The temporal binding deficit hypothesis of autism

Frith has argued that people with autism show “weak central coherence,” an unusual bias toward piecemeal rather than configurational processing and a reduction in the normal tendency to process information in context. However, the precise cognitive and neurological mechanisms underlying weak central coherence are still unknown. We propose the hypothesis that the features of autism associated with weak central coherence result from a reduction in the integration of specialized local neural networks in the brain caused by a deficit in temporal binding. The visuoperceptual anomalies associated with weak central coherence may be attributed to a reduction in synchronization of high-frequency gamma activity between local networks processing local features. The failure to utilize context in language processing in autism can be explained in similar terms. Temporal binding deficits could also contribute to executive dysfunction in autism and to some of the deficits in socialization and communication

Alien Registration- Boucher, Francis C. (Bath, Sagadahoc County)

https://digitalmaine.com/alien_docs/9640/thumbnail.jp

Whole-school elementary literacy programs: variation in implementation and the relationship to student literacy achievement

Research suggests that whole-school early literacy program reform should take precedence in our schools (Pikulski, 1994; Snow, Burns, & Griffin, 1998). Discovering how the components of a whole-school early literacy program interact to affect student achievement is the next step in planning for program development. Studies focusing on effective schools have not yet provided information about the impact of a whole-school program on student achievement or about the contribution of each the individual components to the whole program (Anderson & Pellicer, 1998; Creemers, 1997; Creemers & Reezigt, 1996; Wong & Meyer, 1997). However, descriptive studies spanning several decades conducted in effective schools have identified ten essential components for the implementation of complete and effective programs (Creemers & Reezigt, 1996; Levine & Lezotte, 1990; Purkey & Smith, 1983; Stringfield, Ross, & Smith, 1996; Wong & Meyer, 1997). For this study, a survey designed to measure the degree to which schools implement each of the whole-school components was used with a sample of 39 elementary school teams in Maine. This study examined the variation in implementation of the ten essential components of elementary literacy programs among schools in Maine using Analysis of Variance (ANOVA). Further, it measured the contribution of each of the ten components to the whole program using bivariate correlations and factor analysis. The effects of each of the components and socioeconomic status on student achievement were analyzed using multiple regression free-response analysis. Finally, how schools varied was examined using content analysis of free-response answers, frequency distribution of checklist-type responses, and comparison of demographic information. The results of ANOVA indicated that there was great variation in the implementation of the components of the early literacy programs among schools. The greatest variation was in the component measuring school standards. The components of program administration, professional development, and beliefs contributed the most to the whole literacy program. The multiple regression analyses showed that socioeconomic status was the only consistent predictor of student achievement. The final analyses pinpointed 22 of the 69 measured characteristics that were found exclusively in high-achieving schools but not in others

Chemical modulation of airway epithelial permeability.

The mucosal surface of the conducting airways has specialized structures for respiratory defense. Glands secret mucus that may act as a barrier to particle penetration and participate in particle clearance. Intraepithelial irritant receptors aid in particle clearance through airway constriction and cough. The epithelium acts as a barrier to the penetration of inhaled material into the airway wall. Morphologic studies have identified the tight junctions adjoining respiratory epithelial cells as the principal barrier to passive solute translocation across the airway. New approaches have been used to study airway epithelial function. Use of excised canine trachea mounted in Ussing chambers has permitted quantitative estimates of probe molecule permeation, the correlation of permeability with bioelectric properties, and estimation of equivalent pore radii. Probe molecule diffusion across canine trachea [mean transmucosal electric potential difference (PD) = 33 mV, lumen negative] is directly related to conductance (2.9 mS/cm2) and is compatible with an equivalent pore radius of 7.5 nm. Direct measurement of tracheal PD in vivo (-29 mV) facilitates study of the genesis of the biopotential in intact animals. Measurement of the movement of HRP by radioimmunoassay has allowed correlation of the rate of probe flow across airway walls in vivo with ultrastructure. These approaches lend themselves to the study of pharmacologic and toxicologic effects on epithelial function. Antigen challenge, diethyl ether, and unfractionated cigarette smoke have been shown to increase epithelial permeability to HRP accompanied by ultrastructural evidence of tight junctional damage. Application of pharmacologic agents, e.g. amphotericin, ouabain, onto the respiratory epithelium induces similar changes in in vitro and in vivo PD. We conclude that techniques that have been used to measure permeability and transport in other epithelia may help elucidate modes of action of environmental agents on airways

Cladism, Monophyly and Natural Kinds

Cladism, today the dominant school of systematics in biology, includes a classification component—the view that classification ought to reflect phylogeny only, such that all and only taxa are monophyletic (i.e. consist of an ancestor and all its descendants)—and a metaphysical component— the view that all and only real groups or kinds of organisms are monophyletic. For the most part these are seen as amounting to much the same thing, but I argue they can and should be distinguished, in particular that cladists about classification need not accept the typically cladist view about real groups or kinds. Cladists about classification can and should adopt an explanatory criterion for the reality of groups or kinds, on which being monophyletic is neither necessary nor sufficient for being real or natural. Thus the line of reasoning that has rightly led to cladism becoming dominant within systematics, and the attractive line of reasoning in the philosophical literature that advocates a more liberal approach to natural kinds, are seen to be, contrary to appearances, compatible

Inbuilt Mechanisms for Overcoming Functional Problems Inherent in Hepatic Microlobular Structure

This paper is funded by an MRC/EPSRC Discipline Bridging Initiative Grant (G0502256-77947) to W. Wan

Inferring bounded evolution in phenotypic characters from phylogenetic comparative data

Our understanding of phenotypic evolution over macroevolutionary timescales largely relies on the use of stochastic models for the evolution of continuous traits over phylogenies. The two most widely used models, Brownian motion and the Ornstein–Uhlenbeck (OU) process, differ in that the latter includes constraints on the variance that a trait can attain in a clade. The OU model explicitly models adaptive evolution toward a trait optimum and has thus been widely used to demonstrate the existence of stabilizing selection on a trait. Here we introduce a new model for the evolution of continuous characters on phylogenies: Brownian motion between two reflective bounds, or Bounded Brownian Motion (BBM). This process also models evolutionary constraints, but of a very different kind. We provide analytical expressions for the likelihood of BBM and present a method to calculate the likelihood numerically, as well as the associated R code. Numerical simulations show that BBM achieves good performance: parameter estimation is generally accurate but more importantly BBM can be very easily discriminated from both BM and OU. We then analyze climatic niche evolution in diprotodonts and find that BBM best fits this empirical data set, suggesting that the climatic niches of diprotodonts are bounded by the climate available in Australia and the neighboring islands but probably evolved with little additional constraints. We conclude that BBM is a valuable addition to the macroevolutionary toolbox, which should enable researchers to elucidate whether the phenotypic traits they study are evolving under hard constraints between bounds