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Search Results: 1 - 10 of 475055 matches for " Mark A. "
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Gender and Anxiety: A Comparison of Student Anxiety Levels in Face-to-Face and Video Conferencing Courses  [PDF]
Jodi McKnight, Mark A. McKnight
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.31015
Abstract: This research focuses on the role of gender in face-to-face instruction and video conferencing instruction on students’ levels of anxiety. This is due, in part, to the fact that gender and anxiety levels of students enrolled in remote video conferencing learning environments has received little attention in either psychological or educational research. A difference in gender as it relates to education is an important focus of research. This is due to the increasing learning opportunities for female students (online in particular). Explored later, further research should investigate various demographics and delivery options for courses.
Forest Fragmentation and Its Potential Implications in the Brazilian Amazon between 2001 and 2010  [PDF]
Izaya Numata, Mark A. Cochrane
Open Journal of Forestry (OJF) , 2012, DOI: 10.4236/ojf.2012.24033
Abstract: In recent decades, human development pressures have results in conversions of vast tracts of Amazonian tropical rain forests to agriculture and other human land uses. In addition to the loss of large forest cover, remaining forests are also fragmented into smaller habitats. Fragmented forests suffer several biological and ecological changes due to edge effects that can exacerbate regional forest degradation. The Brazilian Amazon has had greatly contrasting land cover dynamics in the past decade with the highest historical rates of deforestation (2001-2005) followed by the lowest rates of forest loss in decades, since 2006. Currently, the basin-wide status and implications of forest fragmentation on remnant forests is not well known. We performed a regional forest fragmentation analysis for seven states of the Brazilian Amazon between 2001 and 2010 using a recent deforestation data. During this period, the number of forest fragments (>2 ha) doubled, nearly 125,000 fragments were formed by human activities with more than 50% being smaller than 10 ha. Over the decade, forest edges increased by an average of 36,335 km/year. However, the rate was much greater from 2001-2005 (50,046 km/year) then 2006-2010 (25,365 km/year) when deforestation rates dropped drastically. In 2010, 55% of basin-wide forest edges were < 10 years old due to the creation of large number of small fragments where intensive biological and ecological degradation is ongoing. Over the past decade protected areas have been expanded dramatically over the Brazilian Amazon and, as of 2010, 51% of remaining forests across the basin are within protected areas and only 1.5% of protected areas has been deforested. Conversely, intensive forest cover conversion has been occurred in unprotected forests. While 17% of Amazonian forests are within 1 km of forest edges in 2010, the proportion increases to 34% in unprotected areas varying between 14% and 95% among the studied states. Our results indicate that the Brazilian Amazon now largely consists of two contrasting forest conditions: protected areas with vast undisturbed forests and unprotected forests that are highly fragmented and disturbed landscapes.
The Effects of Forest Thinning Practices and Altered Nutrient Supply on Soil Trace Gas Fluxes in Colorado  [PDF]
Mark A. Gathany, Ingrid C. Burke
Open Journal of Forestry (OJF) , 2014, DOI: 10.4236/ojf.2014.43034
Abstract:

Increases in wildfire activity in the western United States have prompted land managers to reevaluate management practices. In the Colorado Front Range, where population density is high, there is often a great concern regarding wildfire which leads to efforts that will reduce fire hazard. The most common method of achieving this goal is to thin the forest of small diameter trees. Oftentimes these practices are undertaken with little knowledge of the ecological consequences of such treatments. We investigated the effect(s) of three treatments (control, thinning-only and broadcast chipping) on trace gas fluxes (CO2, CH4, and N2O), litter mass, and soil carbon and nitrogen. In a small plot study, we used a 2 × 3 × 3 randomized complete block design to determine the influence of nutrient amendments (woodchips, nitrogen, and phosphorus availability) on trace gas fluxes. The stand-management study revealed that neither thinning-only nor broadcast chipping significantly affected soil carbon or nitrogen, while thinning-only significantly reduced the amount of forest floor litter. Each trace gas flux was significantly affected by the date of sampling (June or August). CO2 and N2O fluxes each had a significant interaction between treatment and sampling date. We attribute this to a difference in moisture availability between the sampling times. In the plot study we found that only the interaction between woodchip addition and phosphorus

