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Öğe Pseudo-Projective and Quasi-Conformal Curvature Tensors on Riemannian Submersions.(2021) Ayar, GülhanIn this study, pseudo-projective and quasi-conformal curvature tensors on a Riemannian submersion have been examined and on a Riemannian submersion new curvature relations for pseudo-projective curvature tensor and quasi-conformal curvature tensor under certain conditions have been obtained.Öğe Concircular Curvature Tensor of Nearly Cosymplectic Manifolds in Terms of The Generalized Tanaka-Webster Connection(2024) Ayar, Gülhan; Aktan, N.; Madan, Ç.In this paper, we study concircular curvature tensor of nearly cosymplectic manifolds in terms of the generalized Tanaka-Webster connection and then, we emphasized the properties that concircular curvature tensor of nearly cosymplectic manifolds in terms of the generalized Tanaka-Webster connection provides in case of flatness, ?-concircularly flatness, ?-concircularly semisymmetric.Öğe Conharmonic Curvature Tensor on Nearly Cosymplectic Manifolds with Generalized Tanaka-Webster Connection(2021) Ayar, Gülhan; Çavuşoğlu, H. R.In this paper, we study conharmonic curvature tensor of nearly cosymplectic manifolds with generalized Tanaka-Webster connection and we give a conharmonically flat nearly cosymplectic manifold with respect to the connection.Öğe Nearly Cosymplectic Manifolds wth Nullity Conditions.(2019) Yıldırım, M.; Ayar, GülhanWe investigate nearly cosymplectic manifolds with k-nullity distribution. Also, we consider pseudo-projectively flat N(?)-nearly cosymplectic manifold and study Ze · P = 0 condition.Öğe New Curvature Tensors along Riemannian Submersions(2020) Ayar, Gülhan; Akyol M. A.In 1966, B. O’Neill [The fundamental equations of a submersion, Michigan Math. J., Volume 13, Issue 4 (1966), 459-469.] obtained some fundamental equations and curvature relations between the total space, the base space and the fibres of a submersion. In the present paper, we define new curvature tensors along Riemannian submersions such as Weyl projective curvature tensor, concircular curvature tensor, conharmonic curvature tensor, conformal curvature tensor and M?projective curvature tensor, respectively. Finally, we obtain some results in case of the total space of Riemannian submersions has umbilical fibres for any curvature tensors mentioned by the above.Öğe Ricci Solitons and Gradient Ricci Solitons on Nearly Kenmotsu Manifold(2019) Ayar, Gülhan; Yıldırım, M.In this article, a number of properties have been obtained by examining Ricci solitons and gradient Ricci solitons on nearly cosymplectic manifolds.Öğe ?-Ricci Solitons on Nearly Kenmotsu Manifolds(2019) Ayar, Gülhan; Yıldırım, M.In this paper, we study the geometry and topology of ?-Ricci solitons satisfying Ricci semisymmetry condition, S · R = 0 condition and finally Einstein-semisymmetry condition on nearly Kenmotsu manifolds.Öğe A Schur Type Theorem For Almost Cosymplectic Manifolds With Kaehlerian Leaves.(2013) Aktan, N.; Ayar, Gülhan; Bektas, I.In this study, we give a Schur type theorem for almost cosymplectic manifolds with Keahlerian leaves.Öğe Geometry of Kenmotsu Manifolds via Q-Curvature Tensor and Schouten–Van Kampen Connection.(2025) Yıldırım, M.; Beyendi, S.; Ayar, Gülhan; Aktan, N.This research paper aims to study the Q-curvature tensor on Kenmotsu manifolds endowed with the Schouten–van Kampen connection. Using the Q-curvature tensor, whose trace is the well-known Z-tensor, we characterized Kenmotsu manifolds by introducing the notion of ?-Q flat and ?-Q flat manifolds and novel tensor conditions, such as Q(?,X)Q=0, Q(?X)R=0, Q(?,X)S=0, Q(?,X)C=0 ,Q(?,X)H=0, and Q(?,X)P=0, with the Schouten–van Kampen connection. To validate some of our results, we constructed a non-trivial example of Kenmotsu manifolds endowed with the Schouten–van Kampen connection.Öğe A Physical Classification of Killing Magnetic Fields In Thurston Geometries.