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Search Results: 1 - 10 of 3448 matches for " Megan Phillips "
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Temporal introduction patterns of invasive alien plant species to Australia
Brad Murray,Megan Phillips
NeoBiota , 2012, DOI: 10.3897/neobiota.13.2422
Abstract: We examined temporal introduction patterns of 132 invasive alien plant species (IAPS) to Australia since European colonisation in 1770. Introductions of IAPS were high during 1810–1820 (10 species), 1840–1880 (51 species, 38 of these between 1840 and 1860) and 1930–1940 (9 species). Conspicuously few introductions occurred during 10-year periods directly preceding each introduction peak. Peaks during early European settlement (1810–1820) and human range expansion across the continent (1840-1860) both coincided with considerable growth in Australia’s human population. We suggest that population growth during these times increased the likelihood of introduced plant species becoming invasive as a result of increased colonization and propagule pressure. Deliberate introductions of IAPS (104 species) far outnumbered accidental introductions (28 species) and were particularly prominent during early settlement. Cosmopolitan IAPS (25 species) and those native solely to South America (53 species), Africa (27 species) and Asia (19 species) have been introduced deliberately and accidentally to Australia across a broad period of time. A small number of IAPS, native solely to Europe (5 species) and North America (2 species), were all introduced to Australia prior to 1880. These contrasting findings for native range suggest some role for habitat matching, with similar environmental conditions in Australia potentially driving the proliferation of IAPS native to southern-hemisphere regions. Shrub, tree and vine species dominated IAPS introduced prior to 1840, with no grasses or forbs introduced during early colonisation. Since 1840, all five growth forms have been introduced deliberately and accidentally in relatively large numbers across a broad period of time. In particular, a large number of grass and forb IAPS were deliberately introduced between 1840 and 1860, most likely a direct result of the introduction of legislation promoting intensive agriculture across large areas of the continent. Since the 1980s, only three IAPS have been introduced (all deliberately introduced forbs). The decline in IAPS introductions is most likely a reflection of both increased surveillance and biosecurity efforts and the likelihood that many potential IAPS are still within a pre-expansion lag period.
Differences in Leaf Flammability, Leaf Traits and Flammability-Trait Relationships between Native and Exotic Plant Species of Dry Sclerophyll Forest
Brad R. Murray, Lyndle K. Hardstaff, Megan L. Phillips
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079205
Abstract: The flammability of plant leaves influences the spread of fire through vegetation. Exotic plants invading native vegetation may increase the spread of bushfires if their leaves are more flammable than native leaves. We compared fresh-leaf and dry-leaf flammability (time to ignition) between 52 native and 27 exotic plant species inhabiting dry sclerophyll forest. We found that mean time to ignition was significantly faster in dry exotic leaves than in dry native leaves. There was no significant native-exotic difference in mean time to ignition for fresh leaves. The significantly higher fresh-leaf water content that was found in exotics, lost in the conversion from a fresh to dry state, suggests that leaf water provides an important buffering effect that leads to equivalent mean time to ignition in fresh exotic and native leaves. Exotic leaves were also significantly wider, longer and broader in area with significantly higher specific leaf area–but not thicker–than native leaves. We examined scaling relationships between leaf flammability and leaf size (leaf width, length, area, specific leaf area and thickness). While exotics occupied the comparatively larger and more flammable end of the leaf size-flammability spectrum in general, leaf flammability was significantly correlated with all measures of leaf size except leaf thickness in both native and exotic species such that larger leaves were faster to ignite. Our findings for increased flammability linked with larger leaf size in exotics demonstrate that exotic plant species have the potential to increase the spread of bushfires in dry sclerophyll forest.
Teaching Feminist Poststructuralism: Founding Scholars Still Relevant Today  [PDF]
Megan Aston
Creative Education (CE) , 2016, DOI: 10.4236/ce.2016.715220
Abstract: This article presents the experiences of one academic educator/researcher learning about and ultimately teaching feminist poststructuralism (FPS) over 20 years. Ideas from foundational postructural and feminist theorists such as Foucault, Butler, Scott and Weedon are presented and brought together into to a particular understanding of FPS. A discussion of how FPS is applied to health education and research will be presented along with clinical examples. After many years of mentoring and teaching students and colleagues about FPS, the author has created a general guide for beginners to help them use FPS in research and practice. This guide has successfully been used with students and colleagues in Canada as well as with colleagues in Tanzania.
