BACKGROUND The critical mass hypothesis for atrial fibrillation (AF) was proposed in 1914. There has never been a systematic investigation defining the relationship between tissue geometry and AF. The purpose of this study was to determine the association among the probability of maintaining AF and the width, area, weight, effective refractory period (ERP), and wavelength in atrial tissue. ME...

The present contribution represents an extension of David Singleton’s (2005) IRAL chapter, ‘‘The Critical Period Hypothesis: A coat of many colours’’. I suggest that the CPH in its application to L2 acquisition could benefit from methodological and theoretical tailoring with respect to: the shape of the function that relates age of acquisition to proficiency, the use of nativelikeness for falsi...

This paper discusses whether or not a critical period of development exists for auditory memory and the educational implications for children who are deaf or hard of hearing.

In a previous article (Hakuta, Bialystok, & Wiley, 2003), we tested the critical-period hypothesis for second-language learning using 1990 U.S. census data. Our findings failed to support a critical period for second-language acquisition, demonstrating greater evidence for a steady decline throughout the life span. Stevens (2004) questioned these findings, suggesting they might have resulted in...

Adult second language learning seems to be more difficult and less efficient than first language acquisition during childhood. By using event-related brain potentials, we show that adults who learned a miniature artificial language display a similar real-time pattern of brain activation when processing this language as native speakers do when processing natural languages. Participants trained i...

In second language acquisition research, the critical period hypothesis (cph) holds that the function between learners' age and their susceptibility to second language input is non-linear. This paper revisits the indistinctness found in the literature with regard to this hypothesis's scope and predictions. Even when its scope is clearly delineated and its predictions are spelt out, however, emp...

D uring the past few decades, a significant body of literature has emerged from the basic science community demonstrating neuroprotective effects and synaptic enhancements induced by estrogen in brain regions that mediate memory and cognition, such as the hippocampus (1). A parallel but less consistent literature emerged from clinical studies suggesting that estrogen treatment (ET) is protectiv...

Larval reef fish possess considerable swimming and sensory abilities, which could enable navigation towards settlement habitat from the open ocean. Due to their small size and relatively low survival, tagging individual larvae is not a viable option, but numerical modeling studies have proven useful for understanding the role of orientation throughout ontogeny. Here we combined the theoretical ...

The universal period-doubling scaling of a unimodal map with an asymmetric critical point is governed by a period-2 point of a renormalisation operator. The period-2 point is parametrised by the degree of the critical point and the asymmetry modulus. In this paper we study the asymptotics of period-2 points and their associated scaling parameters in the singular limit of degree tending to 1.