(2024) Dündar, F S.; Kelekçi, Ö.; Ayar, GülhanIn recent years, numerous studies have appeared that considered Killing vectors of three-dimensional Riemannian manifolds as magnetic fields, since these vector fields are divergenceless by definition. The existence of adivergenceless vector field modeled as a magnetic field does not imply that it is physically realizable. In this study, we propose a physical classification scheme based on the divergences of the integral that defines the energy of a Killing magnetic field. We consider all the Killing magnetic fields of Thurston geometries studied in the literature and classify them as either physical or nonphysical.Öğe On a Type of ?-Cosymplectic Manifolds.(2019) Beyendi, S. ,; Ayar, Gülhan; Aktan, N.The ob ject of this paper is to study alpha-cosymplectic manifolds admitting a W2-curvature tensor.Öğe Classification of Killing Magnetic Curves In H3Kelekçi, Ö.; Dündar, F. S.; Ayar, GülhanIn this paper, we study classification of magnetic curves corresponding to Killing vector fields of H3. First, we solve the geodesic equation analytically. Then we calculate the trajectories generated by all the six Killing vector fields, which are considered as magnetic field vectors, by using perturbation method up to first order with respect to the strength of the magnetic field. We present a comparison of our solution with the numerical solution for one case. We also prove that 3-dimensional (?)-Kenmotsu manifolds cannot have any magnetic vector field in the direction of their Reeb vector fields.Öğe Analysis of Forming Limit Diagrams of DP600 Steel at Various Deformation Speeds(2010) Uysal, Emrah; Öztürk, FahrettinÖğe Biochemical and structural differences between C3 cotyledons and C4 leaves in species of Salsoloideae (Chenopodiaceae)(Nature, 2025) Kocacinar, F.; Ceylan, Faik; Cömertpay, S.C4 plants had evolved from C3 ancestors in at least more than 60 independent lineages of angiosperms, most probably in response to decreasing levels of atmospheric CO2 and environmental conditions promoting photorespiration. Salsola, Petrosimonia, and Cyathobasis genera of Salsoloideae subfamily contain some species with C3 cotyledons followed by C4 leaves. The aim of this study was to determine and compare the biochemical and structural differences between C3 cotyledons and subsequent C4 leaves in these genera. The results showed that there were isopalisade C3 cotyledons in Salsola grandis and isolateral C3 cotyledons in Cyathobasis fruticulosa, while salsoloid type C4 Kranz anatomy was present in subsequent leaves. Petrosimonia nigdeensis had dorsiventral C3 cotyledons and salsoloid-type C4 leaves. The proteins of C4 isoform phosphoenolpyruvate carboxylase (PEPC) and pyruvate orthophosphate dikinase (PPDK) enzymes were absent or very sparse in C3 cotyledons of these species, whereas they were abundant in their C4 leaves. The proteins of photorespiratory isoform glycolate oxidase (GOX) and glycine decarboxylase-H subunit (GDC-H) were generally higher in cotyledons than leaves. The protein level of photosynthetic isoform ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) enzyme was lower in C4 leaves compared to C3 cotyledons. Transcript levels of these enzymes were generally consistent with their protein content except for GOX in S. grandis and S. tragus and glycine decarboxylase complex (GDC) in S. tragus. As a result, we demonstrated that not only the protein and transcript levels of the enzymes required for C4 pathway increased, but also those levels of C3 and photorespiratory enzymes decreased during the transition from C3 cotyledons to C4 leaves. These results are considered significant in terms of shedding light on the understanding of evolutionary transition from C3 to C4 biochemical pathway in a single plant and contributing to C4 engineering.Öğe Effects of different nitrogen doses on thymoquinone and fatty acid composition in seed oil of black cumin ( Nigella sativa L.)(Wiley, 2022) Telci, İsa; İzgi, M. N.|Özek, T.; Yasak, Selma; Devrim, Selma; Yur, S.