Evaluating Displayed Depression Symptoms on Social Media Sites  [PDF]
Megan A. Moreno, Erin Kelleher, Megan Pumper
Social Networking (SN) , 2013, DOI: 10.4236/sn.2013.24018
Abstract:

Social networking sites (SNSs) are immensely popular and allow for display of personal information, including references to depression. Evaluating displayed content on a SNS for research purposes requires a systematic approach and a precise data collection instrument. The purpose of this paper is to describe one approach to the development of a research codebook for depression so that others may develop and test their own codebooks for use in SNS research. The depression SNS research codebook was grounded in ethics, theory and clinical criteria.The key elements in the codebook developmental process included an iterative team approach to develop variables of interest and data collection sheet layout. Training protocols involve coding practice and reliability assessments. Interrater reliability remains a critical assessment tool. Codebook successes include consistently high interrater reliability. Challenges include time investment in coder training, SNS server changes, and social or cultural norms regarding public displays of mental health. We provide detailed information about a systematic approach to codebook development so that other researchers may use this structure to develop and test their own codebooks for use in SNS research. Future directions for the codebook include expanding areas of interest such as anxiety or other depression evaluation criteria, and expansion to other SNSs such as Twitter.

Elevated Stream Pathogenic Indicator Bacteria Concentrations in Livestock Grazing Areas across a Single National Forest  [PDF]
Lindsey Myers, Megan Fiske, Megan Layhee
Natural Resources (NR) , 2017, DOI: 10.4236/nr.2017.810042
Abstract:

Livestock presence in proximity to forest streams has been shown to contribute pathogenic bacteria in excess of water quality standards established to protect human health. However, the degree to which livestock fecal contamination in streams on national forest lands is either a limited or a potentially widespread occurrence is still debated. This study provides additional insight into the matter. We analyzed water in small streams near known cattle grazing areas within the Stanislaus National Forest in the Sierra Nevada, California from 2012 to 2016. Fourteen stream sites were sampled before and after cattle were released onto the forest (four of these sites were sampled across multiple years) to compare indicator bacteria concentrations (fecal coliform—FC, Escherichia coli—EC) to standards established for recreational contact for surface waters. One control site was also sampled. There were 194 water quality violations of either state or federal regulatory standards for recreational contact, all of which occurred once cattle were on the forest. Mean (max) FC and EC concentrations were on orders of magnitude higher after cattle were released onto the forest [FC 1307 (30,000) and EC 1033 (17,000) MPN/100 mL] than during the time period before cattle were on the forest [FC 19 (220) and EC 17 (220) MPN/100 mL; FC, F1,210 = 105, p < 0.001; EC, F1,210 = 85.5, p < 0.001]. In addition, the presence of cattle, visual evidence of recent cattle-related disturbances, and sampling week were important predictor variables of FC and EC. These findings support the link between cattle presence and increased levels of stream pathogenic bacteria, and also demonstrate that stream pathogenic bacteria pollution occurs widely across the forest. This research indicates the need to consider alternative range management practices to better protect water quality and human health.

Regularities in Sequences of Observations  [PDF]
Mahkame Megan Khoshyaran
Open Journal of Statistics (OJS) , 2012, DOI: 10.4236/ojs.2012.24049
Abstract: The objective of this paper is to propose an adjustment to the three methods of calculating the probability that regularities in a sample data represent a systemic influence in the population data. The method proposed is called data profiling. It consists of calculating vertical and horizontal correlation coefficients in a sample data. The two correlation coefficients indicate the internal dynamic or inter dependency among observation points, and thus add new information. This information is incorporated in the already established methods and the consequence of this integration is that one can conclude with certainty that the probability calculated is indeed a valid indication of systemic influence in the population data.
The Impact of Vehicular Networks on Urban Networks  [PDF]
Mahkame Megan Khoshyaran
Journal of Transportation Technologies (JTTs) , 2014, DOI: 10.4236/jtts.2014.44027
Abstract: The objective of this paper is to study the impact of a vehicular network on a physical (road) network consisting of several intersections controlled by traffic lights. The vehicular network is considered to be a random graph superimposed on a regular Hamiltonian graph. The two graphs are connected by hyperlinks. The evolution of traffic at intersections given the existence of vehicular networks is measured by the method of reflective triangles.
