Algorithms for Stable Matching and Clustering in a Grid

We study a discrete version of a geometric stable marriage problem originally proposed in a continuous setting by Hoffman, Holroyd, and Peres, in which points in the plane are stably matched to cluster centers, as prioritized by their distances, so that each cluster center is apportioned a set of points of equal area. We show that, for a discretization of the problem to an $n\times n$ grid of pixels with $k$ centers, the problem can be solved in time $O(n^2 \log^5 n)$, and we experiment with two slower but more practical algorithms and a hybrid method that switches from one of these algorithms to the other to gain greater efficiency than either algorithm alone. We also show how to combine geometric stable matchings with a $k$-means clustering algorithm, so as to provide a geometric political-districting algorithm that views distance in economic terms, and we experiment with weighted versions of stable $k$-means in order to improve the connectivity of the resulting clusters.Comment: 23 pages, 12 figures. To appear (without the appendices) at the 18th International Workshop on Combinatorial Image Analysis, June 19-21, 2017, Plovdiv, Bulgari

Positive and negative well-being and objectively measured sedentary behaviour in older adults: evidence from three cohorts

Background: Sedentary behaviour is related to poorer health independently of time spent in moderate to vigorous physical activity. The aim of this study was to investigate whether wellbeing or symptoms of anxiety or depression predict sedentary behaviour in older adults. Method: Participants were drawn from the Lothian Birth Cohort 1936 (LBC1936) (n = 271), and the West of Scotland Twenty-07 1950s (n = 309) and 1930s (n = 118) cohorts. Sedentary outcomes, sedentary time, and number of sit-to-stand transitions, were measured with a three-dimensional accelerometer (activPAL activity monitor) worn for 7 days. In the Twenty-07 cohorts, symptoms of anxiety and depression were assessed in 2008 and sedentary outcomes were assessed ~ 8 years later in 2015 and 2016. In the LBC1936 cohort, wellbeing and symptoms of anxiety and depression were assessed concurrently with sedentary behaviour in 2015 and 2016. We tested for an association between wellbeing, anxiety or depression and the sedentary outcomes using multivariate regression analysis. Results: We observed no association between wellbeing or symptoms of anxiety and the sedentary outcomes. Symptoms of depression were positively associated with sedentary time in the LBC1936 and Twenty-07 1950s cohort, and negatively associated with number of sit-to-stand transitions in the LBC1936. Meta-analytic estimates of the association between depressive symptoms and sedentary time or number of sit-to-stand transitions, adjusted for age, sex, BMI, long-standing illness, and education, were β = 0.11 (95% CI = 0.03, 0.18) and β = − 0.11 (95% CI = − 0.19, −0.03) respectively. Conclusion: Our findings indicate that depressive symptoms are positively associated with sedentary behavior. Future studies should investigate the causal direction of this association

Correlations of Behavioral Deficits with Brain Pathology Assessed through Longitudinal MRI and Histopathology in the R6/2 Mouse Model of HD

Huntington's disease (HD) is caused by the expansion of a CAG repeat in the huntingtin (HTT) gene. The R6/2 mouse model of HD expresses a mutant version of exon 1 HTT and develops motor and cognitive impairments, a widespread huntingtin (HTT) aggregate pathology and brain atrophy. Despite the vast number of studies that have been performed on this model, the association between the molecular and cellular neuropathology with brain atrophy, and with the development of behavioral phenotypes remains poorly understood. In an attempt to link these factors, we have performed longitudinal assessments of behavior (rotarod, open field, passive avoidance) and of regional brain abnormalities determined through magnetic resonance imaging (MRI) (whole brain, striatum, cortex, hippocampus, corpus callosum), as well as an end-stage histological assessment. Detailed correlative analyses of these three measures were then performed. We found a gender-dependent emergence of motor impairments that was associated with an age-related loss of regional brain volumes. MRI measurements further indicated that there was no striatal atrophy, but rather a lack of striatal growth beyond 8 weeks of age. T2 relaxivity further indicated tissue-level changes within brain regions. Despite these dramatic motor and neuroanatomical abnormalities, R6/2 mice did not exhibit neuronal loss in the striatum or motor cortex, although there was a significant increase in neuronal density due to tissue atrophy. The deposition of the mutant HTT (mHTT) protein, the hallmark of HD molecular pathology, was widely distributed throughout the brain. End-stage histopathological assessments were not found to be as robustly correlated with the longitudinal measures of brain atrophy or motor impairments. In conclusion, modeling pre-manifest and early progression of the disease in more slowly progressing animal models will be key to establishing which changes are causally related. © 2013 Rattray et al

