Singularly Perturbed Monotone Systems and an Application to Double Phosphorylation Cycles

The theory of monotone dynamical systems has been found very useful in the modeling of some gene, protein, and signaling networks. In monotone systems, every net feedback loop is positive. On the other hand, negative feedback loops are important features of many systems, since they are required for adaptation and precision. This paper shows that, provided that these negative loops act at a comparatively fast time scale, the main dynamical property of (strongly) monotone systems, convergence to steady states, is still valid. An application is worked out to a double-phosphorylation ``futile cycle'' motif which plays a central role in eukaryotic cell signaling.Comment: 21 pages, 3 figures, corrected typos, references remove

Education qualification levels and school careers of unilateral versus bilateral hearing aid users.

Contains fulltext : 51872.pdf (publisher's version ) (Closed access)OBJECTIVE: Analyse the difference in school careers and secondary school qualification levels between unilateral hearing aid users and bilateral hearing aid users. STUDY DESIGN: Retrospective questionnaire study. SETTING: Postal-based questionnaire. PARTICIPANTS: Names of adults known to have been fitted with unilateral or bilateral hearing aids during childhood were retrieved. This resulted in 292 names. Participants were selected using the following criteria: availability of the medical record, presence of bilateral hearing loss, completed secondary school education, normal IQ and a minimum aided word-recognition score of 70% at 10 years of age. The questionnaire was sent to 50 potential participants of whom 40 responded, resulting in two groups comprising 19 unilateral and 21 bilateral hearing aid users. METHODS: A questionnaire was developed to obtain data on secondary school levels and aspects of the school careers, such as type of schools attended (mainstream versus special), repeating a school year and additional assistance (speech and language therapy, personal frequency modulation systems). MAIN OUTCOME MEASURES: Comparison of the benefit of bilateral hearing aid fitting versus unilateral hearing aid fitting on secondary school qualification level, type of school the children attended, class failure and additional assistance used. RESULTS: The group of bilaterally fitted hearing aid users eventually completed secondary school at a superior level than the unilaterally fitted users. 33% of binaural hearing aid users achieved qualifications giving access to a bachelors degree compared with 21% of unilateral users. There were no differences between those fitted with unilateral and bilateral hearing aids in the type of schools attended, repeating a school year and additional assistance. CONCLUSIONS: The bilateral hearing aid users obtained superior secondary school qualifications than the unilateral users but their school careers were comparable