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2009

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Articles 6061 - 6090 of 6353

Full-Text Articles in Physical Sciences and Mathematics

Enhancing The Perceived Threat Of Vehicle Approach To Deer, Bradley F. Blackwell, Thomas W. Seamans Jan 2009

Enhancing The Perceived Threat Of Vehicle Approach To Deer, Bradley F. Blackwell, Thomas W. Seamans

United States Department of Agriculture Wildlife Services: Staff Publications

In North America and Europe, deer (Cervidae)–vehicle collisions (DVCs) are common and result not only in injury and death to the animals involved, but also human injury and property damage. Given that most DVCs occur during crepuscular periods, we questioned whether the perceived threat to deer posed by vehicle approach could be enhanced. We hypothesized that a vehicle-based lighting system that better complements peak visual capabilities of deer at night relative to standard tungsten-halogen (TH) lighting alone would elicit a greater flight-initiation distance (FID) by free-ranging white-tailed deer (Odocoileus virginianus). Our lighting system comprised 2 TH lamps and …

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Regional Assessment On Influence Of Landscape Configuration And Connectivity On Range Size Of White-Tailed Deer, W. David Walter, Kurt C. Vercauteren, Henry Campa Iii, William R. Clark, Justin W. Fischer, Scott E. Hygnstrom, Nancy E. Mathews, Clayton K. Nielsen, Eric M. Schauber, Timothy R. Van Deelen, Scott R. Winterstein Jan 2009

Regional Assessment On Influence Of Landscape Configuration And Connectivity On Range Size Of White-Tailed Deer, W. David Walter, Kurt C. Vercauteren, Henry Campa Iii, William R. Clark, Justin W. Fischer, Scott E. Hygnstrom, Nancy E. Mathews, Clayton K. Nielsen, Eric M. Schauber, Timothy R. Van Deelen, Scott R. Winterstein

United States Department of Agriculture Wildlife Services: Staff Publications

Variation in the size of home range of white-tailed deer (Odocoileus virginianus) has broad implications for managing populations, agricultural damage, and disease spread and transmission. Size of home range of deer also varies seasonally because plant phenology dictates the vegetation types that are used as foraging or resting sites. Knowledge of the landscape configuration and connectivity that contributes to variation in size of home range of deer for the region is needed to fully understand differences and similarities of deer ecology throughout the Midwest. We developed a research team from four Midwestern states to investigate how size of …

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Survival And Cause-Specific Mortality Of Wild Turkeys In Northern Indiana, Lee A. Humberg, Travis L. Devault, Olin E. Rhodes Jr. Jan 2009

Survival And Cause-Specific Mortality Of Wild Turkeys In Northern Indiana, Lee A. Humberg, Travis L. Devault, Olin E. Rhodes Jr.

United States Department of Agriculture Wildlife Services: Staff Publications

Information regarding survival and cause-specific mortality of eastern wild turkeys (Meleagris gallopavo silvestris) is vital to their management, especially in small or isolated populations. Between January 2003 and August 2005, we used radio telemetry to investigate survival and cause-specific mortality of 87 [44 male (24 adult and 20 juvenile) and 43 female (34 adult and 9 juvenile)] wild turkeys in northern Indiana. We estimated annual and seasonal survival using the Kaplan-Meier product-limit method. Mean male and female annual survival estimates were 0.257 and 0.777, respectively. Annual survival estimates were different between sexes within years, but were homogenous within …

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A Review Of Mitigation Measures For Reducing Wildlife Mortality On Roadways, David J. Glista, Travis L. Devault, J. Andrew Dewoody Jan 2009

A Review Of Mitigation Measures For Reducing Wildlife Mortality On Roadways, David J. Glista, Travis L. Devault, J. Andrew Dewoody

