9,891 research outputs found

    Encephalization in Commensal Raccoons: A Unique Test of the Cognitive Buffer Hypothesis

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    This study investigated selective pressures associated with encephalization in mammals and discussed broader implications. Relative brain size as measured by EQ (Encephalization Quotient) was compared between ecological categories. Omnivores had higher average EQ than ecological specialists. Since specialists are disproportionately affected by extinction events, selection for ecological generalism is proposed as encephalization mechanism. This mechanism may reinforce the more widely known Cognitive Buffer Hypothesis (CBH)—the idea that possessing relatively large brains has buffered lineages against environmental change. CBH is tested here by comparing EQs in Procyon lotor (raccoon) in urban and rural environments. CBH predicts that raccoons in the most radically altered environment, the city, experience the strongest selection for encephalization. Urban raccoons studied here exhibit a higher EQ. Although results are preliminary, data suggest that encephalization is accelerated during abrupt periods of environmental change. Finally, implications for the evolution of biological complexity more generally are discussed

    Superfluid transitions in bosonic atom-molecule mixtures near Feshbach resonance

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    We study bosonic atoms near a Feshbach resonance, and predict that in addition to a standard normal and atomic superfluid phases, this system generically exhibits a distinct phase of matter: a molecular superfluid, where molecules are superfluid while atoms are not. We explore zero- and finite-temperature properties of the molecular superfluid (a bosonic, strong-coupling analog of a BCS superconductor), and study quantum and classical phase transitions between the normal, molecular superfluid and atomic superfluid states.Comment: 4 revtex pages, 3 eps figures; submitted to PR

    Ethyl and isopropyl 4-ferrocenylbenzoate.

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    The title compounds, [Fe(C5H5)(C14H13O2)] and [Fe(C5H5)- (C15H15O2)], respectively, contain the ferrocenyl 5(C5H4) and phenylene ±C6H4± rings in a nearly coplanar arrangement, with interplanar angles of 6.88 (12) and 10.5 (2), respectively. Molecules of the ethyl ester form dimers through 5(C5H5)CÐ H O C hydrogen bonds, with graph set R22 (20), and, together with Csp3ÐH (C5H5) interactions, generate a one-dimensional column (irregular ladder). Molecules of the isopropyl ester aggregate through 5(C5H5)CÐH (C6H4) interactions

    Education Fever and the East Asian Fertility Puzzle: A Case Study of Low Fertility in South Korea

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    Fertility throughout East Asia has fallen rapidly over the last five decades and is now below the replacement rate of 2.1 in every country in the region. While similar but less extreme declines occurred throughout Europe during this same period, the declines to lowest-low fertility during the 1990s have been reversed in the last ten years as the pace of tempo changes (i.e., the postponement of childbearing) has slowed. Recent literature has shown that many European countries have in fact also experienced increases in cohort fertility. No such widespread fertility reversal has occurred in East Asia, where family size (i.e., cohort fertility) continues to decline. In this paper we seek to explain the precipitous (and in some cases, continual) fertility declines in East Asia. Using South Korea as a case study, we argue that East Asia’s ultra-low fertility rates can be partially explained by the steadfast parental drive to have competitive and successful children. Parents throughout the region invest high amounts of time and money to ensure their children are able to enter prestigious universities and obtain top jobs. Accordingly, children have become so expensive that the average couple cannot afford to have more than just one or two. We argue that the trend of high parental investment in child education, also known as “education fever”, exemplifies the notion of “quality over quantity” and is an important contributing factor to understanding low-fertility in East Asia

    Demographic Transition Revisited: Low Fertility, Socioeconomic Development, and Gender Equity

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    While new empirical findings and theoretical frameworks provide insight into the interrelations between socioeconomic development, gender equity, and low fertility, puzzling exceptions and outliers in these findings call for a more all-encompassing framework to understand the inter-play between these processes. We argue that the pace and onset of development are two important factors to be considered when analyzing gender equity and fertility. Within the developed world, “first-wave developers”—or countries that began socioeconomic development in the 19th/early 20th century – currently have much higher fertility levels than “late developers”. We lay out a novel theoretical approach to explain why this is the case and provide empirical evidence to support our argument. Our approach not only explains historical periods of low fertility but also sheds light on why there exists such large variance in fertility rates among to-day’s developed countries

