Comparing methods for modelling spreading cell fronts

Spreading cell fronts play an essential role in many physiological processes. Classically, models of this process are based on the Fisher-Kolmogorov equation; however, such continuum representations are not always suitable as they do not explicitly represent behaviour at the level of individual cells. Additionally, many models examine only the large time asymptotic behaviour, where a travelling wave front with a constant speed has been established. Many experiments, such as a scratch assay, never display this asymptotic behaviour, and in these cases the transient behaviour must be taken into account. We examine the transient and asymptotic behaviour of moving cell fronts using techniques that go beyond the continuum approximation via a volume-excluding birth-migration process on a regular one-dimensional lattice. We approximate the averaged discrete results using three methods: (i) mean-field, (ii) pair-wise, and (iii) one-hole approximations. We discuss the performace of these methods, in comparison to the averaged discrete results, for a range of parameter space, examining both the transient and asymptotic behaviours. The one-hole approximation, based on techniques from statistical physics, is not capable of predicting transient behaviour but provides excellent agreement with the asymptotic behaviour of the averaged discrete results, provided that cells are proliferating fast enough relative to their rate of migration. The mean-field and pair-wise approximations give indistinguishable asymptotic results, which agree with the averaged discrete results when cells are migrating much more rapidly than they are proliferating. The pair-wise approximation performs better in the transient region than does the mean-field, despite having the same asymptotic behaviour. Our results show that each approximation only works in specific situations, thus we must be careful to use a suitable approximation for a given system, otherwise inaccurate predictions could be made.

Spiritual wisdom of Taoism in business : through the lens of interpretation realism in a Cisco end-to-end case study

This paper explores how the amalgamated wisdom of East and West can instigate a wisdombased renaissance of humanistic epistemology (Rooney & McKenna, 2005) to provide a platform of harmony in managing knowledge-worker productivity, one of the biggest management challenges of the 21st century (Drucker, 1999). The paper invites further discussions from the social and business research communities on the significance of "interpretation realism" technique in comprehending philosophies of Lao Tzu Confucius and Sun Tzu (Lao/Confucius/Sun] written in "Classical Chinese." This paper concludes with a call to build prudent, responsible practices in management which affects the daily lives of many (Rooney & McKenna, 2005) in today's knowledgebased economy. Interpretation Realism will be applied to an analysis of three Chinese classics of Lao/Confucius/Sun which have been embodied in the Chinese culture for over 2,500 years. Comprehending Lao/Confucius/Sun's philosophies is the first step towards understanding Classical Chinese culture. However, interpreting Chinese subtlety in language and the yin and yang circular synthesis in their mode of thinking is very different to understanding Western thought with its open communication and its linear, analytical pattern of Aristotelian/Platonic wisdom (Zuo, 2012). Furthermore, Eastern ways of communication are relatively indirect and mediatory in culture. Western ways of communication are relatively direct and litigious in culture (Goh, 2002). Furthermore, Lao/Confucius/Sun's philosophies are difficult to comprehend as there are four written Chinese formats and over 250 dialects: Pre-classical Chinese Classical Chinese Literary Chinese and modern Vernacular Chinese Because Classical Chinese is poetic, comprehension requires a mixed approach of interpretation realism combining logical reasoning behind "word splitting word occurrences", "empathetic metaphor" and "poetic appreciation of word.

Effect of ramipril on walking times and quality of life among patients with peripheral artery disease and intermittent claudication : a randomized controlled trial

Importance Approximately one-third of patients with peripheral artery disease experience intermittent claudication, with consequent loss of quality of life. Objective To determine the efficacy of ramipril for improving walking ability, patient-perceived walking performance, and quality of life in patients with claudication. Design, Setting, and Patients Randomized, double-blind, placebo-controlled trial conducted among 212 patients with peripheral artery disease (mean age, 65.5 [SD, 6.2] years), initiated in May 2008 and completed in August 2011 and conducted at 3 hospitals in Australia. Intervention Patients were randomized to receive 10 mg/d of ramipril (n = 106) or matching placebo (n = 106) for 24 weeks. Main Outcome Measures Maximum and pain-free walking times were recorded during a standard treadmill test. The Walking Impairment Questionnaire (WIQ) and Short-Form 36 Health Survey (SF-36) were used to assess walking ability and quality of life, respectively. Results At 6 months, relative to placebo, ramipril was associated with a 75-second (95% CI, 60-89 seconds) increase in mean pain-free walking time (P < .001) and a 255-second (95% CI, 215-295 seconds) increase in maximum walking time (P < .001). Relative to placebo, ramipril improved the WIQ median distance score by 13.8 (Hodges-Lehmann 95% CI, 12.2-15.5), speed score by 13.3 (95% CI, 11.9-15.2), and stair climbing score by 25.2 (95% CI, 25.1-29.4) (P < .001 for all). The overall SF-36 median Physical Component Summary score improved by 8.2 (Hodges-Lehmann 95% CI, 3.6-11.4; P = .02) in the ramipril group relative to placebo. Ramipril did not affect the overall SF-36 median Mental Component Summary score. Conclusions and Relevance Among patients with intermittent claudication, 24-week treatment with ramipril resulted in significant increases in pain-free and maximum treadmill walking times compared with placebo. This was associated with a significant increase in the physical functioning component of the SF-36 score. Trial Registration clinicaltrials.gov Identifier: NCT00681226

