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23 articles for “Extinction”
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Research ArticleOpen accessIn the keywordsON RESERVES, STABILITY AND THE MAXIMUM SUSTAINABLE YIELD PROBLEMArild WikanDue to the fact that several species of commercial interest have been overexploited throughout the years it is important to understand how harvest and other factors like introducing reserves influence the dynamic behaviour of a population with respect to stability and possible extinction. Therefore, simple one-population models are analysed and it is shown that harvest acts in a strong stabilizing … …Journal of Mathematics and Statistics, Vol. 9, Issue 4 · 24 Oct 2013 · 6,816 accessesView PDFCite
Research ArticleOpen accessIn the keywordsDetermining Optical Constants of Selenium Thin Films using the Envelope MethodNehad M. Tashtoush, Osamah ALkasassbehTwo Selenium thin films were deposited on glass substrates using thermal evaporation technique. The optical constants (refractive index, absorption coefficient and extinction coefficient and energy gap) were calculated using the Transmittance (T) spectrums of the films in the spectral range of 500-900 nm. The envelope method was used to determine optical constants. The calculated refractive index was found to be … …American Journal of Applied Sciences, Vol. 10, Issue 2 · 15 Feb 2013 · 6,337 accessesView PDFCite
Research ArticleOpen accessIn the keywordsStudy on Optical Constants and Refractive Index Dispersion of Neutral red Doped Polymer FilmHussain A. BadranProblem statement: The some optical constants polymer thin film with red dye 3-amino-7-dimethylamino-2-methyl phenazine (NR) as the guest material and Polyvinylpyrrolidone (PVP) as the host material were prepared by adulteration and spin-coating methods. Approach: The values of some important parameters (refractive index n, extinction coefficient K and dielectric constant ε∞) of polymer thin film are determined from these spectra. Results: … …American Journal of Applied Sciences, Vol. 9, Issue 2 · 26 Dec 2011 · 8,919 accessesView PDFCite
Research ArticleOpen accessIn the abstractBiodiversity and Spatial Distribution of Hornbills in Pondok Buluh Educational Forest, North Sumatra, IndonesiaBudi Utomo, Nabillah Saraswita, Cindy Siahaan et al.Hornbills are large birds, several species of which are protected under national and international conservation legislation and face significant extinction risk. This study was conducted in the Specific Purposes Pondok Buluh Forest Area, North Sumatra, Indonesia, with the aim of identifying hornbill species present, estimating their population density, and characterizing their habitat. Hornbill surveys were carried out using the point … …OnLine Journal of Biological Sciences, Vol. 26, Issue 1 · 28 Mar 2026 · 1,405 accessesView PDFCite
Research ArticleOpen accessIn the abstractPhenotypic Characterisation of the Bapedi SheepKgothatso Masethe, Thinawanga Joseph Mugwabana, Tlou Caswell Chokoe et al.Bapedi sheep are at risk of extinction, which necessitates thorough documentation to inform and drive effective conservation efforts. We aimed to characterize Bapedi Sheep phenotypic characteristics using 231 Bapedi sheep (≥1 year of age) from Limpopo and Gauteng Provinces. The Bapedi Sheep were grazed on natural pasture and the data was collected during the autumn season. Qualitative and quantitative phenotypic … …American Journal of Animal and Veterinary Sciences, Vol. 20, Issue 3 · 3 Sep 2025 · 5,909 accessesView PDFCite
Research ArticleOpen accessIn the abstractImproving the Technology for Assessing the Semen of Beige Karakul SheepAigerim Turekyzy Bigarayeva, Nuradin Alibayev, Arkadiy Kanurovich Natyrov et al.The article presents the research results on the effective use of seed products from breeding rams in reproduction for the conservation and targeted propagation of genetic resources of Karakul sheep of rare beige color, which are on the verge of extinction. Selected freshly obtained ejaculates from 6 beige rams of the Karakul breed in the amount of 32 samples, meeting … …OnLine Journal of Biological Sciences, Vol. 25, Issue 1 · 17 Feb 2025 · 4,501 accessesView PDFCite
Research ArticleOpen accessIn the abstractAnalysis of Land Cover Changes and Sustainable Reforestation in Sianjur Mula-Mula District, Samosir Regency, IndonesiaBudi Utomo, Rezky Nizar, Rizky Wahyudi et al.The increase in population and technological advances have had a significant impact on land use changes. there are changes in land cover 2017-2022 in the local ecosystem. there have been significant changes but can still be maintained. This is to prevent the extinction of species such as fish, land animals and other marine animals. Changes in land cover that are … …OnLine Journal of Biological Sciences, Vol. 24, Issue 4 · 6 Jun 2024 · 5,182 accessesView PDFCite
Research ArticleOpen accessIn the abstractGenetic Diversity of Common Wild Wheat Species in Armenia Using ISSR MarkersManvel Badalyan, Tatevik Aloyan, Varya Dilanyan et al.Armenia is one of the primary genealogical centers of numerous crops, the wild relatives of many of which are still found in Armenia today. Population limits of three out of 4 species of wild relatives of endemic wheat in Armenia (T. araraticum Jakubz, T. urartu Tumanian ex Gandilyan, T. boeoticum Boiss.) have been reduced in recent decades as a result … …OnLine Journal of Biological Sciences, Vol. 23, Issue 3 · 15 Aug 2023 · 5,217 accessesView PDFCite
Research ArticleOpen accessIn the abstractOptimal Control Techniques for the Role of Antiretroviral Therapy (ART) Abuse in HIV/AIDS Treatment DynamicsBassey Echeng Bassey, Adagba Odey HenryFrom the studies of HIV/AIDS transmission and treatment dynamicsusing mathematical modeling, literature reviews have shown that attention hadnot been given to the behavioral attitude of screen-aware infectives not readyto receive treatment, HIV-aware infectives that initiated treatment buttruncated only to resume treatment later (therapy abuse) and those onconsistent treatment protocols. Moreso, following the non-outright eradicationof the deadly HI-virus, recommendations have been … …Journal of Mathematics and Statistics, Vol. 18, Issue 1 · 24 Nov 2022 · 5,819 accessesView PDFCite
Research ArticleOpen accessIn the abstractThe Relationship Between Egg Weight of Olive Ridley Sea Turtle (Lepidochelys Olivacea) on Hatchability using “Maticgator” (Automatic Turtle Egg Incubator)Sukandar Sukandar, Sunardi, Vian Dedi Pratama, Zaenal AbidinSea turtles are reptile animals that live primarily in oceans but migrate to sandy beaches to produce and lay eggs in large quantities. However, the hundreds of eggs produced, only a dozen hatch and return to the sea. Also, factors of climate change and global warming have an impact on decreasing the wild sea turtle population, where female turtles are … …American Journal of Animal and Veterinary Sciences, Vol. 17, Issue 2 · 7 Jun 2022 · 6,660 accessesView PDFCite