Locked and Unlocked Chains of Planar Shapes

We extend linkage unfolding results from the well-studied case of polygonal linkages to the more general case of linkages of polygons. More precisely, we consider chains of nonoverlapping rigid planar shapes (Jordan regions) that are hinged together sequentially at rotatable joints. Our goal is to characterize the families of planar shapes that admit locked chains, where some configurations cannot be reached by continuous reconfiguration without self-intersection, and which families of planar shapes guarantee universal foldability, where every chain is guaranteed to have a connected configuration space. Previously, only obtuse triangles were known to admit locked shapes, and only line segments were known to guarantee universal foldability. We show that a surprisingly general family of planar shapes, called slender adornments, guarantees universal foldability: roughly, the distance from each edge along the path along the boundary of the slender adornment to each hinge should be monotone. In contrast, we show that isosceles triangles with any desired apex angle less than 90 degrees admit locked chains, which is precisely the threshold beyond which the inward-normal property no longer holds.Comment: 23 pages, 25 figures, Latex; full journal version with all proof details. (Fixed crash-induced bugs in the abstract.

Localizability of Wireless Sensor Networks: Beyond Wheel Extension

A network is called localizable if the positions of all the nodes of the network can be computed uniquely. If a network is localizable and embedded in plane with generic configuration, the positions of the nodes may be computed uniquely in finite time. Therefore, identifying localizable networks is an important function. If the complete information about the network is available at a single place, localizability can be tested in polynomial time. In a distributed environment, networks with trilateration orderings (popular in real applications) and wheel extensions (a specific class of localizable networks) embedded in plane can be identified by existing techniques. We propose a distributed technique which efficiently identifies a larger class of localizable networks. This class covers both trilateration and wheel extensions. In reality, exact distance is almost impossible or costly. The proposed algorithm based only on connectivity information. It requires no distance information

Current Challenges in Autonomous Vehicle Development

The field of autonomous vehicles is a rapidly growing one, with significant interest from both government and industry sectors. Autonomous vehicles represent the intersection of artificial intelligence (AI) and robotics, combining decision-making with real-time control. Autonomous vehicles are desired for use in search and rescue, urban reconnaissance, mine detonation, supply convoys, and more. The general adage is to use robots for anything dull, dirty, dangerous or dumb. While a great deal of research has been done on autonomous systems, there are only a handful of fielded examples incorporating machine autonomy beyond the level of teleoperation, especially in outdoor/complex environments. In an attempt to assess and understand the current state of the art in autonomous vehicle development, a few areas where unsolved problems remain became clear. This paper outlines those areas and provides suggestions for the focus of science and technology research. The first step in evaluating the current state of autonomous vehicle development was to develop a definition of autonomy. A number of autonomy level classification systems were reviewed. The resulting working definitions and classification schemes used by the authors are summarized in the opening sections of the paper. The remainder of the report discusses current approaches and challenges in decision-making and real-time control for autonomous vehicles. Suggested research focus areas for near-, mid-, and long-term development are also presented

Characterizing the universal rigidity of generic frameworks

A framework is a graph and a map from its vertices to E^d (for some d). A framework is universally rigid if any framework in any dimension with the same graph and edge lengths is a Euclidean image of it. We show that a generic universally rigid framework has a positive semi-definite stress matrix of maximal rank. Connelly showed that the existence of such a positive semi-definite stress matrix is sufficient for universal rigidity, so this provides a characterization of universal rigidity for generic frameworks. We also extend our argument to give a new result on the genericity of strict complementarity in semidefinite programming.Comment: 18 pages, v2: updates throughout; v3: published versio

The CKD.QLD data linkage framework: chronic kidney disease and health services utilisation in Queensland, Australia

