Acoustic Signals of \u3ci\u3eGraminella Nigrifrons\u3c/i\u3e (Homoptera: Cicadellidae)

The deltocephaline leafhopper, Graminella nigrifrons, produces low intensity sub- strate transmitted vibrations (signals) to facilitate location of virgin females by males during courtship. In the laboratory, signals produced on maize leaves were received by a phonographic cartridge, amplified, and analyzed on an oscillograph and sonograph. Male calls, that are produced spontaneously, are complex, consisting of three consecutive sections. Section 1 consists of ca. 3 sec of irregular clicks. Section 2 has ca. 4 sec of repeated phrases consisting of a continuous series of 0.4 sec chirps and a roll. Section 3 consists of ca. 5 sec of an intermittent series of 0.2 sec chirps and a roll. Female calls are produced in response to male calls. Female calls are simple compared to male calls and consist of ca. 4-5 sec of low frequency clicking. Signal patterns of G. nigrifrons are compared to those of other leafhoppers and evolutionary scenarios are presented to account for the observed gender differ­ences in signals

Zea diploperennis: A Primitive Relative Offers New Traits to Improve Corn

Four years ago, a young Mexican botanist made what may someday be recognized as the botanical find of the century. Rafael Guzmán, a student at the University of Guadalajara, was searching for one of the wild relatives of corn in the mountains of southern Mexico. Guzmán was looking for Zea perennis, a perennial teosinte thought to be extinct in the wild since the early 1920\u27s. This primitive corn relative was considered more of a botanical curiosity than a boon to mankind. As a tetraploid, perennial teosinte produces sterile offspring when crossed with corn, a diploid species. Guzmán found perennial teosinte growing in a remote mountain site

Differentiation of Some Canadian Coniferous Woods by Combined Diffuse and Specular Reflectance Fourier Transform Infrared Spectrometry

Infrared spectroscopy was used to differentiate coniferous woods commonly found in mixtures in lumber producing mills in British Columbia. The method required collection of reflectance Fourier transform infrared spectra of wood samples at a 2 cm-1 resolution. From a small subset of spectra, frequencies useful for species differentiation were selected using a combination of correlation analysis and principal component analysis. The selected frequencies were used to develop methods for differentiating species using discriminant analysis. These models were then tested against the remainder of the spectra. This approach was successfully used to classify the same wood samples in freeze-dried and green conditions, but was unsuccessful in classifying extractive free samples

Measuring Risk from IT Initiatives Using Implied Volatility

We propose an underrecognized measure to capture changes in firm risk from information technology (IT) announcements: implied volatility (IV) from a firm’s exchange-traded options. An IV is obtained from a priced stock option and represents the option market’s expectation of the firm’s average stock return volatility over the remaining duration of the option. Using the change in IV around IT announcements, we can directly assess changes in IT-induced firm risk. IVs are straightforward to obtain, and are forward-looking based on option market investors’ estimates of future stock return volatility. They do not rely on historical volatility that is confounded with other events. In addition, options have different expiration dates—each with an IV—allowing us to distinguish between short- and long-term risk. We show how a change in IV can be employed to assess changes in short- and long-term firm risk from IT announcements and demonstrate this methodological innovation empirically using a set of IT announcements that have been utilized in previous studies

Species Differentiation of Two Common Lumber Mixes by Diffuse Reflectance Fourier Transform Infrared (DRIFT) Spectroscopy

Diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy was used to differentiate coniferous woods by species. Species mixtures studied were SPF (composed of white spruce [Picea glauca Voss], Engelmann spruce [Picea engelmannii Parry], lodgepole pine [Pinus contorta Dougl.] and subalpine fir [Abies lasiocarpa Nutt.]) and HEM/FIR (composed of western hemlock [Tsuga heterophylla Sarg.], amabilis fir [Abies amabilis Dougl.] and Sitka spruce [Picea sitchensis Carr.]). DRIFT spectra of the green wood samples were used in SIMCA (simple modeling of class analogy) pattern recognition to differentiate species. This approach was able to classify SPF with 90% accuracy when all samples were identified, and 94% accuracy when poorly classified samples were eliminated. For the HEM/FIR group, the method was able to classify all samples with 81% accuracy, and up to 99% accuracy when poorly classified samples were eliminated

Relative Importance, Specific Investment and Ownership in Interorganizational Systems.

