Forensic analysis of video file formats

AbstractVideo file format standards define only a limited number of mandatory features and leave room for interpretation. Design decisions of device manufacturers and software vendors are thus a fruitful resource for forensic video authentication. This paper explores AVI and MP4-like video streams of mobile phones and digital cameras in detail. We use customized parsers to extract all file format structures of videos from overall 19 digital camera models, 14 mobile phone models, and 6 video editing toolboxes. We report considerable differences in the choice of container formats, audio and video compression algorithms, acquisition parameters, and internal file structure. In combination, such characteristics can help to authenticate digital video files in forensic settings by distinguishing between original and post-processed videos, verifying the purported source of a file, or identifying the true acquisition device model or the processing software used for video processing

Tree-ring stable isotopes and radiocarbon reveal pre- and post-eruption effects of volcanic processes on trees on Mt. Etna (Sicily, Italy)

Early detection of volcanic eruptions is of major importance for protecting human life. Ground deformation and changes in seismicity, geochemistry, petrology, and gravimetry are used to assess volcanic activity before eruptions. Studies on Mt. Etna (Italy) have demonstrated that vegetation can be affected by pre-eruptive activity before the onset of eruptions. During two consecutive years before Mt. Etna's 2002/2003 flank eruption, enhanced vegetation index (NDVI) values were detected along a distinct line which later developed into an eruptive fissure. However, the mechanisms by which volcanic activity can lead to changes in pre-eruption tree growth processes are still not well understood. We analysed ${\delta}^{13}$C, ${\delta}^{18}$O and $^{14}$C in the rings of the survived trees growing near to the line where the pre-eruptive increase in NDVI was observed in order to evaluate whether the uptake of water vapour or fossil volcanic CO2 could have contributed to the enhanced NDVI. We found a dramatic decrease in ${\delta}^{18}$O in tree rings formed before 2002/2003 in trees close to the eruption fissure, suggesting uptake of volcanic water by trees during pre-eruptive magma degassing. Moist conditions caused by outgassing of ascending magma may also have led to an observed reduction in tree-ring ${\delta}^{13}$C following the eruption. Furthermore, only ambiguous evidence for tree uptake of degassed CO2 was found. Our results suggest that additional soil water condensed from degassed water vapour may have promoted photosynthesis, explaining local increases in NDVI before the 2002/2003 Mt. Etna flank eruption. Tree-ring oxygen stable isotopes might be used as indicators of past volcanic eruptions

Zonation of glucokinase in rat liver changes during postnatal development

AbstractIn the liver many metabolic pathways are preferentially localized in different zones of the acinus. It is assumed that this zonation allows an efficient adaptation to different states of nutrition, because alternative pathways can be regulated independently. It is reported that the rate limiting enzyme for the glycolytic pathway, glucokinase (EC 2.7.1.2), is predominantly located in the pericentral zone. The gene expression of glucokinase is induced to a maximum level after a carbohydrate-rich diet. In starved or diabetic rats glucokinase gene expression is barely detectable. In postnatal development glucokinase is induced to significant levels only from day 14 onwards. The distribution of the glucokinase protein in the rat liver lobule in the first 4 weeks of postnatal life was investigated by immunohistochemistry and compared to the distribution observed in adult rats. In adult rats considerably high levels of glucokinase are measureable as shown by immunoblotting utilizing a monospecific antibody and a photometric assay of glucokinase enzyme activity, respectively. Immunohistochemically the hepatic glucokinase protein is detected in the perivenous area. During postnatal development, the quantities of hepatic glucokinase protein and glucokinase enzyme activity start to increase significantly from day 15 onwards. Subsequently, glucokinase levels rise further until day 29. In contrast to the results obtained by immunoblotting, glucokinase is already detectable in some liver cells in sections from 6-day-old rats by immunohistochemistry. The liver lobule structure at this age is not completely developed, therefore it is not possible to definitely assign these cells to periportal or pericentral areas. At day 10 post partum the number of glucokinase expressing cells, which appear to be localized preferentially in the periportal zone, increases. In agreement with the immunoblotting, an immense increase in glucokinase activity was observed at day 14. The periportal zonation, clearly detectable at this time, remains stable until day 24. In sections from 29-day-old rats the periportal zonation begins to change into a more homogeneous pattern with a slight preference for periportal areas. The observed appearance of the periportal zonation of glucokinase during neonatal development is obviously in contrast to the perivenous expression of glucokinase in adult rats