United States Department of Agriculture Wildlife Services: Staff Publications

A growing literature in the field of road ecology suggests that vehicle/wildlife collisions are important to biologists and transportation officials alike. Roads can affect the quality and quantity of available wildlife habitat, most notably through fragmentation. Likewise, vehicular traffic on roads can be direct sources of wildlife mortality and in some instances, can be catastrophic to populations. Thus, connectivity of habitat and permeability of road systems are important factors to consider when developing road mortality mitigation systems. There are a variety of approaches that can be used to reduce the effects of roads and road mortality on wildlife populations. Here, …

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Avian Visual System Configuration And Behavioural Response To Object Approach, Bradley F. Blackwelll, Esteban Fernández-Juricic, Thomas W. Seamans, Tracy Dolan Jan 2009

Avian Visual System Configuration And Behavioural Response To Object Approach, Bradley F. Blackwelll, Esteban Fernández-Juricic, Thomas W. Seamans, Tracy Dolan

United States Department of Agriculture Wildlife Services: Staff Publications

Antipredator behavior theory provides a framework to understand the mechanisms behind human–wildlife interactions; however, little is known about the role of visual systems in the responses to humans. We quantified responses of brown-headed cowbirds, Molothrus ater (Boddaert), and mourning doves, Zenaida macroura (Linnaeus), to object approach (a ground-based vehicle) and vehicle lighting regimen, and we examined two visual properties (visual acuity and visual fields) that could influence antipredator behavior. Brown-headed cowbird groups exposed to vehicle approach and constant illumination of the vehicle-mounted lamp showed alert behavior earlier than did groups exposed to pulsating treatments or no lamp. Interestingly, light treatments …

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Use Of Infrared Thermography To Detect Thermographic Changes In Mule Deer (Odocoileus Hemionus) Experimentally Infected With Foot-And-Mouth Disease, Mike R. Dunbar, Shylo R. Johnson, Jack C. Ryan, Matt Mccollum Jan 2009

Use Of Infrared Thermography To Detect Thermographic Changes In Mule Deer (Odocoileus Hemionus) Experimentally Infected With Foot-And-Mouth Disease, Mike R. Dunbar, Shylo R. Johnson, Jack C. Ryan, Matt Mccollum

United States Department of Agriculture Wildlife Services: Staff Publications

Infrared thermography (IRT) measures the heat emitted from a surface, displays that information as a pictorial representation called a thermogram, and is capable of being a remote, noninvasive technology that provides information on the health of an animal. Foot-and-mouth disease (FMD) caused by FMD virus (FMDV) is a severe, highly communicable viral disease of cloven-hoofed animals, including both domestic and wild ruminants. Early detection of the disease may reduce economic loss and loss of susceptible wildlife. The objective of this study was to evaluate the use of IRT to detect possible heat changes associated with sites of infection with FMDV …

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Dogs Gone Wild: Feral Dog Damage In The United States, David Bergman, Stewart W. Breck, Scott Bender Jan 2009

Dogs Gone Wild: Feral Dog Damage In The United States, David Bergman, Stewart W. Breck, Scott Bender

United States Department of Agriculture Wildlife Services: Staff Publications

Feral dogs have been documented in all 50 states and estimates of damage in the U.S. from these animals amount to >$620 million annually. In Texas alone, it is estimated that over $5 million in damage to livestock annually can be attributed to feral dogs. We reviewed national statistics on feral dog damage reported to USDA, APHIS, Wildlife Services for a 10-year period from 1997 through 2006. Damage by feral dogs crossed multiple resource categories (e.g., agriculture, natural resources); some examples of damage include killing and affecting the behavior and habitat use of native wildlife; killing and maiming livestock; and …

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Biology And Impacts Of Pacific Island Invasive Species. 5. Eleutherodactylus Coqui, The Coqui Frog (Anura: Leptodactylidae), Karen H. Beard, William C. Pitt, Emily A. Price Jan 2009

Biology And Impacts Of Pacific Island Invasive Species. 5. Eleutherodactylus Coqui, The Coqui Frog (Anura: Leptodactylidae), Karen H. Beard, William C. Pitt, Emily A. Price

