Preadult development of necrophagous flies is commonly recognized as an accurate method for estimating the minimum postmortem interval (PMImin). However, once the PMImin exceeds the duration of preadult development, the method is less accurate. Recently, fly puparial hydrocarbons were found to significantly change with weathering time in the field, indicating their potential use for PMImin estimates. However, additional studies are required to demonstrate how the weathering varies among species. In this study, the puparia of Chrysomya rufifacies were placed in the field to experience natural weathering to characterize hydrocarbon composition change over time. We found that weathering of the puparial hydrocarbons was regular and highly predictable in the field. For most of the hydrocarbons, the abundance decreased significantly and could be modeled using a modified exponent function. In addition, the weathering rate was significantly correlated with the hydrocarbon classes. The weathering rate of 2-methyl alkanes was significantly lower than that of alkenes and internal methyl alkanes, and alkenes were higher than the other two classes. For mono-methyl alkanes, the rate was significantly and positively associated with carbon chain length and branch position. These results indicate that puparial hydrocarbon weathering is highly predictable and can be used for estimating long-term PMImin.
Depth sensitive Raman spectroscopy has been shown effective in the detection of depth dependent Raman spectra in layered tissues. However, the current techniques for depth sensitive Raman measurements based on fiber-optic probes suffer from poor depth resolution and significant variation in probe-sample contact. In contrast, those lens based techniques either require the change in objective-sample distance or suffer from slow spectral acquisition. We report a snapshot depth-sensitive Raman technique based on an axicon lens and a ring-to-line fiber assembly to simultaneously acquire Raman signals emitted from five different depths in the non-contact manner without moving any component. A numerical tool was developed to simulate ray tracing and optimize the snapshot depth sensitive setup to achieve the tradeoff between signal collection efficiency and depth resolution for Raman measurements in the skin. Moreover, the snapshot system was demonstrated to be able to acquire depth sensitive Raman spectra from not only transparent and turbid skin phantoms but also from ex vivo pork tissues and in vivo human thumbnails when the excitation laser power was limited to the maximum permissible exposure for human skin. The results suggest the great potential of snapshot depth sensitive Raman spectroscopy in the characterization of the skin and other layered tissues in the clinical setting or other similar applications such as quality monitoring of tablets and capsules in pharmaceutical industry requiring the rapid measurement of depth dependent Raman spectra.
Livestock grazing affects grassland stability, resilience, and productivity owing to trampling, foraging, and excretion. Over time, trampling influences a wide range of grassland components and can have lasting effects. Trampling helps maintain grassland health but may also cause its degradation. In a field experiment over two growing seasons, we simulated yak and sheep trampling at different intensities and investigated their effects on the reproductive and photosynthetic characteristics of Medicago ruthenica var. inschanica in a Tianzhu alpine meadow in Gansu Province, China. Our results show that simulated trampling inhibited the asexual and sexual reproduction and growth of M. ruthenica. The root surface area, root volume, root biomass, pod length, pod number per unit area, number of seeds per pod, thousand-seed weight, and seed yield were significantly reduced under simulated trampling in the upper 30 cm of soil (P < 0.05) but were not reduced in the deeper soil layers (> 30 cm). Light trampling by both yak and Tibetan sheep promoted photosynthesis, while heavy trampling by both species inhibited photosynthesis. Yak trampling inhibited photosynthesis more than Tibetan sheep trampling, and overall, the adverse effects of yak trampling on asexual and sexual reproduction and growth of M. ruthenica were greater than those of Tibetan sheep trampling. Thus, the effect of yak trampling is greater than the effect of trampling by Tibetan sheep, where the different trampling intensities of yak and Tibetan sheep can result in direct but varied influences on grasslands, potentially leading to grassland differentiation.
In this study, 20 Y-specific short tandem repeat (STR) loci (DYS434, Y-GATA-A10, Y-GATA-H4, DYS438, DYS439, DYS443, DYS444, DYS446, DYS447, DYS448, DYS456, DYS458, DYS460, DYS520, DYS531, DYS557, DYS622, DYS630, DYS635(Y-GATA-C4), and DYS709) were analyzed in 158 unrelated healthy men from southeast China by three fluorescence-labeled multiplex polymerase chain reaction systems. The Y-STR multiplexes developed have followed the published nomenclature and International Society for Forensic Genetics (ISFG) guidelines for STR analysis. Gene diversity ranged from 0.2506 at DYS434 to 0.8034 at DYS447. A total of 157 different haplotypes were observed, and among these, 156 were unique, while 1 was found two times. The haplotype diversity value calculated from all 20 loci combined was 0.9997, which is informative. Furthermore, 80 father-son pairs, previously confirmed by autosomal STR analysis, were typed using the same 20 Y-STR loci, and four mutation events were identified at the Y-GATA-H4, DYS439, DYS456, and DYS458 loci, giving an average mutation rate of 0.25% per locus per generation (95% confidence interval 0.09-0.54). These results including the haplotype data at 20 Y-STR loci would enrich Chinese genetic informational resources and provide useful information in forensic practice.
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