International contact lens prescribing in 2009

This is the eighth consecutive year that we have presented data from a survey of international contact lens prescribing in Contact Lens Spectrum. In this article we report on an assessment of 25,801 fits across 28 contact lens markets located in North America, Europe, the Middle East, Asia, and Africa. As in previous years, we opted for a prospective approach to this work. Up to 1,000 survey forms were randomly disseminated in each market to contact lens practitioners (ophthalmologists, optometrists, and/or opticians depending on the market), and information about the first 10 patients prescribed with lenses after receipt of paper or electronic survey forms was anonymously recorded.

RGP lenses 2010 : the last decade and the next decade

The results of the annual survey on international contact lens fits have become available again, which presents a great opportunity to distill the RGP lens data to see what the status of RGP lenses is today as well as to revisit the last decade of RGP lens fitting and to look ahead to the next decade.

International contact lens prescribing in 2010

For the past nine years, we have described the current state of contact lens fitting worldwide in Contact Lens Spectrum. This year, we report on 24,642 lens fits in 27 markets. As in all previous years, coordinators in each market distributed up to 1,000 paper or electronic survey forms to contact lens practitioners who, in turn, collected information about their next 10 fits. Data were processed and checked in the survey administrative offices in Manchester, United Kingdom and in Waterloo, Canada.

Globalisation of CL prescribing : the UK perspective

Globalisation is a concept that templates onto many aspects of the commercial world, and the contact lens field is no exception. The major international companies have worldwide distribution networks and supply lenses of the same product names and replacement frequencies to all nations, with a few minor adjustments for marketing and regulatory reasons. Small and mediumsized companies, often producing more specialist lenses, are also active in markets across the world.

Evolution or revolution?

Cosmetic tinted soft lenses, which were prescribed in 4-8 per cent of soft lens fits between 1997-2001, have declined in use and since 2003 have accounted for less than 2 per cent of soft lens fits. In general, there has been a slow but steady increase in the rate of prescribing for presbyopia.

The science behind the “stain”

It has been almost fi ve years since I fi rst published the article entitled “Much Ado About Staining” in Review of Optometry, which explored what we really knew in 2006 about the relationship between “corneal staining” and contact lens multipurpose solutions (MPS). This was published just prior to the controversial “staining grid.” While the Grid showed MPS-associated hyperfl uorescence under the slitlamp at two hours, it did not explain the “what” or “why” behind it; even so, many proponents of the Grid continue to suggest that it shows us which solution/lens combinations are “biocompatible” and which are not. New evidence suggests that the preservative-associated transient hyperfl uorescence (or PATH) observed at two hours after lens insertion is a benign phenomenon due to an interaction between fl uorescein, MPS preservatives, and corneal cell membranes. The misinterpretation of PATH as “real” corneal staining, like that observed in pathological conditions, may be due in part to the fact that there is not a lot of teaching regarding the true properties of fl uorescein and what is actually occurring when we see either PATH or corneal staining. To discuss the science of fl uorescein, corneal staining, and PATH, I have asked some of the preeminent research experts in the study of fl uorescence spectroscopy and corneal staining from around the world to share their new research and personal opinions on these topics...

Trends in Australian contact lens prescribing 2011

The 12th annual survey of Australian contact lens prescribing was conducted between January and April 2011, employing the same format as in previous years. About 3,000 optometrist members of Optometrists Association Australia were sent an e-mail message with a link to a downloadable questionnaire, and a request that this be accessed, printed and completed to provide details of the first 10 patients fitted with contact lenses after receipt of the questionnaire.

The science of compliance

A survey conducted in Australia and the Asian region of the way in which contact lens wearers use and maintain their lenses reveals disturbingly low levels of compliance with recommended practice. Key problem areas are identified, and a plea is made for practitioners to help reverse this trend.