United States Department of Agriculture Wildlife Services: Staff Publications

The nocturnal, terrestrial frog Eleutherodactylus coqui, known as the Coqui, is endemic to Puerto Rico and was accidentally introduced to Hawai‘i via nursery plants in the late 1980s. Over the past two decades E. coqui has spread to the four main Hawaiian Islands, and a major campaign was launched to eliminate and control it. One of the primary reasons this frog has received attention is its loud mating call (85–90 dB at 0.5 m). Many homeowners do not want the frogs on their property, and their presence has influenced housing prices. In addition, E. coqui has indirectly impacted the …

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Ecological Correlates Of Risk And Incidence Of West Nile Virus In The United States, Brian F. Allan, R. Brian Langerhans, Wade A. Ryberg, William J. Landesman, Nicholas W. Griffin, Rachael S. Katz, Brad J. Oberle, Michele R. Schutzenhofer, Kristina N. Smyth, Annabelle De St. Maurice, Larry Clark, Kevin R. Crooks, Daniel E. Hernandez, Robert G. Mclean, Richard S. Ostfeld, Jonathan M. Chase Jan 2009

Ecological Correlates Of Risk And Incidence Of West Nile Virus In The United States, Brian F. Allan, R. Brian Langerhans, Wade A. Ryberg, William J. Landesman, Nicholas W. Griffin, Rachael S. Katz, Brad J. Oberle, Michele R. Schutzenhofer, Kristina N. Smyth, Annabelle De St. Maurice, Larry Clark, Kevin R. Crooks, Daniel E. Hernandez, Robert G. Mclean, Richard S. Ostfeld, Jonathan M. Chase

United States Department of Agriculture Wildlife Services: Staff Publications

West Nile virus, which was recently introduced to North America, is a mosquito-borne pathogen that infects a wide range of vertebrate hosts, including humans. Several species of birds appear to be the primary reservoir hosts, whereas other bird species, as well as other vertebrate species, can be infected but are less competent reservoirs. One hypothesis regarding the transmission dynamics of West Nile virus suggests that high bird diversity reduces West Nile virus transmission because mosquito blood-meals are distributed across a wide range of bird species, many of which have low reservoir competence. One mechanism by which this hypothesis can operate …

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Comparison Of Injuries To Coyote From 3 Types Of Cable Foot-Restraints, Patrick Darrow, Ramona Skirpstunas, S. Wade Carlson, John Shivik Jan 2009

Comparison Of Injuries To Coyote From 3 Types Of Cable Foot-Restraints, Patrick Darrow, Ramona Skirpstunas, S. Wade Carlson, John Shivik

United States Department of Agriculture Wildlife Services: Staff Publications

We compared injury rates among captured coyotes (Canis latrans) to determine if modifications to cable foot-restraints would decrease resulting injuries. Mean International Standardization Organization’s injury scores of coyotes caught in 3 types of cable foot-restraints were 22.2, 37.9, and 60.4 (F2,41 = 4.63, P = 0.015) for a chain-loop, standard cable, and sleeved cable, respectively. These results may be important for trappers and researchers to consider when using a cable foot-restraint device to capture wildlife.

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Influence Of Exogenous Gonadotropin-Releasing Hormone On Seasonal Reproductive Behavior Of The Coyote (Canis Latrans), D. A. Carlson, E. M. Gese Jan 2009

Influence Of Exogenous Gonadotropin-Releasing Hormone On Seasonal Reproductive Behavior Of The Coyote (Canis Latrans), D. A. Carlson, E. M. Gese

United States Department of Agriculture Wildlife Services: Staff Publications

Wild Canis species such as the coyote (C. latrans) express a suite of reproductive traits unusual among mammals, including perennial pair-bonds and paternal care of the young. Coyotes also are monestrous, and both sexes are fertile only in winter; thus, they depend upon social and physiologic synchrony for successful reproduction. To investigate the mutability of seasonal reproduction in coyotes, we attempted to evoke an out-of-season estrus in October using one of two short-acting gonadotropin-releasing hormone (GnRH) agents: (1) a GnRH analogue, deslorelin (6-D-tryptophan-9-(N-ethyl-L-prolinamide)-10-deglycinamide), 2.1 mg pellet sc; or (2) gonadorelin, a GnRH (5-oxoPro-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-GlyNH2) porcine hypothalamic extract, …

