Plastic occurrence in commercial fish species of the Black Sea

The occurrence of micro- ( 5 mm), meso- (5-25 mm) and macroplastics ( 25mm) was investigated in seven commercial fish species of the Black Sea. Plastics were found in gastrointestinal track of all species analysed: Engraulis encrasicolus, Trachurus mediterraneus, Sarda sarda, Belone belone, Pomatus saltatrix, Merlangius merlangus and Mullus barbatus. A total of 352 plastic particles were removed from 190 individuals (29% of all individuals examined). The mean number of plastic particles per fish was 0.81 +/- 1.42 par.ind-1 (considering all fish analysed, n=650) and 2.06 +/- 1.09 par.ind-1 (considering only the fish that ingested plastic, n=190). The most common types of plastics were fibres (68.5%), followed by films (19%), fragments (11.9%), foams (0.3 %) and microbeads (0.3%). The most common plastic colour was black (39.3%) followed by blue (19.5%) and transparent (18.1%). The length of plastics ranged from 0.05 to 26.5 mm with an average of 1.84 +/- 2.80 mm. 93.2% of plastics were microplastics, 6.5 % as mesoplastics and 0.3% macroplastics. Plastic occurrence was higher in S. sarda (plastic in 70% of the analysed individuals) and lower in M. merlangus (plastic in 9% of the analysed individuals). The main synthetic polymers identified by Fourier-transform infrared (FTIR) spectroscopy were polypropylene (29.8%), polyester (17.5%), acrylic (15.8%), polyethylene (14%) and polystyrene (1.8%) and 21.1% of polymers were cellulosic. Results show that commercial fish of the Black Sea is contaminated by plastics. This might affect vital functions of fish and pose a risk to ecosystem and human health. The study contributes to a better understanding of the status of plastic pollution in the fish from different habitats of the Black Sea and provides baseline data to implement the Marine Strategy Framework Directive in the basin

Hopf bifurcation and stability analyses of a neural network model with delay and a predator-prey model with delay

