2,249 research outputs found

    From phonetics to phonology : The emergence of first words in Italian

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    This study assesses the extent of phonetic continuity between babble and words in four Italian children followed longitudinally from 0; 9 or 0; 10 to 2;0-two with relatively rapid and two with slower lexical growth. Prelinguistic phonetic characteristics, including both (a) consistent use of specific consonants and (b) age of onset and extent of consonant variegation in babble, are found to predict rate of lexical advance and to relate to the form of the early words. In addition, each child's lexical profile is analyzed to test the hypothesis of non-linearity in phonological development. All of the children show the expected pattern of phonological advance: 'Relatively accurate first word production is followed by lexical expansion, characterized by a decrease in accuracy and an increase of similarity between word forms. We interpret such a profile as reflecting the emergence of word templates, a first step in phonological organization

    From cellular properties to population asymptotics in the Population Balance Equation

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    Proliferating cell populations at steady state growth often exhibit broad protein distributions with exponential tails. The sources of this variation and its universality are of much theoretical interest. Here we address the problem by asymptotic analysis of the Population Balance Equation. We show that the steady state distribution tail is determined by a combination of protein production and cell division and is insensitive to other model details. Under general conditions this tail is exponential with a dependence on parameters consistent with experiment. We discuss the conditions for this effect to be dominant over other sources of variation and the relation to experiments.Comment: Exact solution of Eq. 9 is adde

    Light trapping and guidance in plasmonic nanocrystals

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    We illustrate the possibility of light trapping and funneling in periodic arrays of metallic nanoparticles. A controllable minimum in the transmission spectra of such constructs arises from a collective plasmon resonance phenomenon, where an incident plane wave sharply localizes in the vertical direction, remaining delocalized in the direction parallel to the crystal plane. Using hybrid arrays of different structures or different materials, we apply the trapping effect to structure the eigen-mode spectrum, introduce overlapping resonances, and hence direct the light in space in a wavelength-sensitive fashion

    Our Theories, Ourselves: Hierarchies of Place and Status in U.S. Academia

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    The politics of fresh water: setting the stage

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    This chapter identifies insights into the politics of fresh water and introduces the contributions to the book The Politics of Fresh Water: Access, conflict and identity. First, the social, physical, and ecological components of water systems are interconnected, forming a hydro-social system. Second, instead of being inevitable, freshwater crisis is a socially constructed experience, a lived phenomenon. Water scarcity is not simply the result of what nature has to offer but always involves power relations and political decisions. The water crisis is not only about who is granted access to safe, clean water (when, where, and why), but also about the extent to which the shrinking of available fresh water influences people’s everyday lives at the national and subnational scales. The water crisis also reflects the impact of modernization and neoliberal policies on identity and sense of community. After all, water is the source of livelihood and survival for all people, in every location, at every geographical scale, and the meaning of access to water is inextricably connected to cultural, societal, and political identities. This chapter is part of the edited book The Politics of Fresh Water: Access, conflict and identity

    Ovarian reserve and anti-Mullerian hormone (AMH) in mothers of dizygotic twins

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    This study aimed to explore if natural dizygotic (DZ) twinning is associated with earlier menopause and lower anti-Mullerian hormone (AMH) values. We investigated if advanced biological reproductive aging, which can be responsible for the multiple follicle growth in familial twinning, is similar to mechanisms that occur in normal ovarian aging, reflected by earlier menopause in mothers of DZ twins and lower levels of AMH. A total of 16 mothers of DZ twins enrolled with the Netherlands Twin Register (average age at first assessment: 35.9 +/- 3.0 years) and 14 control mothers (35.1 +/- 3 years) took part in a prospective study. Fifteen years after entry into the study, which included follicle-stimulating hormone (FSH) assessment, AMH was measured in stored serum samples and menopause status was evaluated. Average AMH levels were not significantly different between DZ twin mothers and controls (2.1 +/- 2.4 mu g/L vs. 1.9 +/- 1.9 mu g/L). Among the 16 mothers of twins, 7 had an elevated (FSH) value over 10 U/L at first assessment. Their AMH levels were lower than the nine twin mothers with normal FSH values: 0.6 +/- 0.4 versus 3.4 +/- 2.6 mu g/L (p = .01). Of the mothers of twins, eight mothers had entered menopause at the second assessment compared with only one control mother (p = .07). Thus, slightly more DZ mothers were in menopause than the control mothers, although this difference was not significant. The subgroup of DZ twin mothers who had an increased FSH concentration 15 years ago had a limited ovarian reserve as reflected by lower AMH levels. These data indicate that advanced ovarian aging can be a feature in familial DZ twinning, particularly with elevated early follicular phase FSH
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