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Search Results: 1 - 10 of 1819 matches for " Derek Craighead "
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Lead Exposure in Bald Eagles from Big Game Hunting, the Continental Implications and Successful Mitigation Efforts
Bryan Bedrosian, Derek Craighead, Ross Crandall
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0051978
Abstract: Studies suggest hunter discarded viscera of big game animals (i.e., offal) is a source of lead available to scavengers. We investigated the incidence of lead exposure in bald eagles in Wyoming during the big game hunting season, the influx of eagles into our study area during the hunt, the geographic origins of eagles exposed to lead, and the efficacy of using non-lead rifle ammunition to reduce lead in eagles. We tested 81 blood samples from bald eagles before, during and after the big game hunting seasons in 2005–2010, excluding 2008, and found eagles had significantly higher lead levels during the hunt. We found 24% of eagles tested had levels indicating at least clinical exposure (>60 ug/dL) during the hunt while no birds did during the non-hunting seasons. We performed driving surveys from 2009–2010 to measure eagle abundance and found evidence to suggest that eagles are attracted to the study area during the hunt. We fitted 10 eagles with satellite transmitters captured during the hunt and all migrated south after the cessation of the hunt. One returned to our study area while the remaining nine traveled north to summer/breed in Canada. The following fall, 80% returned to our study area for the hunting season, indicating that offal provides a seasonal attractant for eagles. We fitted three local breeding eagles with satellite transmitters and none left their breeding territories to feed on offal during the hunt, indicating that lead ingestion may be affecting migrants to a greater degree. During the 2009 and 2010 hunting seasons we provided non-lead rifle ammunition to local hunters and recorded that 24% and 31% of successful hunters used non-lead ammunition, respectively. We found the use of non-lead ammunition significantly reduced lead exposure in eagles, suggesting this is a viable solution to reduce lead exposure in eagles.
Cyanobacteria Produce N-(2-Aminoethyl)Glycine, a Backbone for Peptide Nucleic Acids Which May Have Been the First Genetic Molecules for Life on Earth
Sandra Anne Banack,James S. Metcalf,Liying Jiang,Derek Craighead,Leopold L. Ilag,Paul Alan Cox
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049043
Abstract: Prior to the evolution of DNA-based organisms on earth over 3.5 billion years ago it is hypothesized that RNA was the primary genetic molecule. Before RNA-based organisms arose, peptide nucleic acids may have been used to transmit genetic information by the earliest forms of life on earth. We discovered that cyanobacteria produce N-(2-aminoethyl)glycine (AEG), a backbone for peptide nucleic acids. We detected AEG in axenic strains of cyanobacteria with an average concentration of 1 μg/g. We also detected AEG in environmental samples of cyanobacteria as both a free or weakly bound molecule and a tightly bound form released by acid hydrolysis, at concentrations ranging from not detected to 34 μg/g. The production of AEG by diverse taxa of cyanobacteria suggests that AEG may be a primitive feature which arose early in the evolution of life on earth.
Seasonal Foraging Ecology of Non-Migratory Cougars in a System with Migrating Prey
L. Mark Elbroch, Patrick E. Lendrum, Jesse Newby, Howard Quigley, Derek Craighead
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0083375
Abstract: We tested for seasonal differences in cougar (Puma concolor) foraging behaviors in the Southern Yellowstone Ecosystem, a multi-prey system in which ungulate prey migrate, and cougars do not. We recorded 411 winter prey and 239 summer prey killed by 28 female and 10 male cougars, and an additional 37 prey items by unmarked cougars. Deer composed 42.4% of summer cougar diets but only 7.2% of winter diets. Males and females, however, selected different proportions of different prey; male cougars selected more elk (Cervus elaphus) and moose (Alces alces) than females, while females killed greater proportions of bighorn sheep (Ovis canadensis), pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus) and small prey than males. Kill rates did not vary by season or between males and females. In winter, cougars were more likely to kill prey on the landscape as: 1) elevation decreased, 2) distance to edge habitat decreased, 3) distance to large bodies of water decreased, and 4) steepness increased, whereas in summer, cougars were more likely to kill in areas as: 1) elevation decreased, 2) distance to edge habitat decreased, and 3) distance from large bodies of water increased. Our work highlighted that seasonal prey selection exhibited by stationary carnivores in systems with migratory prey is not only driven by changing prey vulnerability, but also by changing prey abundances. Elk and deer migrations may also be sustaining stationary cougar populations and creating apparent competition scenarios that result in higher predation rates on migratory bighorn sheep in winter and pronghorn in summer. Nevertheless, cougar predation on rare ungulates also appeared to be influenced by individual prey selection.
Circling the Blood in the Water: The Difficulties in Endangered Species Protections for the Great White Shark  [PDF]
Derek Julio
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.511058
Abstract:
The purpose of legislation like the Endangered Species Act is to provide a means to conserve the ecosystems of endangered and threatened species, but not all species that may appear to need conservation are granted protection. An estimated 100 million sharks are killed each year largely due to exploitation, yet few shark species are ever granted protection under state or federal endangered species acts. The Northeastern Pacific population of the Great White Shark is no exception. Despite the numerous threats facing the white shark, NOAA denied a petition to list it as an endangered or threatened species under the federal Endangered Species Act. In light of the pending California decision to list the white shark under its state endangered species act, this paper considers whether or not such extreme protections are necessary. This paper first discusses the threats facing the white shark, the listing processes of both the federal and the California endangered species acts, and NOAA’s 12-month negative finding. Finally, this paper concludes that endangered species protections are not warranted in the case of the Northeastern Pacific white shark because of prior government intervention and conservation efforts already in place.