Chronic kidney disease (CKD) is one of the most common chronic diseases in the western world. In Australia, around 1.7 million Australians aged 18 years and over (about one in ten) have indicators of CKD, and 1.8 million hospitalisations were associated with CKD in 2017–18. There is currently very little understanding of the impact of CKD on health service utilisation and costs. Understanding the disease pathways of CKD and its effects on service utilisation and patient outcomes is essential to predicting the course of the disease in the future, its effects on health services utilisation and capacity to better manage the burden of premature deaths or the need for dialysis that results from CKD. We describe the establishment of a data linkage framework to study hospital admissions of CKD patients in the public renal services in the Australian state of Queensland, and its potential to advance understanding of their course and outcomes. Seven years of retrospective data (2011–2018) on hospital-based health services utilisation were provided by Queensland Health for all 7,341 patients who enrolled in the CKD.QLD Registry up to Jan 2019. The data were supplied from three datasets: the Queensland Hospital Admitted Patient Data Collection, the Queensland Registrar General deaths, and the Activity Based Funding Model Output data. In addition, data were supplied from two cohorts of de-identified patients admitted to hospital in the same interval (22,023 patients each), who were not in the CKD.QLD Registry, the first with CKD and the second without CKD as indicated by International Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification. The comprehensive and multifaceted data via the data linkage will enable us to identify opportunities for efficiencies in management of patients with CKD and for interventions that improve their outcomes

Frailty exists in younger adults admitted as surgical emergency leading to adverse outcomes

Background: Frailty is prevalent in the older adult population (≥65 years of age) and results in adverse outcomes in the emergency general surgical population. Objective: To determine whether frailty exists in the younger adult emergency surgical population (<65 years) and what influence frailty may have on patient related outcomes. Design: Prospective observational cohort study. Setting: Emergency general surgical admissions. Participants: All patients ≥40 years divided into 2 groups: younger adults (40-64.9 years) and older adult comparative group (≥65). Measurements: Over a 6-month time frame the following data was collected: demographics; Scottish Index of Multiple Deprivation (SIMD); blood markers; multi-morbidities, polypharmacy and cognition. Frailty was assessed by completion of the Canadian Study of Health and Ageing (CSHA). Each patient was followed up for 90 days to allow determination of length of stay, re-admission and mortality. Results: 82 young adults were included and the prevalence of frailty was 16% (versus older adults 38%; p=0.001) and associated with: multi-morbidity; poly-pharmacy; cognitive impairment; and deprivation. Frailty in older adults was only significantly associated with increasing age. Conclusions: This novel study has found that frailty exists in 16% of younger adults admitted to emergency general surgical units, potentially leading to adverse short and long-term outcomes. Strategies need to be developed that identify and treat frailty in this vulnerable younger adult population

Do Not Attempt Resuscitation (DNAR) status in people with suspected COVID-19 : secondary analysis of the PRIEST observational cohort study

Background: Cardiac arrest is common in people admitted with suspected COVID-19 and has a poor prognosis. Do Not Attempt Resuscitation (DNAR) orders can reduce the risk of futile resuscitation attempts but have raised ethical concerns. Objectives: We aimed to describe the characteristics and outcomes of adults admitted to hospital with suspected COVID-19 according to their DNAR status and identify factors associated with an early DNAR decision. Methods: We undertook a secondary analysis of 13977 adults admitted to hospital with suspected COVID-19 and included in the Pandemic Respiratory Infection Emergency System Triage (PRIEST) study. We recorded presenting characteristics and outcomes (death or organ support) up to 30 days. We categorised patients as early DNAR (occurring before or on the day of admission) or late/no DNAR (no DNAR or occurring after the day of admission). We undertook descriptive analysis comparing these groups and multivariable analysis to identify independent predictors of early DNAR. Results: We excluded 1249 with missing DNAR data, and identified 3929/12748 (31%) with an early DNAR decision. They had higher mortality (40.7% v 13.1%) and lower use of any organ support (11.6% v 15.7%), but received a range of organ support interventions, with some being used at rates comparable to those with late or no DNAR (e.g. non-invasive ventilation 4.4% v 3.5%). On multivariable analysis, older age (p<0.001), active malignancy (p<0.001), chronic lung disease (p<0.001), limited performance status (p<0.001), and abnormal physiological variables were associated with increased recording of early DNAR. Asian ethnicity was associated with reduced recording of early DNAR (p=0.001). Conclusions: Early DNAR decisions were associated with recognised predictors of adverse outcome, and were inversely associated with Asian ethnicity. Most people with an early DNAR decision survived to 30 days and many received potentially life-saving interventions. Registration: ISRCTN registry, ISRCTN28342533, http://www.isrctn.com/ISRCTN2834253