Estimating a Personalized Basal Insulin Dose from Short-Term Closed-Loop Data in Type 2 Diabetes

In type 2 diabetes (T2D) treatment, finding a safe and effective basal insulin dose is a challenge. The dose-response is highly individual and to ensure safety, people with T2D titrate by slowly increasing the daily insulin dose to meet treatment targets. This titration can take months. To ease and accelerate the process, we use short-term artificial pancreas (AP) treatment tailored for initial titration and apply it as a diagnostic tool. Specifically, we present a method to automatically estimate a personalized daily dose of basal insulin from closed-loop data collected with an AP. Based on AP-data from a stochastic simulation model, we employ the continuous-discrete extended Kalman filter and a maximum likelihood approach to estimate parameters in a simple dose-response model for 100 virtual people. With the identified model, we compute a daily dose of basal insulin to meet treatment targets for each individual. We test the personalized dose and evaluate the treatment outcomes against clinical reference values. In the tested simulation setup, the proposed method is feasible. However, more extensive tests will reveal whether it can be deemed safe for clinical implementation.Comment: 6 pages, 4 figures, 1 table. Accepted for publication in Proceedings of the 2022 61st IEEE Conference on Decision and Control (CDC

Sphinx measurements of the 2009 solar minimum x-ray emission

The SphinX X-ray spectrophotometer on the CORONAS-PHOTON spacecraft measured soft X-ray emission in the 1-15 keV energy range during the deep solar minimum of 2009 with a sensitivity much greater than GOES. Several intervals are identified when the X-ray flux was exceptionally low, and the flux and solar X-ray luminosity are estimated. Spectral fits to the emission at these times give temperatures of 1.7-1.9 MK and emission measures between 4 x 10^47 cm^-3 and 1.1 x 10^48 cm^-3. Comparing SphinX emission with that from the Hinode X-ray Telescope, we deduce that most of the emission is from general coronal structures rather than confined features like bright points. For one of 27 intervals of exceptionally low activity identified in the SphinX data, the Sun's X-ray luminosity in an energy range roughly extrapolated to that of ROSAT (0.1-2.4 keV) was less than most nearby K and M dwarfs.Comment: Astrophysical Journal, in press. 14 pp, 3 figure

Conceptualising quality of life for older people with aphasia

Background: There is an increasing need in speech and language therapy for clinicians to provide intervention in the context of the broader life quality issues for people with aphasia. However, there is no descriptive research that is explicitly focused on quality of life (QoL) from the perspectives of older people with aphasia. Aims: The current study explores how older people with chronic aphasia who are living in the community describe their QoL in terms of what contributes to and detracts from the quality in their current and future lives. The study is descriptive in nature, and the purpose is to conceptualize the factors that influence QoL. Methods & Procedures: Thirty older participants (16 women, 14 men) with mild to moderate aphasic impairment took part. All participants had adequate communication skills to participate: demonstrating reliable yes/no response and moderate auditory comprehension ability. Participants were interviewed in their own homes using six brief unprompted open questions about QoL, in a structured interview. The first five questions were drawn from previous gerontological research (Farquhar, 1995), and a sixth question specifically targeting communication was added. Content analysis was used, identifying discrete units of data and then coding these into concepts and factors. Additional demographic information was collected, and participants’ mood on day of interviewing was assessed using the Geriatric Depression Scale (Sheikh & Yesavage, 1986). Outcomes & Results: Activities, verbal communication, people, and body functioning were the core factors in QoL for these participants, and they described how these factors both contributed quality in life as well as detracted from life quality. Other factors that influenced QoL included stroke, mobility, positive personal outlook, in/dependence, home and health. Whilst the findings are limited by the lack of probing of participants’ responses, the study does present preliminary evidence for what is important in QoL to older people with aphasia. Conclusions: Quality of life for older people with predominantly mild to moderate chronic aphasia who are living in the community is multifactorial in nature. Some factors lie within the remit of speech and language therapy, some lie beyond the professional role, but all are relevant for consideration in rehabilitation and community practice. Further qualitative research is implicated to better understand QoL with aphasia, using in-depth interviewing with a broader range of people with aphasia

Relaxation Methods for Mixed-Integer Optimal Control of Partial Differential Equations

We consider integer-restricted optimal control of systems governed by abstract semilinear evolution equations. This includes the problem of optimal control design for certain distributed parameter systems endowed with multiple actuators, where the task is to minimize costs associated with the dynamics of the system by choosing, for each instant in time, one of the actuators together with ordinary controls. We consider relaxation techniques that are already used successfully for mixed-integer optimal control of ordinary differential equations. Our analysis yields sufficient conditions such that the optimal value and the optimal state of the relaxed problem can be approximated with arbitrary precision by a control satisfying the integer restrictions. The results are obtained by semigroup theory methods. The approach is constructive and gives rise to a numerical method. We supplement the analysis with numerical experiments