268 research outputs found

    The continuity of the inversion and the structure of maximal subgroups in countably compact topological semigroups

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    In this paper we search for conditions on a countably compact (pseudo-compact) topological semigroup under which: (i) each maximal subgroup H(e)H(e) in SS is a (closed) topological subgroup in SS; (ii) the Clifford part H(S)H(S)(i.e. the union of all maximal subgroups) of the semigroup SS is a closed subset in SS; (iii) the inversion inv ⁣:H(S)H(S)\operatorname{inv}\colon H(S)\to H(S) is continuous; and (iv) the projection π ⁣:H(S)E(S)\pi\colon H(S)\to E(S), π ⁣:xxx1\pi\colon x\longmapsto xx^{-1}, onto the subset of idempotents E(S)E(S) of SS, is continuous

    Topological monoids of monotone injective partial selfmaps of N\mathbb{N} with cofinite domain and image

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    In this paper we study the semigroup I(N)\mathscr{I}_{\infty}^{\nearrow}(\mathbb{N}) of partial cofinal monotone bijective transformations of the set of positive integers N\mathbb{N}. We show that the semigroup I(N)\mathscr{I}_{\infty}^{\nearrow}(\mathbb{N}) has algebraic properties similar to the bicyclic semigroup: it is bisimple and all of its non-trivial group homomorphisms are either isomorphisms or group homomorphisms. We also prove that every locally compact topology τ\tau on I(N)\mathscr{I}_{\infty}^{\nearrow}(\mathbb{N}) such that (I(N),τ)(\mathscr{I}_{\infty}^{\nearrow}(\mathbb{N}),\tau) is a topological inverse semigroup, is discrete. Finally, we describe the closure of (I(N),τ)(\mathscr{I}_{\infty}^{\nearrow}(\mathbb{N}),\tau) in a topological semigroup

    Anthropologists Respond to The Lancet EAT Commission

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    The Lancet Commissions are widely known as aspirational pieces, providing the mechanisms for consortia and networks of researchers to organize, collate, interrogate and publish around a range of subjects. Although the Commissions are predominantly led by biomedical scientists and cognate public health professionals, many address social science questions and involve social science expertise. Medical anthropologist David Napier was lead author of the Lancet Commission on Culture and Health (2014), for example, and all commissions on global health (https://www.thelancet.com/global-health/commissions) address questions of social structure, everyday life, the social determinants of health, and global inequalities.The Nutrire CoLab: Diana Burnett; Megan A. Carney; Lauren Carruth; Sarah Chard; Maggie Dickinson: Diana Burnett, Megan A. Carney, Lauren Carruth, Sarah Chard, Maggie Dickinson, Alyshia Gálvez, Hanna Garth, Jessica Hardin, Adele Hite, Heather Howard, Lenore Manderson, Emily Mendenhall, Abril Saldaña-Tejeda, Dana Simmons, Natali Valdez, Emily Vasquez, Megan Warin, Emily Yates-Doer

    The NOURISH randomised control trial: Positive feeding practices and food preferences in early childhood - a primary prevention program for childhood obesity

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    Background Primary prevention of childhood overweight is an international priority. In Australia 20-25% of 2-8 year olds are already overweight. These children are at substantially increased the risk of becoming overweight adults, with attendant increased risk of morbidity and mortality. Early feeding practices determine infant exposure to food (type, amount, frequency) and include responses (eg coercion) to infant feeding behaviour (eg. food refusal). There is correlational evidence linking parenting style and early feeding practices to child eating behaviour and weight status. A focus on early feeding is consistent with the national focus on early childhood as the foundation for life-long health and well being. The NOURISH trial aims to implement and evaluate a community-based intervention to promote early feeding practices that will foster healthy food preferences and intake and preserve the innate capacity to self-regulate food intake in young children. Methods/Design This randomised controlled trial (RCT) aims to recruit 820 first-time mothers and their healthy term infants. A consecutive sample of eligible mothers will be approached postnatally at major maternity hospitals in Brisbane and Adelaide. Initial consent will be for re-contact for full enrolment when the infants are 4-7 months old. Individual mother- infant dyads will be randomised to usual care or the intervention. The intervention will provide anticipatory guidance via two modules of six fortnightly parent education and peer support group sessions, each followed by six months of regular maintenance contact. The modules will commence when the infants are aged 4-7 and 13-16 months to coincide with establishment of solid feeding, and autonomy and independence, respectively. Outcome measures will be assessed at baseline, with follow up at nine and 18 months. These will include infant intake (type and amount of foods), food preferences, feeding behaviour and growth and self-reported maternal feeding practices and parenting practices and efficacy. Covariates will include sociodemographics, infant feeding mode and temperament, maternal weight status and weight concern and child care exposure. Discussion Despite the strong rationale to focus on parents’ early feeding practices as a key determinant of child food preferences, intake and self-regulatory capacity, prospective longitudinal and intervention studies are rare. This trial will be amongst to provide Level II evidence regarding the impact of an intervention (commencing prior to age 12 months) on children’s eating patterns and behaviours. Trial Registration: ACTRN1260800005639

