416 research outputs found

    Linking fire and decomposition in gymnosperm trees: the role of biotic disturbances

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    Forests play a crucial role in providing key ecosystem services, including climate regulation through carbon absorption and storage. However, climate warming poses a threat to this function by increasing the frequency and severity of disturbances such as droughts, fires, and insect outbreaks. These disturbances can directly and indirectly affect forest functions and carbon stocks. Wildfires, in particular, are significant ecological processes influenced by factors like ignition sources, fuel types, and climates, with drought being a primary driver under climate change. Understanding the interactions between abiotic disturbances like wildfires and biotic disturbances such as tree attacks by plant pathogens and invertebrates is essential. However, the causes and consequences of these interactions of biotic and abiotic disturbances for tree and forest carbon dynamics, whether or not via plant traits, are still poorly understood. Therefore, in this thesis, I put focus on surface fires driven by fine plant litter and coarse wood of gymnosperm tree species, and investigate how fire and decomposition, and their mutual interactions, are driven by important forest biotic disturbance agents (parasitic fungi and beetles) for coarse deadwood and by plant-centered biotic factors, i.e. the ‘legacy effects’ of variations in leaf litter SSS (the size and shape spectrum) and PES (the plant economics spectrum) traits. From Chapters 2 to 5, this thesis addresses four main research questions: (a) Are leaf litter decomposability and flammability decoupled across gymnosperm species based on their trait spectra? (b) Will the opportunistic parasitic fungus Armillaria affect the flammability of coarse deadwood in exotic pine plantations? (c) Does the legacy of this opportunistic parasitic fungus speed up the coarse wood decomposition of exotic pine plantations? (d) Do wood-boring beetles influence the flammability of deadwood across decomposition stages? In summary, the findings of this thesis demonstrate that both plant traits and biotic disturbances are important drivers of decomposition rates and fire properties, and their interactions. First, different (mostly decoupled) plant trait spectra drive the decomposability and flammability of fine litters. Second, specifically parasitic fungal attacks and wood-boring beetle infestations, have a notable impact on coarse deadwood. These disturbances lower the wildfire threshold or extend the smoldering phase, promoting decay processes. These dynamics, from fine litters to deadwood, have significant environmental implications, as together they expedite carbon release and contribute to climate warming. However, it is important to acknowledge that this thesis primarily focused on model species, and future research should encompass a broader range of species, also in mixture, to enhance the generalizability and practicality of the findings

    Outlets matter : an ethnographic study of an organized clandestine Chinese immigrant social network in the United States

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    The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Title from PDF of title page (University of Missouri--Columbia, viewed on January 28, 2011).Thesis advisor: Professor John Galliher.VitaPh. D. University of Missouri--Columbia 2009.Recent government statistics shows an astonishing figure of illegal Chinese workers coming into the US every year. Reportedly, it represents only a portion of the Chinese illegally residing in the United States. There exist multiple layers of barriers, such as the Pacific Ocean and other cultural and language obstacles. The question would be why, how, and who kept coming? The ethnographic study of Chinese workers is to reveal the patterns of social network that has been operating well in the process. The network is a broader sense network from societal level, including three dimensions: nodes, ties and outlets. The network must also be treated as the mediator for economic incentive in order to fully understand illegal Chinese immigration in the US. The study also finds that cultural and network patterns are the most important determinant of the illegal Chinese Immigrant to US. A social network analysis exhibits that the network structure is so special and encompasses at least four key outlets in the system. These findings have important theoretical and practical implications. The research contributes to the theoretical development in light of discovering a unique three dimensional network pattern within Chinese ethnic immigrants' culture, different from the universally accepted traditional two elements network analysis-either in a "whole ecological network", or an "egocentric network". In practice, the study findings strongly suggest the significance of such network as to immigration culture. It provides the bedrock for the whole system and gives rise to the issue of illegal immigration. Namely, if the criminal justice system cuts the sustainable network off at any level, there would be no more illegal Chinese immigrants. The findings show specifics of the type of social network that is the fount and matrix of Chinese clandestine immigration systems.Includes bibliographical references

    Regulation, Targets and Functions of CHK

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    Src family kinases (SFKs) play pivotal roles in multiple signaling pathways (Yeatman, 2004). SFK activity is inhibited by phosphorylation at its C-terminal tyrosine, by CSK (C-terminal Src kinase) and CHK (CSK-homologous kinase). CHK expression is restricted to normal hematopoietic cells, brain, and colon tissues. Downregulation of CHK in brain and colon tumors contributes to tumorigenicity in these tissues. CHK does not phosphorylate Src efficiently, however, in contrast to CSK, CHK inhibits Src kinase activity allosterically. Although the functions of CHK are still largely unknown, potential substrates of CHK including β-synuclein, α-tubulin, α-spectrin, 14-3-3, and Hsp90 have been identified. CHK is regulated epigenetically via promoter methylation. As the unknown roles of CHK are beginning to be revealed, current knowledge of regulation, molecular targets and functions of CHK is summarized, and important topics for future CHK research are discussed

