209 research outputs found
Growth status and physiological changes of sugar beet seedlings in response to acidic pH environments
No full textSugar beet (Beta vulgaris L.) is an important sugar crop that is popularly cultivated in a variety of agriculture conditions. Here, we studied sugar beet growth in different pH soils (pH 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, and 9.0) and analyzed their growth status and physiology. Sugar beet growth was best at pH 9.0 and worst at pH 5.0. As the soil pH decreased from 9.0 to 5.0, the osmoregulatory substances, antioxidant enzyme activity, and elemental contents in leaves and roots showed increasing trends, while photosynthesis and macronutrient contents showed decreasing trends. To explore the physiological mechanisms sugar beet use to respond to different pH environments, we analyzed the correlations between leaf net photosynthesis rate and physiological changes and nutrient contents of sugar beet. One of the factors inhibiting sugar beet growth in low pH soils was a reduction in photosynthetic capacity. The accumulation of osmoregulatory substances and increased peroxidative damage may have led to the decrease in leaf net photosynthesis rate. Furthermore, the decrease in nutrient content and accumulation of metal elements were correlated with the decrease in leaf photosynthetic rate. QRT-PCR analysis showed higher expression levels of antioxidant enzyme genes in the leaves and roots of sugar beet grown in low pH environments compared to those in high pH environments. Correspondingly, antioxidant enzyme activity was significantly higher in beets in low pH environments than in beets in high pH environments. These results provide important insight into the physiological responses by which sugar beet can adapt to different pH soils
Moderate deviations for a class of recursions
No full textAbstractIn this paper, we establish a moderate deviation principle for a class of recursions which have the form of Zn+1=(1−Γn+1gn)Zn+Vn+1gn, where gn are constants, Vn,Γn are random variables for any n≥1. These recursions often occur in stochastic approximation algorithms
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Plasmonic properties of subwavelength structures and plasmonic optical devices
No full texttextThis thesis proposes a metallic hole array of a rectangular converging-diverging channel (RCDC) shape with extraordinary transmission. We use a three-dimensional (3D) finite element method to analyze the transmission characteristics of two-dimensional metallic hole arrays (2D-MHA) with RCDC. For a straight channel MHA, when the aperture size is reduced, the transmission peaks have a blue-shift. The same result is observed for a smaller gap throat for the RCDC structure. For the rectangular holes with a high length-width ratio, a similar blue-shift in the transmission peaks as well as a narrower full width at half maximum (FWHM) are observed. The asymmetry from the rectangular shape gives this structure high selectivity for light with different polarizations. Furthermore, the RCDC shape gives extra degrees of geometrical variables to 2D-MHA for tuning the location of the transmission peak and FWHM. The tunable transmission property of this structure shows promise for applications in tunable filters, photonic circuits, and biosensors.Mechanical Engineerin
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Modulating physical and chemical properties of biomaterials in rapid 3D printing
No full textUnderstanding the physical and chemical properties of biomaterials in rapid 3D printing could pave a way for the construction of complex structures with specific functionalities. Both the material conditions and printing techniques play crucial roles in modulating these properties. This dissertation was dedicated to answering the basic questions about how to engineer and improve the mechanical performance of rapidly 3D printed structure from synthesis and printing process. Three distinct groups of materials, namely plastic, soft hydrogels, and elastomeric polymers were used as case studies to reveal their relationships. Additionally, the toughening mechanism of networks with different mechanical properties was discovered and tested. These results could help future studies in rapid prototyping of medical devices, as well as adapting 3D printing in tissue engineering as a new direction
An All-In-One NLP Stock Market Backtester:
No full textDespite the popularity, we noticed that it is rather hard to verify a NLP/text-mining like stock prediction model's performance due to the amount of "groundwork" needed. It is very typical a researcher will have to gather the plain text data, the company info, the stock market data, and categorize them in a way that is communicable with each other and the model; then the researcher will need to build a virtual trading platform that keeps track of all the trading signals generated by the model, log the activities in a certain way, then do some kinds of visualization for evaluations. To implement all these steps from ground up, it is required for a researcher to have certain level of proficiency on skills which are, from a research stand-point, fairly deviated from the nature of the NLP/text-mining model itself (like scraping a website and understanding the fundamental mechanism of trading in stock market). Thus, we like to build a set of lightweight tools that may automate such process to a certain degree
The Protection, Designation and Management of Cultural Routes: A Case Study of the Tea & Horse Road in China
No full textCultural routes are a relatively new, and much discussed concept in heritage designation and management. The extent to which this concept provides an effective theoretical framework for management of diverse sites, monuments, and landscapes, encompassing multiple stakeholders and values, is under debate.
The research explores the so-called Tea & Horse Road (THR), which stretched from southwestern China to the South Asian subcontinent. It is an intriguing example of a historic network of interactions, combining multidimensional issues of protection, designation, and management, within a challenging contemporary social and political context.
Using literature reviews, case studies, semi-structured interviews, and field investigations, the thesis focuses on the THR within Yunnan Province in China. The selected case study was divided into three categories: productive regions, transfer regions and consuming regions, in order to both articulate the assorted THR heritage, and to explore relevant crucial issues: the nature of the physical remains; their integrity and authenticity; the potential and impacts of tourism; local, regional and state-based values; and the prospective management, protection and designation of these areas.
The research concludes that introducing the concept of cultural routes enables these multifaceted sites and landscapes to be integrated within a wider systematic framework, which offers possible approaches to top-down preservation and management of the THR. However, the research also reveals the tensions between cultural route and cultural landscape approaches, with the latter far easier to implement at a local/regional level. More broadly, it also raises questions about the implementation of cultural routes as a nomination strategy when dealing with diverse heritage resources, landscapes and communities
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Discrete event simulation analysis on multiple class single server queueing system with abandonments and promotions
No full textIn the United States, the Model for End-Stage Liver Disease (MELD) scoring system is implemented to rank patients that are on the liver transplantation waiting list. However, this system is too complex to be directly analyzed. Thus, a multiple class single server queueing model with abandonments and promotions is developed as a simplified version of the original system. The queueing model is analyzed using discrete event simulation. In general, the simulation results indicate that the [rho alpha] rule and the c / [alpha] rule seem to hold for minimizing the system abandonment rate and the total holding cost respectively. While the r [alpha] rule does not seem to hold for maximizing the system reward.Operations Research and Industrial Engineerin
A Survey and Research on the Use of Artificial Intelligence by Chinese Design-College Students
No full textThe relationship between AI and design has attracted extensive academic attention and research, and the future relationship between AI and designers relies on current design students’ knowledge of AI, in addition to technological developments. To clarify the basic situation of Chinese design-college students’ use of AI software, the basic situation and status of using AI software to participate in design work, and the current relationship with AI, this study constructs a questionnaire on the status of the use of AI programs, with the help of the UTAUT model and the general program of design as a basis. The results of the research on 487 Chinese design-college students were analyzed by frequency analysis, descriptive statistics, etc., to clarify that currently more than 60% of design students have used AI programs, which are mainly used for data collection; providing ideas for design, e.g., when brainstorming; and conceptual ideas for design. Moreover, students generally believe that AI helps to improve personal skills and work efficiency, but the in-depth application and reliance on AI is relatively low; students hold anxiety about the development of AI, especially those who have not been exposed to AI. The education sector should focus on popularizing and deepening AI education, as well as helping students establish a correct concept of AI usage
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