Contrasting arbuscular mycorrhizal communities colonizing different host plants show a similar response to a soil phosphorus concentration gradient

High soil phosphorus (P) concentration is frequently shown to reduce root colonization by arbuscular mycorrhizal (AM) fungi, but the influence of P on the diversity of colonizing AM fungi is uncertain. We used terminal restriction fragment length polymorphism (T-RFLP) of 18S rDNA and cloning to assess diversity of AM fungi colonizing maize (Zea mays), soybean (Glycene max) and field violet (Viola arvensis) at three time points in one season along a P gradient of 10–280 mg l−1 in the field. Percentage AM colonization changed between sampling time points but was not reduced by high soil P except in maize. There was no significant difference in AM diversity between sampling time points. Diversity was reduced at concentrations of P > 25 mg l−1, particularly in maize and soybean. Both cloning and T-RFLP indicated differences between AM communities in the different host species. Host species was more important than soil P in determining the AM community, except at the highest P concentration. Our results show that the impact of soil P on the diversity of AM fungi colonizing plants was broadly similar, despite the fact that different plants contained different communities. However, subtle differences in the response of the AM community in each host were evident

FAA Safety Seminar (Open to the General Public)

This seminar will focus on reducing the aviation accident rate through the enhancement of safety culture. Human factors influences on accident and incidents will also be discussed with an emphasis on the prevention of future occurrences. The keynote speaker is Robert Sumwalt, current member of the National Transportation Safety Board (NTSB). A pilot with more than 30 years of experience including 24 years as an airline pilot, Sumwalt was appointed to a two-year term with the NTSB as Vice Chairman in 2006 by President George W. Bush. He was then reappointed to the Board as a member for an additional five-year term by President Barack Obama in 2011. He has been involved with and led numerous airline safety programs and is co-founder of the Air Line Pilots Association (ALPA) Critical Incident Response Program, which provides guidance to airline personnel involved in traumatic incidents. For more information about Mr. Sumwalt, http://www.ntsb.gov/about/bio_sumwalt.html Daniel McCune is currently the University Safety Officer for Embry-Riddle Aeronautical University. He is also the Chairman of the Safety committee for the University Aviation Association, and serves on several national Safety advisory committees. Mr. McCune retired from the United States Army after serving 27 years. Mr. McCune\u27s last flying position in the Army was a Citation Jet Captain at Dobbins Air Force Base. He has flown over 6500 accident free hours. He has flown a multitude of aircraft a few are: CE-560, King Air, Queen Air, C-182, UH-1 Helicopter

The front door to the fourth corner: variations on the sample unit × trait matrix in community ecology

Calculating a sample unit × trait matrix provides a flexible first step in analyzing the relationships between species traits and explanatory variables. This matrix is obtained by multiplying a sample unit × species matrix by a species × trait matrix, but the content of the resulting matrix depends on whether and how traits are standardized and whether or not the multiplication is followed by a weighted averaging step. To maximize versatility of the SU × trait matrix, including comparability among traits, and usability with a wide range of distance measures, we recommend first standardizing traits by min-to-max, then calculating abundance-weighted trait averages in each sample unit

Do ecological differences between taxonomic groups influence the relationship between species’ distributions and climate? A global meta-analysis using species distribution models

Understanding whether and how ecological traits affect species’ geographic distributions is a fundamental issue that bridges ecology and biogeography. While climate is thought to be the major determinant of species’ distributions, there is considerable variation in the strength of species’ climate–distribution relationships. One potential explanation is that species with relatively low dispersal ability cannot reach all geographic areas where climatic conditions are suitable. We tested the hypothesis that species from different taxonomic groups varied in their climate–distribution relationships because of differences in life history strategies, in particular dispersal ability. We conducted a meta-analysis by combining the discrimination ability (AUC values) from 4317 species distribution models (SDMs) using fit as an indication of the strength of the species’ climate–distribution relationship. We found significant differences in the strength of species’ climate–distribution relationships across taxonomic groups, however we did not find support for the dispersal hypothesis. Our results suggest that relevant ecological trait variation among broad taxonomic groups may be related to differences in species’ climate–distribution relationships, however which ecological traits are important remains unclear

Effect of plant regulators on set and berry development in certain seedless and seeded varieties of Vitis vinifera L.