Surface Engineering and Patterning Using Parylene for Biological Applications
Christine P. Tan,Harold G. Craighead
Materials , 2010, DOI: 10.3390/ma3031803
Abstract: Parylene is a family of chemically vapour deposited polymer with material properties that are attractive for biomedicine and nanobiotechnology. Chemically inert parylene “peel-off” stencils have been demonstrated for micropatterning biomolecular arrays with high uniformity, precise spatial control down to nanoscale resolution. Such micropatterned surfaces are beneficial in engineering biosensors and biological microenvironments. A variety of substituted precursors enables direct coating of functionalised parylenes onto biomedical implants and microfluidics, providing a convenient method for designing biocompatible and bioactive surfaces. This article will review the emerging role and applications of parylene as a biomaterial for surface chemical modification and provide a future outlook.
A Wavelet Spectrum Technique for Machinery Fault Diagnosis  [PDF]
Derek Kanneg, Wilson Wang
Journal of Signal and Information Processing (JSIP) , 2011, DOI: 10.4236/jsip.2011.24046
Abstract: Rotary machines are widely used in various applications. A reliable machinery fault detection technique is critically needed in industries to prevent the machinery system’s performance degradation, malfunction, or even catastrophic failures. The challenge for reliable fault diagnosis is related to the analysis of non-stationary features. In this paper, a wavelet spectrum (WS) technique is proposed to tackle the challenge of feature extraction from these non-stationary signatures; this work will focus on fault detection in rolling element bearings. The vibration signatures are first analyzed by a wavelet transform to demodulate representative features; the periodic features are then enhanced by cross-correlating the resulting wavelet coefficient functions over several contributive neighboring wavelet bands. The effectiveness of the proposed technique is examined by experimental tests corresponding to different bearing conditions. Test results show that the developed WS technique is an effective signal processing approach for non-stationary feature extraction and analysis, and it can be applied effectively for bearing fault detection.
Value Theory and Online Video Gaming  [PDF]
Derek A. Burrill
Advances in Journalism and Communication (AJC) , 2014, DOI: 10.4236/ajc.2014.23010
Abstract: Online video gaming has been an important object of study because of its complex social and cultural processes. However, few studies exist in the discipline of games studies that inspect actual gamers’ concepts of online gaming value. Value theory exists in other disciplines (economics, sociology, axiology, etc.), but has not yet been fully explored in relation to online gaming worlds. This study seeks to inspect how gamers define value and how this is expressed through their online gaming experiences. Additionally, the survey seeks to establish a link between the internal value of the games and the concept of value in the external, real world. The analysis of the survey in this paper shows that gamers establish value in online gaming in relation to value in the external.
纳米尺寸微结构制备
henry i.smith,haroldg.craighead,解思深
物理 , 1991,
Abstract: ?10年前,电子器件的研究和制备刚刚跨入微米的量级.今天,已经在研究100nm尺寸的器件了.从而也就出现了若干新的术语如纳米尺度器件(nanoscaledevice),纳米制版术(nanolithography),纳米尺寸微结构制备或简称纳米制备(nanofabrication).纳米尺度器件(以下简称纳米器件)可分成两类常规器件和量子器件.通道长度短于100nm的场效应管是常规器件的例子.?...
Can Resilience be Reconciled with Globalization and the Increasingly Complex Conditions of Resource Degradation in Asian Coastal Regions?
Derek Armitage,Derek Johnson
Ecology and Society , 2006,
Abstract: This paper explores the relationship between resilience and globalization. We are concerned, most importantly, with whether resilience is a suitable conceptual framework for natural resource management in the context of the rapid changes and disruptions that globalization causes in social-ecological systems. Although theoretical in scope, we ground this analysis using our experiences in two Asian coastal areas: Junagadh District in Gujarat State, India and Banawa Selatan, in Central Sulawesi, Indonesia. We present the histories of resource exploitation in the two areas, and we attempt to combine a resilience perspective with close attention to the impact of globalization. Our efforts serve as a basis from which to examine the conceptual and practical compatibility of resilience with globalization. The first challenge we address is epistemological: given that resilience and globalization have roots in different disciplines, do they share a sufficiently common perception of change and human action to be compatible? Second, we address the issue of how resilience can be a viable management objective in the rapidly changing context of globalization. We identify scale as particularly important in this regard.
The Consequences of Human Behavior
Derek Hodgson
Humanities , 2012, DOI: 10.3390/h1030205
Abstract: Human behavior is founded on a complex interaction of influences that derive from sources both extraneous and intrinsic to the brain. It is the ways these various influences worked together in the past to fashion modern human cognition that can help elucidate the probable course of future human endeavor. A particular concern of this chapter is the way cognition has been shaped and continues to depend on prevailing environmental and ecological conditions. Whether the human predicament can be regarded simply as another response to such conditions similar to that of other organisms or something special will also be addressed. More specifically, it will be shown that, although the highly artificial niche in which most humans now live has had profound effects on ways of thinking, constraints deriving from a shared evolutionary heritage continue to have substantial effects on behavior. The way these exigencies interact will be explored in order to understand the implications for the future wellbeing of humanity.
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