SetMargin loss applied to deep keystroke biometrics with circle packing interpretation

This work presents a new deep learning approach for keystroke biometrics based on a novel Distance Metric Learning method (DML). DML maps input data into a learned representation space that reveals a “semantic” structure based on distances. In this work, we propose a novel DML method specifically designed to address the challenges associated to free-text keystroke identification where the classes used in learning and inference are disjoint. The proposed SetMargin Loss (SM-L) extends traditional DML approaches with a learning process guided by pairs of sets instead of pairs of samples, as done traditionally. The proposed learning strategy allows to enlarge inter-class distances while maintaining the intra-class structure of keystroke dynamics. We analyze the resulting representation space using the mathematical problem known as Circle Packing, which provides neighbourhood structures with a theoretical maximum inter-class distance. We finally prove experimentally the effectiveness of the proposed approach on a challenging task: keystroke biometric identification over a large set of 78,000 subjects. Our method achieves state-of-the-art accuracy on a comparison performed with the best existing approachesThis work has been supported by projects: PRIMA ( MSCA-ITN- 2019-860315 ), TRESPASS-ETN (MSCA-ITN-2019-860813), BIBECA (RTI2018-101248-B-I00 MINECO), edBB (UAM), and Instituto de In- genieria del Conocimiento (IIC). A. Acien is supported by a FPI fel- lowship from the Spanish MINEC

Productivity, Efficiency and Environmental Effects of Whole-Tree Harvesting in Spanish Coppice Stands Using a Drive-to-Tree Disc Saw Feller-Buncher

Whole tree harvesting was conducted on two coppice stands with different tree composition (Q. ilex and Q. pyrenaica) in gentle terrain. Felling and bunching were performed by a drive-to-tree wheeled feller-buncher with disc saw head. Operations were analyzed on 17 plots 25x25 m2 in order to develop productivity models and to assess operational costs. The study also aimed at determining biomass collection efficiency and evaluating the impact of the new harvesting method on the soil, the remaining trees and stumps. The treatment consisted in a strong coppice thinning leaving standards. Productivity ranged from 2.8 to 4.6 odt/pmh in the Q. ilex coppice, and from 0.9 to 2.6 in the Q. pyrenaica stand. Tree species, dry weight per tree and percentage of removed basal area were the main independent variables affecting productivity. Approximately 50% of the standards showed damages. Most wounds were light, caused by the drive-to-tree work pattern, followed through GPS tracking. Soil damage was also light; in no plots, deep disturbances were found. However, most of the stumps were damaged. Forwarding and chipping productivity and cost were also evaluated. The slash left on the terrain averaged 3.0 and 1.5 odt/ha in Q. ilex and Q. pyrenaica, respectively, including scrub debris. As a conclusion, while this heavy feller-buncher can be useful in coppice heavy thinnings with larger trees, it would be a good option to try lighter disc saw felling heads mounted on the harvester boom tip, which probably would reach better productivity and reduce the frequency of stand damage

Operational and Environmental Comparison of Two Felling and Piling Alternatives for Whole Tree Harvesting in Quercus Coppices for Bioenergy Use

Coppices are a major potential source of forest biomass in Spain, where they occupy around 4M ha. Quercus coppices are mostly neglected because of their high harvesting costs and the small size of their products. This makes them very interesting to test and compare alternative means for utilizing their resources in an optimized way. Hence, a comparative study of motormanual and mechanized felling and bunching was conducted when thinning dense coppice stands of the two most important oak species in Spain to obtain biomass for bioenergy use. In particular, the study matched chainsaw felling and manual piling against the work of a driveto- tree feller-buncher previously analyzed in the very same sites. Productivity functions for motor-manual felling and piling were fitted for each species. The derived unit cost functions show that the felling-bunching costs are lower for the motor-manual option in stands of both species, particularly for the smaller tree sizes. Nevertheless, when the strongly reduced loading times in forwarding associated to the mechanization are taken into account, the total harvesting cost is often lower for the mechanized option. That is true for all tree sizes of Q. ilex, and for trees larger than 13 cm diameter at breast height (DBH) for Q. pyrenaica. Residual stand damage was low to moderate, but always significantly greater for the mechanized option compared with the motormanual one. Soil damage was very low for both alternatives. The stumps experimented significantly greater damages in the mechanized felling and bunching, but further research is needed to determine if those damages have any impact on stump mortality, sprouting capability and future plants vigor. The greater productivity and level of tree damages found in Q. ilex when compared to Q. pyrenaica are likely due to the narrower and lighter crown of the latter