Fiscal Multipliers and Public Debt Dynamics in Consolidations

The success of a consolidation in reducing the debt ratio depends crucially on the value of the multiplier, which measures the impact of consolidation on growth, and on the reaction of sovereign yields to such a consolidation. We present a theoretical framework that formalizes the re spo nse of the public debt ratio to fiscal consolidations in relation to the value of fiscal multipliers, the starting debt level and the cyclical elasticity of the budget balance. We also assess the role of markets confidence to fiscal consolidations under al ternative scenarios. We find that with high levels of public debt and sizeable fiscal multipliers , debt ratios are likely to increase in the short term in response to fiscal consolidations. Hence, the typical horizon for a consolidation during crises episo des to reduce the debt ratio is two - three years , although this horizon depends critically on the size and persistence of fiscal multipliers and the reaction of financial markets. Anyway, such undesired debt responses are mainly short - lived. This effect is very unlikely in non - crisis times, as it requires a number of conditions difficult to observe at the same time , especially high fiscal multipliers

Mild cognitive impairment is associated with poor physical function but not bone structure or density in late adulthood:Findings from the Hertfordshire Cohort Study

Mini Abstract This study investigated the association between mild cognitive impairment (MCI) and physical function and bone health in older adults. MCI was associated with poor physical performance but not bone mineral density or bone microarchitecture. Abstract Purpose: Cross-sectional study to investigate the association between mild cognitive impairment (MCI) and physical performance, and bone health, in a community-dwelling cohort of older adults. Methods: Cognitive function of 222 men and 221 women (mean age 75.5 and 75.8 years in men and women, respectively) was assessed by the Strawbridge questionnaire and Mini Mental State Exam (MMSE). Participants underwent dual-energy x-ray absorptiometry (DXA), peripheral-quantitative computed tomography (pQCT) and high-resolution peripheral-quantitative computed tomography (HR-pQCT) scans to assess their bone density, strength and microarchitecture. Their physical function was assessed and a physical performance (PP) score was recorded. Results: 11.8% of women and 8.1% of men in the study were cognitive impaired on the MMSE (score<24). 24% of women were deemed cognitively impaired on the Strawbridge questionnaire, compared to 22.3% of men. Cognitive impairment on the Strawbridge questionnaire was associated with poorer physical performance score in men but not women in the unadjusted analysis. MMSE <24 was strongly associated with the risk of low physical performance in men (OR 12.9, 95% CI 1.67, 99.8, p=0.01) Higher MMSE score was associated with better physical performance in both sexes. Poorer cognitive function, whether assessed by the Strawbridge questionnaire, or by MMSE score, was not associated with bone density, shape or microarchitecture, in either sex. Conclusion: MCI in older adults was associated with poor physical performance, but not bone density, shape or microarchitecture

A critical analysis of Child and Adolescent Mental Health Services policy in England

Policy in Child and Adolescent Mental Health (CAMH) in England has undergone radical changes in the last 15 years, with far reaching implications for funding models, access to services and service delivery. Using corpus analysis and critical discourse analysis, we explore how childhood, mental health, and CAMHS are constituted in 15 policy documents, 9 pre-2010, and 6 post 2010. We trace how these constructions have changed over time, and consider the practice implications of these changes. We identify how children’s distress is individualised, through medicalising discourses and shifting understandings of the relationship between socioeconomic context and mental health. This is evidenced in a shift from seeing children’s mental health challenges as produced by social and economic inequities, to a view that children’s mental health must be addressed early to prevent future socio-economic burden. We consider the implications CAMHS policies for the relationship between children, families, mental health services and the state. The paper concludes by exploring how concepts of ‘parity of esteem’ and ‘stigma reduction’ may inadvertently exacerbate the individualisation of children’s mental health

