The scale free and scale - bound properties of land surfaces: fractal analysis and specific geomorphometry from digital terrain models

The scale-bound view of landsurfaces, being an assemblage of certain landforms, occurring within limited scale ranges, has been challenged by the scale-free characteristics of fractal geometry. This thesis assesses the fractal model by examining the irregularity of landsurface form, for the self-affine behaviour present in fractional Brownian surfaces. Different methods for detecting self-affine behaviour in surfaces are considered and of these the variogram technique is shown to be the most effective. It produces the best results of two methods tested on simulated surfaces, with known fractal properties. The algorithm used has been adapted to consider log (altitude variance) over a sample of log (distances) for: complete surfaces; subareas within surfaces; separate directions within surfaces. Twenty seven digital elevation models of landsurfaces arc re-examined for self- affine behaviour. The variogram results for complete surfaces show that none of these are self-affine over the scale range considered. This is because of dominant slope lengths and regular valley, spacing within areas. For similar reasons subarea analysis produces the non-fractal behaviour of markedly different variograms for separate subareas. The linearity of landforms in many areas, is detected by the variograms for separate directions. This indicates that the roughness of landsurfaces is anisotropic, unlike that of fractal surfaces. Because of difficulties in extracting particular landforms from their landsurfaces, no clear links between fractal behaviour, and landform size distribution could be established. A comparative study shows the geomorphometric parameters of fractal surfaces to vary with fractal dimension, while the geomorphometry of landsurfaces varies with the landforms present. Fractal dimensions estimated from landsurfaces do not correlate with geomorphometric parameters. From the results of this study, real landsurfaces would not appear to be scale- free. Therefore, a scale-bound approach towards landsurfaces would seem to be more appropriate to geomorphology than the fractal alternative

Description and Vorticity Analysis of 50-Day Oscillations in the Western Tropical Region of the CME Model

The WOCE Community Modeling Effort (CME) general circulation model of the North Atlantic was used to investigate the behavior, nature, and dynamics of 50-day oscillations seen in the meridional component of velocity between 5 degrees and 11 degrees N, 35 degrees and 55 degrees W. Oscillations of the meridional component of velocity, with a period of about 50 days, appear as the seasonal meander pattern of the North Equatorial Countercurrent starts to break down in December. They appear first near 35 degrees W and are advected westward. They have a westward phase velocity of about 0.1 m s(-1), wavelength of about 600 km, and a very slow eastward group velocity. Their period, phase speed, and wavelength agree with recent observations. Calculation of the leading terms from the full vorticity equation following a modal decomposition in the propagation region showed that the oscillations were first and second mode baroclinic Rossby waves. Repetition of the vorticity analysis on an undecomposed snapshot during the period of the retroflection revealed the NECC meanders also to be baroclinic Rossby waves, the same as the 50-day oscillations. These findings, together with the time evolution of the individual flow components over an annual cycle, suggested that the 50-day oscillations were the westward advected residue of the NECC meander pattern that is released as the NECC slows in December. The retroflecting North Brazil Current produces Rossby waves with very slow eastward group velocity that are advected eastward by the NECC until they reach 35 degrees W, where they dissipate. A standing wave pattern is established for several months, while the NECC is active. Once it slows, the waves are advected westward and disappear totally by May. Neither wind forcing nor barotropic instability were considered to be responsible for the oscillations in the model

Feynman’s Clock, a New Variational Principle, and Parallel-in-Time Quantum Dynamics

We introduce a discrete-time variational principle inspired by the quantum clock originally proposed by Feynman and use it to write down quantum evolution as a ground-state eigenvalue problem. The construction allows one to apply ground-state quantum many-body theory to quantum dynamics, extending the reach of many highly developed tools from this fertile research area. Moreover, this formalism naturally leads to an algorithm to parallelize quantum simulation over time. We draw an explicit connection between previously known time-dependent variational principles and the time-embedded variational principle presented. Sample calculations are presented, applying the idea to a hydrogen molecule and the spin degrees of freedom of a model inorganic compound, demonstrating the parallel speedup of our method as well as its flexibility in applying ground-state methodologies. Finally, we take advantage of the unique perspective of this variational principle to examine the error of basis approximations in quantum dynamics.Chemistry and Chemical Biolog

Effects of Exercise Intensity on Postexercise Endothelial Function and Oxidative Stress

Purpose. To measure endothelial function and oxidative stress immediately, 90 minutes, and three hours after exercise of varying intensities. Methods. Sixteen apparently healthy men completed three exercise bouts of treadmill running for 30 minutes at 55% V˙O2max (mild); 20 minutes at 75% V˙O2max (moderate); or 5 minutes at 100% V˙O2max (maximal) in random order. Brachial artery flow-mediated dilation (FMD) was assessed with venous blood samples drawn for measurement of endothelin-1 (ET-1), lipid hydroperoxides (LOOHs), and lipid soluble antioxidants. Results. LOOH increased immediately following moderate exercise (P<0.05). ET-1 was higher immediately after exercise and 3 hours after exercise in the mild trial compared to maximal one (P<0.05). Transient decreases were detected for ΔFMD/ShearAUC from baseline following maximal exercise, but it normalised at 3 hours after exercise (P<0.05). Shear rate was higher immediately after exercise in the maximal trial compared to mild exercise (P<0.05). No changes in baseline diameter, peak diameter, absolute change in diameter, or FMD were observed following any of the exercise trials (P>0.05). Conclusions. Acute exercise at different intensities elicits varied effects on oxidative stress, shear rate, and ET-1 that do not appear to mediate changes in endothelial function measured by FMD

