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Search Results: 1 - 10 of 4159 matches for " Landscape mutation "
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Discrete Evolutionary Genetics: Multiplicative Fitnesses and the Mutation-Fitness Balance  [PDF]
Thierry Huillet, Servet Martinez
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.21002
Abstract: We revisit the multi-allelic mutation-fitness balance problem especially when fitnesses are multiplicative. Using ideas arising from quasi-stationary distributions, we analyze the qualitative differences between the fitness-first and mutation-first models, under various schemes of the mutation pattern. We give some stochastic domination relations between the equilibrium states resulting from these models.
Metabolismul urban i mobilitatea informa ional n peisaj
Cerasella Cr?ciun
Urbanism. Arhitectura. Constructii , 2010,
Abstract: The actual urban material and energetic metabolism is a concept that considers both the mutation and the exchange of substances in an urban body, similar to both the biological metabolism and energetic metabolism, as information expression. Landscape planning, urban planning and architecture confer shape to information, in the sense of information emission, reception, exchange and generation. The energetic metabolism level forces us to understand energy and control the living spaces of the human informational network, connected through the human factor and the plant factor, which becomes a major element in the metabolic-urban relation between man and city.
The Bocage Landscape in the ‘Bourbonnais’ (Allier Department, France): between Heritage and Modern Dynamics
MATHIEU GUITTON
Romanian Review of Regional Studies , 2006,
Abstract: The Allier department has an incredible range of landscapes among which the bocage is the most representative. The bocage is an enclosed field with scattered households. Some areas are also totally free of hedge. We did not want to compare the openfield and the bocage but we tried to prove that there was a different type of bocage. So we studied two opposed sectors situated in the East and in the West of this department. The use of aerial shootings and their processing in a G.I.S. (Geographical Information System) allowed us to map the differences between the two areas in the last 50 years. This objective description obtained from actual and past data helped us analyse the change factors in the whole bocage of the Allier department.
A New Method for Fastening the Convergence of Immune Algorithms Using an Adaptive Mutation Approach  [PDF]
Mohammed Abo-Zahhad, Sabah M. Ahmed, Nabil Sabor, Ahmad F. Al-Ajlouni
Journal of Signal and Information Processing (JSIP) , 2012, DOI: 10.4236/jsip.2012.31011
Abstract: This paper presents a new adaptive mutation approach for fastening the convergence of immune algorithms (IAs). This method is adopted to realize the twin goals of maintaining diversity in the population and sustaining the convergence capacity of the IA. In this method, the mutation rate (pm) is adaptively varied depending on the fitness values of the solutions. Solutions of high fitness are protected, while solutions with sub-average fitness are totally disrupted. A solution to the problem of deciding the optimal value of pm is obtained. Experiments are carried out to compare the proposed approach to traditional one on a set of optimization problems. These are namely: 1) an exponential multi-variable function; 2) a rapidly varying multimodal function and 3) design of a second order 2-D narrow band recursive LPF. Simulation results show that the proposed method efficiently improves IA’s performance and prevents it from getting stuck at a local optimum.
An Analysis of Climate Impact on Landscape Design  [PDF]
Xuepeishan Chen
Atmospheric and Climate Sciences (ACS) , 2016, DOI: 10.4236/acs.2016.63037
Abstract: According to the severe climate change in recent days, professionals among different fields now pay more attention to the management and adjustment when meeting the issues of climate. Moreover, climate also obviously affects the natural and designed landscape. To systematically and specifically understand how landscape is designed in response to different climate, this paper will firstly discuss the fundamental interaction between landscape design and climate. And then it will evaluate the different landscape elements dealing with different types of climate, finally and importantly to analysis the definite impact on practical landscape design based on former findings. The result will focus on the decision making on design methods within climate change and provide rational recommendations for designers and planning of future landscape design.
Genetic risk factors and retinal ganglion cell degeneration in primary open-angle glaucoma (POAG): A bird’s eye view  [PDF]
Barkur S. Shastry
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.45082
Abstract: Glaucoma is an optic neuropathy and often associated with elevated intraocular pressure (IOP). It is the second leading cause of irreversible blindness worldwide and is characterized by the optic nerve degeneration and loss of retinal ganglion cells (RGCs). This may lead to loss of vision. The primary cause of glaucoma is unknown but several risk factors including elevated IOP and age have been suggested. In most population, primary open-angle glaucoma (POAG) is the most common type of glaucoma and is often associated with elevated IOP. Genetic analyses have identified at least 14 chromosomal loci but only three genes which when mutated can cause POAG have been well documented. These genes account for less than 5% of all POAG cases suggesting that more than 90% of the genetic contribution of POAG cases is unknown. RGC consists of cell body, axon and dendritic arbor and each of these three parts can independently degenerate. Several molecular signals such as oxidative stress, mitochondrial dysfunction, disruption of neurotrophic factor (NTF), dysfunction of immune system, glial activation and the release of tumor necrosis factor (TNF) have been found to be involved in the optic nerve degeneration. Therefore, therapies aimed at axonal and cell body protection may have a greater protective role in early or progressive glaucoma. In the future, an understanding of gene-gene and gene-environmental factor interaction as well as epigenetic regulation of gene expression by environmental factors may provide an opportunity to develop neuroprotective therapies and DNA based diagnostic tests.
Epistemological bases of landscape ecology
Lia Maris Orth Ritter,Rosemeri Segecin Moro
Journal of Biotechnology and Biodiversity , 2012,
Abstract: Landscape began to be cited as a scientific technical term in the nineteenth century. Since then it has been definedaccording to different philosophical references, where it is possible to see a clear dualism in its meaning. This is amatter of intense debate within the social and natural sciences: the physical geography proposes an understandingof the landscape as an ecological system, whereas the human geography turns to the interpretative vision. There areEuropean and North American roots of the ecological landscape, being the latter more recent (1980s), which isbased on ecosystem ecology and spatial modeling/analysis. Its development was favored by the advent of satelliteimagery and popularization of personal computers, therefore providing important resources for imaging and geostatisticalanalyzes. But still, there are different positions to be taken by the researcher working in this area.Metzger (2001) suggests adopting an integrated approach, where the ecological context and human action areconsidered and managed as mandatory elements in environmental dynamics. Our study aimed to list some of the keyconcepts of landscape considered by biologists in their research on landscape ecology.
Towards Semantic Mutation Testing of Aspect-Oriented Programs  [PDF]
Abdul Azim Abdul Ghani
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.610A002
Abstract:

