Partial Differential Equations for Missing Boundary Conditions in the Linear-Quadratic Optimal Control Problem

New equations involving the unknown final states and initial costates corresponding to families of LQR problems are found, and their solutions are computed and validated. Having the initial values of the costates, the optimal control can then be constructed, for each particular problem, from the solution to the Hamiltonian equations, now achievable through on-line integration. The missing boundary conditions are obtained by solving (offline) two uncoupled, first-order, quasi-linear, partial differential equations for two auxiliary n × n matrices, whose independent variables are the timehorizon duration T and the final-penalty matrix S. The solutions to these PDEs give information on the behavior of the whole two-parameter family of control problems, which can be used for design purposes. The mathematical treatment takes advantage of the symplectic structure of the Hamiltonian formalism, which allows to reformulate one of Bellman's conjectures related to the “invariantimbedding” methodology. Results are tested against solutions of the differential Riccati equations associated with these problems, and the attributes of the two approaches are illustrated and discussed.Fil: Costanza, Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Neuman, C. E.. Universidad Nacional del Litoral; Argentin

Effects of combination drug therapy on the subcutaneous and pulmonary growth of a slow and a fast-growing C3H/He mammary carcinoma

Changes in susceptibility to treatment with Cytoxan, methotrexate, 5-fluorouracil, and Adriamycin, single or in combination, have been studied during the initial and progressive stages of s.c. and pulmonary (via tail vein injection) growth of two transplanted syngeneic C3H/He mammary carcinomas. One tumor was fast growing, reaching a size of 3 mm from a 1-mm s.c. implant in 7 days; the second tumor would grow to the same size in 30 days. The tumor with the slower growth rate was more susceptible to drug treatment, manifested by delayed growth as well as by prevented growth. The slower-growing tumor also remained susceptible longer, when treatment was delayed, than did the faster-growing tumor. Pulmonary growth was more often prevented by drug treatment than was s.c. growth. Tumor implants s.c. which had reached palpable size could be reduced temporarily to impalpable size by effective drug treatment but were rarely cured. The importance of early treatment relative to the time of tumor implantation was indicated when early treatment with a single drug proved more effective than did delayed treatment with a more potent combination of drugs

Data Acquisition, Management and Tracking

As part of the mini-symposium entitled Data Acquisition, Data Management, and Subject Tracking in Clinical and Translational Research: Seeking Solutions to Persistent Challenges, Drs. Barton and Costanza introduce the symposium with a presentation explaining the importance of data acquisition, management, and tracking of clinical research data

Students’ perceptions of research projects in a first-year integrated science program

Science One at the University of British Columbia (UBC) is an intensive, integrated first-year science program in which the 75 accepted students take math, chemistry, physics, and biology in a year-long cohort. They participate in term projects each semester which are supported by lessons in Scientific Thinking & Literacy, faculty mentorship and reflective exercises. In the term 2 project, students are tasked with answering a scientific research question of their choosing through experimentation or modeling. The term 2 project culminates in a written and oral report at the end of the year. This is a unique opportunity for students to gain hands-on experience with the scientific method while placing an emphasis on transferable skills. We investigated the impact of the term 2 project on students’ perception of learning the scientific method. Students from the most recent cohort of Science One (2022-23) were recruited to participate. Using a mixed methods approach, we conducted a survey to assess the students’ perceptions of the project following completion of their final oral and written reports. Students were also invited to consent to the use of their term 2 reflection assignments to assess their attitudes and perspectives at multiple points throughout the project. This presentation will detail the process of the term 2 project for both students and instructors and provide a detailed discussion of our results. We will conclude with an analysis of the benefits and limitations of expanding small-scale research projects into the broader science curriculum. This research was approved by the UBC Behavioural Research Ethics Board

The complex relationships between economic inequality and biodiversity: A scoping review

Biodiversity change and increasing within-country economic inequalities represent two of the greatest global challenges of the Anthropocene. The most marginalized in society are often the most vulnerable to biodiversity change but there is no consensus on the relationships between biodiversity change and rising economic inequalities. To address this gap, we conducted a systematic scoping review of the literature and found 27 studies that explicitly examined the relationships between economic inequality and biodiversity. These were predominantly quantitative but also included qualitative, scenario, and review papers. The majority of studies (21/27) found evidence to suggest that more unequal regions had lower levels of biodiversity, and also that wealthier areas had higher levels of biodiversity. However, few studies investigated the causal mechanisms underlying the reported relationships, and there was little consistency in the metrics used to measure either inequality or biodiversity. Future research needs to focus on testing, or in-depth explorations, of causal mechanisms, with both quantitative and qualitative approaches needed. It is crucial that we understand how economic inequality and biodiversity interact if we are to meet the aims of reducing economic inequality and preventing further biodiversity loss

