34,484 research outputs found

    Patterns and driving factors of leaf C, N, and P stoichiometry in two forest types with different stand ages in a mid-subtropical zone

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    Background: Carbon (C), nitrogen (N), and phosphorus (P) stoichiometry is a key indicator of nutrient utilization in plants, and C/N/P ratios are related to the life histories and adaptation strategies of tree species. However, no consensus has been reached on how leaf stoichiometric characteristics are affected by forest type and stand ages. The relationships between leaf stoichiometry and geographical, meteorological, and soil factors also remain poorly understood. Methods: Leaf and soil were sampled from forest stands of different age groups (young, middle-aged, near-mature, and mature) in two forest types (Chinese fir (Cunninghamia lanceolata) forests and evergreen broadleaved forests). The relationships between leaf C, N, and P stoichiometric parameters and geographical, meteorological, and soil factors were analysed by using redundancy analysis (RDA) and stepwise linear regression analysis. Results: Leaf C concentrations peaked in the near-mature stands with increasing age irrespective of forest type. Leaf N and P concentrations fluctuated with a rising trend in Chinese fir forests, while decreased first and increased later from young to mature phases in natural evergreen broadleaved forests. Chinese fir forests were primarily limited by N and P, while natural evergreen broadleaved forests were more susceptible to P limitation. Leaf C, N, and P stoichiometric characteristics in Chinese fir forests were mainly affected by the soil total P concentration (SP), longitude (LNG), growing season precipitation (GSP) and mean temperature in July (JUT). The leaf C concentration was mainly affected by GSP and JUT; leaf N and P concentrations were both positively correlated with LNG; and leaf P was positively correlated with SP. In evergreen broadleaved forests, however, leaf stoichiometric parameters displayed significant correlations with latitude (LAT) and mean annual precipitation (MAP). Conclusions: Leaf stoichiometry differed among forest stands of different age groups and forest types. Leaf C, N, and P stoichiometry was primarily explained by the combinations of SP, LNG, GSP and JUT in Chinese fir forests. LAT and MAP were the main controlling factors affecting the variations in the leaf C, N, and P status in natural evergreen broadleaved forests, which supports the temperature-plant physiological hypothesis. These findings improve the understanding of the distribution patterns and driving mechanisms of leaf stoichiometry linked with stand age and forest type

    The Professional Identity of Doctors who Provide Abortions: A Sociological Investigation

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    Abortion is a medicalised problem in England and Wales, where the law places doctors at the centre of legal provision and puts doctors in control of who has an abortion. However, the sex-selection abortion scandal of 2012 presented a very real threat to 'abortion doctors', when the medical profession's values and practices were questioned in the media, society and by Members of Parliament. Doctors found themselves at the centre of a series of claims that stated doctors were acting both illegally and unethically, driven by profit rather than patient needs. Yet, the perspectives of those doctors who provide abortions has been under-researched; this thesis aims to fill that gap by examining the beliefs and values of this group of doctors. Early chapters highlight the ambiguous position of the abortion provider in Britain, where doctors are seen as a collective group of professionals motivated by medical dominance and medical autonomy. They outline how this position is then questioned and contested, with doctors being presented as unethical. By studying abortion at the macro-, meso- and micro-levels, this thesis seeks to better understand the values of the 'abortion doctor', and how these levels shape the work and experiences of abortion providers in England and Wales. This thesis thus addresses the question: 'What do abortion doctors' accounts of their professional work suggest about the contemporary dynamics of the medicalisation of abortion in Britain?'. It investigates the research question using a qualitative methodological approach: face-to-face and telephone interviews were conducted with 47 doctors who provide abortions in England and Wales. The findings from this empirical study show how doctors' values are linked to how they view the 'normalisation of abortion'. At the macro-level doctors, openly resisted the medicalisation of abortion through the position ascribed to them by the legal framework, yet at the meso-level doctors construct an identity where normalising abortion is based on further medicalising services. Finally, at the micro-level, the ambiguous position of the abortion provider is further identified in terms of being both a proud provider and a stigmatised individual. This thesis shows that while the existing medicalisation literature has some utility, it has limited explanatory power when investigating the problem of abortion. The thesis thus provides some innovative insights into the relevance and value of medicalisation through a comprehensive study on doctors' values, beliefs and practices

    What is the importance of sperm subpopulations?