Aspect-oriented programs have received much attention from software testing researchers. Various testing techniques and approaches have been proposed to tackle issues and challenges when testing aspect-oriented programs including traditional mutation testing. In traditional mutation testing of aspect-oriented programs, mutants are generated by making small changes to the syntax of the aspect-oriented language. Recently, a new approach known as semantic mutation testing has been proposed. This approach mutates the semantics of the language in which the program is written. The mutants generated misunderstandings of the language which are different classes of faults. Aspect-oriented programming presents itself with different properties that can be further explored with respect to semantic mutation testing. This paper describes various possible scenarios that semantic mutation testing strategy might have particular value in testing aspect-oriented programs.

Antiretroviral-Drug Resistant Mutations and Genetic Diversity in HIV-1 Infected Individuals in Nigeria  [PDF]
Olubunmi Ruth Negedu-Momoh, Olayeni Stephen Olonitola, Lillian Emiola Odama, Helen Ineigo Inabo, Henry Akwen Mbah, Alex Nganga Kasembeli, Seth Chekata Inzaule, Edward Adekola Oladele, Titilope Badru, Simon Magaji Agwale
World Journal of AIDS (WJA) , 2014, DOI: 10.4236/wja.2014.42024
Abstract:

Introduction: Despite the success derived from antiretroviral therapy, drug resistance (DR) mutations are known to develop and are major impediments to treatment of HIV patients. Therefore, periodic assessment of HIVDR is needed to ensure continuous HAART efficacy. This study assessed the magnitude of drug resistance as well as HIV genetic variability in drug-naive and treated patients in Nigeria. Methodology: Genotypic analysis was performed by sequencing plasma specimens from 40 individuals in a cross sectional study involving 202 HIV infected patients from all the six geopolitical zones of Nigeria. Sequences were analyzed for presence of HIVDR mutation using the algorithm in Stanford HIVDR database and confirmed by IAS-USA 2009 mutation list. Phylogenetic and recombination analyses were done using PAUP V4.0 and REGA V2.0 respectively. Results: Major DR mutations were detected in the reverse transcriptase (RT) gene of 5 (33%) drug experienced and 2 (8%) na?ve patients. Most common mutations were M184V and K103N with no protease (PR) mutations detected. Thymidine analogue mutations (TAMs) and a complex multi resistance mutation Q151M were detected in 3 samples. Polymorphic substitutions were observed in both PR and RT gene. Phylogenetic analysis revealed Group M isolates of G (20), J (1), circulating recombinant forms: CRF02_AG (14), CRF-18-cpx (1), CRF06_cpx (3) and a unique AD recombinant (1). Conclusion: Our findings corroborate previous studies on circulating DR viruses in Nigeria while genetic diversity is on the increase. In view of ART scale-up, monitoring the resistance pattern and genetic diversity will aid in appropriate prevention strategies.

Testing the Mutation Accumulation Theory of Aging Using Bioinformatic Tools  [PDF]
Abdullah Salah Elamoudi
Advances in Aging Research (AAR) , 2018, DOI: 10.4236/aar.2018.72002
Abstract: Objective: An interplay of many variant mechanisms is thought to underlie aging or senescence. The Mutation Accumulation Theory proposes the accumulation of mutations in proteins to engender their aging phenotype. Testing whether random mutations lead to the aging phenotype was never done and is deemed infeasible. Bioinformatic algorithms provide an a-priori approach that allows testing; they employ prior knowledge of well-studied proteins to predict the changes brought on by mutations. Here, the Mutation Accumulation Theory of aging is tested using such bioinformatic tools. Methods: This is a simulation study, conducted 2017, September, using algorithms with Web accessibility. Three well-studied proteins implicated in aging were chosen: Collagen, Beta-amyloid Precursor Protein (β-APP) and Low-density-lipoprotein-receptor (LDL-receptor). Random mutations were introduced to their native coding sequences. Then, the mutated sequences were tested using three different prediction algorithms: SPpred for solubility, I-mutant for stability (delta-free energy), SNP and GO for pathogenicity. The new mutated phenotype was then correlated to the aging phenotype of the protein; decrease in solubility for Collagen and β-APP; and accelerated atherosclerosis for LDL-receptor. Results: 15 mutated variants for each protein (45 in total). For collagen and β-APP, the SPpred algorithm did not predict changes in solubility of the naked protein, but the I-mutant and SNP and GO definitely predicted changes that fit the aging phenotype. However, for LDL-receptors, none of the mutated variants when studied could account for the aging phenotype. Conclusion: for Collagen and β-APP, it is shown here that random mutations and their accumulation could explain the aging phenotype of both proteins; backing the Mutation Accumulation Theory for aging.
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