Bu tez çalışmasında temel amaç, gecikmeli diferensiyel denklem sistemlerinin kararlılık ve Hopf çatallanma analizlerini incelemektir. Bunun için, popülasyon dinamiği ve yapay sinir ağları alanlarında yer alan, farklı iki alana ait diferensiyel denklem sistemleri belirlenmiş, sistemlerde gerekli yerlere gecikme terimleri eklenerek sistemler iyileştirilmiş ve sistemlerin dinamik davranışları incelenmiştir. Çatallanma teorisi, seçilen bir kontrol parametresine bağlı olarak sistemlerin dinamiğini inceleyen dinamik sistemlerin bir araştırma sahasıdır. Amaç, kontrol parametresine göre değişimini gözlemlemek istediğimiz sistemin uzun vadedeki davranışını incelemektir. Çatallanma ise, değişen parametre değerlerine karşılık dinamik sistemin kalitatif yapısında değişiklik olmasıdır. Fark denklemleri ve diferensiyel denklemlere göre farklı çeşitlerde birçok çatallanma tipi mevcuttur. Ayrıca, modelin boyutuna göre de çatallanma tipleri ve adları değişmektedir. Dinamik sistemler teorisinde periyodik çözümler çok geniş bir yer tutmaktadır. Sürekli dinamik sistemlerde, bir parametreye bağlı lokal olarak periyodik çözümleri belirlemenin yolu ise Hopf çatallanma analizidir. Hopf çatallanması, en az iki boyutlu diferensiyel denklem sistemlerinde görülen, kritik parametre değerinden sonra denge noktasının kararlılık yapısının değiştiği (bakılan eksene göre yön değişebilir) ve limit döngülerinin (periyodik çözümlerin) ortaya çıktığı çatallanma tipidir. Gecikmeli diferensiyel denklemlerde, gecikme parametresini çatallanma parametresi olarak seçmek yaygındır. Bir dinamik sistemde, geçmiş zamanın etkilerini sisteme yansıtmak için modellere gecikme terimi eklenir. Gecikme terimi eklenilen denklemleri çalışmak biraz daha zor olsa da doğada gecikmeler daima mevcuttur. Popülasyon dinamiğinde, bir türün avlanabilmesi için olgunlaşma süreci veya avlanma için gerekli olan süre, bir bakterinin kuluçka süresi, bir sinir hücresinin uyarıldıktan sonra çıktının oluşabilmesi için geçmesi gereken süre gecikmelere örnek olarak verilebilir. Bu tez çalışması, esas itibariyle iki kısımdan oluşmaktadır: Tezin ilk kısmında, popülasyon dinamiğinde zengin bir içeriğe sahip olan bir oran-bağımlı denklem sistemine kesikli gecikme terimleri eklenmiştir. Bu bölüm, kendi içerisinde eşit gecikmeli terimli ve farklı gecikmeli terimli olmak üzere iki farklı sistemin Hopf çatallanma ve kararlılık analizlerini içermektedir. Tezin ikinci kısmında ise iki sinir hücreli geri beslemeli bir yapay sinir ağı sistemine hem kesikli hem dağılımlı gecikme terimi eklenmiş ve sistem yine iki farklı kategoride incelenmiştir. İki sistemde de, Hopf çatallanmanın varlığını garantileyebilmek için parametreler üzerine konacak gerekli şartlar belirlenmiş ve periyodik çözümlerin ortaya çıktığı gösterilmiştir. Çalışılan dört sistem için elde edilen teorik bulgular, MATLAB programı kullanılarak nümerik örneklerle desteklenmiştir.In this thesis, the main aim is to investigate the stability and Hopf bifurcation analyses of delayed differential equation systems. For this, we take two different differential equation systems which belong to population dynamics and artificial neural networks areas. These systems are enhanced by incorporating delay terms where needed and their dynamical behaviours are studied. Bifurcation theory is a research area that observes the changes of dynamical systems that depend on time according to a chosen control parameter. The goal is to study the large time behaviour of the system with respect to a control parameter that we want to observe. Bifurcation is the change of qualitative structure of dynamical systems associated with varying parameter values. There are many different bifurcation types in both difference and differential equations. Also, the names and types of bifurcations change according to the dimension of models. In dynamical systems literature, periodic solutions have an extensive study area. In continuous time dynamical systems, the method of determination of local periodic solutions that depend on a control parameter is Hopf bifurcation analysis. Hopf bifurcation is a type of bifurcation that after a critical parameter value the stability of the equilibrium point changes (the direction may change according to axes which we look) and limit cycles (periodic solutions) occur. Hopf bifurcation can be seen in at least two dimensional differential equation systems. It is very common to choose the delay parameter as a bifurcation parameter. In order to reflect dynamical behaviour of models that depend on the past history of the system, we often incorporate time delays into models. Even it is more difficult to analyse systems with delays, delays always exist in nature. In population dynamics, maturation time to be a prey of a specie or time needed for predation, incubation period of a bacteria, time needed for a response after a neuron is fired can be given for examples. This thesis mainly involves two parts: In the first part, it has been incorporated a discrete delay term into a ratio-dependent differential equation system which has rich content in population dynamics. This part includes Hopf bifurcation and stability analyses of two different systems, that is, one is the system with equal time delays and the other one is the system with different two time delays. In the second part, it has been incorporated a discrete and a distributed delay term into a recurrent neural network system with two neurons. Again, the system is considered in two categories. Both in two systems, the conditions on parameters are determined to guarantee that two systems have Hopf bifurcation and existence of periodic solutions is demonstrated. Theoretical results that have been obtained for four systems supported with numerical examples by using MATLAB program

Ortaokul fen bilimleri dersi öğretmen adaylarının astroloji, ufoloji, aşı karşıtlığı hareketi ve şifalı taşlar inanışları