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    .The study of sperm subpopulations spans three decades. The origin, meaning, and practical significance, however, are less clear. Current technology for assessing sperm morphology (CASA-Morph) and motility (CASA-Mot) has enabled the accurate evaluation of these features, and there are many options for data classification. Subpopulations could occur as a result of the stage of development of each spermatozoon in the subpopulation. Spermatogenesis might contribute to the production of these subpopulations. Insights from evolutionary biology and recent molecular research are indicative of the diversity among male gametes that could occur from unequal sharing of transcripts and other elements through cytoplasmic bridges between spermatids. Sperm cohorts exiting the gonads would contain different RNA and protein contents, affecting the spermatozoon physiology and associations with the surrounding environmental milieu. Subsequently, these differences could affect how spermatozoa interact with the environmental milieu (maturation, mixing with seminal plasma, and interacting with the environmental milieu, or female genital tract and female gamete). The emergence of sperm subpopulations as an outcome of evolution, related to the reproductive strategies of the species, genital tract structures, and copulatory and fertilization processes. This kind of approach in determining the importance of sperm subpopulations in fertilization capacity should have a practical impact for conducting reproductive technologies, inspiring and enabling new ways for the more efficient use of spermatozoa in the medical, animal breeding, and conservation fields. This manuscript is a contribution to the Special Issue in memory of Dr. Duane GarnerS

    Prospective life cycle assessment of hydrogen production by waste photoreforming

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    Identifying sustainable energy vectors is perhaps one of the most critical issues that needs addressing to achieve a climate-neutral society by 2050. In this context, the hydrogen economy has been proposed as a solution to mitigate our current fossil-based energy system while the concept of the circular economy aims to boost the efficient use of resources. Photoreforming offers a promising opportunity for recycling and transforming widely available biomass-derived wastes (e.g., crude glycerol from biodiesel) into clean hydrogen fuel. This processing technology may be a versatile method that can be performed not only under UV light but also under visible light. However, this approach is currently at the lab-scale and some inherent challenges must be overcome, not least the relatively modest hydrogen production rates for the lamps? substantial energy consumption. This study aims to assess the main environmental impacts, identifying the hotspots and possible trade-off in which this technology could operate feasibly. We introduce an assessment of the windows of opportunity using seven categories of environmental impact with either artificial light or sunlight as the source of photocatalytic conversion. We compared the environmental indicators from this study with those of the benchmark water electrolysis and steam?methane reforming (SMR) technologies, which are currently operating at a commercial scale. The results obtained in this study situate biowaste photoreforming within the portfolio of sustainable H2 production technologies of interest for future development in terms of target H2 production rates and lifetimes of sustainable operation.Financial support from projects RTI2018-099407-B-I00 and RTI2018-099407-B-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER and by “ERDF A way of making Europe” by the “European Union” is gratefully acknowledged. We would like also to thank MICIN for providing Marta Rumayor with a Juan de la Cierva postdoctoral contract IJCI-2017-32621

    CO2 electroreduction: sustainability analysis of the renewable synthetic natural gas

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    Capture and utilization of industrial CO2 emissions into low-carbon fuels is a promising alternative to store renewable electricity into chemical vectors while decarbonizing the economy. This work evaluates the viability pathways of producing synthetic natural gas (SNG) by direct CO2 electroreduction (ER) in Power-To-Synthetic Natural Gas electrolyzers (PtSNG). We perform an ex-ante techno-economic (TEA) and life cycle analysis (LCA) for a 2030 framework in Europe. ER performance is varied in defined scenarios and assessed using a built-in process model of the PtSNG system, revealing uncharted limitations and benchmarks to achieve. Results show that substitution of fossil natural gas with renewable SNG could avoid more than 1 kg CO2e/kg SNG under moderate ER conditions when using low-carbon electricity (< 60 kg CO2e/MWh). SNG profitability for 2030 would rely on: i) higher CH4 current densities (800–1000 mA/cm2), ii) improvements in energy efficiency (higher than 60%), and iii) valorization of the anodic product or additional carbon incentives. Our study proves that if market and technology evolve appropriately in the coming years, the SNG by CO2 ER may be a mid-term climate change mitigation technology, among others.The authors thank the Spanish Ministry of Economy and Competitiveness for the financial support through the project PID2020–114,787-RB-I00. Javier Fernández-González and Marta Rumayor would also like to thank the financial support of the Spanish Ministry of Science and Innovation for the concession of a FPU grant (FPU19/05483) and a Juan de la Cierva postdoctoral contract (IJCI-2017-32621), respectively

