On The Spin Evolution Of Isolated Pulsars

Neutron stars are the remnants of supernova explosions, and harbor the densest matter found in the universe. Because of their extreme physical characteristics, neutron stars make superb laboratories from which to study the nature of matter under conditions of extreme density that are not reproducible on Earth. The understanding of QCD matter is of fundamental importance to modern physics, and neutron stars provide a means of probing into the cold, dense region of the QCD phase diagram. Isolated pulsars are rotating neutron stars that emit beams of electromagnetic radiation into space which appear like lighthouses to observers on Earth. Observations of these objects have been documented with very high accuracy. Measurements of pulsar rotational velocity, along with its first and second time derivatives, show that they slow down over time. The generally accepted explanation for the spin-down is that the pulsars behave like giant magnetic dipoles that lose energy in the form of electromagnetic radiation. This assumption of magnetic dipole radiation (MDR) leads to a general power law constructed from observation and governed by the braking index n, which relates the frequency to spin-down. The theoretical value for n is exactly 3 for MDR, but accurate observational measurements consistently yield values between 1.0 and 2.8. The goal of this thesis is to improve understanding of the braking index through a two pronged investigation into this important quantity. We develop a frequency dependent model of the braking index that allows changing moment of inertia of the star, and changes in magnetic field properties in the MDR torque mechanism. For the first time, we use physically realistic equations of state, along with state of the art computational codes to determine the dynamic neutron star properties required. We probe the stars at constant baryonic rest masses ranging from 1.0 to 2.2 solar masses over a range of frequency spanning from zero to the Kepler frequency for each star. We also develop a toy model of two interacting dipoles to make a first attempt at describing a plausible scenario by which the pulsar magnetic moment may evolve in time

Fault controlled fluid flow and quartz cementation in porous sandstones

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

El uso de los objetos de aprendizaje reutilizables en la enseñanza de la poesía inglesa: explorando la influencia de las prácticas pedagógicas predominantes

peer-reviewedDespite the attempts to integrate ICT across the curriculum of all post-primary education systems in the developed world there remains low levels of use. One of the major reasons for this low level of use is the availability of curriculum relevant software. In recent years the availability of high quality authoring tools has provided opportunities for the low-cost development of highly reusable curricular relevant materials. The increasing use of educational repositories can now facilitate the wide-scale distribution of these resources. This has the potential to reconceptualise use of ICT across the curriculum in schools, particularly in the Humanities area. This research aimed to design curriculum specific educational software and explore the ways in which it was used by Irish post-primary teachers in their teaching of English. The research found that teachers used the software in different ways largely mirroring existing pedagogical practices. The research raises a number of issues for the development of such tailor-made solutions and highlights opportunities for future developers. The research concludes by presenting a tentative conceptual model of the nature of Reusable Learning Objects (RLOs) use and the implications for future development and use of reusable learning objects

Undersampling raster scans in spectromicroscopy for a reduced dose and faster measurements

Combinations of spectroscopic analysis and microscopic techniques are used across many disciplines of scientific research, including material science, chemistry and biology. X-ray spectromicroscopy, in particular, is a powerful tool used for studying chemical state distributions at the micro and nano scales. With the beam fixed, a specimen is typically rastered through the probe with continuous motion and a range of multimodal data is collected at fixed time intervals. The application of this technique is limited in some areas due to: long scanning times to collect the data, either because of the area/volume under study or the compositional properties of the specimen; and material degradation due to the dose absorbed during the measurement. In this work, we propose a novel approach for reducing the dose and scanning times by undersampling the raster data. This is achieved by skipping rows within scans and reconstructing the x-ray spectromicroscopic measurements using low-rank matrix completion. The new method is robust and allows for x 5-6 reduction in sampling. Experimental results obtained on real data are illustrated.Comment: 22 pages,11 figure

Willingness to participate in a randomized trial comparing catheters to fistulas for vascular access in incident hemodialysis patients: an international survey of nephrologists