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Feral Swine Damage And Damage Management In Forested Ecosystems, Tyler A. Campbell, David B. Long Jan 2009

Feral Swine Damage And Damage Management In Forested Ecosystems, Tyler A. Campbell, David B. Long

United States Department of Agriculture Wildlife Services: Staff Publications

Invasive feral swine (Sus scrofa) cause deleterious impacts to ecosystem processes and functioning throughout their worldwide distribution, including forested ecosystems in the United States. Unfortunately, many feral swine damage management programs are conducted in a piecemeal fashion, are not adequately funded, and lack clearly stated or realistic objectives. This review paper identifies damage caused by feral swine to forest resources and presents techniques used to prevent and control feral swine damage. Concluding points related to planning a feral swine damage management program are: (1) the value of using a variety of techniques in an integrated fashion cannot be …

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Testing A Passive Tracking Index For Monitoring The Endangered Ethiopian Wolf, Paul Paul Evangelista, Richard M. Engeman, Lucy Tallents Jan 2009

Testing A Passive Tracking Index For Monitoring The Endangered Ethiopian Wolf, Paul Paul Evangelista, Richard M. Engeman, Lucy Tallents

United States Department of Agriculture Wildlife Services: Staff Publications

The endangered Ethiopian wolf is considered the rarest canid in Africa. The species faces many threats and is particularly vulnerable to diseases such as rabies. A simple, low-technology means to monitor populations would greatly facilitate conservation efforts, through early detection of population changes and behavior, and signaling a need for intervention. We tested a passive tracking index methodology, which has been a valuable tool for indexing canids and other species around the world. The method uses counts of track intrusions into plots placed in the animals’ routes of travel as the basis for calculating an index. Unlike for other species, …

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Ctenosaura Similis (Black Spiny-Tailed Iguana), ,I>Gopherus Polyphemus (Gopher Tortoise) Concurrent Burrow Use, Richard M. Engeman, Bernice Constantin, Missy Christie, Parker Hall Jan 2009

Ctenosaura Similis (Black Spiny-Tailed Iguana), ,I>Gopherus Polyphemus (Gopher Tortoise) Concurrent Burrow Use, Richard M. Engeman, Bernice Constantin, Missy Christie, Parker Hall

United States Department of Agriculture Wildlife Services: Staff Publications

Ctenosaura similis is exotic to Florida (Meshaka et al. 2004. The Exotic Amphibians and Reptiles of Florida, Krieger Publ. Co., Malabar, Florida. 155 pp.), whereas Gopherus polyphemus is listed as a species of special concern by the state of Florida (Florida Wildlife Code Chap. 39 F.A.C.), and as a threatened species by the Florida Committee on Rare and Endangered Plants and Animals (FCREPA) (Moler 1992. Rare and Endangered Biota of Florida: Volume III, Reptiles and Amphibians. University Press of Florida, Gainesville, Florida. 291 pp.).

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Working Dogs: The Last Line Of Defense For Preventing Dispersal Of Brown Treesnakes From Guam, Daniel S. Vice, Richard M. Engeman, Marc A. Hall, Craig S. Clark Jan 2009

Working Dogs: The Last Line Of Defense For Preventing Dispersal Of Brown Treesnakes From Guam, Daniel S. Vice, Richard M. Engeman, Marc A. Hall, Craig S. Clark

United States Department of Agriculture Wildlife Services: Staff Publications

The inadvertent introduction of the brown treesnake (Boiga irregularis) to Guam resulted in unprecedented losses to the island’s fragile ecology and economy. A primary management objective is preventing the spread of brown treesnakes to other locations via Guam’s transportation network. To achieve this, snake populations are suppressed in and around port and cargo staging areas through an integrated wildlife damage management approach, with the last line of defense for preventing their entrance into the outbound cargo flow inspection by trained snake detector dogs. The efficacy of working dogs on Guam has been evaluated from a variety of aspects.