    Network Slicing for Industrial IoT and Industrial Wireless Sensor Network: Deep Federated Learning Approach and Its Implementation Challenges

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    5G networks are envisioned to support heterogeneous Industrial IoT (IIoT) and Industrial Wireless Sensor Network (IWSN) applications with a multitude Quality of Service (QoS) requirements. Network slicing is being recognized as a beacon technology that enables multi-service IIoT networks. Motivated by the growing computational capacity of the IIoT and the challenges of meeting QoS, federated reinforcement learning (RL) has become a propitious technique that gives out data collection and computation tasks to distributed network agents. This chapter discuss the new federated learning paradigm and then proposes a Deep Federated RL (DFRL) scheme to provide a federated network resource management for future IIoT networks. Toward this goal, the DFRL learns from Multi-Agent local models and provides them the ability to find optimal action decisions on LoRa parameters that satisfy QoS to IIoT virtual slice. Simulation results prove the effectiveness of the proposed framework compared to the early tools

    Analyzing Tail Latency in Serverless Clouds with STeLLAR

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    Interactive Sonic Environments: Sonic artwork via gameplay experience

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    The purpose of this study is to investigate the use of video-game technology in the design and implementation of interactive sonic centric artworks, the purpose of which is to create and contribute to the discourse and understanding of its effectiveness in electro-acoustic composition highlighting the creative process. Key research questions include: How can the language of electro-acoustic music be placed in a new framework derived from videogame aesthetics and technology? What new creative processes need to be considered when using this medium? Moreover, what aspects of 'play' should be considered when designing the systems? The findings of this study assert that composers and sonic art practitioners need little or no coding knowledge to create exciting applications and the myriad of options available to the composer when using video-game technology is limited only by imagination. Through a cyclic process of planning, building, testing and playing these applications the project revealed advantages and unique sonic opportunities in comparison to other sonic art installations. A portfolio of selected original compositions, both fixed and open are presented by the author to complement this study. The commentary serves to place the work in context with other practitioners in the field and to provide compositional approaches that have been taken

    Studies of strategic performance management for classical organizations theory & practice

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    Nowadays, the activities of "Performance Management" have spread very broadly in actually every part of business and management. There are numerous practitioners and researchers from very different disciplines, who are involved in exploring the different contents of performance management. In this thesis, some relevant historic developments in performance management are first reviewed. This includes various theories and frameworks of performance management. Then several management science techniques are developed for assessing performance management, including new methods in Data Envelopment Analysis (DEA) and Soft System Methodology (SSM). A theoretical framework for performance management and its practical procedures (five phases) are developed for "classic" organizations using soft system thinking, and the relationship with the existing theories are explored. Eventually these results are applied in three case studies to verify our theoretical development. One of the main contributions of this work is to point out, and to systematically explore the basic idea that the effective forms and structures of performance management for an organization are likely to depend greatly on the organizational configuration, in order to coordinate well with other management activities in the organization, which has seemingly been neglected in the existing literature of performance management research in the sense that there exists little known research that associated particular forms of performance management with the explicit assumptions of organizational configuration. By applying SSM, this thesis logically derives some main functional blocks of performance management in 'classic' organizations and clarifies the relationships between performance management and other management activities. Furthermore, it develops some new tools and procedures, which can hierarchically decompose organizational strategies and produce a practical model of specific implementation steps for "classic" organizations. Our approach integrates popular types of performance management models. Last but not least, this thesis presents findings from three major cases, which are quite different organizations in terms of management styles, ownership, and operating environment, to illustrate the fliexbility of the developed theoretical framework
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