Redescription of Wushaichthys exquisitus and phylogenetic revision of Thoracopteridae

Wushaichthys exquisitus, a small fish from the Middle Triassic of Guizhou Province, China, was named and studied by Xu et al. (2015), and Xu et al. interpreted it as the most primitive species in the family Thoracopteridae because of the presence of the following features: the skull roof is formed by the frontal bone, which is laterally expanded whereas the dermopterotic is expanded posteriorly; the parietal bone is fused with the dermopterotic; the supraorbital sensory canal ends in the frontal; presence of a triangular extrascapular, which is separated from its counterpart medially by the posttemporals; and presence of a narrow and vertical preopercle with an anterior process contacting the maxilla. However, this hypothesis was questioned because W. exquisitus also shares some features with Peltopleuridae, such as the deepened-flank scales, which means W. exquisitus should be a peltopleurid fish. A redescription of Wushaichthys exquisitus is conducted here based on five new specimens. Several new characters are described here, including the vertical preopercle sensory canal, which extends from ventral to dorsal margin of preopercle with a branch to the maxillary process; a small hyomandibular process on the antero-dorsal margin of opercle; and the presence of two lateral lines. A phylogenetic analysis based on 101 characters and 23 taxa was conducted. The results of the phylogenetic analysis suggest that W. exquisitus is the most basal taxon of the extinct family Thoracopteridae, confirming previous studies. The new results also indicate that Thoracopteridae is the sister group of Peltopleuridae, and these two families form the order Peltopleuriformes. This conclusion also agrees with several previous studies. Based on the detailed redescription, the diagnosis of the genus Wushaichthys is emended as well as the diagnoses of Wushaichthy exquisitus and of the family Thoracopteridae

Impacts of Ocean Acidification on Coralline Algae : From Species to Community Consequences

Oceanic uptake of rising anthropogenic CO₂ emissions has caused the emergence of ocean acidification as a major threat to marine ecosystems worldwide. Along eastern boundary current systems, seawater is naturally acidified due to coastal upwelling of low pH seawater from depth. Compounded by ocean acidification, upwelling regions are expected to become increasingly corrosive to calcifying organisms, potentially forcing them beyond their physiological tolerance windows. In my dissertation, I focused on the impacts of ocean acidification on calcareous coralline algae in the California Current System. Using coralline algae in rocky intertidal habitats as model organisms, I extend the implications of ocean acidification from the organismal level to the broader community level. Global environmental change implies not only gradual changes in the mean values of environmental variables but also an increase in variability and the likelihood of rare, extreme events. In Chapter 2, I conducted a laboratory experiment to explore potential interactions between two different types of environmental stressors. Specifically, I tested the effects of elevated pCO₂, including variable pCO₂ treatments, and a severe desiccation event on the coralline species, Corallina vancouveriensis. I found that C. vancouveriensis growth was negatively impacted by both elevated pCO₂ and desiccation stress, although their combined effects were approximately additive rather than synergistic. Furthermore, while high pCO₂ at constant levels only caused small reductions in algal growth over a two-week period, these effects were exacerbated by pCO₂ variability. One criticism of laboratory experiments testing species responses to environmental change is that they isolate organisms under simplified conditions. The potential of overlooking important biotic or abiotic factors present in the natural environment limits the inferences that can be made from laboratory studies. In Chapter 3, I conducted a reciprocal removal experiment at two field sites and two wave exposures to investigate potential changes in the interactions between coralline and fleshy turf-forming algae since the 1980s. I used as a baseline the results from a similar study conducted nearly 30 years ago that failed to detect spatial competition between coralline and fleshy algae. Despite the progression of ocean acidification over the last three decades, my results indicated that the lack of competition between coralline and fleshy algae persists to this day, with results consistent across both sites and wave exposures. The findings in Chapter 3 refer to present-day interactions, but in the future, ocean acidification is expected to be detrimental to coralline algae while potentially benefitting fleshy algae. Both coralline and fleshy algae form turf habitats that shelter diverse epifaunal communities. Thus, changes in the algal composition of turf habitats may lead to broader changes encompassing epifaunal communities, depending on the degree of specialization displayed in epifaunal habitat associations. In Chapter 4, I compared the abundance, richness, and community composition of epifauna between coralline and fleshy turf habitats at four sites along the Oregon-California coast. I found that epifauna were more abundant in coralline turfs due to higher turf density. However, epifaunal richness and community composition were similar between turf types, indicating high levels of redundancy in habitat provision between coralline and fleshy algae. Since most species of epifauna tended to be turf generalists, they may be resistant to the potential indirect effects of ocean acidification involving declines in coralline turf habitat. My dissertation combined a variety of standard ecological methodologies to help translate ocean acidification impacts from the organismal level to the community level. Overall, while I found that elevated pCO₂ decreased coralline growth in the laboratory, evidence from the field suggested a capacity for communities to resist the effects of ocean acidification and remain resilient. In the natural environment, ocean acidification impacts may be moderated by multiple environmental variables working in different directions, the temporal dynamics of stressors allowing for periods of recovery, and species interactions having dampening effects. One way forward to unite theories of change with those of resistance is to identify ecosystem indicators and critical thresholds that may help provide a more comprehensive view of ecosystem functioning and stability in the face of global change