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Testudines - Turtles, James Delutes Iii, Richard M. Engeman Jan 2009

Testudines - Turtles, James Delutes Iii, Richard M. Engeman

United States Department of Agriculture Wildlife Services: Staff Publications

Chelydra serpentine serpentine (Common Snapping Turtle). Nesting Behavior and Site Selection. On May 31, 2008, we observed a ca. 36 cm CL Chelydra serpentine serpentine in unexpected nesting circumstances. Observations were made from 0908 to 1027 h on clear day with ambient temp ca 24° C. The nest site near Longmont, Colorado, USA (40.1599528°N, 105.1259861°W; WGS84) was 4.3 m from a seasonal ditch running north-south to connect two lakes, one on either side of a busy road. The intriguing aspect of the nest location was that it was immediately adjacent to a heavily traveled concrete sidewalk that bordered a road …

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Field Test Of A Single-Injection Gonadotrophin-Releasing Hormone Immunocontraceptive Vaccine In Female White-Tailed Deer, James P. Gionfriddo, John D. Eisemann, Kevin J. Sullivan, Ronald S. Healey, Lowell A. Miller, Kathleen A. Fagerstone, Richard M. Engeman, Christi A. Yoder Jan 2009

Field Test Of A Single-Injection Gonadotrophin-Releasing Hormone Immunocontraceptive Vaccine In Female White-Tailed Deer, James P. Gionfriddo, John D. Eisemann, Kevin J. Sullivan, Ronald S. Healey, Lowell A. Miller, Kathleen A. Fagerstone, Richard M. Engeman, Christi A. Yoder

United States Department of Agriculture Wildlife Services: Staff Publications

The development and use of safe, effective and practical wildlife contraceptive agents could reduce reproduction in locally overabundant deer populations in situations where traditional management tools such as regulated hunting cannot be employed. GonaCon Immunocontraceptive Vaccine (the commercial name for a particular gonadotrophin-releasing hormone (GnRH)-based emulsion) was tested in adult female white-tailed deer in a fenced herd near Silver Spring, Maryland, USA. Observations of udder condition were used to identify does that had become pregnant. Necropsy observations, histopathology and serum concentrations of anti-GnRH antibodies, luteinising hormone and progesterone were used to compare health and reproductive status of treated (n = …

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Feasibility Of Infectious Prion Digestion Using Mild Conditions And Commercial Subtilisin, John L. Pilona, Paul B. Nash, Terry Arver, Don Hoglund, Kurt C. Vercauteren Jan 2009

Feasibility Of Infectious Prion Digestion Using Mild Conditions And Commercial Subtilisin, John L. Pilona, Paul B. Nash, Terry Arver, Don Hoglund, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Two serine protease enzymes, subtilisin 309 and subtilisin 309-v,were used to digest brain homogenates containing high levels of prion infectivity using mildly alkaline conditions to investigate prion decontamination methods. To establish that PrPres infectivity was eliminated, we utilized the Rocky Mountain Laboratory (RML) mouse-adapted scrapie model system for bioassay. Only one digestion condition (subtilisin 309 at 138mAU/ml, 55 ◦C and 14 h digestion time pH 7.9) was considered to be highly relevant statistically (P < 0.001) compared to control, with 52% of challenged mice surviving until the end of the study period. In contrast, treatment of PrPres by autoclaving at 134 ◦C or treatment with hypochlorite at a concentration of 20,000ppm completely protected mice from prionosis. Further, in vitro assays suggest …

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Intraspecific Comparison Of Population Structure, Genetic Diversity, And Dispersal Among Three Subspecies Of Townsend’S Big-Eared Bats, Corynorhinus Townsendii Townsendii, C. T. Pallescens, And The Endangered C. T. Birginianus, Antoinette J. Piaggio, Kirk W. Navo, Craig W. Stihler Jan 2009

