3,402 research outputs found
An Effective Chemical Deterrent for Invasive Cuban Treefrogs
Introduced vertebrates have a variety of impacts on ecosystems and economies, and many cause problems for humans. One such problem is the loss of electrical power when invasive animals cause short circuits in power-transmission equipment. Cuban treefrogs (Osteopilus septentrionalis) are known to cause power outages and are a nuisance to humans when they invade homes and defecate on doors and windows. These large, slightly toxic treefrogs were introduced into Florida from the Caribbean. They now occur throughout the peninsula of Florida and are spreading to other states in the Southeast. We used refuge choice experiments to test the effectiveness of Sniff ’n’ StopTM animal deterrent to exclude Cuban treefrogs from enclosed spaces, such as utility switchgear boxes. We found that the deterrent was effective and showed potential as a low-cost means to prevent frog-related power outages and reduce conflicts with residents in the urbanized areas preferred by these invasive frog
Frogs (Coqui Frogs, Greenhouse Frogs, Cuban Tree Frogs, and Cane Toads)
Amphibians are perhaps most well known for their highly threatened status, which often masks appreciation for the great numbers of species that are widespread global invaders (Kraus 2009). Both purposeful and accidental introductions of amphibians have occurred worldwide. Motivations for purposeful amphibian introductions include their use as biocontrol agents and culinary ambitions (Storer 1925; Kraus 2009). However, there are an increasing number of amphibians that are being accidentally introduced and becoming widespread (Kraus 2009). These introductions are in some ways more disconcerting because they may be the most difficult to prevent in the future.
There are 19 nonnative amphibians that have become successfully established in 28 of the 50 U.S. states (Figure 9.1; Kraus 2009). The most successful non-native amphibian is the bullfrog (Lithobates catesbeianus), which has become established in 19 states outside of its native range on the eastern side of the United States, followed by the Cuban greenhouse frog (Eleutherodactylus planirostris), which has established itself in six states, and five frog species, including the Puerto Rican coqui (E. coqui), which are now established in three states outside of their native range (Figure 9.1; Kraus 2009). The state with the most nonnative frogs is California with eight species, followed by Hawaii with six, and Florida and Arizona with four (Table 9.1; Kraus 2009). Many nonnative amphibians in the United States, particularly in the western United States, are from other parts of the United States, namely, east of the Mississippi River. However, there are also many nonnative amphibians with tropical or subtropical origins that are primarily successful in tropical and subtropical states, such as Florida and Hawaii, and territories, such as Guam
The Intramolecular Loss of Fluorescence by Lysine Derivatized with Naphthalenedialdehyde
This is the publisher's version, also available electronically from http://www.opticsinfobase.org/as/abstract.cfm?URI=as-44-5-858.Derivatization of primary amines such as amino acids and peptides with naphthalenedialdehyde (NDA) in the presence of cyanide ion yields cyanobenzo[f]-isoindole (CBI) adducts that are highly fluorescent. However, the fluorescence is seriously quenched with amines that possess more than one primary amine site, as is the case with lysine. Although it was found that the adsorption of CBI2-lysine on a solid substrate restored the fluorescence, the reason for the solution quenching, with respect to results for mono-derivatized amines, was investigated. The experiments to probe the quenching were based on the assumption that the mechanism responsible for quenching involved a charge-transfer (CT) excited state. Thus, it was found that the solvent properties of viscosity and polarity affected the lifetime and quantum yield of fluorescence in a manner consistent with the proposed mechanism
Fault Detection in Surface PMSM with Applications to Heavy Hybrid Vehicles
This report explores detecting inter-turn short circuit (ITSC) faults in surface permanent magnet synchronous machines (SPMSM). ITSC faults are caused by electrical insulation failures in the stator windings and can lead to shorts to ground and even fires. This report proposes methods for detecting these faults using a moving horizon observer (MHO) to reduce the chance of electrical shocks and fires. Specifically, this report constructs a MHO for ITSC fault detection in SPMSM.
ITSC fault tolerant control is investigated for a 2004 Toyota Prius hybrid vehicle having a traction SPMSM. Once the supervisory-level powertrain power flow control becomes aware of the presence of a fault and its degree from the MHO, the control (i) reduces the maximum possible vehicle speed to ensure SPMSM thermal constraints are not violated and (ii) switches to a traction motor input-output power efficiency appropriate for the degree of fault. These steps are taken during a fault rather than shutting down the traction motor to provide a “limp home” capability. The traction motor cannot simply be turned off because its rotation is not independent of drive wheel rotation. The control is demonstrated by simulating the Prius over a 40 s drive velocity profile with faults levels of 0.5%, 1%, 2%, and 5% detected at the midpoint of the profile. For comparison, the Prius is also simulated without a traction motor fault. Results show that the control reduced vehicle velocity upon detection of a fault to appropriate safe values. Further, the challenges of ITSC fault tolerant control for heavy hybrid vehicles are examined.
This work is partially supported by the Department of Energy, Award No. DE-EE0005568.
The authors would like to acknowledge the support of Greg Shaver and the Hoosier Heavy Hybrid Center of Excellence.
S. Johnson, R. DeCarlo, and S. Pekarek are with the Department of Electrical and Computer Engineering at Purdue University, 610 Purdue Mall, West Lafayette, IN 47907 (email: [email protected], [email protected], [email protected]).