    The toxic effect of mobile phone radiation on rabbit organs

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    Whether electromagnetic radiation (EMR) emitted from mobile phones is hazardous to human health is largely unknown. We investigated the effects of mobile phone radiation on critical organs in a rabbit model by exposing the animals to mobile phone radiation with sub-thermal specific absorption rate (SAR) of 1.0 and 0.7 W/kg for the head and the body, respectively, for 16 weeks (6 h/day, 6 days/week). There is no apparent change at the organ level. However, H&E staining showed that radiation-exposure significantly increased inflammatory cell infiltration in the liver and the lungs with a lesser degree of myocardial cell cytoplasmic vacuolation. In addition, results from γ-H2AX staining suggest that radiation can also cause DNA damage in the brain. Of note, no apparent activation of Caspase-3 in the organs examined. Our data altogether suggest that mobile phone radiation may be more hazardous to both the liver and the lungs, and less toxic to the brain and heart

    Automaticity in processing spatial-numerical associations: Evidence from a perceptual orientation judgment task of Arabic digits in frames.

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    Human adults are faster to respond to small/large numerals with their left/right hand when they judge the parity of numerals, which is known as the SNARC (spatial-numerical association of response codes) effect. It has been proposed that the size of the SNARC effect depends on response latencies. The current study introduced a perceptual orientation task, where participants were asked to judge the orientation of a digit or a frame surrounding the digit. The present study first confirmed the SNARC effect with native Chinese speakers (Experiment 1) using a parity task, and then examined whether the emergence and size of the SNARC effect depended on the response latencies (Experiments 2, 3, and 4) using a perceptual orientation judgment task. Our results suggested that (a) the automatic processing of response-related numerical-spatial information occurred with Chinese-speaking participants in the parity task; (b) the SNARC effect was also found when the task did not require semantic access; and (c) the size of the effect depended on the processing speed of the task-relevant dimension. Finally, we proposed an underlying mechanism to explain the SNARC effect in the perceptual orientation judgment task

    Emerging Therapeutic Strategies for COVID-19 Patients

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    Over 100,000 cases of COVID-19 patients infected with the novel coronavirus SARS-COV-2 have been reported worldwide in approximately 2 months, resulting in over 3000 deaths. Potential therapeutic strategies, including remdesivir, chloroquine phosphate, abidol, lopinavir/ritonavir, plasma, antibody, vaccine and stem cells are discussed in this review. With the number of patients increasing daily, there is an urgent need for effective therapeutic intervention

    Regulation, targets and functions of CSK.

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    The Src family kinases (SFK) plays an important role in multiple signal transduction pathways. Aberrant activation of SFKs leads to diseases such as cancer, blood disorders, and bone pathologies. By phosphorylating and inactivating SFKs, the C-terminal Src kinase (CSK) serves as the key negative regulator of SFKs. Similar to Src, CSK is composed of SH3, SH2, and a catalytic kinase domain. However, while the Src kinase domain is intrinsically active, the CSK kinase domain is intrinsically inactive. Multiple lines of evidence indicate that CSK is involved in various physiological processes including DNA repair, permeability of intestinal epithelial cells (IECs), synaptic activity, astrocyte-to-neuron communication, erythropoiesis, platelet homeostasis, mast cell activation, immune and inflammation responses. As a result, dysregulation of CSK may lead to many diseases with different underlying molecular mechanisms. Furthermore, recent findings suggest that in addition to the well-established CSK-SFK axis, novel CSK-related targets and modes of CSK regulation also exist. This review focuses on the recent progress in this field for an up-to-date understanding of CSK

    A New Method on Software Reliability Prediction

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    As we all know, relevant data during software life cycle can be used to analyze and predict software reliability. Firstly, the major disadvantages of the current software reliability models are discussed. And then based on analyzing classic PSO-SVM model and the characteristics of software reliability prediction, some measures of the improved PSO-SVM model are proposed, and the improved model is established. Lastly, simulation results show that compared with classic models, the improved model has better prediction precision, better generalization ability, and lower dependence on the number of samples, which is more applicable for software reliability prediction

    The Economic and Social Impact of GMOs in China

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    The use of modern biotechnology to create genetically modified organisms (GMOs) is allowing our main food agricultural crops to be altered in ways that were not believed possible even by specialists who took part in the green revolution only decades ago. Agriculture and food production are going through another revolution, the current technology of moving individual genes through biotechnology—genetic engineering. Plants and animals have been modified to resist pests and diseases. Even though..
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