Intraspecific Comparison Of Population Structure, Genetic Diversity, And Dispersal Among Three Subspecies Of Townsend’S Big-Eared Bats, Corynorhinus Townsendii Townsendii, C. T. Pallescens, And The Endangered C. T. Birginianus, Antoinette J. Piaggio, Kirk W. Navo, Craig W. Stihler

United States Department of Agriculture Wildlife Services: Staff Publications

Townsend’s big-eared bat, Corynorhinus townsendii, is distributed broadly across western North America and in two isolated, endangered populations in central and eastern United States. There are five subspecies of C. townsendii; C. t. pallescens, C. t. australis, C. t. townsendii, C. t. ingens, and C. t. virginianus with varying degrees of concern over the conservation status of each. The aim of this study was to use mitochondrial and microsatellite DNA data to examine genetic diversity, population differentiation, and dispersal of three C. townsendii subspecies. C. t. virginianus is found in isolated populations in the eastern United States and …

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Experimental Infection Of Richardson’S Ground Squirrels (Spermophilus Richardsonii ) With Attenuated And Virulent Strains Pf Brucella Abortus, Pauline Nol, Steven C. Olsen, Jack C. Rhyan Jan 2009

Experimental Infection Of Richardson’S Ground Squirrels (Spermophilus Richardsonii ) With Attenuated And Virulent Strains Pf Brucella Abortus, Pauline Nol, Steven C. Olsen, Jack C. Rhyan

United States Department of Agriculture Wildlife Services: Staff Publications

A previous investigation of the safety of Brucella abortus strain RB51 (sRB51) in various nontarget species suggested that Richardson’s ground squirrels (Spermophilus richardsonii) may develop persistent infections when orally inoculated with the vaccine. In the present study, sRB51, B. abortus strain 19 (s19), and virulent B. abortus strain 9941 (s9941) were administered orally to Richardson’s ground squirrels to further characterize B. abortus infection in this species. Six groups of nongravid ground squirrels were orally inoculated with 6x108 colony forming units (cfu) sRB51 (n=10), 2.5x104 cfu s19 (n=10), 2.5x107 cfu s19 (n=6), 1.3x106 cfu s9941 …

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Captive Coyotes Compared To Their Counterparts In The Wild: Does Environmental Enrichment Help?, John A. Shivik, Gernrna L. Palmer, Eric M. Gese, Britta Osthaus Jan 2009

Captive Coyotes Compared To Their Counterparts In The Wild: Does Environmental Enrichment Help?, John A. Shivik, Gernrna L. Palmer, Eric M. Gese, Britta Osthaus

United States Department of Agriculture Wildlife Services: Staff Publications

This article attempts to determine the effects of environment (captive or wild) and a simple form of environmental enrichment on the behavior and physiology of a nonhuman animal. Specifically, analyses first compared behavioral budgets and stereotypic behavior of captive coyotes (Canis latrans) in kennels and pens to their counterparts in the wild. Second, experiments examined the effect of a simple form of environmental enrichment for captive coyotes (food-filled bones) on behavioral budgets, stereotypes, and corticosteroid levels. Overall, behavioral budgets of captive coyotes in both kennels and pens were similar to those observed in the wild, but coyotes in …

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Longevity Of Dayglo Fluorescent Particle Marker Used To Mark Birds In Flight Pen And Field, Shelagh K. Tupper, John L. Cummings, Richard M. Engeman Jan 2009

Longevity Of Dayglo Fluorescent Particle Marker Used To Mark Birds In Flight Pen And Field, Shelagh K. Tupper, John L. Cummings, Richard M. Engeman

United States Department of Agriculture Wildlife Services: Staff Publications

Spray application of fluorescent particles is a widely used and very valuable technique for marking birds. This remains one of the few practical means to mark large numbers of birds for monitoring movement, despite recent availability of a variety of more technologically advanced options. We monitored the longevity of the DayGlo fluorescent particle marker on red-winged blackbirds under simulated field conditions in a flight pen, and in an observational field experiment. In the pen study we banded 52 red-winged blackbirds with individually numbered leg bands, and sprayed them with DayGlo fluorescent particle marker from a distance of ~50 cm, on …

