used for data acquisition of a scene illuminated by three virtual radars in three different states of occupancy showing the potential of mmWave FMCW radar for indoor and distance-based localization applications

Sintered glass-ceramic matrix composites made from Latvian silicate wastes

Powder technology and sintering were used to fabricate glass-ceramic matrix composites from Latvian industrial wastes and alumina platelets reinforcement. The optimization of the sintering behaviour of glass-ceramic compositions containing clay and alumina platelets was carried out. Highly crystalline and dense products (> 90 % theoretical density) were fabricated by sintering at temperatures in the range 1040 to 1060 °C, depending on composition. Addition of waste glass to influence the sintering temperature and sintering interval was also investigated. Composites showed higher fracture strength (up to 97 MPa) and hardness than unreinforced glass-ceramics. The "best" composition in terms of density and mechanical properties contained 20 wt% alumina platelets. The matrix exhibited a microstructure composed mainly of elongated crystals of pyroxene type in a residual glassy matrix. These composites are candidates for applications as building materials, such as floor and wall tiles, and for manufacturing machine elements and parts

Impact of the antenna orientation for distance estimation

Indoor localization is important for a wide range of use cases including industrial, medical and scientific applications. The location accuracy is affected by the localization algorithm and the quality of the measurements as input for the algorithm. Many indoor localization systems employ ultra-wideband distance measurements, as they offer high accuracy and are cost effective. One of the methods for distance measurement is twoway ranging. This paper investigates the impact of the antenna orientation on the distance measurement based on symmetrical double-sided two-way ranging. We show that up to 0.25m of the measurement error is attributed to the orientation of the antennas. We provide explanations and suggest solutions to reduce the effect

Regional Variability and Driving Forces behind Forest Fires in Sweden

Extreme forest fires have been a historic concern in forests in Canada, the Russian Federation, or the USA, and are now becoming an increasing threat in boreal Europe where recent fire events in 2014 and 2018 caught the attention of those in Sweden. Our study objective was to understand the vulnerability of Swedish forests to fire by spatially analyzing historical burned areas and linking fire events with weather, landscape, and fire-related socioeconomic factors. We developed an extensive database at 1 × 1 km2 homogenous grid, where monthly areas burned in a forest were derived from the MODIS FireCCI51 dataset. Spatial factors, including camping sites, lakes, and roads, topographic features, including aspect, slope, and mean elevation, population density, forest management intensity, and forest stand volume, were collected from various sources and pre-processed. Monthly Fine Fuel Moisture Code (FFMC) values over 2011–2018 were calculated from daily weather data by IIASA’s FLAM model. To include new factors into FLAM, we developed a random forest model to assess the spatial probabilities of burned areas. Due to Sweden’s geographical diversity, the fire dynamics vary between six biogeographical zones. Therefore, the model was applied to each zone separately. As an outcome, we obtained probabilities of burned areas in the forests across Sweden and optimized thresholds. Observed burned areas were well captured by the model. Result accuracy differs with respect to zones; area under the curve (AUC) was 0.875 and 0.94 for zones with a few fires, but above 0.95 for zones with a higher number of fire events. Feature importance analysis and its variability across Sweden provide important information to understand the factors behind forest fires. FFMC, population and road densities, slope and aspect, and forest stand volume were found to be among the key fire-related factors in Sweden. Our modeling approach can be extended to hotspot mapping in other Boreal regions

Regional Variability and Driving Forces behind Forest Fires in Sweden

Extreme forest fires have been a historic concern in the forests of Canada, the Russian Federation, and the USA, and are now an increasing threat in boreal Europe, where recent fire events in 2014 and 2018 drew attention to Sweden. Our study objective was to understand the vulnerability of Swedish forests to fire by spatially analyzing historical burned areas, and to link fire events with weather, landscape, and fire-related socioeconomic factors. We developed an extensive database of 1 × 1 km2 homogenous grids, where monthly burned areas were derived from the MODIS FireCCI51 dataset. The database consists of various socio-economic, topographic-, forest-, and weather-related remote sensing products. To include new factors in the IIASA’s FLAM model, we developed a random forest model to assess the spatial probabilities of burned areas. Due to Sweden’s geographical diversity, fire dynamics vary between six biogeographical zones. Therefore, the model was applied to each zone separately. As an outcome, we obtained probabilities of burned areas in the forests across Sweden and observed burned areas were well captured by the model. The result accuracy differs with respect to zone; the area under the curve (AUC) was 0.875 and 0.94 for zones with few fires, but above 0.95 for zones with a higher number of fire events. Feature importance analysis and their variability across Sweden provide valuable information to understand the reasons behind forest fires. The Fine Fuel Moisture Code, population and road densities, slope and aspect, and forest stand volume were found to be among the key fire-related factors in Sweden. Our modeling approach can be extended to hotspot mapping in other boreal regions and thus is highly policy-relevant. Visualization of our results is available in the Google Earth Engine Application

Gre factors are required fot biofilm formation in Salmonella enterica serovar Typhimurium by targeting transcription of the cgsD gene

Rdar biofilm formation of Salmonella typhimurium and Escherichia coli is a common ancient multicellular behavior relevant in cell-cell and inter-organism interactions equally, as in interaction with biotic and abiotic surfaces. With the expression of the characteristic extracellular matrix components amyloid curli fimbriae and the exopolysaccharide cellulose, the central hub for the delicate regulation of rdar morphotype expression is the orphan transcriptional regulator CsgD. Gre factors are ubiquitously interacting with RNA polymerase to selectively overcome transcriptional pausing. In this work, we found that GreA/GreB are required for expression of the csgD operon and consequently the rdar morphotype. The ability of the Gre factors to suppress transcriptional pausing and the 147 bp 5′-UTR of csgD are required for the stimulatory effect of the Gre factors on csgD expression. These novel mechanism(s) of regulation for the csgD operon might be relevant under specific stress conditions

Child labor and conflict: evidence from Afghanistan

We study the impact of conflict on both the extensive and the intensive margin of child labor in Afghanistan. We identify and test two main mechanisms. First, if conflict reduces a household income through a decline in parent's compensations, child labor may insure against the decrease in consumption (extensive margin). Second, a child may work longer hours if the marginal benefits of working under conflict is greater than its marginal cost, which may depend on the relative compensations between adults and children, and on the alternative activities (e.g. schooling). Using detailed conflict data from the Afghan War Diary we identify the effect of conflict relying on a shift-share IV strategy. We find that conflict increases the probability that girls work, but reduces the number of hours worked. Our results suggest that this is due to a decrease in household income and an increase in the relative compensations of adults

"It's a gut feeling" - Escherichia coli biofilm formation in the gastrointestinal tract environment

Escherichia coli can commonly be found, either as a commensal, probiotic or a pathogen, in the human gastrointestinal (GI) tract. Biofilm formation and its regulation is surprisingly variable, although distinct regulatory pattern of red, dry and rough (rdar) biofilm formation arise in certain pathovars and even clones. In the GI tract, environmental conditions, signals from the host and from commensal bacteria contribute to shape E. coli biofilm formation within the multi-faceted multicellular communities in a complex and integrated fashion. Although some major regulatory networks, adhesion factors and extracellular matrix components constituting E. coli biofilms have been recognized, these processes have mainly been characterized in vitro and in the context of interaction of E. coli strains with intestinal epithelial cells. However, direct observation of E. coli cells in situ, and the vast number of genes encoding surface appendages on the core or accessory genome of E. coli suggests the complexity of the biofilm process to be far from being fully understood. In this review, we summarize biofilm formation mechanisms of commensal, probiotic and pathogenic E. coli in the context of the gastrointestinal tract