West Lafayette, IN, United States


West Lafayette, IN, United States
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Dranski J.A.L.,Cooperativa Central de Pesquisa Agricola | Malavasi U.C.,West Parana State University | Malavasi M.M.,West Parana State University | Jacobs D.F.,PurdueUniversity
Revista Arvore | Year: 2013

Immediately after planting, tree seedlings face adverse environmental and biotic stresses that must be overcome to ensure survival and to yield a desirable growth. Hardening practices in the nursery may help improve seedling stress resistance through reduction of aboveground plant tissues and increased root volume and biomass. We conducted an assay to quantify changes in the morphogenesis following application of ethephon on seedlings of Pachystroma longifolium (Ness) I. M. Johnst.during hardening. The results showed no effect of the ethephon treatments on the number of leaves but a reduction of up to 50% in seedling height increment, and an increase in stem diameter increment of up to 44% with the 600 mg L-1ethephon treatment, which consequently altered seedling Dickson Quality Index. Our results indicate that ethephon may help to promote desired morphological changes that occur during seedling hardening in nurseries.

Lim J.,PurdueUniversity | Zheng J.Q.,U.S. Army | Masters K.,U.S. Army | Chen W.W.,PurdueUniversity
International Journal of Impact Engineering | Year: 2011

Axial tension and transverse compression experiments on single fibers were performed to investigate the mechanical behavior of three high-performance fibers (Kevlar®, Kevlar® 129, and Twaron ®) with diameters in the order of 9-12 μm. The single fibers were manufactured from 1998 through 2008. A miniaturized tensile Kolsky bar was used to determine the tensile response of PPTA single fibers at a high strain rate. Gage length and strain rate were found to have minimum effects on the tensile strength of PPTA single fibers. Manufacturing time over a decade was found to have negligible effects on the tensile strength of the fibers. Initial transverse compression on the fibers reduces their ultimate tensile strengths. A high resolution scanning electron microscope (SEM) was also used to examine the fracture modes of transversely deformed fibers. Different types of fracture morphology were observed. © 2010 Elsevier Ltd. All rights reserved.

Braasch J.,PurdueUniversity | Kaplan I.,PurdueUniversity
Entomologia Experimentalis et Applicata | Year: 2012

As studies demonstrating attraction of natural enemies to synthetic herbivore-induced plant volatiles (HIPVs) accumulate, it is becoming increasingly important to investigate how deployment of these compounds influences arthropod behavior and distribution in the field. There is currently an unexplained dichotomy in the literature regarding the distance over which HIPVs are thought to be effective. It is assumed that these compounds increase recruitment of natural enemies into fields, whereas experiments have found the effects of attraction to dissipate as little as 1.5 m from lures. Through the use of the common HIPV phenylethyl alcohol in soybean [Glycine max (L.) Merr (Fabaceae)] fields, we used replicated mini plots to test the spatial scale and consequences of attraction by analyzing the response of a complex arthropod community to HIPVs along a distance gradient from the HIPV source. Although repellent effects were more common than attractive ones, we found that insect responses to HIPVs are generally consistent out to a range of 8 m, corroborating the idea that volatiles can influence a wide area and are capable of increasing arthropod recruitment at a field scale. Evidence of redistribution (i.e., depletion of patches surrounding HIPV-augmented plots) was found for a single taxon, braconid wasps, for which augmentation occurred around the lure, but with a reciprocal decline in abundance at greater distances from the emission site. These results are both encouraging and cautionary. Although broad-scale diffusion of HIPVs appears to be common, redistribution of key predators and/or parasitoids may complicate natural enemy management on a landscape scale by aggravating pest outbreaks in areas robbed of their normal carnivore assemblage. © 2012 The Netherlands Entomological Society.

Bertino E.,PurdueUniversity
Proceedings - International Computer Software and Applications Conference | Year: 2013

This paper summarizes opportunities and challenges of big data. It identifies important research directions and includes a number of questions that have been debated by the panel. © 2013 IEEE.

PubMed | PurdueUniversity
Type: Journal Article | Journal: Applied optics | Year: 2010

The bidirectional spectral reflectance of a set of V-grooved surfaces has been investigated in an attempt to separate the influences of the mean slope and the peak-to-valley height. The experimental results show good agreement with the theoretical models in both the geometrical optics and diffraction ranges.

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