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Antemortem Detection Of PrpCwd In Preclinical, Ranch-Raised Rocky Mountain Elk (Cervus Elaphus Nelson) By Biopsy Of The Rectal Mucosa, Terry R. Spraker, Kurt C. Vercauteren, Thomas Gidlewski, David A. Schneider, Randy Munger, Aru Balachandran, Katherine I. O’Rourke Jan 2009

Antemortem Detection Of PrpCwd In Preclinical, Ranch-Raised Rocky Mountain Elk (Cervus Elaphus Nelson) By Biopsy Of The Rectal Mucosa, Terry R. Spraker, Kurt C. Vercauteren, Thomas Gidlewski, David A. Schneider, Randy Munger, Aru Balachandran, Katherine I. O’Rourke

United States Department of Agriculture Wildlife Services: Staff Publications

Antemortem biopsy of the rectal mucosa was evaluated as a method for the preclinical diagnosis of chronic wasting disease (CWD) in a herd of ranch-raised Rocky Mountain elk (Cervus elaphus nelson) quarantined because of exposure to CWD. Biopsy samples were obtained from 41 elk during the winter of 2005–2006 and from 26 elk from that herd still alive and available for testing during the winter of 2006–2007. Samples were examined for PrPCWD, the protein marker for CWD infection, by immunohistochemistry. PrPCWD was detected in follicles of the rectoanal mucosa-associated lymphoid tissue in biopsy samples from …

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Analysis Of Connections Between Pseudocodewords, Nathan Axvig, Deanna Dreher, Katherine Morrison, Eric T. Psota, Lance C. Pérez, Judy L. Walker Jan 2009

Analysis Of Connections Between Pseudocodewords, Nathan Axvig, Deanna Dreher, Katherine Morrison, Eric T. Psota, Lance C. Pérez, Judy L. Walker

Department of Mathematics: Faculty Publications

The role of pseudocodewords in causing noncodeword outputs in linear programming (LP) decoding, graph cover decoding, and iterative message-passing decoding is investigated. The three main types of pseudocodewords in the literature — linear programming pseudocodewords, graph cover pseudocodewords, and computation tree pseudocodewords — are reviewed and connections between them are explored. Some discrepancies in the literature on minimal and irreducible pseudocodewords are highlighted and clarified, and a value for the minimal degree cover necessary to realize an LP pseudocodeword is found. Additionally, some conditions for the existence of connected realizations of graph cover pseudocodewords are given. This allows for further …

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Connections Between Computation Trees And Graph Covers, Deanna Dreher, Judy L. Walker Jan 2009

Connections Between Computation Trees And Graph Covers, Deanna Dreher, Judy L. Walker

Department of Mathematics: Faculty Publications

Connections between graph cover pseudocodewords and computation tree pseudocodewords are investigated with the aim of bridging the gap between the theoretically attractive analysis of graph covers and the more intractable analysis of iterative message-passing algorithms that are intuitively linked to graph covers. Both theoretical results and numerous examples are presented.

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Does Sedimentary 231Pa/230Th From The Bermuda Rise Monitor Past Atlantic Meridional Overturning Circulation?, Jörg Lippold, Jens Grützner, Diane Winter, Yann Lahaye, Augusto Mangini, Marcus Christl Jan 2009

Does Sedimentary 231Pa/230Th From The Bermuda Rise Monitor Past Atlantic Meridional Overturning Circulation?, Jörg Lippold, Jens Grützner, Diane Winter, Yann Lahaye, Augusto Mangini, Marcus Christl

