8,804 research outputs found
European airline cockpit and cabin crew well-being during the COVID-19 lockdown : does union satisfaction have a buffering effect on mental health, organizational dehumanization, medication use, and job insecurity?
No full textThe COVID-19 pandemic has challenged the airline industry and airline companies to an extreme extent. Consequently, the European flight crew members have experienced diverse adverse outcomes. Historically, unions play a protective role in restructuring periods and challenging times, that is, union instrumentality. However, can unions still play a significant role in their members’ satisfaction when confronting an unknown pandemic? The present study explores the relationship between union satisfaction and four well-being indicators—mental health, organizational dehumanization, medication use, and job insecurity among European flight crew during the Covid-19 lockdown. A total of 1293 crew members (271 cockpit crew and 1022 cabin crew) across 53 major European airlines involving 42 nationalities completed an online survey. We control the following variables, e.g., age, gender, marital status, children (yes or no), professional group (cockpit crew or cabin crew), types of airline, relationship with the principal airline, and employment status—hours worked during lockdown. We test our hypotheses using hierarchical regression analyses and demonstrate the following novel discoveries. First, during the lockdown, employees with higher union satisfaction experience a lower level of airline management’s organizational dehumanization. We mainly observe a buffering effect of union representation at the airline-specific level. Second, other exciting buffering effects illustrate that a higher level of satisfaction with the union representation is significantly and positively associated with mental health and negatively associated with medication usage and job insecurity, even after controlling for confounding variables. Third, our results suggest that union representation can indirectly affect safety performance for the vulnerable target group at this critical time. Finally, we offer practical implications regarding policy and workplace management
Biomedical Applications of Liquid Metal Nanoparticles: A Critical Review
No full textThis review is focused on the basic properties, production, functionalization, cytotoxicity, and biomedical applications of liquid metal nanoparticles (LMNPs), with a focus on particles of the size ranging from tens to hundreds of nanometers. Applications, including cancer therapy, medical imaging, and pathogen treatment are discussed. LMNPs share similar properties to other metals, such as photothermal conversion ability and a propensity to form surface oxides. Compared to many other metals, especially mercury, the cytotoxicity of gallium is low and is considered by many reports to be safe when applied in vivo. Recent advances in exploring different grafting molecules are reported herein, as surface functionalization is essential to enhance photothermal therapeutic effects of LMNPs or to facilitate drug delivery. This review also outlines properties of LMNPs that can be exploited in making medical imaging contrast agents, ion channel regulators, and anti-pathogenic agents. Finally, a foresight is offered, exemplifying underexplored knowledge and highlighting the research challenges faced by LMNP science and technology in expanding into applications potentially yielding clinical advances
Organic semiconductors in the limit of a few monolayers : molecular surface doping of pentacene thin film transistors
No full textAutomatic Image Annotation and Object Detection
No full textWe live in the midst of the information era, during which organising and indexing information more effectively is a matter of essential importance. With the fast development of digital imagery, how to search images - a rich form of information - more efficiently by their content has become one of the biggest challenges. Content-based image retrieval (CBIR) has been the traditional and dominant technique for searching images for decades. However, not until recently have researchers started to realise some vital problems existing in CBIR systems. One of the most important is perhaps what people call the semantic gap, which refers to the gap between the information that can be extracted from images and the interpretation of the images for humans. As an attempt to bridge the semantic gap, automatic image annotation has been gaining more and more attentions in recent years. This thesis aims to explore a number of different approaches to automatic image annotation and some related issues. It begins with an introduction into different techniques for image description, which forms the foundation of the research on image auto-annotation. The thesis then goes on to give an in-depth examination of some of the quality issues of the data-set used for evaluating auto-annotation systems. A series of approaches to auto-annotation are presented in the follow-up chapters. Firstly, we describe an approach that incorporates the salient based image representation into a statistical model for better annotation performance. Secondly, we explore the use of non-negative matrix factorisation (NMF), a matrix decomposition technique, for two tasks; object class detection and automatic annotation of images. The results imply that NMF is a promising sub-space technique for these purposes. Finally, we propose a model named the image based feature space (IBFS) model for linking image regions and keywords, and for image auto-annotation. Both image regions and keywords are mapped into the same space in which their relationships can be measured. The idea of multiple segmentations is then implemented in the model, and better results are achieved than using a single segmentation
Lithium distribution across the membrane of motoneurons in the isolated frog spinal cord
No full textLithium sensitive microelectrodes were used to investigate the transmembrane distribution of lithium ions (Li+) in motoneurons of the isolated frog spinal cord. After addition of 5 mmol·l–1 LiCl to the bathing solution the extracellular diffusion of Li+ was measured. At a depth of 500 m, about 60 min elapsed before the extracellular Li+ concentration approached that of the bathing solution. Intracellular measurements revealed that Li+ started to enter the cells soon after reaching the motoneuron pool and after up to 120 min superfusion, an intra — to extracellular concentration ratio of about 0.7 was obtained. The resting membrane potential and height of antidromically evoked action potentials were not altered by 5 mmol·l–1 Li+
On certain moduli spaces of ideal sheaves and Donaldson-Thomas invariants
No full textWe determine the structure of certain moduli spaces of ideal sheaves by generalizing an earlier result of the first author. As applications, we compute the (virtual) Hodge polynomials of these moduli space, and calculate the Donaldson-Thomas invariants of certain 3-folds with trivial canonical classes.</p
Imagining Opera: Ideas of Western Opera in the British India, Singapore and Shanghai (1860s-1920s)
No full textThe focus of this thesis is on how “opera” as an idea was received and adapted beyond the Western world, in particular in these Asian regions: the British India, Singapore, and China. The thesis includes four topics: the relationship between travelling opera troupes and the European community in Singapore, opera burlesques in black face minstrelsy in the British India, Malay opera Bangsawan in Singapore and Li Jinhui’s children’s musical drama in Shanghai. This research attempts to answer three groups of questions: 1. In colonial cities in Asia, how did overseas Westerners and natives understand European opera as a cultural import? Was the opera culture in Asian colonies the replication of that in Europe? Moreover, was this culture transplanted directly from Europe? How did opera become an icon of colonial culture and stimulate the overseas Westerners’ collective imagination to it? 2. What is the relationship between canonic opera, including opera works and operatic conventions, and theatres derived from the canonic opera but belonging to popular culture, for instance, opera burlesques by minstrel actors? 3. Further the thesis attempts to investigate: how did Western opera influence native theatrical practices in Asia? And how did natives react and adapt the new ideas of musical theatre imported from the West and backed by Western powers? These questions are important not only for understanding the reception history of Western opera in Asia but also for inquiring how has “opera” become a global musical concept
A Study of the Thermodynamics and Kinetics of LiₓFePO₄ as a Cathode Material for Li Batteries
No full textOlivine-type LiFePO4 has been recognized as one of the most promising cathode materials for rechargeable Li batteries. Its advantages include high capacity, high stability, nontoxicity, and low cost. Our methods for synthesizing nanocrystalline LixFePO4 with the olivine structure are described. Solid-state reactions and precipitation reactions were both successful, and ball milling was especially effective at reducing crystallite sizes. Diffractometry and microscopy were used to characterize these materials, and results of impurity phases, excess Fe3+, and internal stresses are reported for the different types of synthesis.