|Özek, G.Black cumin, Nigella sativa L. belonging to Ranunculaceae, is a valuable medicinal plant because of the curative effects of seed and oil. Despite studies on black cumin, there are few studies on the effects of nitrogen on fatty acid composition, no records on thymoquinone yield, and the thymoquinone content of the seed oil. In this study, the effects of different nitrogen doses on the seed oil yield, thymoquinone ratio/yield, and fatty acid compositions were investigated. Field studies with nitrogen doses (0, 40, 60, 80, and 100?kg/ha) were studied using the randomized plot design. As a result of the research, nitrogen doses significantly affected the oil and thymoquinone yields while insignificant on the thymoquinone ratio. The highest oil yield with 501.6 kg/ha was obtained from 80?kg/ha of the nitrogen doses, while the highest thymoquinone yield with 10.24?kg/ha was obtained from the control plots. Thymoquinone yields were in the same statistical group with other nitrogen doses, except for means of 100?kg/ha nitrogen doses. Linoleic, oleic, and palmitic acids were major fatty acids of black cumin, and their variations were insignificant in nitrogen applications. The values of butyric, capric, and linolenic acids varied significantly in different nitrogen doses. As a result of the study, it was determined that the highest oil yield was obtained from 80?kg/ha nitrogen application. It has been determined that nitrogen doses above 60–80?kg/ha should be avoided for the seed oil and thymoquinone yields in black cumin.Öğe Age and growth of the needlefish, Tylosurus imperialis (Rafinesque, 1810) from the Levantine coast, North-Eastern Mediterranean(Univ Oradea Publ House, 2025) Erguden, Deniz; Turan, Cemal; Ivanova, Petya Pavlova; Dogdu, Servet Ahmet; Raykov, Violin Stoyanov; Yankova, Maria; Yaglioglu, DenizThe present study is the first to determine the age and growth parameters of the needlefish Tylosurus imperialis in the Northeastern Mediterranean. A total of 320 specimens of T. imperialis were caught by gill nets from Turkish coasts (Iskenderun Bay) in the Northeastern Mediterranean between October 2020 and September 2021. The maximum age was 5 years for both sexes combined, and the age group 3-4 comprised 77.5 % of the samples. The total length distribution of T. imperialis was 60 to 109 cm, and the weight distribution was 309 to 1985 g. The b value was between 3.20 and 3.31 for females and males, respectively. The parameter b from the length-weight relationship characterizes a positive allometric growth. Growth equations were calculated as W=0.0006xL(3.2026) (R-2= 0.912) for females, W=0.0004xL(3.3163) (R-2= 0.896) for males, and W= 0.0005xL(3.2456) (R-2=0.904) for all specimens. Von Bertalanffy growth parameters were L-infinity= 139.29 cm, K= 0.119 year(-1), t(0)= -1.819 year for females, L-infinity= 138.50 cm, K= 0.113 year(-1), t(0)= -1.834 year for males and L-infinity= 138.33 cm, K= 0.112 year(-1), t(0)= -1.839 year for all specimens. The spawning period of T. imperialis was determined to be between April and August for both sexes. This data will be useful for the fisheries management of needlefish stocks in our study area and elsewhere.Öğe EFFECTS OF LITHOSPERMIC ACID SUPPLEMENTATION AGAINST ACUTE EXERCISE-INDUCED OXIDATIVE STRESS IN RATS(Nobel Ilac, 2024) Coknaz, Hakki; Karaoglan, Esen Sezen; Ozgen, UfukObjective: The aim of the study was to investigate whether lithospermic acid (LSA), a naturally derived polyphenolic compound, supplementation could prevent acute exercise- induced oxidative damage to skeletal muscle tissue in the rats. Material and Method: Rats were randomly selected and divided into three groups (n= 7/group): Group 1Control group (non-exercise, UT), Group 2- Exercise group (exercise, T) and Group 3- Exercise+lithospermic acid group (exercise+lithospermic acid, T/LSA). At the end of the exercise protocol, the samples were removed from the right leg quadriceps muscle. Malondialdehyde (MDA), myeloperoxidase (MPO), glutathione (GSH) and superoxide dismutase (SOD) levels were measured in the muscle samples. Result: Compared to the UT group, malondialdehyde (MDA) and myeloperoxidase (MPO) activity levels in the muscle tissue of the T group significantly increased (p<0.001). MDA and MPO activity levels significantly decreased in the T/LSA group compared to the T group (p<0.05). Glutathione (GSH) and superoxide dismutase (SOD) activity levels significantly decreased in the T group compared to the UT group (p<0.05). GSH and SOD activity levels in muscle tissue significantly increased in the T/LSA group compared to the T group (p<0.05). No significant difference was found in MDA, MPO, GSH, and SOD levels between the UT group and T/LSA group (p>0.05). Conclusion: In conclusion, our study shows that oxidative activity levels in the muscle tissue of the T/LSA group decreased significantly in skeletal muscle-induced acute exercise in rats, so it can be considered that lithospermic acid has a protective effect against oxidative damage.