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Article Citation - WoS: 15Contractive Multivalued Maps in Terms of q-functions on Complete Quasimetric Spaces(Springer international Publishing Ag, 2014) Karapinar, Erdal; Romaguera, Salvador; Tirado, PedroIn this paper we prove the existence of a fixed point for multivalued maps satisfying a contraction condition in terms of Q-functions, and via Bianchini-Grandolfi gauge functions, for complete T-0-quasipseudometric spaces. Our results extend, improve, and generalize some recent results in the literature. We present some examples to validate and illustrate our results.Article Citation - WoS: 13Citation - Scopus: 19A Note on Caristi-Type Cyclic Maps: Related Results and Applications(Springer international Publishing Ag, 2013) Du, Wei-Shih; Karapinar, ErdalIn this note, we first introduce the concept of Caristi-type cyclic map and present a new convergence theorem and a best proximity point theorem for Caristi-type cyclic maps. It should be mentioned that in our results, the dominated functions need not possess the lower semicontinuity property. Some best proximity point results and convergence theorems in the literature have been derived from our main results. Consequently, the presented results improve, extend and generalize some of the existence results on the topic.Article Citation - WoS: 51Citation - Scopus: 57Tripled Coincidence Point Results for Generalized Contractions in Ordered Generalized Metric Spaces(Springer international Publishing Ag, 2012) Aydi, Hassen; Karapinar, Erdal; Shatanawi, WasfiIn this paper, we establish some tripled coincidence point results for a mixed g-monotone mapping F : X (3) -> X satisfying (psi, I center dot)-contractions in ordered generalized metric spaces. Also, an application and some examples are given to support our results.Article Citation - WoS: 21Citation - Scopus: 23Best Proximity Points of Generalized Almost Ψ-Geraghty Contractive Non-Self(Springer international Publishing Ag, 2014) Aydi, Hassen; Karapinar, Erdal; Erhan, Inci M.; Salimi, PeymanIn this paper, we introduce the new notion of almost psi-Geraghty contractive mappings and investigate the existence of a best proximity point for such mappings in complete metric spaces via the weak P-property. We provide an example to validate our best proximity point theorem. The obtained results extend, generalize, and complement some known fixed and best proximity point results from the literature.Article Citation - WoS: 13Citation - Scopus: 14The Existence of Optimal Approximate Solution Theorems for Generalized Α-Proximal Contraction Non-Self Mappings and Applications(Springer international Publishing Ag, 2013) Karapinar, Erdal; Sintunavarat, WutipholIn this paper, we investigate the sufficient conditions to find a best proximity point for a certain class of non-self mappings. It is well known that optimization problems can be transformed to the problems of the existence of a best proximity point. Hence, improvement in the best proximity point theory implicitly develops the theory of optimization. Our presented results generalize, extent and improve various well-known results on the topic in the literature. In particular, we consider some applications of our results to the best proximity point theorems on a class of metric spaces endowed with an arbitrary binary relation which involves the partially ordered metric spaces.Book Part Citation - WoS: 15Citation - Scopus: 15Comparison of Hematopoietic and Spermatogonial Stem Cell Niches From the Regenerative Medicine Aspect(Springer international Publishing Ag, 2018) Kose, Sevil; Yersal, Nilgun; Onen, Selin; Korkusuz, PetekRecent advances require a dual evaluation of germ and somatic stem cell niches with a regenerative medicine perspective. For a better point of view of the niche concept, it is needed to compare the microenvironments of those niches in respect to several components. The cellular environment of spermatogonial stem cells' niche consists of Sertoli cells, Leydig cells, vascular endothelial cells, epididymal fat cells, peritubular myoid cells while hematopoietic stem cells have mesenchymal stem cells, osteoblasts, osteoclasts, megacaryocytes, macrophages, vascular endothelial cells, pericytes and adipocytes in their microenvironment. Not only those cells', but also the effect of the other factors such as hormones, growth factors, chemokines, cytokines, extracellular matrix components, biomechanical forces (like shear stress, tension or compression) and physical environmental elements such as temperature, oxygen level and pH will be clarified during the chapter. Because it is known that the microenvironment has an important role in the stem cell homeostasis and disease conditions, it is crucial to understand the details of the microenvironment and to be able to compare the niche concepts of the different types of stem cells from each other, for the regenerative interventions. Indeed, the purpose of this chapter is to point out the usage of niche engineering within the further studies in the regenerative medicine field. Decellularized, synthetic or non-synthetic scaffolds may help to mimic the stem cell niche. However, the shared or different characteristics of germ and somatic stem cell microenvironments are necessary to constitute a proper niche model. When considered from this aspect, it is possible to produce some strategies on the personalized medicine by using those artificial models of stem cell microenvironment.Article Citation - WoS: 61Citation - Scopus: 81Dislocated metric space to metric spaces with some fixed point theorems(Springer international Publishing Ag, 2013) Karapinar, Erdal; Salimi, PeymanIn this paper, we notice the notions metric-like space and dislocated metric space are exactly the same. After this historical remark, we discuss the existence and uniqueness of a fixed point of a cyclic mapping in the context of metric-like spaces. We consider some examples to illustrate the validity of the derived results of this paper.Article Citation - WoS: 60Citation - Scopus: 72Remarks on some coupled fixed point theorems in G-metric spaces(Springer international Publishing Ag, 2013) Agarwal, Ravi P.; Karapinar, ErdalIn this paper, we show that, unexpectedly, most of the coupled fixed point theorems in the context of (ordered) G-metric spaces are in fact immediate consequences of usual fixed point theorems that are either well known in the literature or can be obtained easily.Article Citation - WoS: 31Citation - Scopus: 43On Best Proximity Point of Ψ-Geraghty Contractions(Springer international Publishing Ag, 2013) Karapinar, ErdalVery recently, Caballero, Harjani and Sadarangani (Fixed Point Theory Appl. 2012: 231, 2012) observed some best proximity point results for Geraghty contractions by using the P-property. In this paper, we introduce the notion of psi-Geraghty contractions and show the existence and uniqueness of the best proximity point of such contractions in the setting of a metric space. We state examples to illustrate our result.Article Citation - WoS: 3Citation - Scopus: 6Fixed Points of Α-Admissible Meir-Keeler Contraction Mappings on Quasi-Metric Spaces(Springer international Publishing Ag, 2015) Alsulami, Hamed H.; Gulyaz, Selma; Erhan, Inci M.We introduce alpha-admissible Meir-Keller and generalized alpha-admissible Meir-Keller contractions on quasi-metric spaces and discuss the existence of fixed points of such contractions. We apply our results to G-metric spaces and express some fixed point theorems in G-metric spaces as consequences of the results in quasi-metric spaces.