Impact of Inorganically Bound Sulfur on Late Shale Gas Generation

Nonisothermal, confined pyrolysis was applied to a mature shale sample from the Ordovician Salgan Formation in Tarim Basin, northwest China. Experiments were conducted using gold-tubes with added water at a very slow heating rate (2 °C/h) and end temperatures between 336 and 600 °C. To investigate the influence of inorganically bound sulfur on the generation of gases and to consider the geological occurrence of sulfur-containing minerals, such as prevalent pyrite in shales, the experiments were carried out with and without admixtures of MgSO₄, CaSO₄, and pyrite. High amounts of methane along with lower amounts of wet gases were formed from highly mature shale without minerals added, demonstrating a huge late gas generation potential at post peak-oil window maturities. In the experiments with added sulfates and pyrite, all organic gases were consumed in varying proportions, resulting in different chemical and stable carbon isotopic compositions. Pyrite treatment affects wet gas (C₂–C₅) evolution directly, but it affects methane (C₁) evolution indirectly. In contrast, sulfate treatments affect C₁–C₅ evolution directly. The cumulative yield ratio of CO₂/H₂S indicates that pyrite impacts on the hydrocarbon gas generation through low valence sulfur such as S⁰ or others, which are associated with H₂S generation. In the pyrite series, the smooth increase in ethane yield at temperatures exceeding 504 °C, together with a concomitant stable carbon isotope reversal, demonstrates a new origin for ethane at high temperatures. The isotopic reversal may come from reactions between water and solid kerogen/coke/pyrobitumen. Isotopic reversal of ethane occurs only in the control and pyrite series but not in the sulfate treatments. This provides evidence that anoxic conditions are required. Thus, one can expect to encounter isotopic reversals in high maturity, unconventional gas shale environments in the presence of pyrite

Learning Conditional Attributes for Compositional Zero-Shot Learning

Compositional Zero-Shot Learning (CZSL) aims to train models to recognize novel compositional concepts based on learned concepts such as attribute-object combinations. One of the challenges is to model attributes interacted with different objects, e.g., the attribute ``wet" in ``wet apple" and ``wet cat" is different. As a solution, we provide analysis and argue that attributes are conditioned on the recognized object and input image and explore learning conditional attribute embeddings by a proposed attribute learning framework containing an attribute hyper learner and an attribute base learner. By encoding conditional attributes, our model enables to generate flexible attribute embeddings for generalization from seen to unseen compositions. Experiments on CZSL benchmarks, including the more challenging C-GQA dataset, demonstrate better performances compared with other state-of-the-art approaches and validate the importance of learning conditional attributes. Code is available at https://github.com/wqshmzh/CANet-CZSLComment: 10 pages, 4 figures, accepted in CVPR202

Acute toxicity and responses of antioxidant systems to dibutyl phthalate in neonate and adult Daphnia magna

Dibutyl phthalate (DBP) poses a severe threat to aquatic ecosystems, introducing hazards to both aquatic species and human health. The ecotoxic effects of DBP on aquatic organisms have not been fully investigated. This study investigates acute toxicity, oxidative damage, and antioxidant enzyme parameters in neonate and adult Daphnia magna exposed to DBP. The obtained results show comparable DBP toxic responses in neonates and adults. The median lethal concentrations (LC50) of DBP in neonates exposed for 24 and 48 h were 3.48 and 2.83 mg/L, respectively. The LC50 of adults for the same DBP exposure durations were 4.92 and 4.31 mg/L, respectively. Increased hydrogen peroxide and malondialdehyde were found in neonates and adults at both 24 and 48 h, while the total antioxidant capacity decreased. Superoxide dismutase activity increased significantly in neonates and adults exposed to 0.5 mg/L DBP, and subsequently diminished at higher DBP concentrations and prolonged exposure. Catalase and glutathione S-transferases activities both decreased markedly in neonates and adults. The changes observed were found to be time and concentration dependent. Overall, these data indicated that the acute toxic effects of DBP exposure on neonates were more pronounced than in adults, and oxidative injury may be the main mechanism of DBP toxicity. These results provide a functional link for lipid peroxidation, antioxidant capacity, and antioxidant enzyme levels in the Daphnia magna response to DBP exposure

The impact of farm size on agricultural sustainability

Farm size plays a critical role in agricultural sustainability. This may have far-reaching consequences for the economic and environmental performance of agricultural production, resulting, for instance, in an excessive use of mineral fertilizers. However, the magnitude of such effects and their main causes are not well understood, while being essential for effective policy development, especially for countries like China where the agricultural sector is still largely dominated by smallholder farms. In this paper, we review the current understanding of how farm size affects agricultural sustainability using China's crop farming as an example from economic, environment and social aspects. We analyze impacts from both a Chinese and a global perspective to identify intervention points to improve agricultural performance. We found that increasing farm size has a positive impact on farmer’s net profit, as well as economic, technical and labor efficiency with mean coefficients 0.005, 0.02 and 2.25 in economic performance, respectively. Nevertheless, the relationships between farm size and overall productivity, total factor productivity and allocative efficiency are still not well understood and therefore require more research. Meanwhile, increase in farm size is associated with statistically significant decrease in fertilizer and pesticide use per hectare, showing clear benefits for environmental protection. In line with the experiences documented for the evolution of agricultural practices in developed countries, the expansion of large-scale farming is a critical path for modernizing agricultural production and ensuring sustainable food production from the social perspective. Measures concerning farm size should be implemented in an interaction between farmers and the government to promote the green development of agriculture

Flux density measurements for 32 pulsars in the 20 cm band

Flux density measurements provide fundamental observational parameters that describe a pulsar. In the current pulsar catalogue, 27% of radio pulsars have no flux density measurement in the 20 cm observing band. Here, we present the first measurements of the flux densities in this band for 32 pulsars observed using the Parkes radio telescope and provide updated pulse profiles for these pulsars. We have used both archival and new observations to make these measurements. Various schemes exist for measuring flux densities. We show how the flux densities measured vary between these methods and how the presence of radio-frequency-interference will bias flux density measurementsComment: Accepted by RA