Department of Earth and Atmospheric Sciences: Faculty Publications

Ocean circulation may have undergone reductions and reinvigorations in the past closely tied to regional climate changes. Measurements of 231Pa/230Th ratios in a sediment core from the Bermuda Rise have been interpreted as evidence that the Atlantic Meridional Overturning Circulation (AMOC) was weakened or completely eliminated during a period of catastrophic iceberg discharges (Heinrich-Event 1, H1). Here we present new data from the Bermuda Rise that show further 231Pa/230Th peaks during Heinrich-2 (H2) and Heinrich-3 (H3). Additionally, a tight correlation between diatom abundances (biogenic silica) and 231Pa/230Th is discovered in this …

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On The Role Of Groundwater And Soil Texture In The Regional Water Balance: An Investigation Of The Nebraska Sand Hills, Usa, Tiejun Wang, Erkan Istanbulluoglu, John D. Lenters, Durelle T. Scott Jan 2009

On The Role Of Groundwater And Soil Texture In The Regional Water Balance: An Investigation Of The Nebraska Sand Hills, Usa, Tiejun Wang, Erkan Istanbulluoglu, John D. Lenters, Durelle T. Scott

Department of Earth and Atmospheric Sciences: Faculty Publications

Partitioning of precipitation between evapotranspiration and runoff at the basin scale is primarily controlled by climate and basin characteristics. Here we use the Budyko hypothesis to investigate the impacts of soil texture and groundwater (e.g., baseflow) on annual and long-term mean annual water balances of basins in a semiarid region located in and around the Sand Hills region of Nebraska, USA. Native grasslands are dominant across the study area with soil textures dramatically different for the Nebraska Sand Hills (primarily sand deposits) and the adjacent regions (mainly less permeable silt loam). For each basin, long-term hydrologic and meteorological data are …

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Optimal Segment Size For Fixed-Sized Segment Protection In Wavelength-Routed Optical Networks, Raghunath Tewari, Byrav Ramamurthy Jan 2009

Optimal Segment Size For Fixed-Sized Segment Protection In Wavelength-Routed Optical Networks, Raghunath Tewari, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

Protecting a network against link failures is a major challenge faced by network operators. The protection scheme has to address two important objectives - fast recovery and minimizing the amount of backup resources needed. Every protection algorithm is a tradeoff between these two objectives.

In this paper, we study the problem of segment protection. In particular, we investigate what is the optimal segment size that obtains the best tradeoff between the time taken for recovery and minimizing the bandwidth used by the backup segments. We focus on the uniform fixed-length segment protection method, where each primary path is divided into …

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A Flexible Divide-And-Conquer Protocol For Multi-View Peer-To-Peer Live Streaming, Miao Wang, Lisong Xu, Byrav Ramamurthy Jan 2009

A Flexible Divide-And-Conquer Protocol For Multi-View Peer-To-Peer Live Streaming, Miao Wang, Lisong Xu, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

Multi-view peer-to-peer (P2P) live streaming systems have recently emerged, where a user can simultaneously watch multiple channels. Previous work on multi-view P2P streaming solves the fundamental inter-channel bandwidth competition problem at the individual peer level, and thus can be used with very limited types of streaming protocols. In this paper, we propose a new protocol for multi-view P2P streaming, called Divide-and-Conquer (DAC), which efficiently solves the inter-channel bandwidth competition problem using a divide-and-conquer strategy at the channel level, and thus is flexible to work with various streaming protocols. This makes DAC more suitable for upgrading current single-view P2P live streaming …

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Directed Test Suite Augmentation, Zhihong Xu, Gregg Rothermel Jan 2009

Directed Test Suite Augmentation, Zhihong Xu, Gregg Rothermel

School of Computing: Conference and Workshop Papers

As software evolves, engineers use regression testing to evaluate its fitness for release. Such testing typically begins with existing test cases, and many techniques have been proposed for reusing these cost-effectively. After reusing test cases, however, it is also important to consider code or behavior that has not been exercised by existing test cases and generate new test cases to validate these. This process is known as test suite augmentation. In this paper we present a directed test suite augmentation technique, that utilizes results from reuse of existing test cases together with an incremental concolic testing algorithm to augment …

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