Surface Waves

Contains reports on one research project

Interplay between function and structure in complex networks

We show that abrupt structural transitions can arise in functionally optimal networks, driven by small changes in the level of transport congestion. Our results offer an explanation as to why so many diverse species of network structure arise in Nature (e.g. fungal systems) under essentially the same environmental conditions. Our findings are based on an exactly solvable model system which mimics a variety of biological and social networks. We then extend our analysis by introducing a novel renormalization scheme involving cost motifs, to describe analytically the average shortest path across multiple-ring-and-hub networks. As a consequence, we uncover a 'skin effect' whereby the structure of the inner multi-ring core can cease to play any role in terms of determining the average shortest path across the network.Comment: Expanded version of physics/0508228 with additional new result

Fluid and Diffusion Limits for Bike Sharing Systems

Bike sharing systems have rapidly developed around the world, and they are served as a promising strategy to improve urban traffic congestion and to decrease polluting gas emissions. So far performance analysis of bike sharing systems always exists many difficulties and challenges under some more general factors. In this paper, a more general large-scale bike sharing system is discussed by means of heavy traffic approximation of multiclass closed queueing networks with non-exponential factors. Based on this, the fluid scaled equations and the diffusion scaled equations are established by means of the numbers of bikes both at the stations and on the roads, respectively. Furthermore, the scaling processes for the numbers of bikes both at the stations and on the roads are proved to converge in distribution to a semimartingale reflecting Brownian motion (SRBM) in a $N^{2}$-dimensional box, and also the fluid and diffusion limit theorems are obtained. Furthermore, performance analysis of the bike sharing system is provided. Thus the results and methodology of this paper provide new highlight in the study of more general large-scale bike sharing systems.Comment: 34 pages, 1 figure

Air Navigation

Contains a report on a research project

Keeping Rural Medical Students Connected to their Roots: A “Home for the Holidays” Immersion Experience

Keeping Rural Medical Students Connected to their Roots: A “Home for the Holidays” Immersion Experience Abstract Introduction Preclinical medical students with an initial affinity for rural practice often experience urban disruption during training. Longer summer rural immersion experiences have been shown to be somewhat effective in keeping rural students connected to their rural roots. Some students cannot adapt their schedules to these longer experiences. In response, a brief practice experience near home during the winter break of the academic year was established. Methods Nineteen detailed rural practice assessments were completed by preclinical medical students during school years 2009-2014 and essays and anonymous evaluations of the experience were analyzed. Results All students reported the four components of the experience increased understanding of rural medicine and all but 2 reported it was relevant to their career objectives. These two, at this early stage in training, decided rural practice was not for them and subsequently chose sub-specialty training. Six of the 12 (50%) who have completed medical school chose a family medicine residency. The themes in the essay portion included insights into rural lifestyle, returning home, health system organization issues, and patient expectations and traditions. Conclusions Initial experience with a “home for the holidays” approach for rural immersion of rural medical students was successful in reconnecting these students to their roots, and 17/19 (90%) reported their intention to choose rural practice

Gene induction during differentiation of human monocytes into dendritic cells: an integrated study at the RNA and protein levels

Changes in gene expression occurring during differentiation of human monocytes into dendritic cells were studied at the RNA and protein levels. These studies showed the induction of several gene classes corresponding to various biological functions. These functions encompass antigen processing and presentation, cytoskeleton, cell signalling and signal transduction, but also an increase in mitochondrial function and in the protein synthesis machinery, including some, but not all, chaperones. These changes put in perspective the events occurring during this differentiation process. On a more technical point, it appears that the studies carried out at the RNA and protein levels are highly complementary.Comment: website publisher: http://www.springerlink.com/content/ha0d2c351qhjhjdm