A Review of Artificial Immune System Based Security Frameworks for MANET  [PDF]
Lincy Elizebeth Jim, Mark A. Gregory
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2016, DOI: 10.4236/ijcns.2016.91001
Abstract: Mobile ad hoc networks (MANETs) are collections of wireless mobile devices that form a communication network with restricted broadcast range, limited resources and without fixed infrastructure. Routing is a critical function in multi-hop MANETs. At the same time, security in MANETs—especially routing security—presents a number of new and interesting challenges. Communication is achieved by relaying data along routes that are dynamically discovered and maintained through collaboration between the nodes. Advances in the field of artificial immune systems provide an opportunity to improve MANET security and performance. Artificial immune systems mimic the functionality of the human immune system wherein there is clear distinction between self and non self and this delineation is important in a MANET where there is no centralized management. The high level of protection provided to the human body by an evolved immune system can be applied as a security feature in MANET. The current security techniques proposed for MANET have varying degrees of success due to the dynamic nature of a MANET. This paper will review different strategies for the application of artificial immune systems to MANETs.
The Potential Impact of Incentives on Managed Lane Travel  [PDF]
Namoo A. Han, Mark W. Burris
Journal of Transportation Technologies (JTTs) , 2018, DOI: 10.4236/jtts.2018.84014
Abstract: The use of managed lanes to control and maximize freeway throughput is increasing. One way of encouraging more managed lane use is through the implementation of incentives. In the Dallas-Fort Worth area, a managed lane is being added to the I-30 (Tom Landry freeway) and incentives to maximize the use of this lane were planned. Since the managed lanes were not yet open and the incentives were hypothetical, a stated preference survey was used to gauge the potential impact of the incentives on traveler behavior. The stated preference questions were designed using Db-efficient and random adaptive designs. The incentives were chosen by looking at other programs around the country and through discussion with transportation experts. Once ready, the survey was administered online to travelers in the area and a total of 898 usable responses were gathered. From the responses, a mixed-logit model was developed to describe and predict traveler behavior. From the model, elasticities were calculated to predict the impact of the incentives on mode choice. The model found that incentives with discounts and free trips (a transit fare discount, express bus service to downtown, a free trip for every X number of paid trips, and a discount offered to select businesses) were more effective at encouraging managed lane use. The other incentives (gift card worth $5 for every X number of trips and $5 in credit for every X number of trips taken by transit) had less of an impact.
Signal transduction and activation of the NADPH oxidase in eosinophils
Lindsay, Mark A;Giembycz, Mark A;
Memórias do Instituto Oswaldo Cruz , 1997, DOI: 10.1590/S0074-02761997000800016
Abstract: activation of the eosinophil nadph oxidase and the subsequent release of toxic oxygen radicals has been implicated in the mechanism of parasite killing and inflammation. at present, little is known of the signal transduction pathway that govern agonist-induced activation of the respiratory burst and is the subject of this review. in particular, we focus on the ability of leukotrine b4 to activate the nadph oxidase in guinea-pig peritoneal eosinophils which can be obtained in sufficient number and purity for detailed biochemical experiments to be performed.
Signal transduction and activation of the NADPH oxidase in eosinophils
Lindsay Mark A,Giembycz Mark A
Memórias do Instituto Oswaldo Cruz , 1997,
Abstract: Activation of the eosinophil NADPH oxidase and the subsequent release of toxic oxygen radicals has been implicated in the mechanism of parasite killing and inflammation. At present, little is known of the signal transduction pathway that govern agonist-induced activation of the respiratory burst and is the subject of this review. In particular, we focus on the ability of leukotrine B4 to activate the NADPH oxidase in guinea-pig peritoneal eosinophils which can be obtained in sufficient number and purity for detailed biochemical experiments to be performed.
The Quality and Health Implications of Urban Irrigation Water Used for Vegetable Production in the Accra Metropolis  [PDF]
Mark O. Akrong, Joseph A. Ampofo, Seth K. A. Danso
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.311167
Abstract: The quality of irrigation water from different sources used by urban farmers in the Accra Metropolis was investigated. These were, tap water stored in dugout, surface water (from stream) and wastewater in drains. The samples were analysed for their bacteriological, physical and chemical qualities using standard methods. Analytical Profile Index (API) identification system was used to characterize and identify the bacterial species isolated in the samples. The results showed that heavy metal concentrations in the samples were within the FAO/WHO recommended limits for irrigation. The concentrations of highly toxic Lead and Cadmium were even below detection limit. Total and faecal coliform bacteria loads in all three potential irrigation water sources were above the WHO recommended limit for irrigation. Different bacteria species belonging to seven genera were identified in the three irrigation water sources. These included Citrobacter, Chryseomonas, Enterobacter, Klebseila, Proteus, Providencia, Pseudomonas. Generally, the most dominant bacterial species were Pseudomonas aeruginosa and Chryseomonas luteola. Some of these bacteria spp. can pose a health threat to farmers especially those who have challenges with their health and immune system. For example, infection with some of the bacteria species such as Pseudomonas aeruginosa in patients with cystic fibrosis is known to be deadly over periods of time.
Mechanical response of uterine tissue under the influence of hemostatic clips: A non-linear finite-element approach  [PDF]
Mark A. Nicosia, Donald A. Wood, Daniel Mazzucco
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.612A004
Abstract:

A modeling strategy to predict the ability of surgical clips to achieve mechanical hemostasis when applied to the cut edge of a thick and muscular tissue is presented in this work. Although such a model may have broad utility in the design of hemostatic clips and other surgical and wound closure applications, our particular focus was on uterine closure following a Cesarean delivery. Mechanical closure of a blood vessel, which is the first step in the hemostatic process, is established when the compressive forces on the outer surface of a blood vessel are sufficient to overcome the local blood pressure and collapse the vessel. For thick tissue, forces applied to the tissue surface set up a stress distribution within the tissue that, if sufficient to mechanically close all vessels, will lead to cessation of local blood flow. The focus of the current work was on utilization of a planar and nonlinear finite element model to predict the pressure distribution within uterine tissue under the influence of hemostatic clips. After experimental model validation with a polymer tissue phantom, design curves were numerically developed, which consisted of the clip force necessary to achieve hemostasis for a given thickness tissue as well as the resulting deformed tissue thickness. Such curves could form the basis for a preliminary clip design, which would provide initial design guidance before more expensive experimental studies were required.

 

Alterations in Caspase-3 in Juvenile Rats Treated Neonatally with Domoic Acid  [PDF]
Mark A. Robbins, Catherine L. Ryan, Tracy A. Doucette
Journal of Behavioral and Brain Science (JBBS) , 2016, DOI: 10.4236/jbbs.2016.69034
Abstract: The clinical presentation of schizophrenia involves a variety of symptoms, which in many cases include hallucinations and delusions. Experimentally revealed alterations in both pre-pulse inhibition (PPI) and latent inhibition (LI) are also apparent in individuals afflicted with this disorder. Many have speculated that altered synaptic connections are, in part, responsible for this subset of behavioral abnormalities. We have previously reported that neonatal chronic low-dose injections of domoic acid (DOM) produce adult rats with deficits in PPI and LI. The current study was conducted to determine whether this toxin-treatment would alter the degree of apoptosis occurring in the developing brain. Results revealed significant decreases in caspase-3 within the right prelimbic cortex (PrL) in both male and female DOM-treated rats suggesting that even modest alterations in glutamate (Glu) signaling during critical periods of central nervous system (CNS) maturation will modify ontogenetic processes in the prefrontal cortex (PFC) of the juvenile rat.
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