Productivity, Efficiency and Environmental Effects of Whole-Tree Harvesting in Spanish Coppice Stands Using a Drive-to-Tree Disc Saw Feller-Buncher

Whole tree harvesting was conducted on two coppice stands with different tree composition (Q. ilex and Q. pyrenaica) in gentle terrain. Felling and bunching were performed by a drive-to-tree wheeled feller-buncher with disc saw head. Operations were analyzed on 17 plots 25x25 m2 in order to develop productivity models and to assess operational costs. The study also aimed at determining biomass collection efficiency and evaluating the impact of the new harvesting method on the soil, the remaining trees and stumps. The treatment consisted in a strong coppice thinning leaving standards. Productivity ranged from 2.8 to 4.6 odt/pmh in the Q. ilex coppice, and from 0.9 to 2.6 in the Q. pyrenaica stand. Tree species, dry weight per tree and percentage of removed basal area were the main independent variables affecting productivity. Approximately 50% of the standards showed damages. Most wounds were light, caused by the drive-to-tree work pattern, followed through GPS tracking. Soil damage was also light; in no plots, deep disturbances were found. However, most of the stumps were damaged. Forwarding and chipping productivity and cost were also evaluated. The slash left on the terrain averaged 3.0 and 1.5 odt/ha in Q. ilex and Q. pyrenaica, respectively, including scrub debris. As a conclusion, while this heavy feller-buncher can be useful in coppice heavy thinnings with larger trees, it would be a good option to try lighter disc saw felling heads mounted on the harvester boom tip, which probably would reach better productivity and reduce the frequency of stand damage

Host-pathogen coevolution increases genetic variation in susceptibility to infection

It is common to find considerable genetic variation in susceptibility to infection in natural populations. We have investigated whether natural selection increases this variation by testing whether host populations show more genetic variation in susceptibility to pathogens that they naturally encounter than novel pathogens. In a large cross-infection experiment involving four species of Drosophila and four host-specific viruses, we always found greater genetic variation in susceptibility to viruses that had coevolved with their host. We went on to examine the genetic architecture of resistance in one host species, finding that there are more major-effect genetic variants in coevolved host-pathogen interactions. We conclude that selection by pathogens has increased genetic variation in host susceptibility, and much of this effect is caused by the occurrence of major-effect resistance polymorphisms within populations

FHV titer qPCR data in experiment 1 (Original hosts)

Column headers correspond to the Wolbachia infection status (Status), the Wolbachia strain (W_strain), the Ct values for FHV and the control fly gene Rpl32 (2 technical replicates for each)

FHV titer qPCR data in experiment 2 (Original hosts and STCP line)

Column headers correspond to the type of host, the fly species, the Wolbachia strain (W_strain), the Wolbachia infection status (Status), the Ct values for FHV and the control fly gene Rpl32 (2 technical replicates for each)

Survival data in experiment 1 (Original hosts)

Column headers correspond to the Fly species, the Wolbachia strain (W_strain), the Wolbachia infection status (Status), the virus infection treatment (Treatment), the vial number, the total number of flies in a replicate vial (Sum), the number of flies lost during the experiment (Lost) and the number of days post-viral infection. Values in the latter columns indicate the cumulative number of dead flies after virus infection

Survival data in experiment 2 (Original hosts and STCP line)

Column headers correspond to the batch of infection, the type of host, the Fly species, the Wolbachia strain (W_strain), the Wolbachia infection status (Status), the virus infection treatment (Treatment), the vial number, the total number of flies in a replicate vial (Sum), the number of flies lost during the experiment (Lost) and the number of days post-viral infection. Values in the latter columns indicate the cumulative number of dead flies after virus infection

Wolbachia density qPCR data in experiment 2 (Original hosts and STCP line)

Column headers correspond to the type of host, the fly species, the Wolbachia strain (W_strain), the Ct values for the Wolbachia gene atpD and the control fly gene Rpl32 (2 technical replicates for each)