Civic revolutionaries : igniting the passion for change in America's communities

xviii, 265 p. ; 24 c

Controlling water permeability of composite films of polylactide acid, cellulose, and xyloglucan

To test the hypothesis that the introduction of a hydrophilic hemicellulose would affect viscoelastic properties and increase water permeability, xyloglucan (XG) was adsorbed onto the surface of microcrystalline cellulose (MCC) in water dispersion prior to the extrusion of 79–80 wt % polylactide acid (PLA), 20 wt % MCC, and 0–1 wt % XG. For comparison, composites of PLA, MCC, and non-absorbed XG were produced. Analysis of thermal properties showed no differences for glass-transition or melting temperatures, but the crystallinity of the films increased with the addition of MCC and XG. Storage modulus of the composite materials increased with XG content; however, at higher humidities storage modulus decreased, probably because of lower interfacial adhesion. Water permeability through the films increased more with the addition of XG adsorbed to the MCC than with the MCC and XG simply mixed in the same amounts

The Chemical Senses in Birds

7.1 CHEMICAL SENSES The chemical senses generally fall into three categories: chemesthesis (irritation and pain), olfaction (smell), and gustation (taste). Traditionally, the emphasis in describing responsiveness to chemical stimuli has been placed on taste and smell. The reality is more complex. For example, the sensory afferents for chemesthetic perception are in close proximity with olfactory receptors in the nasal cavity and with gustatory receptors in the oral cavity. Because external chemical stimuli can be processed by multiple sensory systems, there has been a great deal of confusion in the literature on the importance of individual sensory modalities. Generally, the principal mediating sensory modality may be related to stimulus type, concentration, and presentation. However, when perception of external chemical stimuli occurs via the integrated perception across modalities, the combined perceptual quality is commonly referred to as flavor

The underestimated role of olfaction in avian reproduction?

Until the second half of the 20th century, it was broadly accepted that most birds are microsmatic if not anosmic and unable to detect and use olfactory information. Exceptions were eventually conceded for species like procellariiforms, vultures or kiwis that detect their food at least in part based on olfactory signals. During the past 20-30 years, many publications have appeared indicating that this view is definitely erroneous. We briefly review here anatomical, electrophysiological and behavioral data demonstrating that birds in general possess a functional olfactory system and are able to use olfactory information in a variety of ethological contexts, including reproduction. Recent work also indicates that brain activation induced by sexual interactions with a female is significantly affected by olfactory deprivation in Japanese quail. Brain activation was measured via immunocytochemical detection of the protein product of the immediate early gene c-fos. Changes observed concerned two brain areas that play a key role in the control of male sexual behavior, the medial preoptic nucleus and the bed nucleus of the stria terminalis therefore suggesting a potential role of olfaction in the control of reproduction. The widespread idea that birds are anosmic or microsmatic is thus not supported by the available experimental data and presumably originates in our anthropomorphic view that leads us to think that birds do not smell because they have a rigid beak and nostrils and do not obviously sniff. Experimental analysis of this phenomenon is thus warranted and should lead to a significant change in our understanding of avian biology