Variation in Preen Oil Composition Pertaining to Season,Sex, and Genotype in the Polymorphic White-Throated Sparrow

Evidence for the the ability of birds to detect olfactory signals is now well documented, yet it remains unclear whether birds secrete chemicals that can be used as social cues. A potential source of chemical cues in birds is the secretion from the uropygial gland, or preen gland, which is thought to waterproof, maintain, and protect feathers from ectoparasites. However, it is possible that preen oil also may be used for individual recognition, mate choice, and signalling social/sexual status. If preen oil secretions can be used as socio-olfactory signals, we should be able to identify the volatile components that could make the secretions more detectable, determine the seasonality of these secretions, and determine whether olfactory signals differ among relevant social groups. We examined the seasonal differences in volatile compounds of the preen oil of captive white-throated sparrows, Zonotrichia albicollis. This species is polymorphic and has genetically determined morphs that occur in both sexes. Mating is almost exclusively disassortative with respect to morph, suggesting strong mate choice. By sampling the preen oil from captive birds in breeding and non-breeding conditions, we identified candidate chemical signals that varied according to season, sex, morph, and species. Linear alcohols with a 10–18 carbon chains, as well as methyl ketones and carboxylic acids, were the most abundant volatile compounds. Both the variety and abundances of some of these compounds were different between the sexes and morphs, with one morph secreting more volatile compounds in the non-breeding season than the other. In addition, 12 compounds were seasonally elevated in amount, and were secreted in high amounts in males. Finally, we found that preen oil signatures tended to be species-specific, with white-throated sparrows differing from the closely related Junco in the abundances and/or prevalence of at least three compounds. Our data suggest roles for preen oil secretions and avian olfaction in both non-social as well as social interactions.     

Colonial Irrigation: Myths of Emptiness

This paper examines the role of public art in urban redevelopment, focusing on the reconstruction of Coventry (UK) in the post-war years. Overseen by the city's Chief Architect, Donald Gibson, this redevelopment has often been described as resulting in a placeless and artless urban landscape indistinguishable from other redeveloped city centres in post-war Britain. To the contrary, here it is suggested that public art was an important feature of Coventry's new urban landscape, with the attempt to create a new civic identity manifest in a series of highly symbolic and distinctive public artworks. Analysing both the official symbolism of these artworks and their reception in the public sphere, it is concluded that, although just one aspect of the urban landscape, the production and consumption of public art encapsulated the tensions that existed between different visions of the city.     

Perspecta 20, Perspecta 21

In preparation of the JAE Jubilee issue many invitations were made to respond to the paragraph printed below. Because of a highly condensed schedule in the production of this special issue, the cut-off date for receipt of articles had to be moved up and several individuals, whose invited responses were in the final stages of preparation or even in transit to JAE, could not be included in that issue. This is regrettable; however, during the upcoming year we will be printing those articles and again invite our readership to respond and discuss those issues put forward in the Jubilee statement.—Ed.     

Low temperature cure of epoxy thermosets attaining high Tg using a uniform microwave field

It is demonstrated for the first time that an epoxy thermoset resin can be cured at temperatures well below its T_g∞. This study compared the use of a uniform variable frequency microwave (VFM) field to standard oven curing at temperatures above and below T_g∞. Using T_g, tan δ, modulus, and FTIR measurements, it is shown that the reaction of BFDGE with MDA to attain a product with T_g∞ of 133 °C is achieved by VFM at temperatures from 100 to 140 °C; in contrast, the thermal cure normally requires 170 °C to attain the same T_g∞ and the same extent of cure. By following the pregel cure reaction with ¹³C‐NMR spectroscopy, it was determined that the lower cure temperatures of VFM cure predominately lead to chain extension and smaller amounts of crosslinking compared to the thermal cure. To explain these results, it is suggested that, after gelation, with VFM cure there is higher mobility from dipole rotations that continues the cure to completion without vitrification. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44222.     

Structure–Property Relationships in Aligned Electrospun Barium Titanate Nanofibers

Barium titanate nanofibers were uniaxially aligned by electrospinning onto a rotating copper wire drum and alignment was maintained during calcination of the fibers. Two methods for maintaining alignment during calcination were tested, by either using carbon tape or a peeling off method to remove the aligned fibers from the mandrel followed by calcination. The carbon tape removal method led to the formation of shorter aligned nanowires while the peeling off method resulted in longer nanofibers. Additionally, the effects of calcination temperature and time on crystal structure were also examined. The degree of tetragonality in the barium titanate nanofibers increased at higher calcination temperatures and times. Piezoelectricity was confirmed in the nanofibers calcined using piezoeresponse force microscopy, yielding a d₃₃ value of 15.5 pm/V. Using the methods presented here, large quantities of aligned piezoelectric barium titanate and other ceramic fibers or wires can be produced to fulfill their demand in novel microelectronics.     

DNA Antenna Tile‐Associated Deoxyribozyme Sensor with Improved Sensitivity

Some natural enzymes increase the rate of diffusion‐limited reactions by facilitating substrate flow to their active sites. Inspired by this natural phenomenon, we developed a strategy for efficient substrate delivery to a deoxyribozyme (DZ) catalytic sensor. This resulted in a three‐ to fourfold increase in sensitivity and up to a ninefold improvement in the detection limit. The reported strategy can be used to enhance catalytic efficiency of diffusion‐limited enzymes and to improve sensitivity of enzyme‐based biosensors.