    Observation of the critical regime near Anderson localization of light

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    Diffusive transport is among the most common phenomena in nature [1]. However, as predicted by Anderson [2], diffusion may break down due to interference. This transition from diffusive transport to localization of waves should occur for any type of classical or quantum wave in any media as long as the wavelength becomes comparable to the transport mean free path \ell^* [3]. The signatures of localization and those of absorption, or bound states, can however be similar, such that an unequivocal proof of the existence of wave localization in disordered bulk materials is still lacking. Here we present measurements of time resolved non-classical diffusion of visible light in strongly scattering samples, which cannot be explained by absorption, sample geometry or reduction in transport velocity. Deviations from classical diffusion increase strongly with decreasing \ell^* as expected for a phase transition. This constitutes an experimental realization of the critical regime in the approach to Anderson localization.Comment: 5 pages, 4 figure

    Social Functioning in Children with Brain Insult

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    Social dysfunction is commonly reported by survivors of brain insult, and is often rated as the most debilitating of all sequelae, impacting on many areas of daily life, as well as overall quality of life. Within the early brain insult (EBI) literature, physical and cognitive domains have been of primary interest and social skills have received scant attention. As a result it remains unclear how common these problems are, and whether factors predictive of recovery (insult severity, lesion location, age at insult, environment) in other functional domains (motor, speech, cognition) also contribute to social outcome. This study compared social outcomes for children sustaining EBI at different times from gestation to late childhood to determine whether EBI was associated with an increased risk of problems. Children with focal brain insults were categorized according to timing of brain insult: (i) Congenital (n = 38): EBI: first–second trimester; (ii) Perinatal (n = 33); EBI: third trimester to 1-month post-natal; (iii) Infancy (n = 23): EBI: 2 months–2 years post-birth; (iv) Preschool (n = 19): EBI: 3–6 years; (v) Middle Childhood (n = 31): EBI: 7–9 years; and (vi) Late Childhood (n = 19): EBI: after age 10. Children's teachers completed questionnaires measuring social function (Strengths and Difficulties Questionnaire, Walker–McConnell Scale of Social Competence and School Adjustment). Results showed that children with EBI were at increased risk for social impairment compared to normative expectations. EBI before age 2 years was associated with most significant social impairment, while children with EBI in the preschool years and in late childhood recorded scores closer to normal. Lesion location and laterality were not predictive of social outcome, and nor was social risk. In contrast, presence of disability (seizures) and family function were shown to contribute to aspects of social function

    Does money matter in inflation forecasting?

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    This paper provides the most fully comprehensive evidence to date on whether or not monetary aggregates are valuable for forecasting US inflation in the early to mid 2000s. We explore a wide range of different definitions of money, including different methods of aggregation and different collections of included monetary assets. In our forecasting experiment we use two non-linear techniques, namely, recurrent neural networks and kernel recursive least squares regression - techniques that are new to macroeconomics. Recurrent neural networks operate with potentially unbounded input memory, while the kernel regression technique is a finite memory predictor. The two methodologies compete to find the best fitting US inflation forecasting models and are then compared to forecasts from a naive random walk model. The best models were non-linear autoregressive models based on kernel methods. Our findings do not provide much support for the usefulness of monetary aggregates in forecasting inflation.Forecasting ; Inflation (Finance) ; Monetary theory

    Report from space plasma science

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    Space plasma science, especially plasma experiments in space, is discussed. Computational simulations, wave generation and propagation, wave-particle interactions, charged particle acceleration, particle-particle interactions, radiation transport in dense plasmas, macroscopic plasma flow, plasma-magnetic field interactions, plasma-surface interactions, prospects for near-term plasma science experiments in space and three-dimensional plasma experiments are among the topics discussed
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