Bu çalışma, ortaokul fen bilimleri dersi öğretmen adaylarının astroloji, ufoloji, aşı karşıtlığı hareketi ve şifalı taşlara inanış düzeyleri ve bu sözdebilim konularına ait görüşlerini araştırmaktadır. Çalışmaya Ege Üniversitesi Eğitim Fakültesi Fen Bilimleri Öğretmen adaylarından 173 kişi katılmıştır. Karma çalışma desenlerinden biri olan yakınsak desen kullanılmıştır. Bu desenin amacı bir konuda farklı fakat birbirini tamamlayan veri toplamaktır. Fen Bilimleri dersi öğretmen adaylarının sözdebilim inanışlarını ortaya çıkarmak için açık uçlu ve kapalı uçlu sorulardan oluşan karma bir veri toplama aracı kullanılmıştır. Araştırmada nicel veriler betimsel istatistik, nitel veriler ise şablon analizi ile analiz edilmiştir. Daha sonra araştırmaya ait nicel bulgular ile nitel bulgular karşılaştırılarak araştırma sorusu cevaplanmıştır. Bulgular; Fen bilimleri öğretmen adaylarının astroloji, ufoloji, aşı karşıtlığı hareketi ve şifalı taşlar sözdebilim alanlarına karşı olan inanç düzeyleri ile bu konulardaki görüşlerinin bütünleştiğini göstermektedir. Fen bilimleri öğretmen adayları, çalışmaya konu olan sözdebilim alanlarına inanma veya inanmama nedenlerini, çeşitli unsurlara dayalı olarak ifade etmiştir. Her sözdebilim alanı için bir örnek verilirse, astrolojiye inanma kişilik özellikleri, inanmama bilimsellik, ufolojiye inanma evrenin büyüklüğü, inanmama bilgi kaynakları, aşı karşıtlığı hareketine inanma yan etki, inanmama bilime güven, şifalı taşlara inanma pozitif enerji, inanmama batıl inanç ile açıklanmıştır. Fen bilimleri öğretmen adaylarının sözdebilimsel konulara ilişkin görüşlerinin gelişmesi veya değişmesi için eğitim dönemlerinde çalışmalar, tartışmalar, etkinlikler düzenlenebilir. Anahtar Sözcükler: Astroloji, Aşı karşıtlığı hareketi, Fen bilimleri öğretmen adayları, Sözdebilim, Şifalı taşlar, Ufoloji.This study, investigates the level of belief in astrology, ufology, the anti-vaccination movement and healing crystals and the views of pre-service middle school science teachers on these pseudoscience topics. A total of 173 pre-service science teachers from Ege University Faculty of Education participated in the study. Convergent design, one of the mixed study designs, was used. The aim of this design is to collect different but complementary data on a topic. A mixed data collection tool consisting of open-ended and closed-ended questions was used to reveal the pseudoscience beliefs of pre-service science teachers. In the study, quantitative data were analyzed using descriptive statistics and qualitative data were analyzed using template analysis. The research question was then answered by comparing the quantitative findings of the study with the qualitative findings. The findings show that pre-service science teachers' levels of belief in astrology, ufology, the anti-vaccination movement and the pseudoscience of healing crystals match up with their views on these subjects. The pre-service science teachers expressed their reasons for believing or not believing in the pseudoscience fields subject to the study based on various factors. If an example is given for each pseudoscience field, belief in astrology is explained by personality traits, disbelief by scientificity, belief in ufology by the size of the universe, disbelief by sources of information, belief in the anti-vaccine movement by side effects, disbelief by trust in science, belief in healing stones by positive energy, disbelief by superstition. Studies, discussions, and activities can be organized during the training periods for the development or change of pre-service science teachers' views on pseudoscientific issues

Complex Dynamics of a Discrete-Time Prey-Predator System with Leslie Type: Stability, Bifurcation Analyses and Chaos

Dynamic behavior of a discrete-Time prey-predator system with Leslie type is analyzed. The discrete mathematical model was obtained by applying the forward Euler scheme to its continuous-Time counterpart. First, the local stability conditions of equilibrium point of this system are determined. Then, the conditions of existence for flip bifurcation and Neimark-Sacker bifurcation arising from this positive equilibrium point are investigated. More specifically, by choosing integral step size as a bifurcation parameter, these bifurcations are driven via center manifold theorem and normal form theory. Finally, numerical simulations are performed to support and extend the theoretical results. Analytical results show that an integral step size has a significant role on the dynamics of a discrete system. Numerical simulations support that enlarging the integral step size causes chaotic behavior