Mapping regional risks from climate change for rainfed rice cultivation in India

Global warming is predicted to increase in the future, with detrimental consequences for rainfed crops that are dependent on natural rainfall (i.e. non-irrigated). Given that many crops grown under rainfed conditions support the livelihoods of low-income farmers, it is important to highlight the vulnerability of rainfed areas to climate change in order to anticipate potential risks to food security. In this paper, we focus on India, where ~ 50% of rice is grown under rainfed conditions, and we employ statistical models (climate envelope models (CEMs) and boosted regression trees (BRTs)) to map changes in climate suitability for rainfed rice cultivation at a regional level (~ 18 × 18 km cell resolution) under projected future (2050) climate change (IPCC RCPs 2.6 and 8.5, using three GCMs: BCC-CSM1.1, MIROC-ESM-CHEM, and HadGEM2-ES). We quantify the occurrence of rice (whether or not rainfed rice is commonly grown, using CEMs) and rice extent (area under cultivation, using BRTs) during the summer monsoon in relation to four climate variables that affect rice growth and yield namely ratio of precipitation to evapotranspiration (PER), maximum and minimum temperatures (Tmax and Tmin), and total rainfall during harvesting. Our models described the occurrence and extent of rice very well (CEMs for occurrence, ensemble AUC = 0.92; BRTs for extent, Pearson's r = 0.87). PER was the most important predictor of rainfed rice occurrence, and it was positively related to rainfed rice area, but all four climate variables were important for determining the extent of rice cultivation. Our models project that 15%–40% of current rainfed rice growing areas will be at risk (i.e. decline in climate suitability or become completely unsuitable). However, our models project considerable variation across India in the impact of future climate change: eastern and northern India are the locations most at risk, but parts of central and western India may benefit from increased precipitation. Hence our CEM and BRT models agree on the locations most at risk, but there is less consensus about the degree of risk at these locations. Our results help to identify locations where livelihoods of low-income farmers and regional food security may be threatened in the next few decades by climate changes. The use of more drought-resilient rice varieties and better irrigation infrastructure in these regions may help to reduce these impacts and reduce the vulnerability of farmers dependent on rainfed cropping

Group Assessments to Help Build Online Learning Communities in Biomedical Science Distance Learning Programmes

Introduction: Biomedical Science distance learning courses offer flexibility in study while in employment. Asynchronous and self-learning approaches are common within such courses and often student-student interaction is limited. The aims of this study were to establish learning communities, develop confidence in participating in online teamwork and foster an appreciation of transferable skills including digital capabilities through remote group activities. Materials and Methods: Two cohorts of students (n = 20/n = 21) were enrolled in a microbiology module of an IBMS accredited MSc distance learning course. Groups of 4–5 students produced a digital output relating to current global infection-related issues, namely, assignment 1, production of a slide deck, which peers could use as learning resources and assignment 2, a voiceover PowerPoint debate, and infographic, voting assessment and peer/self-marking. Students also prepared reflections using written format and a FlipGrid video-recording. A qualitative content analysis was conducted on reflections from all students. Students completed a pre- and post-assignment survey focused on the development of transferable skills for the biomedical sector. Results: Students’ skills and confidence increased following completion of the group assignment, as evident from the pre- and post-questionnaire responses, namely, possession of digital skills and digital creation abilities (29% v 83%), applying for jobs which require digital skills (54% v 89%), talking about examples of using digital media during job interviews (21% v 78%) and demonstration of creativity during assignment tasks (33% v 90%). Critical thinking was more commonly demonstrated during the debate in comparison to the slide deck activity (p = 0.001). The importance of developing digital skills, was higher following completion of the group activities (p = 0.03). Students reflected on the value of the group activities in relation to knowledge acquisition (85%, 86%), collegiality (70%, 71%), digital skills development (80%, 90%), the fact that the activities were enjoyable (70%, 67%) and the development of peer interaction and support (50%, 67%) in relation to assignment 1 and 2, respectively. Discussion: Increasingly digital technologies are being used in the healthcare sector resulting in updated HCPC Standards of Proficiency. This study highlights that virtual group activities promote the establishment of supportive learning communities and the development of transferable skills including digital capabilities for application within the biomedical science workplace

Molecular and Cellular Biology Animations: Development and Impact on Student Learning

Educators often struggle when teaching cellular and molecular processes because typically they have only two-dimensional tools to teach something that plays out in four dimensions. Learning research has demonstrated that visualizing processes in three dimensions aids learning, and animations are effective visualization tools for novice learners and aid with long-term memory retention. The World Wide Web Instructional Committee at North Dakota State University has used these research results as an inspiration to develop a suite of high-quality animations of molecular and cellular processes. Currently, these animations represent transcription, translation, bacterial gene expression, messenger RNA (mRNA) processing, mRNA splicing, protein transport into an organelle, the electron transport chain, and the use of a biological gradient to drive adenosine triphosphate synthesis. These animations are integrated with an educational module that consists of First Look and Advanced Look components that feature captioned stills from the animation representing the key steps in the processes at varying levels of complexity. These animation-based educational modules are available via the World Wide Web at http://vcell.ndsu.edu/animations. An in-class research experiment demonstrated that student retention of content material was significantly better when students received a lecture coupled with the animations and then used the animation as an individual study activity