Analyzing Capitalism  [PDF]
Mahkame Megan Khoshyaran
Modern Economy (ME) , 2015, DOI: 10.4236/me.2015.61004
Abstract: The intent of this paper is to show that for the capitalist system to survive some specific form of economic activities have to be practiced. These economic activities are introduced in this paper in the form of economic theorems. Their existence and credibility are exhibited through structured proofs. Six economic theorems are introduced in total. In theorem 1 it is stated that for a capitalistic system to survive the domestic and international market share of territorial manufacturing and businesses should be kept limited. In theorem 2, it is stated that both manufacturing and businesses should have a limited life span. In theorem 3, it is stated that growth should be based on production and creation of real values. In theorem 4, it is stated that the relationship between (manufacturing, businesses) and banks should be based on wealth collected out of production activities and creation of real values in manufacturing and services. In theorem 5, it is stated that monopolistic and oligopolistic based economic activities are in conflict with small manufacturing and service activities. In theorem 6, it is stated that the capitalist system should evolve into a Parallel-Multi-Layer Capitalism (PMLC) where small and large economic activities can work on parallel levels with no interference.
The Active Role of Material Things: An Environment-Based Conceptual Framework to Understand the Well-Being of People with Dementia  [PDF]
Hui Ren, Megan Strickfaden
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.66002
Abstract:
This study discusses the relationships of material things to people with dementia and proposes the development of material environments to enhance their well-being. Integrating research on well-being from existential, ecological, and place-based perspectives, this study develops a new understanding of the well-being of people with dementia when considering the active role of material things in the process of developing well-being. “Well-being of people with dementia” refers to the awareness of self-existence in a real-world environment established by the interactions of people and material things. Based on this understanding, this study integrates four types of environmental embodiments, including obliviousness, watching, noticing, and heightened contact, providing specific guides to understand people’s associations with their material environments. An environment-based conceptual framework, based on the new understanding of the meanings of well-being and its association with material things, allows designers and professional/family caregivers to understand the lived experiences of people with dementia, in order to enhance the well-being of their clients and their families by using material things to create a more holistic environment.
Proteomic Analysis of Neisseria gonorrhoeae Biofilms Shows Shift to Anaerobic Respiration and Changes in Nutrient Transport and Outermembrane Proteins
Nancy J. Phillips, Christopher T. Steichen, Birgit Schilling, Deborah M. B. Post, Richard K. Niles, Thomas B. Bair, Megan L. Falsetta, Michael A. Apicella, Bradford W. Gibson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038303
Abstract: Neisseria gonorrhoeae, the causative agent of gonorrhea, can form biofilms in vitro and in vivo. In biofilms, the organism is more resistant to antibiotic treatment and can serve as a reservoir for chronic infection. We have used stable isotope labeling by amino acids in cell culture (SILAC) to compare protein expression in biofilm and planktonic organisms. Two parallel populations of N. gonorrhoeae strain 1291, which is an arginine auxotroph, were grown for 48 h in continuous-flow chambers over glass, one supplemented with 13C6-arginine for planktonic organisms and the other with unlabeled arginine for biofilm growth. The biofilm and planktonic cells were harvested and lysed separately, and fractionated into three sequential protein extracts. Corresponding heavy (H) planktonic and light (L) biofilm protein extracts were mixed and separated by 1D SDS-PAGE gels, and samples were extensively analyzed by liquid chromatography-mass spectrometry. Overall, 757 proteins were identified, and 152 unique proteins met a 1.5-fold cutoff threshold for differential expression with p-values <0.05. Comparing biofilm to planktonic organisms, this set included 73 upregulated and 54 downregulated proteins. Nearly a third of the upregulated proteins were involved in energy metabolism, with cell envelope proteins making up the next largest group. Of the downregulated proteins, the largest groups were involved in protein synthesis and energy metabolism. These proteomics results were compared with our previously reported results from transcriptional profiling of gonococcal biofilms using microarrays. Nitrite reductase and cytochrome c peroxidase, key enzymes required for anaerobic growth, were detected as highly upregulated in both the proteomic and transcriptomic datasets. These and other protein expression changes observed in the present study were consistent with a shift to anaerobic respiration in gonococcal biofilms, although changes in membrane proteins not explicitly related to this shift may have other functions.
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