R. Meyer is with the Department of Mechanical and Aerospace Engineering at Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008 (email: [email protected])
Soil Bulk Density Variability in a Restored Prairie Ecosystem
Soils act as the foundation for all terrestrial biotic activity. Given this it is important to consider the factors that influence the physical makeup of soil as well as the management practices that can lead to changes and significant biological implications. Beginning in 1999 Cedarville University established a Prairie Restoration Site. In the past fifteen years work has been to done to reseed the area with native prairie grasses as well as to introduce regular disturbances that are common to prairie grasslands, such as fire. The goal of this work the goal has been to aid a system in ecological succession. In the current study, we seek to evaluate the success of this with regard to the corresponding changes in the soil environment. We look to distinguish this source of variability from the natural variability introduced by the physical landscape (slope) and the resulting soil series. To evaluate these ideas we will investigate how two factors, soil series (corresponding to slope position) and prairie restoration, affect soil bulk density.
We collected soil samples (to a depth of 15 cm) from the restored prairie as well as the adjacent area. In addition to this variable, we acquired samples in both locations across a range of three different soil series distributed within this same area. Specifically, we collected samples from the “XeB-Xenia B,” “Ra-Ragsdale,” and “Russel-Miamian - RvB2” soil types. We will use a two factor ANOVA to evaluate the impact of a change in soil series, or prairie restoration on soil bulk density
Predicted aircraft effects on stratospheric ozone
The possibility that the current fleet of subsonic aircraft may already have caused detectable changes in both the troposphere and stratosphere has raised concerns about the impact of such operations on stratospheric ozone and climate. Recent interest in the operation of supersonic aircraft in the lower stratosphere has heightened such concerns. Previous assessments of impacts from proposed supersonic aircraft were based mostly on one-dimensional model results although a limited number of multidimensional models were used. In the past 15 years, our understanding of the processes that control the atmospheric concentrations of trace gases has changed dramatically. This better understanding was achieved through accumulation of kinetic data and field observations as well as development of new models. It would be beneficial to start examining the impact of subsonic aircraft to identify opportunities to study and validate the mechanisms that were proposed to explain the ozone responses. The two major concerns are the potential for a decrease in the column abundance of ozone leading to an increase in ultraviolet radiation at the ground, and redistribution of ozone in the lower stratosphere and upper troposphere leading to changes in the Earth's climate. Two-dimensional models were used extensively for ozone assessment studies, with a focus on responses to chlorine perturbations. There are problems specific to the aircraft issues that are not adequately addressed by the current models. This chapter reviews the current status of the research on aircraft impact on ozone with emphasis on immediate model improvements necessary for extending our understanding. The discussion will be limited to current and projected commercial aircraft that are equipped with air-breathing engines using conventional jet fuel. The impacts are discussed in terms of the anticipated fuel use at cruise altitude
Neoproterozoic 40Ar/39Ar mica ages mark the termination of a billion years of intraplate reworking in the Capricorn Orogen, Western Australia
The tectonic history of the Proterozoic Capricorn Orogen, Western Australia, records complex intraplate reworking lasting nearly one billion years. Although the Paleo-Mesoproterozoic reworking history is well defined in the crystalline basement of the Gascoyne Province, at the western end of the orogen, the younger reactivation history remains unclear. Four reworking events affected the orogen at 1820–1770 Ma, 1680–1620 Ma, 1320–1170 Ma, and 1030–900 Ma. These events were succeeded by a breakout in predominantly dextral strike-slip reactivation of major shear zones across the Gascoyne Province. Currently, the age of this reactivation is constrained by only one date of c. 570 Ma from a single shear zone, but field relationships imply that some of the shear zones must be older than a suite of c. 755 Ma dolerite dykes. In order to constrain the age of fault and shear zone reactivation we obtained new 40 Ar/ 39 Ar dates for mica and in situ SHRIMP U-Pb dates for xenotime within shear zones. Our results when combined with previously published data, show that reactivation occurred between 920 and 830 Ma. These dates overlap with the youngest reworking event, the 1030–900 Ma Edmundian Orogeny. Furthermore, Neoproterozoic U-Pb phosphate ages are known from the bounding cratons and faulting within the adjacent Mesoproterozoic sedimentary basins suggest this event is of regional significance. In contrast to previous suggestions that this Neoproterozoic reactivation was the result of a collision from the west, we propose that it reflects north–south compression that caused dextral strike-slip fault reactivation in the north and exhumation of the southern part of the orogen
The Effects of Stellar Companions on the Observed Transiting Exoplanet Radius Distribution
Understanding the distribution and occurrence rate of small planets was a fundamental goal of the Kepler transiting exoplanet mission, and could be improved with K2 and Transiting Exoplanet Survey Satellite (TESS). Deriving accurate exoplanetary radii requires accurate measurements of the host star radii and the planetary transit depths, including accounting for any "third light" in the system due to nearby bound companions or background stars. High-resolution imaging of Kepler and K2 planet candidate hosts to detect very close (within ~0.”5) background or bound stellar companions has been crucial for both confirming the planetary nature of candidates, and the determination of accurate planetary radii and mean densities. Here we present an investigation of the effect of close companions, both detected and undetected, on the observed (raw count) exoplanet radius distribution. We demonstrate that the recently detected "gap" in the observed radius distribution (also seen in the completeness-corrected distribution) is fairly robust to undetected stellar companions, given that all of the systems in the sample have undergone some kind of vetting with high-resolution imaging. However, while the gap in the observed sample is not erased or shifted, it is partially filled in after accounting for possible undetected stellar companions. These findings have implications for the most likely core composition, and thus formation location, of super-Earth and sub-Neptune planets. Furthermore, we show that without high-resolution imaging of planet candidate host stars, the shape of the observed exoplanet radius distribution will be incorrectly inferred, for both Kepler- and TESS-detected systems
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