Öğe THE INFLUENCE OF SPORTS HOTEL EMPLOYEES'POLITICAL SKILL ON ROLE STRESS: THE MODERATING ROLE OF SELF-EFFICACY(Revista Iberoamericana Psicologia Ejercicio & Deporte, 2024) Ongel, Gokten; Taskiran, Erkan; Celik, Guelsah GencerPolitical skill is one of the most important personal resources that employees have. The presence of political skill can cause employees to manage situations such as conflict, ambiguity and overload caused by their roles more effectively. In addition, depending on whether self-efficacy is high or low, the strength of the influence between the relevant variables may increase or decrease. In this context, the study's main purpose is to investigate the moderating role of self-efficacy in the effect of political skill on employees' role stress. The study population of the study consists of those working in sports tourism hotels. The data obtained from 308 sports tourism hotel employees were analyzed with the help of SPSS and Smart PLS programs. According to the findings, it was determined that political skill did not significantly negatively affect role stress and its sub-dimensions, such as role conflict, role overload and role ambiguity. However, when the analysis was made on the moderating role variable, it was revealed that self-efficacy had a moderating role in the effect of political skill on role conflict and role overload among the sub-dimensions of role stress. The findings were discussed in the last part of the study, and suggestions for future research were presented.Öğe Histopathological Analysis of the Role of Horn on the Memory/Intelligence Processing Areas of the Brain and the Blood Brain Barrier in Female Sheep(Soc Chilena Anatomia, 2024) Ozturk, Cengiz; Yarar, Burhan; Keles, Osman Nuri; Malkoc, Ismail; Cetin, Zehra Aslihan; Tanriverdi, Esra Cinar; Aydin, Mehmet DumluBecause horned animals are prone to conflict, they may have a higher risk of developing a brain contusion as a result of a horn strike. Repeated brain trauma can affect the hippocampus, which is involved in memory and orientation. The aims of study thi was to histopathologically examine the blood-brain barrier (BBB) of the hippocampus in horned and hornless female sheep. 4 Skulls horned of and 6 hornless female sheep aged 16 +/- 4 months were obtained from the abattoir. Brains were carefully removed and preserved in 10 % formalin for 5 days. Sections were taken from bilateral hippocampus. Specimens were stained with hematoxylin-eosin (H&E) neland Tu methods, and the histopathologic structures of the BBB were examined by light microscopy. BBB damage scores evaluated. ltsThe wreresu analyzed by Mann-Whitney U test. The BBB damage score was found to be higher in horned female sheep. Astrocytes was more branching and BBB was more intact in hornless female sheep. This is considered that more astrocyte branches may play an importanthe role in protective mechanism. The difference in intracerebral defense mechanism against brain trauma in female sheep may serveel as fora mod investigating molecular mechanisms. The impairment of the BBB in the hippocampal region of horned female sheep may resulteir in th memory, intelligence, and navigational abilities being lower than those of hornless female sheep. This could open the horizon better f advances in human and animal brain health.Öğe ON GENERALIZED CONFORMABLE FRACTIONAL CALCULUS ON TIME SCALES WITH APPLICATION TO A FRACTIONAL NONLOCAL THERMISTOR PROBLEM(Georgian Natl Acad Sciences, 2025) Bendouma, Bouharket; Sarikaya, Mehmet ZekiIn this paper, we give a new general definition of conformable fractional derivative and integral on time scales, and study some of their important classical properties. As an application, the existence of solutions for the conformable fractional nonlo cal thermistor problem on time scales is studied by using the Banach contraction principle and Schauder's fixed point theorem.
