Precautionary principle or evidence-based conservation? Assessing the information content of threat data for the Yangtze finless porpoise

Conservation management requires evidence, but robust data on key parameters such as threats are often unavailable. Conservation-relevant insights might be available within datasets collected for other reasons, making it important to determine the information content of available data for threatened species and identify remaining data-gaps before investing time and resources in novel data collection. The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) has declined severely across the middle-lower Yangtze, but multiple threats exist in this system and the relative impact of different anthropogenic activities is unclear, preventing identification of appropriate mitigation strategies. Several datasets containing information on porpoises or potential threats are available from past boat-based and fishing community surveys, which might provide novel insights into causes of porpoise mortality and decline. We employed multiple analytical approaches to investigate spatial relationships between live and dead porpoises and different threats, reproductive trends over time, and sustainable offtake levels, to assess whether evidence-based conservation is feasible under current data availability. Our combined analyses provide new evidence that mortality is spatially associated with increased cargo traffic; observed mortality levels (probably a substantial underestimate of true levels) are unsustainable; and population recruitment is decreasing, although multiple factors could be responsible (pollutants, declining fish stocks, anthropogenic noise, reduced genetic diversity). Available data show little correlation between patterns of mortality and fishing activity even when analyzed across multiple spatial scales; however, interview data can be affected by multiple biases that potentially complicate attempts to reconstruct levels of bycatch, and new data are required to understand dynamics and sustainability of porpoise-fisheries interactions. This critical assessment of existing data thus suggests that in situ porpoise conservation management must target multiple co-occurring threats. Even limited available datasets can provide new insights for understanding declines, and we demonstrate the importance of an integrative approach for investigating complex conservation problems and maximizing evidence in conservation planning for poorly known taxa

Study of X-ray spectrum emitted due to the impact of Xe-129(q+) on different ion's charge on Au

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">We report the experiment data of X-ray spectra produced by the impact of Xeq+ (q = 1 0, 15, 20, 26) with 2.4 MeV kinetic energy on Au surface in the National Laboratory of Heavy Ion Research Facility in Lanzhou. Results show that there is different broadening of Au M X-ray owing to multiply ionized effect in the collision with heavy ions, the degree of ionization mainly depends on the distribution of the electronic states in the ions&#39; outer shell. The yield of X-ray is calculated and compared with BEA (binary encounter approximation) model, and the effect of ion charge state on the X-ray yield is also discussed.</span

X-ray emission induced by 1.2-3.6 MeV Kr13+ ions

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">X-ray emission from Kr13+ ions in the energy range 1.2-3.6 MeV in steps of 0.6 MeV impacting on an Au target was investigated on electron cyclotron resonance ion source at the Heavy Ion Research Facility in Lanzhou. It was found that a shift of the X-ray lines to the higher energy side occurred. We measured the relationship between the characteristic of X-ray yield of Au M X-rays and Kr L X-rays as a function of incident energy. Furthermore, M-shell X-ray production cross-section of Au induced by Kr13+ was measured. The measured cross-section of target is compared to the classical binary-encounter approximation and plane-wave-born approximation theoretical model, which is a significant different between experimental and theoretical model.</span

X-ray spectrum emitted by the impact of Eu-152(20+) of near Bohn velocity on Au surface

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The characteristic X-ray spectra produced by the impact of highly charged ions of Eu-152(20+) with energies from 2.0 to 6.0 MeV on Au surface are measured. It is found that highly charged ions could excite both the characteristic X-ray spectra of M-zeta, M-alpha and M-delta of Au and the characteristic X-ray spectra of M-alpha of Eu. The total X-ray yield increases with the ion kinetic energy increasing. The total production cross section of Au induced by Eu20+ is measured and compared with those obtained from the binary encounter approximation, plane-wave-Born approximation, and the energy-loss Coulomb deflection perturbed stationary state relativistic theoretical models.</span

Kr L X-ray and Au M X-ray emission for 1.5 MeV-3.9 MeV Kr13+ ions impacting on an Au target

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Kr L X-ray and Au M X-ray emission for Kr13+ ions with energies of 1.5 MeV and 3.9 MeV impacting on an Au target are investigated at heavy ion research facility in Lanzhou (HIRFL). The L-shell X-ray yield per ion of Kr is measured as a function of incident energy. In addition, Kr L X-ray production cross section is extracted from the yield and compared with the result obtained from the classical binary-encounter approximation (BEA) model. Furthermore, the intensity ratio of the Au M-beta 3 to M-alpha 1 X-ray is investigated as a function of incident energy.</span

Study of Si K-shell X-ray emission induced by H+ and Ar11+ ions

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The L-shell X-rays of Si, induced by 50-250 keV proton and 1.0-3.0 MeV Ar11+ ions impacting are measured. It is found that the X-ray induced by Ar11+ is about 36 eV higher than that induced by proton. That indicates that 3, 4 L-shell electrons of Si atom are multiply-ionized by Ar11+ ion impact. The X-ray production cross section is extracted from the yield data and compared with the results from the BEA, PWBA and ECPSSR models. With the same unit incident energy, the cross section induced by Ar11+ is about 3 orders of magnitude larger than that produced by proton. For proton impact, the ECPSSR model gives an accurate prediction to the cross section data. However, the BEA model, considering the change of fluorescence yield due to the multiple-ionization, presents the results that are in better agreement with the experimental results for Ar11+ ions.</span