Generating inner ear organoids containing putative cochlear hair cells from human pluripotent stem cells

In view of the prevalence of sensorineural hearing defects in an ageing population, the development of protocols to generate cochlear hair cells and their associated sensory neurons as tools to further our understanding of inner ear development are highly desirable. We report herein a robust protocol for the generation of both vestibular and cochlear hair cells from human pluripotent stem cells which represents an advance over currently available methods that have been reported to generate vestibular hair cells only. Generating otic organoids from human pluripotent stem cells using a three-dimensional culture system, we show formation of both types of sensory hair cells bearing stereociliary bundles with active mechano-sensory ion channels. These cells share many morphological characteristics with their in vivo counterparts during embryonic development of the cochlear and vestibular organs and moreover demonstrate electrophysiological activity detected through single-cell patch clamping. Collectively these data represent an advance in our ability to generate cells of an otic lineage and will be useful for building models of the sensory regions of the cochlea and vestibule

Pathophysiological Mechanisms of Severe Anaemia in Malawian Children

BACKGROUND: Severe anaemia is a major cause of morbidity and mortality in African children. The aetiology is multi-factorial, but interventions have often targeted only one or a few causal factors, with limited success. METHODS AND FINDINGS: We assessed the contribution of different pathophysiological mechanisms (red cell production failure [RCPF], haemolysis and blood loss) to severe anaemia in Malawian children in whom etiological factors have been described previously. More complex associations between etiological factors and the mechanisms were explored using structural equation modelling. In 235 children with severe anaemia (haemoglobin<3.2 mMol/L [5.0 g/dl]) studied, RCPF, haemolysis and blood loss were found in 48.1%, 21.7% and 6.9%, respectively. The RCPF figure increased to 86% when a less stringent definition of RCPF was applied. RCPF was the most common mechanism in each of the major etiological subgroups (39.7-59.7%). Multiple aetiologies were common in children with severe anaemia. In the final model, nutritional and infectious factors, including malaria, were directly or indirectly associated with RCPF, but not with haemolysis. CONCLUSION: RCPF was the most common pathway leading to severe anaemia, from a variety of etiological factors, often found in combination. Unlike haemolysis or blood loss, RCPF is a defect that is likely to persist to a significant degree unless all of its contributing aetiologies are corrected. This provides a further explanation for the limited success of the single factor interventions that have commonly been applied to the prevention or treatment of severe anaemia. Our findings underline the need for a package of measures directed against all of the local aetiologies of this often fatal paediatric syndrome

Neonatal jaundice and stool production in breast- or formula-fed term infants

It has remained unclear whether the amount of fecal fat excreted in the stool and stool production influences the severity of neonatal jaundice. We determined the relationship between stool production, fecal fat excretion and jaundice in healthy breast-fed (BF) or formula-fed (FF) (near-)term neonates. From postnatal day 1–4, we quantitatively collected stools from 27 FF and 33 BF infants in daily fractions. Stool production and fecal fat contents were related to unconjugated bilirubin (UCB) levels, as determined by transcutaneous bilirubinometry (TcB). Bilirubin concentrations and stool production did not differ between FF and BF neonates during the study period. Neonatal bilirubin levels were not inversely correlated with stool production. FF and BF infants had similar fecal fat excretion rates. The stool production of FF infants was profoundly lower in the present study than in a 1985 study by De Carvalho et al. [J Pediatr (1985) 107:786–790]. We conclude that increased jaundice during the first postnatal days in healthy term neonates can no longer be attributed to breast-feeding and speculate that improved absorbability of formulas since 1985 has contributed to similar fat excretion and stool production in FF and BF neonates in 2007