Author's post-print on any open access repository after 12 months after publication. Must link to publisher version http://www.ucalgary.ca.ezproxy.lib.ucalgary.ca/bnault/files/bnault/itm_sep_2008.pdfImplementation and maintenance of interorganizational systems (IOS) require investments by all the participating firms. Compared with intraorganizational sys- tems, however, there are additional uncertainties and risks. This is because the benefits of IOS investment depend not only on a firm’s own decisions, but also on those of its business partners. Without appropriate levels of investment by all the firms participating in an IOS, they cannot reap the full benefits. Drawing upon the literature in institutional economics, we examine IOS ownership as a means to induce value-maximizing noncontractible investments. We model the impact of two factors derived from the theory of incomplete contracts and transaction cost economics: relative importance of investments and specificity of investments. We apply the model to a vendor-managed inventory system (VMI) in a supply chain setting. We show that when the specificity of investments is high, this is a more critical determinant of optimal ownership structure than the relative importance of investments. As technologies used in IOS become increasingly redeployable and reusable, and less specific, the relative importance of investments becomes a dominant factor. We also show that the bargaining mechanism—or the agreed upon approach to splitting the incremental payoffs—that is used affects the relationship between these factors in determining the optimal ownership structure of an IOS.Ye

Influence of Honey Bee, Apis mellifera, Hives and Field Size on Foraging Activity of Native Bee Species in Pumpkin Fields

The purpose of this study was to identify bee species active in pumpkin fields in New York and to estimate their potential as pollinators by examining their foraging activity. In addition, we examined whether foraging activity was affected by either the addition of hives of the honey bee, Apis mellifera L., or by field size. Thirty-five pumpkin (Cucurbita spp.) fields ranging from 0.6 to 26.3 ha, 12 supplemented with A. mellifera hives and 23 not supplemented, were sampled during peak flowering over three successive weeks in 2008 and 2009. Flowers from 300 plants per field were visually sampled for bees on each sampling date. A. mellifera, Bombus impatiens Cresson, and Peponapis pruinosa (Say) accounted for 99% of all bee visits to flowers. A. mellifera and B. impatiens visited significantly more pistillate flowers than would be expected by chance, whereas P. pruinosa showed no preference for visiting pistillate flowers. There were significantly more A. mellifera visits per flower in fields supplemented with A. mellifera hives than in fields not supplemented, but there were significantly fewer P. pruinosa visits in supplemented fields. The number of B. impatiens visits was not affected by supplementation, but was affected by number of flowers per field. A. mellifera and P. pruinosa visits were not affected by field size, but B. impatiens visited fewer flowers as field size increased in fields that were not supplemented with A. mellifera hives. Declining A. mellifera populations may increase the relative importance of B. impatiens in pollinating pumpkins in New Yor

Pricing in C2C Sharing Platforms

Sharing platforms such as zilok.com enable sharing of durable goods among consumers, and seek to maximize profits by charging transaction-based platform fees. We develop a model in which consumers who have heterogeneous needs concerning the use of a durable good decide whether to purchase and share (i.e., be a lender) or borrow (i.e., be a borrower), and a monopoly sharing platform determines the platform fees. We find, first, that consumers with greater need to use a durable good purchase and share, and that consumers with lesser need borrow. Second, sharing platforms maximize profits only if the supply of a durable good matches demand—that is, the market must clear in order for platform fees to be profit maximizing. Third, the market-clearing condition requires lender and borrower fees are classic strategic complements. Fourth, to maintain the market-clearing condition, sharing platforms have to increase their lender fee or decrease their borrower fee in response to increases in the sharing price, increases in usage capacity, and decreases in the purchase price of a durable good, and vice versa. These findings indicate that commonly applied one-sided pricing models in sharing platforms can be improved

Using Yellow Rocket as a Trap Crop for Diamondback Moth (Lepidoptera: Plutellidae)

Yellow rocket, Barbarea vulgaris (R. Br.) variety arcuata, was evaluated as a trap crop for diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in cabbage, Brassica oleracea L. variety capitata, in 2003 and 2004. In 2003, the numbers of P. xylostella larvae found in field plots of cabbage alone were 5.2-11.3 times higher than those on cabbage plants in plots that included cabbage and several rows of yellow rocket. In an outdoor experiment in screenhouses, P. xylostella oviposition on cabbage was compared among six treatments that varied in the percentage of yellow rocket in relation to cabbage (0, 4, 8, 16, 24, and 32% of the plants were yellow rocket). Results indicated that the percentage of eggs laid on cabbage decreased as the percentage of yellow rocket in the treatment increased, but this decrease was not significant beyond 20% of the plants being yellow rocket. In 2004, the numbers of P. xylostella larvae in field plots of cabbage alone were 1.6-2.4 and 1.7-2.8 times higher than numbers in treatments with 10 and 20% trap crop, respectively. Sticky trap and sweep net captures of P. xylostella adults indicated that within-field dispersal was reduced by the presence of yellow rocket and aggregation occurred around yellow rocket plants. Our study suggests that using yellow rocket as a trap crop may reduce P. xylostella infestations in cabbage fields, and this possibility is discussed in the context of general crop and insect pest management practices in crucifer