Applications of lithium-ion batteries, including automotive applications, require fast kinetics and high conductivity of ions and electrons. Unfortunately, LixFePO4 has the electronic structure of an insulator, an entirely unsatisfactory situation if it is to be used as a battery electrode. Electrical conductivity in LixFePO4 occurs by the motion of small polarons, which are valence electrons at Fe atoms plus their distorted local environments. Electrical conductivity of LixFePO4 is interpreted in terms of small polaron hopping. There are other factors of importance in these measurements, such as impurities or defects that block the one-dimensional conduction channels of the olivine structure of LixFePO4.
We studied the polaron hopping directly, which allows us to understand the intrinsic electrical conductivity, and how it depends on microstructure and composition of LixFePO4. The experimental technique was Mossbauer spectrometry, which has been used for many years as a means for determining the fractions of Fe2+ and Fe3+ in a material. Usually the spectral signatures of Fe2+ and Fe3+ are distinct. When valence electrons hop between Fe2+ and Fe3+ at a frequency of 108 Hz or higher, however, the valence changes during the timescale of the Mossbauer measurement and the spectrum is blurred. By measuring Mossbauer spectra at elevated temperatures, we can determine the fractions of Fe atoms participating in polaron hopping, and determine the activation energy of the process. From this we estimate intrinsic electrical conductivities of 10-7S/cm at room temperature for nanocrystalline Li0.5FePO4, for example. We find a comparable conductivity for LixFePO4 prepared as a solid solution, but the conductivity of conventional LixFePO4 is much lower.
There has been much discussion about how surface area might thermodynamically stabilize the solid solution phase of nanocrystalline LixFePO4. In a series of X-ray diffraction measurements, some at elevated temperatures, we found the solid solution phase of LixFePO4 to be especially robust at room temperature when the material was prepared in nanocrystalline form. Moreover, the consistent phase transition temperature around 200°C was observed, as evidence for the unchanged equilibrium phase diagram by crystallite size. This is consistent with our evaluation on the boundaries of the two-phase mixture of triphylite and heterosite during Li insertion and extraction. Profiles of entropy and enthalpy changes were evaluated by open-circuit voltage measurements. The boundaries were found at x=0.05 and 0.95 in the LixFePO4 with crystal size of 70 nm, similar to the reported values on bulk-LixFePO4. These are important in practice, because electrochemical lithiation and delithiation at room temperature should remain as a two-phase transformation, even if a solid solution of lithium is present in the initial electrode material.</p
Fig. 5 in Range extension and extended diagnosis of Lycodon pictus: First country record from China
No full textFig. 5. Macrohabitat of Lycodon pictus in Nonggang National Nature Reserve, Longzhou, Guangxi, China. Photograph by Jin-Long Ren.Published as part of Janssen, Helen Yvonne, Jin-Long, Ren, Jia-Tang, Li, Zeng, Wang, Nguyen, Tao Thien, Nguyen, Truong Quang, Bui, Quynh Thi Thuy, Ngo, Hanh Thi, Le, Minh Duc & Ziegler, Thomas, 2020, Range extension and extended diagnosis of Lycodon pictus: First country record from China, pp. 413-422 in Revue suisse de Zoologie 127 (2) on page 420, DOI: 10.35929/RSZ.0030, http://zenodo.org/record/574393
Fig. 1 in Range extension and extended diagnosis of Lycodon pictus: First country record from China
No full textFig. 1. The new record of Lycodon pictus (VNMN 011227) from Vietnam in life. Photograph by Tao Thien Nguyen.Published as part of Janssen, Helen Yvonne, Jin-Long, Ren, Jia-Tang, Li, Zeng, Wang, Nguyen, Tao Thien, Nguyen, Truong Quang, Bui, Quynh Thi Thuy, Ngo, Hanh Thi, Le, Minh Duc & Ziegler, Thomas, 2020, Range extension and extended diagnosis of Lycodon pictus: First country record from China, pp. 413-422 in Revue suisse de Zoologie 127 (2) on page 416, DOI: 10.35929/RSZ.0030, http://zenodo.org/record/574393
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