Activity and Rotation in the young cluster h Per

We study the stellar rotation-activity relation in the crucial age at which stars reach the fastest rotation. To this aim we have analyzed data of the young cluster h Per, very rich and compact, located at 2300 pc, that at an age of 13 Myr should be mainly composed of stars that have ended their contraction phase and that have not lost significant angular momentum viamagnetic breaking. To constrain the activity level of h Per members we have analyzed a deep Chandra/ACIS-I observation. Rotational periods of h Per members have been derived by Moraux et al. (2013) in the framework of the MONITOR project (Aigrain et al. 2007; Irwin et al. 2007). In the Chandra observation we have detected 1010 X-ray sources located in the central field of h Persei. Assuming a distance of 2300 pc their X-ray luminosity ranges between 2x10^29 and 6x10^31 erg/s. Among the 1010 x-ray sources ~600 have as optical counterpart candidate members of the cluster with masses ranging down to 0.3 solar mass, and ˜150 have also measured rotational period. For this sample of ˜150 h Per members we have compared X-ray luminosity and rotational periods for different mass ranges. We have found that solar type stars (~1.3 solar mass) show evidence of supersaturation for short periods. This phenomenon is unobserved for lower mass stars

Designing Natural Language Output for the IoT

A large number of devices categorised as "Internet of Things" (IoT) that are in the consumer market are designed to autonomously monitor things of interest to users. These devices often make use of natural language output, more specifically textual messages, as a way to notify users. These messages are commonly simple predetermined strings. Some IoT devices however are designed to report on complex applications, which may be difficult for users without technical domain knowledge to understand. In this work, we present an initial evaluation in which we investigated how users' inclination to attend to a monitoring system is affected by different levels of information. Based our findings, we discuss future avenues of research which we believe will further our understanding of natural language output's application in the IoT domain

Save Money or Feel Cozy?: A Field Experiment Evaluation of a Smart Thermostat that Learns Heating Preferences

We present the design of a fully autonomous smart thermostat that supports end-users in managing their heating preferences in a realtime pricing regime. The thermostat uses a machine learning algorithm to learn how a user wants to trade off comfort versus cost. We evaluate the thermostat in a field experiment in the UK involving 30 users over a period of 30 days. We make two main contributions. First, we study whether our smart thermostat enables end-users to handle real-time prices, and in particular, whether machine learning can help them. We find that the users trust the system and that they can successfully express their preferences; overall, the smart thermostat enables the users to manage their heating given real-time prices. Moreover, our machine learning-based thermostats outperform a baseline without machine learning in terms of usability. Second, we present a quantitative analysis of the users’ economic behavior, including their reaction to price changes, their price sensitivity, and their comfort-cost trade-offs. We find a wide variety regarding the users’ willingness to make trade-offs. But in aggregate, the users’ settings enabled a large amount of demand response, reducing the average energy consumption during peak hours by 38%

The effectiveness of interventions for optometric referrals into the hospital eye service: A review

Purpose: Ophthalmic services are currently under considerable stress; in the UK, ophthalmology departments have the highest number of outpatient appointments of any department within the National Health Service. Recognising the need for intervention, several approaches have been trialled to tackle the high numbers of false-positive referrals initiated in primary care and seen face to face within the hospital eye service (HES). In this mixed-methods narrative synthesis, we explored interventions based on their clinical impact, cost and acceptability to determine whether they are clinically effective, safe and sustainable. A systematic literature search of PubMed, MEDLINE and CINAHL, guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), was used to identify appropriate studies published between December 2001 and December 2022. Recent Findings: A total of 55 studies were reviewed. Four main interventions were assessed, where two studies covered more than one type: training and guidelines (n = 8), referral filtering schemes (n = 32), asynchronous teleophthalmology (n = 13) and synchronous teleophthalmology (n = 5). All four approaches demonstrated effectiveness for reducing false-positive referrals to the HES. There was sufficient evidence for stakeholder acceptance and cost-effectiveness of referral filtering schemes; however, cost comparisons involved assumptions. Referral filtering and asynchronous teleophthalmology reported moderate levels of false-negative cases (2%–20%), defined as discharged patients requiring HES monitoring. Summary: The effectiveness of interventions varied depending on which outcome and stakeholder was considered. More studies are required to explore stakeholder opinions around all interventions. In order to maximise clinical safety, it may be appropriate to combine more than one approach, such as referral filtering schemes with virtual review of discharged patients to assess the rate of false-negative cases. The implementation of a successful intervention is more complex than a ‘one-size-fits-all’ approach and there is potential space for newer types of interventions, such as artificial intelligence clinical support systems within the referral pathway