Flowering clusters on ungirdled, nondefoliated shoots of 'Black Corinth', and girdled shoots defoliated to 1 /ia leaf, were dipped in 4-CPA at 15 ppm, or GA3 at 5 or 15 ppm. In nondefoliated shoots the set was decreased about 13 °/o at 15 ppm, but there were no significant differences among the other treatments. All treatments produced heavier rachises, berries, and clusters than the ungirdled, untreated controls. In defoliated shoots the set was decreased approximately 85 °/o by GA3 at 15 ppm. 4-CPA significantly increased set, but a mixture of GA3 and 4-CPA did not alter set.Similar experiments were carried on with the seeded varieties 'Pinot Chardonnay', 'Muscat of Alexandria', and 'Grenache'. Clusters on ungirdled nondefoliated shoots were dipped in GA3, 4-CPA, or a mixture of the two compounds. Like treatments were made on other clusters on shoots defoliated to 1/4 leaf. There was a varietal difference in response among the seeded varieties. The compounds injured the Muscat and reduced the set and berry size.All treatments increased the set of seedless berries on nondefoliated shoots of 'Pinot'. In both 'Chardonnay' and 'Grenache' there was a shift from seeded to seedless berries. Application of 4-CPA resulted in a significantly greater set in total number of berries on defoliated shoots of 'Chardonnay' and 'Muscat'.All solutions containing GA3 increased siz'e of seedless berries on nondefoliated shoots of 'Pinot'. GA3 applied at shatter stage increased size of seedless 'Muscat' berries. With one exception, there was no increase in size of one-, two-, or three-seeded berries.Percentage set was significantly increased in defoliated shoots of 'Muscat' by 4-CPA, and in 'Pinot' by 4-CPA or a mixture of 4-CPA and GA3.A kinin, benzyladenine, failed to increase set or berry size, but intensified the development of a purple anthocyanin pigment in 'Muscat'.The possible importance of the ratio of a leaf-produced set factor to gibberellin in berry set in 'Black Corinth' is discussed

Sampling a Littoral Fish Assemblage: Comparison of Small-Mesh Fyke Netting and Boat Electrofishing

We compared small-mesh (4-mm) fyke netting and boat electrofishing for sampling a littoral fish assemblage in Muskegon Lake, Michigan. We hypothesized that fyke netting selects for small-bodied fishes and electrofishing selects for large-bodied fishes. Three sites were sampled during May (2004 and 2005), July (2005 only), and September (2004 and 2005). We found that the species composition of captured fish differed considerably between fyke netting and electrofishing based on nonmetric multidimensional scaling (NMDS). Species strongly associated with fyke netting (based on NMDS and relative abundance) included the brook silverside Labidesthes sicculus, banded killifish Fundulus diaphanus, round goby Neogobius melanostomus, mimic shiner Notropis volucellus, and bluntnose minnow Pimephales notatus, whereas species associated with electrofishing included the Chinook salmon Oncorhynchus tshawytscha, catostomids (Moxostoma spp. and Catostomus spp.), freshwater drum Aplodinotus grunniens, walleye Sander vitreus, gizzard shad Dorosoma cepedianum, and common carp Cyprinus carpio. The total length of fish captured by electrofishing was 12.8 cm (95% confidence interval ¼ 5.5– 17.2 cm) greater than that of fish captured by fyke netting. Size selectivity of the gears contributed to differences in species composition of the fish captured, supporting our initial hypothesis. Thus, small-mesh fyke nets and boat electrofishers provided complementary information on a littoral fish assemblage. Our results support use of multiple gear types in monitoring and research surveys of fish assemblages. Copyright by the American Fisheries Society 2007, Originally published in the North American Journal of Fisheries Management 27: 825-831, 2007

Studying Algebraic Structures Using Prover9 and Mace4

In this chapter we present a case study, drawn from our research work, on the application of a fully automated theorem prover together with an automatic counter-example generator in the investigation of a class of algebraic structures. We will see that these tools, when combined with human insight and traditional algebraic methods, help us to explore the problem space quickly and effectively. The counter-example generator rapidly rules out many false conjectures, while the theorem prover is often much more efficient than a human being at verifying algebraic identities. The specific tools in our case study are Prover9 and Mace4; the algebraic structures are generalisations of Heyting algebras known as hoops. We will see how this approach helped us to discover new theorems and to find new or improved proofs of known results. We also make some suggestions for how one might deploy these tools to supplement a more conventional approach to teaching algebra.Comment: 21 pages, to appear as Chapter 5 in "Proof Technology in Mathematics Research and Teaching", Mathematics Education in the Digital Era 14, edited by G. Hanna et al. (eds.), published by Springe

A method for finding new sets of axioms for classes of semigroups

We introduce a general technique for finding sets of axioms for a given class of semigroups. To illustrate the technique, we provide new sets of defining axioms for groups of exponent n, bands, and semilattices

Transparent code authentication at the processor level

The authors present a lightweight authentication mechanism that verifies the authenticity of code and thereby addresses the virus and malicious code problems at the hardware level eliminating the need for trusted extensions in the operating system. The technique proposed tightly integrates the authentication mechanism into the processor core. The authentication latency is hidden behind the memory access latency, thereby allowing seamless on-the-fly authentication of instructions. In addition, the proposed authentication method supports seamless encryption of code (and static data). Consequently, while providing the software users with assurance for authenticity of programs executing on their hardware, the proposed technique also protects the software manufacturers’ intellectual property through encryption. The performance analysis shows that, under mild assumptions, the presented technique introduces negligible overhead for even moderate cache sizes