The Strong Maximum Circulation Algorithm: A New Method for Aggregating Preference Rankings

We present a new optimization-based method for aggregating preferences in settings where each decision maker, or voter, expresses preferences over pairs of alternatives. The challenge is to come up with a ranking that agrees as much as possible with the votes cast in cases when some of the votes conflict. Only a collection of votes that contains no cycles is non-conflicting and can induce a partial order over alternatives. Our approach is motivated by the observation that a collection of votes that form a cycle can be treated as ties. The method is then to remove unions of cycles of votes, or circulations, from the vote graph and determine aggregate preferences from the remainder. We introduce the strong maximum circulation which is formed by a union of cycles, the removal of which guarantees a unique outcome in terms of the induced partial order. Furthermore, it contains all the aggregate preferences remaining following the elimination of any maximum circulation. In contrast, the well-known, optimization-based, Kemeny method has non-unique output and can return multiple, conflicting rankings for the same input. In addition, Kemeny's method requires solving an NP-hard problem, whereas our algorithm is efficient, based on network flow techniques, and runs in strongly polynomial time, independent of the number of votes. We address the construction of a ranking from the partial order and show that rankings based on a convex relaxation of Kemeny's model are consistent with our partial order. We then study the properties of removing a maximal circulation versus a maximum circulation and establish that, while maximal circulations will in general identify a larger number of aggregate preferences, the partial orders induced by the removal of different maximal circulations are not unique and may be conflicting. Moreover, finding a minimum maximal circulation is an NP-hard problem.Comment: 22 pages, 4 figure

European normative values for physical fitness in children and adolescents aged 9–17 years: results from 2 779 165 Eurofit performances representing 30 countries

OBJECTIVE: To develop sex-specific and age-specific normative values for the nine Eurofit tests in European children and adolescents aged 9-17 years. METHODS: A systematic review was undertaken to identify papers that explicitly reported descriptive results for at least one of nine Eurofit tests (measuring balance, muscular strength, muscular endurance, muscular power, flexibility, speed, speed-agility and cardiorespiratory fitness (CRF)) on children and adolescents. Data were included on apparently healthy (free from known disease/injury) children and adolescents aged 9-17 years. Following harmonisation for methodological variation where appropriate, pseudodata were generated using Monte Carlo simulation, with population-weighted sex-specific and age-specific normative centiles generated using the Lambda Mu Sigma (LMS) method. Sex-specific and age-specific differences were expressed as standardised differences in means, with the percentage of children and adolescents with healthy CRF estimated at the sex-age level. RESULTS: Norms were displayed as tabulated centiles and as smoothed centile curves for the nine Eurofit tests. The final dataset included 2 779 165 results on children and adolescents from 30 European countries, extracted from 98 studies. On average, 78% of boys (95% CI 72% to 85%) and 83% of girls (95% CI 71% to 96%) met the standards for healthy CRF, with the percentage meeting the standards decreasing with age. Boys performed substantially (standardised differences \u3e0.2) better than girls on muscular strength, muscular power, muscular endurance, speed-agility and CRF tests, but worse on the flexibility test. Physical fitness generally improved at a faster rate in boys than in girls, especially during the teenage years. CONCLUSION: This study provides the largest and most geographically representative sex-specific and age-specific European normative values for children and adolescents, which have utility for health and fitness screening, profiling, monitoring and surveillance

Digital technology to facilitate Proactive Assessment of Obesity Risk during Infancy (ProAsk): a feasibility study

