The roles of apex dipoles and field penetration in the physics of charged, field emitting, single-walled carbon nanotubes

A 1 μm long, field emitting, (5, 5) single-walled carbon nanotube (SWCNT) closed with a fullerene cap, and a similar open nanotube with hydrogen-atom termination, have been simulated using the modified neglect of diatomic overlap quantum-mechanical method. Both contain about 80 000 atoms. It is found that field penetration and band bending, and various forms of chemically and electrically induced apex dipole play roles. Field penetration may help explain electroluminescence associated with field emitting CNTs. Charge-density oscillations, induced by the hydrogen adsorption, are also found. Many of the effects can be related to known effects that occur with metallic or semiconductor field emitters; this helps both to explain the effects and to unify our knowledge about FE emitters. However, it is currently unclear how best to treat correlation-and-exchange effects when defining the CNT emission barrier. A new form of definition for the field enhancement factor (FEF) is used. Predicted FEF values for these SWCNTs are significantly less than values predicted by simple classical formulae. The FEF for the closed SWCNT decreases with applied field; the FEF for the H-terminated open SWCNT is less than the FEF for the closed SWCNT but increases with applied field. Physical explanations for this behavior are proposed but the concept of FEF is clearly problematical for CNTs. Curved Fowler-Nordheim plots are predicted. Overall, the predicted field emission performance of the H-terminated open SWCNT is slightly better than that of the closed SWCNT, essentially because a C-H dipole is formed that reduces the height of the tunneling barrier. In general, the physics of a charged SWCNT seems much more complex than hitherto realized. © 2008 American Institute of Physics.published_or_final_versio

Hardware Acceleration in Image Stitching: GPU vs FPGA

Image stitching is a process where two or more images with an overlapping field of view are combined. This process is commonly used to increase the field of view or image quality of a system. While this process is not particularly difficult for modern personal computers, hardware acceleration is often required to achieve real-time performance in low-power image stitching solutions. In this thesis, two separate hardware accelerated image stitching solutions are developed and compared. One solution is accelerated using a Xilinx Zynq UltraScale+ ZU3EG FPGA and the other solution is accelerated using an Nvidia RTX 2070 Super GPU. The image stitching solutions implemented in this paper increase the system’s field of view and involve the end-to-end process of feature detection, image registration, and image mixing. The latency, resource utilization, and power consumption for the accelerated portions of each system are compared and each systems tradeoffs and use cases are considered

Enhancing emergency care in low-income countries using mobile technology-based training tools

In this paper, we discuss the role of mobile technology in developing training tools for health workers, with particular reference to low-income countries (LICs). The global and technological context is outlined, followed by a summary of approaches to using and evaluating mobile technology for learning in healthcare. Finally, recommendations are made for those developing and using such tools, based on current literature and the authors’ involvement in the field

The 1919 Railway Strike: the Government’s Response

This study aims to rethink the 1919 national British rail strike from the perspective of Lloyd George’s Coalition Government. This dissertation argues that the government were willing to use all in their power to defeat the strike. Prior historians have touched upon how the government combatted the strike, but this study will give a more thorough examination of the emergency measures which were implemented. It draws from government and railway company reports on the strike which became available after 1970. There has been sparingly little research on the 1919 rail dispute since Philp Bagwell’s study in 1963. Bagwell’s classical approach to the strike will be rethought in the light of the newly accessible government and Railway Company records. A new regional approach is included, assessing the local and regional newspapers in the northern Home Counties and the north east of England

Analysis of a capped carbon nanotube by linear-scaling density-functional theory.

The apex region of a capped (5,5) carbon nanotube (CNT) has been modelled with the DFT package ONETEP, using boundary conditions provided by a classical calculation with a conducting surface in place of the CNT. Results from the DFT solution include the Fermi level and the physical distribution and energies of individual orbitals for the CNT tip. Application of an external electric field changes the orbital number of the highest occupied molecular orbital (HOMO) and consequently changes its distribution on the CNT

Social resource as a critical and overlooked factor for patient safety in low-resource settings

Clinicians, NGOs, funders and academics (among others) in global health are accustomed to discussion of the “low-resource setting”. Commonly, the resources implicit in this term are physical (equipment, drugs) and infrastructural (electricity, water and sanitation) in nature. Human resources are well recognised as scarce in this context too, and the focus in most “workforce” research is on the number, distribution and/or training of healthcare workers. In this article, we make the case for closer examination of “social resource” as necessary to patient safety and distinct from simple enumeration of available/trained personnel. We use the clinical specialty of anaesthesia as a case study, identifying the different ways in which social resource is necessary to enable safe practice for anaesthesia providers, and the potential challenges to accessing social resource relevant in the low- and middle-income context. Finally, we suggest ways in which social resource for anaesthesia professionals in LMICs might be meaningfully investigated, with a view to improving its priority and access for safe anaesthesia care worldwide