    Maternal feeding practices and fussy eating in toddlerhood: A discordant twin analysis

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    Background: Parental feeding practices are thought to play a causal role in shaping a child's fussiness; however, a child-responsive model suggests that feeding practices may develop in response to a child's emerging appetitive characteristics. We used a novel twin study design to test the hypothesis that mothers vary their feeding practices for twin children who differ in their 'food fussiness', in support of a child-responsive model. Methods: Participants were mothers and their 16 month old twin children (n=2026) from Gemini, a British twin birth cohort of children born in 2007. Standardized psychometric measures of maternal 'pressure to eat', 'restriction' and 'instrumental feeding', as well as child 'food fussiness', were completed by mothers. Within-family analyses examined if twin-pair differences in 'food fussiness' were associated with differences in feeding practices using linear regression models. In a subset of twins (n=247 pairs) who were the most discordant (highest quartile) on 'food fussiness' (difference score≥.50), Paired Samples T-test were used to explore the magnitude of differences in feeding practices between twins. Between-family analyses used Complex Samples General Linear Models to examine associations between feeding practices and 'food fussiness'. Results: Within-pair differences in 'food fussiness' were associated with differential 'pressure to eat' and 'instrumental feeding' (ps<.001), but not with 'restriction'. In the subset of twins most discordant on 'food fussiness', mothers used more pressure (p<.001) and food rewards (p<.05) with the fussier twin. Between-family analyses indicated that 'pressure to eat' and 'instrumental feeding' were positively associated with 'food fussiness', while 'restriction' was negatively associated with 'food fussiness' (ps<.001). Conclusions: Mothers appear to subtly adjust their feeding practices according to their perceptions of their toddler's emerging fussy eating behavior. Specifically, the fussier toddler is pressured more than their less fussy co-twin, and is more likely to be offered food rewards. Guiding parents on how to respond to fussy eating may be an important aspect of promoting feeding practices that encourage food acceptance

    Porphyrin accumulation induced by 5-aminolaevulinic acid esters in tumour cells growing in vitro and in vivo

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    The ability of 5-aminolaevulinic acid and some of its esterified derivatives to induce porphyrin accumulation has been examined in CaNT murine mammary carcinoma cells growing in culture and as tumours in vivo. Topical or intravenous administration of 5-aminolaevulinic acid-esters to mice bearing subcutaneous tumours produced lower porphyrin levels in the tumour than an equimolar dose of 5-aminolaevulinic acid. Reducing the dose of intravenous hexyl- or benzyl-ALA and topical hexyl-5-aminolaevulinic acid resulted in a dose-dependent reduction in porphyrin accumulation. A number of normal tissues accumulated higher concentrations of porphyrins than tumour tissue following intravenous administration of 5-aminolaevulinic acid-esters. Esterase activity in these normal tissues was greater than that in tumour tissue. In contrast to the situation in vivo, all of the 5-aminolaevulinic acid-esters examined were at least as effective as 5-aminolaevulinic acid when applied to cloned CaNT cells in vitro, with the drug concentration required for maximum porphyrin accumulation varying with ester chain-length. Tumour cells growing in culture released esterase activity into the medium. These findings suggest that the efficacy of 5-aminolaevulinic esters may vary depending on the esterase activity of the target tissue, and suggest caution when interpreting the findings of in vitro studies using these and similar prodrugs

    Pathways to ischemic neuronal cell death: are sex differences relevant?

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    We have known for some time that the epidemiology of human stroke is sexually dimorphic until late in life, well beyond the years of reproductive senescence and menopause. Now, a new concept is emerging: the mechanisms and outcome of cerebral ischemic injury are influenced strongly by biological sex as well as the availability of sex steroids to the brain. The principal mammalian estrogen (17 β estradiol or E2) is neuroprotective in many types of brain injury and has been the major focus of investigation over the past several decades. However, it is becoming increasingly clear that although hormones are a major contributor to sex-specific outcomes, they do not fully account for sex-specific responses to cerebral ischemia. The purpose of this review is to highlight recent studies in cell culture and animal models that suggest that genetic sex determines experimental stroke outcome and that divergent cell death pathways are activated after an ischemic insult. These sex differences need to be identified if we are to develop efficacious neuroprotective agents for use in stroke patients
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