OBJECTIVE: To assess the feasibility and acceptability of using digital technology for Proactive Assessment of Obesity Risk during Infancy (ProAsk) with the UK health visitors (HVs) and parents. DESIGN: Multicentre, pre- and post-intervention feasibility study with process evaluation. SETTING: Rural and urban deprived settings, UK community care. PARTICIPANTS: 66 parents of infants and 22 HVs. INTERVENTION: ProAsk was delivered on a tablet device. It comprises a validated risk prediction tool to quantify overweight risk status and a therapeutic wheel detailing motivational strategies for preventive parental behaviour. Parents were encouraged to agree goals for behaviour change with HVs who received motivational interviewing training. OUTCOME MEASURES: We assessed recruitment, response and attrition rates. Demographic details were collected, and overweight risk status. The proposed primary outcome measure was weight-for-age z-score. The proposed secondary outcomes were parenting self-efficacy, maternal feeding style, infant diet and exposure to physical activity/sedentary behaviour. Qualitative interviews ascertained the acceptability of study processes and intervention fidelity. RESULTS: HVs screened 324/589 infants for inclusion in the study and 66/226 (29%) eligible infants were recruited. Assessment of overweight risk was completed on 53 infants and 40% of these were identified as above population risk. Weight-for-age z-score (SD) between the infants at population risk and those above population risk differed significantly at baseline (-0.67 SD vs 0.32 SD). HVs were able to collect data and calculate overweight risk for the infants. Protocol adherence and intervention fidelity was a challenge. HVs and parents found the information provided in the therapeutic wheel appropriate and acceptable. CONCLUSION: Study recruitment and protocol adherence were problematic. ProAsk was acceptable to most parents and HVs, but intervention fidelity was low. There was limited evidence to support the feasibility of implementing ProAsk without significant additional resources. A future study could evaluate ProAsk as a HV-supported, parent-led intervention. TRIAL REGISTRATION NUMBER: NCT02314494 (Feasibility Study Results).This work was supported by the Medical Research Council – Public Health Intervention Development Scheme, grant number PHIND 01/14-15

Electrodynamics of a Clean Vortex Lattice

We report on a microscopic evaluation of electrodynamic response for the vortex lattice state of a model s-wave superconductor. Our calculation accounts self-consistently for both quasiparticle and order parameter response and establishes the collective nature of linear response in the clean limit. We discuss the effects of homogeneous and inhomogeneous pinning on the optical conductivity and the penetration depth, and comment on the relationship between macroscopic and local penetration depths. We find unexpected relationships between pinning arrangements and conductivity due to the strongly non-local response.Comment: 4 pages, 2 figure

The Saturn Ring Skimmer Mission Concept: The next step to explore Saturn's rings, atmosphere, interior, and inner magnetosphere

The innovative Saturn Ring Skimmer mission concept enables a wide range of investigations that address fundamental questions about Saturn and its rings, as well as giant planets and astrophysical disk systems in general. This mission would provide new insights into the dynamical processes that operate in astrophysical disk systems by observing individual particles in Saturn's rings for the first time. The Ring Skimmer would also constrain the origin, history, and fate of Saturn's rings by determining their compositional evolution and material transport rates. In addition, the Ring Skimmer would reveal how the rings, magnetosphere, and planet operate as an inter-connected system by making direct measurements of the ring's atmosphere, Saturn's inner magnetosphere and the material owing from the rings into the planet. At the same time, this mission would clarify the dynamical processes operating in the planet's visible atmosphere and deep interior by making extensive high-resolution observations of cloud features and repeated measurements of the planet's extremely dynamic gravitational field. Given the scientific potential of this basic mission concept, we advocate that it be studied in depth as a potential option for the New Frontiers program.Comment: White paper submitted to the Planetary Science and Astrobiology Decadal Survey (submission #420

The Saturn Ring Skimmer Mission Concept: The next step to explore Saturn's rings, atmosphere, interior and inner magnetosphere

The innovative Saturn Ring Skimmer mission concept enables a wide range of investigations that address fundamental questions about Saturn and its rings, as well as giant planets and astrophysical disk systems in general. This mission would provide new insights into the dynamical processes that operate in astrophysical disk systems by observing individual particles in Saturn's rings for the first time. The Ring Skimmer would also constrain the origin, history, and fate of Saturn's rings by determining their compositional evolution and material transport rates. In addition, the Ring Skimmer would reveal how the rings, magnetosphere, and planet operate as an inter-connected system by making direct measurements of the ring's atmosphere, Saturn's inner magnetosphere and the material owing from the rings into the planet. At the same time, this mission would clarify the dynamical processes operating in the planet's visible atmosphere and deep interior by making extensive high-resolution observations of cloud features and repeated measurements of the planet's extremely dynamic gravitational field. Given the scientific potential of this basic mission concept, we advocate that it be studied in depth as a potential option for the New Frontiers program

