An Overview of Classification Techniques for Human Activity Recognition

In this paper, both classic and less commonly used classification techniques are evaluated in terms of recognizing human activities recorded in the PAMAP2 dataset that was created using three inertial measurement units. Seven algorithms are compared in terms of their accuracy performance with the best classifier being based on the Orthogonal Matching Pursuit algorithm that has been modified to remove the limitation of the number of training vectors per class present in its original version. The overview shows that human activities as defined by the PAMAP2 dataset can be recognized reliably even without any prior data preprocessing

Thermal desorption of CH4 retained in CO2 ice

CO2 ices are known to exist in different astrophysical environments. In spite of this, its physical properties (structure, density, refractive index) have not been as widely studied as those of water ice. It would be of great value to study the adsorption properties of this ice in conditions related to astrophysical environments. In this paper, we explore the possibility that CO2 traps relevant molecules in astrophysical environments at temperatures higher than expected from their characteristic sublimation point. To fulfil this aim we have carried out desorption experiments under High Vacuum conditions based on a Quartz Crystal Microbalance and additionally monitored with a Quadrupole Mass Spectrometer. From our results, the presence of CH4 in the solid phase above the sublimation temperature in some astrophysical scenarios could be explained by the presence of several retaining mechanisms related to the structure of CO2 ice.Comment: 8 pages, accepted for publication in Astrophysics & Space Scienc

Highly stable single-strand-specific 3′-nuclease/nucleotidase from Legionella pneumophila

The Gram-negative bacterium Legionella pneumophila is one of the known opportunistic human pathogens with a gene coding for a zinc-dependent S1–P1 type nuclease. Bacterial zinc-dependent 3′-nucleases/nucleotidases are little characterized and not fully understood, including L. pneumophila nuclease 1 (Lpn1), in contrast to many eukaryotic representatives with in-depth studies available. To help explain the principle properties and role of these enzymes in intracellular prokaryotic pathogens we have designed and optimized a heterologous expression protocol utilizing E. coli together with an efficient purification procedure, and performed detailed characterization of the enzyme. Replacement of Ni2+ ions by Zn2+ ions in affinity purification proved to be a crucial step in the production of pure and stable protein. The production protocol provides protein with high yield, purity, stability, and solubility for structure-function studies. We show that highly thermostable Lpn1 is active mainly towards RNA and ssDNA, with pH optima 7.0 and 6.0, respectively, with low activity towards dsDNA; the enzyme features pronounced substrate inhibition. Bioinformatic and experimental analysis, together with computer modeling and electrostatics calculations point to an unusually high positive charge on the enzyme surface under optimal conditions for catalysis. The results help explain the catalytic properties of Lpn1 and its substrate inhibition

Highly stable single-strand-specific 3′-nuclease/nucleotidase from Legionella pneumophila

The Gram-negative bacterium Legionella pneumophila is one of the known opportunistic human pathogens with a gene coding for a zinc-dependent S1–P1 type nuclease. Bacterial zinc-dependent 3′-nucleases/nucleotidases are little characterized and not fully understood, including L. pneumophila nuclease 1 (Lpn1), in contrast to many eukaryotic representatives with in-depth studies available. To help explain the principle properties and role of these enzymes in intracellular prokaryotic pathogens we have designed and optimized a heterologous expression protocol utilizing E. coli together with an efficient purification procedure, and performed detailed characterization of the enzyme. Replacement of Ni2+ ions by Zn2+ ions in affinity purification proved to be a crucial step in the production of pure and stable protein. The production protocol provides protein with high yield, purity, stability, and solubility for structure-function studies. We show that highly thermostable Lpn1 is active mainly towards RNA and ssDNA, with pH optima 7.0 and 6.0, respectively, with low activity towards dsDNA; the enzyme features pronounced substrate inhibition. Bioinformatic and experimental analysis, together with computer modeling and electrostatics calculations point to an unusually high positive charge on the enzyme surface under optimal conditions for catalysis. The results help explain the catalytic properties of Lpn1 and its substrate inhibition