Türk diş hekimlerinin Alman hocası Alfred Kantorowicz

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2018.This work is a student project of The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.The History of Turkey course (HIST200) is a requirement for all Bilkent undergraduates. It is designed to encourage students to work in groups on projects concerning any topic of their choice that relates to the history of Turkey. It is designed as an interactive course with an emphasis on research and the objective of investigating events, chronologically short historical periods, as well as historic representations. Students from all departments prepare and present final projects for examination by a committee, with 10 projects chosen to receive awards.by Abdürrahim Özer

Synthesis and antimicrobial and antitumor activity of some new [1,2,4] triazole-5-one derivatives

4-[Arylidene-amino]-3-thiophen-2-ylmethyl-4,5-dihydro[1,2,4]triazole-5-one compounds (3a-g) with Schiff base character were obtained from the reaction of 4-amino-3-thiophen-2-ylmethyl-4,5-dihydro-1H-[1,2,4]triazole-5-one (2) with various aldehydes. 1-(2-Oxo-2-phenyl-ethyl)-4-[arylidene-amino]-3-thiophen-2-ylmethyl-4,5-dihydro-1H-[1,2,4]triazole-5-ones (4a-g) were synthesized from the reaction of corresponding compounds 3a-g with bromoacetophenone. 1-(2-Hydroxy-2-phenyl-ethyl)-3-thiophen-2-ylmethyl-4-[aryl-amino]4,5-dihydro-1H-[1,2,4]triazole-5-ones (5a-g) and 1-(2-hydroxy-2-phenyl-ethyl)-3-thiophen-2-ylmethyl-4-[arylidene-amino]4,5-dihydro-1H-[1,2,4]triazole-5-ones (6b,d,e) were obtained from the selective reduction of 1-(2-oxo-2-phenylethyl)-4-[arylidene-amino]-3-thiophen-2ylmethyl-4,5-dihydro-1H-[1,2,4] triazole-5-ones (4) with NaBH4. They were characterized by IR, 1 H-NMR, 13C-NMR, and elemental analyses. Compounds 2, 3a, 3c, 3g, 4f, 5b, and 5g showed good antifungal activity against yeast-like fungi. Compounds selected by the National Cancer Institute (NCI, USA) were investigated for antitumor activity. © TÜBİTAK

Synthesis, and prediction of molecular properties and antimicrobial activity ofsome acylhydrazones derived fromN-(arylsulfonyl)methionine

A series of 38 new acylhydrazones [3{40], derived from (2S)-4-(methylsulfanyl)-2-[[(4-methylphenyl)sulfonyl]amino]butanoic acid hydrazide [2], were synthesized and evaluated for their anti-HIV and antimicrobial activity withthe further aim to develop acylhydrazones carrying an amino acid side chain. All tested compounds possess strongeractivity against gram (+) bacteria. Compound23was found active against methicillin-resistantStaphylococcus aureus(MRSA) with a MIC value of 3.9?g/mL. The MIC value of compound30againstEnterococcus faecalis,Listeriamonocytogenes, andBacillus cereuswas 8?g/mL. A computational study for prediction of ADME and drug-likeproperties (solubility, drug-likeness, and drug score) as well as potential toxicity pro les of compounds2{40wasperformed using the Molinspiration online property calculation toolkit and Osiris Property Explorer. As most of ourcompounds meet Lipinski\'s rule of ve, they promise good solubility and permeability. According to Osiris calculations,the majority of our compounds are supposed to be nonmutagenic and nonirritating

Hopf bifurcation analysis of coupled two-neuron system with discrete and distributed delays

We study the stability and Hopf bifurcation analysis of a coupled two-neuron system involving both discrete and distributed delays. First, we analyze stability of equilibrium point. Choosing delay term as a bifurcation parameter, we also show that Hopf bifurcation occurs under some conditions when the bifurcation parameter passes through a critical value. Moreover, some properties of the bifurcating periodic solutions are determined by using the center manifold theorem and the normal form theory. Finally, numerical examples are provided to support our theoretical results.TUBITAK (The Scientific and Technological Research Council of Turkey