Indigenous family violence : an attempt to understand the problems and inform appropriate and effective responses to criminal justice system intervention

Whilst high levels of concern about the prevalence of family violence within Indigenous communities have long been expressed, progress in the development of evidence-based intervention programs for known perpetrators has been slow. This review of the literature aims to provide a resource for practitioners who work in this area, and a framework from within which culturally specific violence prevention programs can be developed and delivered. It is suggested that effective responses to Indigenous family violence need to be informed by culturally informed models of violence, and that significant work is needed to develop interventions that successfully manage the risk of perpetrators of family violence committing further offences.<br /

Contrast Enhanced Micro-Computed Tomography Resolves the 3-Dimensional Morphology of the Cardiac Conduction System in Mammalian Hearts

The general anatomy of the cardiac conduction system (CCS) has been known for 100 years, but its complex and irregular three-dimensional (3D) geometry is not so well understood. This is largely because the conducting tissue is not distinct from the surrounding tissue by dissection. The best descriptions of its anatomy come from studies based on serial sectioning of samples taken from the appropriate areas of the heart. Low X-ray attenuation has formerly ruled out micro-computed tomography (micro-CT) as a modality to resolve internal structures of soft tissue, but incorporation of iodine, which has a high molecular weight, into those tissues enhances the differential attenuation of X-rays and allows visualisation of fine detail in embryos and skeletal muscle. Here, with the use of a iodine based contrast agent (I2KI), we present contrast enhanced micro-CT images of cardiac tissue from rat and rabbit in which the three major subdivisions of the CCS can be differentiated from the surrounding contractile myocardium and visualised in 3D. Structures identified include the sinoatrial node (SAN) and the atrioventricular conduction axis: the penetrating bundle, His bundle, the bundle branches and the Purkinje network. Although the current findings are consistent with existing anatomical representations, the representations shown here offer superior resolution and are the first 3D representations of the CCS within a single intact mammalian heart

Dysglycemia and Index60 as Prediagnostic End Points for Type 1 Diabetes Prevention Trials

OBJECTIVE: We assessed dysglycemia and a T1D Diagnostic Index60 (Index60) ≥1.00 (on the basis of fasting C-peptide, 60-min glucose, and 60-min C-peptide levels) as prediagnostic end points for type 1 diabetes among Type 1 Diabetes TrialNet Pathway to Prevention Study participants. RESEARCH DESIGN AND METHODS: Two cohorts were analyzed: 1) baseline normoglycemic oral glucose tolerance tests (OGTTs) with an incident dysglycemic OGTT and 2) baseline Index60 <1.00 OGTTs with an incident Index60 ≥1.00 OGTT. Incident dysglycemic OGTTs were divided into those with (DYS/IND+) and without (DYS/IND-) concomitant Index60 ≥1.00. Incident Index60 ≥1.00 OGTTs were divided into those with (IND/DYS+) and without (IND/DYS-) concomitant dysglycemia. RESULTS: The cumulative incidence for type 1 diabetes was greater after IND/DYS- than after DYS/IND- (P < 0.01). Within the normoglycemic cohort, the cumulative incidence of type 1 diabetes was higher after DYS/IND+ than after DYS/IND- (P < 0.001), whereas within the Index60 <1.00 cohort, the cumulative incidence after IND/DYS+ and after IND/DYS- did not differ significantly. Among nonprogressors, type 1 diabetes risk at the last OGTT was greater for IND/DYS- than for DYS/IND- (P < 0.001). Hazard ratios (HRs) of DYS/IND- with age and 30- to 0-min C-peptide were positive (P < 0.001 for both), whereas HRs of type 1 diabetes with these variables were inverse (P < 0.001 for both). In contrast, HRs of IND/DYS- and type 1 diabetes with age and 30- to 0-min C-peptide were consistent (all inverse [P < 0.01 for all]). CONCLUSIONS: The findings suggest that incident dysglycemia without Index60 ≥1.00 is a suboptimal prediagnostic end point for type 1 diabetes. Measures that include both glucose and C-peptide levels, such as Index60 ≥1.00, appear better suited as prediagnostic end points