BACKGROUND: Current guidelines favor fistulas over catheters as vascular access. Yet, the observational literature comparing fistulas to catheters has important limitations and biases that may be difficult to overcome in the absence of randomization. However, it is not clear if physicians would be willing to participate in a clinical trial comparing fistulas to catheters. OBJECTIVES: We also sought to elicit participants' opinions on willingness to participate in a future trial regarding catheters and fistulas. DESIGN: We created a three-part survey consisting of 19 questions. We collected demographic information, respondents' knowledge of the vascular access literature, appropriateness of current guideline recommendations, and their willingness to participate in a future trial. SETTING: Participants were recruited from Canada, Europe, Australia, and New Zealand. PARTICIPANTS: Participants include physicians and trainees who are involved in the care of end-stage renal disease patients requiring vascular access. MEASUREMENTS: Descriptive statistics were used to describe baseline characteristics of respondents according to geographic location. We used logistic regression to model willingness to participate in a future trial. METHODS: We surveyed nephrologists from Canada, Europe, Australia, and New Zealand to assess their willingness to participate in a randomized trial comparing fistulas to catheters in incident hemodialysis patients. RESULTS: Our results show that in Canada, 86 % of respondents were willing to participate in a trial (32 % in all patients; 54 % only in patients at high risk of primary failure). In Europe and Australia/New Zealand, the willingness to participate in a trial that included all patients was lower (28 % in Europe; 25 % in Australia/New Zealand), as was a trial that included patients at high risk of primary failure (38 % in Europe; 39 % in Australia/New Zealand). Nephrologists who have been in practice for a few years, saw a larger volume of patients, or self-identified as experts in vascular access literature were more likely to participate in a trial. LIMITATIONS: Survey distribution was limited to vascular access experts in participating European countries and ultimately led to a discrepancy in numbers of European to non-European respondents overall. Canadian views are likely over-represented in the overall outcomes. CONCLUSIONS: Our survey results suggest that nephrologists believe there is equipoise surrounding the optimal vascular access strategy and that a randomized controlled study should be undertaken, but restricted to those individuals with a high risk of primary fistula failure

A climate-conditioned catastrophe risk model for UK flooding

We present a transparent and validated climate-conditioned catastrophe flood model for the UK, that simulates pluvial, fluvial and coastal flood risks at 1 arcsec spatial resolution (∼ 20–25 m). Hazard layers for 10 different return periods are produced over the whole UK for historic, 2020, 2030, 2050 and 2070 conditions using the UK Climate Projections 2018 (UKCP18) climate simulations. From these, monetary losses are computed for five specific global warming levels above pre-industrial values (0.6, 1.1, 1.8, 2.5 and 3.3 ∘C). The analysis contains a greater level of detail and nuance compared to previous work, and represents our current best understanding of the UK's changing flood risk landscape. Validation against historical national return period flood maps yielded critical success index values of 0.65 and 0.76 for England and Wales, respectively, and maximum water levels for the Carlisle 2005 flood were replicated to a root mean square error (RMSE) of 0.41 m without calibration. This level of skill is similar to local modelling with site-specific data. Expected annual damage in 2020 was GBP 730 million, which compares favourably to the observed value of GBP 714 million reported by the Association of British Insurers. Previous UK flood loss estimates based on government data are ∼ 3× higher, and lie well outside our modelled loss distribution, which is plausibly centred on the observations. We estimate that UK 1 % annual probability flood losses were ∼ 6 % greater for the average climate conditions of 2020 (∼ 1.1 ∘C of warming) compared to those of 1990 (∼ 0.6 ∘C of warming), and this increase can be kept to around ∼ 8 % if all countries' COP26 2030 carbon emission reduction pledges and “net zero” commitments are implemented in full. Implementing only the COP26 pledges increases UK 1 % annual probability flood losses by 23 % above average 1990 values, and potentially 37 % in a “worst case” scenario where carbon reduction targets are missed and climate sensitivity is high.</p

The State of Global Air Quality Funding 2022

The only global snapshot of clean air funding from donor governments and philanthropic foundations. This report highlights funding trends and gaps in 2015-2021, as well as recommendations for smarter investment for people and planet.99% of the world's population breathes air that exceeds World Health Organization air quality guidelines. Cleaning the air is a massive opportunity to improve public health and climate change. Because air pollution and climate change are mainly caused by burning fossil fuels, these problems can be tackled together. By addressing these issues in isolation, funders and policymakers drastically overlook the potential of clean air to realise multiple health, social and sustainable economic benefits.Our fourth annual report is the only global snapshot of projects funded by international development funders and philanthropic foundations to tackle air pollution. We identify gaps in funding, and opportunities for strategic investment and collaboration for systemic change.?As the world prepares for COP27 in Egypt, we call for more joined up policies and funding to address air pollution, climate change and unsustainable economic growth simultaneously. This report provides recommendations for decision makers, policy makers and philanthropic foundations