PubMed İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://gcris.yasar.edu.tr/handle/123456789/11288

Browse

Now showing 1 - 13 of 13

Citation - WoS: 6
Citation - Scopus: 7
Bifurcation analysis of bistable and oscillatory dynamics in biological networks using the root-locus method
(INST ENGINEERING TECHNOLOGY-IET, 2019-12) Neslihan Avcu; Cuneyt Guzelis; Guzelis, Cuneyt; Avcu, Neslihan
Most of the biological systems including gene regulatory networks can be described well by ordinary differential equation models with rational non-linearities. These models are derived either based on the reaction kinetics or by curve fitting to experimental data. This study demonstrates the applicability of the root-locus-based bifurcation analysis method for studying the complex dynamics of such models. The effectiveness of the bifurcation analysis in determining the exact parameter regions in each of which the system shows a certain dynamical behaviour such as bistability oscillation and asymptotically equilibrium dynamics is shown by considering two mostly studied gene regulatory networks namely Gardner's genetic toggle switch and p53 gene network possessing two-phase (mono-stable/oscillation) dynamics.
Citation - WoS: 26
Citation - Scopus: 25
Compensatory usage of the internet: The case of mukbang watching on youtube
(Korean Neuropsychiatric Association, 2021-04-25) Kağan Kircaburun; Sabah Balta; Emrah Emirtekin; Şule Betül Tosuntaş; Zsolt Demetrovics; Mark D. Griffiths; Kircaburun, Kagan; Emirtekin, Emrah; Balta, Sabah; Tosuntaş, Şule Betül; Demetrovics, Zsolt; Griffiths, Mark D.
Objective Accumulating empirical research has emphasized that a wide range of online activities–such as using social networking sites–can be performed in order to compensate unattained needs or to cope with negative affect and psychopathological symptoms. Al-though the correlates of problematic social networking use have been extensively investigated less is known about problematic YouTube use (PYU) an umbrella term grouping a number of different activities (e.g. viewing of online video games watching specific YouTube channels). Furthermore nothing is known concerning increasingly popular and distinct YouTube-related activities such as mukbang watching (i.e. watching livestream “eating broadcasts” where someone eats various foods in front of the camera while interacting with viewers). The aim of the present study was to examine the mediating role of problematic mukbang watching (PMW) on the relationships between depression and loneliness with PYU. Methods An online survey that comprised assessment tools for aforementioned variables was administered to 217 mukbang viewers (mean age=20.58 years range 18–33 years). Results Results indicated that PMW was positively related to loneliness and PYU. Depression was positively and directly associated with PYU but was not associated with PMW. Conclusion Further research is required to better understand the psychological processes underlying problematic mukbang watching and its association with other mental health conditions (e.g. addictive disorders eating disorders). © 2021 Elsevier B.V. All rights reserved.
Computer based Classification of MR Scans in First Time Applicant Alzheimer Patients
(BENTHAM SCIENCE PUBL LTD, 2012-08-01) Fatma Polat; Selcuk Orhan Demirel; Omer Kitis; Fatma Simsek; Damla Isman Haznedaroglu; Kerry Coburn; Emre Kumral; Ali Saffet Gonul
In this study we aimed to classify MR images for recognizing Alzheimer Disease (AD) in a group of patients who were recently diagnosed by clinical history and neuropsychiatric exams by using non-biased machine-learning techniques. T1 weighted MRI scans of 31 patients with probable AD and 31 age- and gender-matched cognitively normal elderly were analyzed with voxel-based morphometry and classified by support vector machine (SVM) a machine learning technique. SVM could differentiate patients from controls with accuracy of 74 % (sensitivity: 70 % and specificity: 77 %) when the whole brain was included the analyses. The classification accuracy was increased to 79 % (sensitivity: 65 % and specificity: 93 %) when the analyses restricted to hippocampus. Our results showed that SVM is a promising tool for diagnosis of AD but needed to be improved.
Citation - WoS: 1
Citation - Scopus: 1
Coupling of cell fate selection model enhances DNA damage response and may underlie BE phenomenon
(INST ENGINEERING TECHNOLOGY-IET, 2020-04) Goekhan Demirkiran; Guleser Kalayc Demir; Cuneyt Guzelis; Guzelis, Cuneyt; Demirkiran, Goekhan; Demir, Guleser Kalayci
Double-strand break-induced (DSB) cells send signal that induces DSBs in neighbour cells resulting in the interaction among cells sharing the same medium. Since p53 network gives oscillatory response to DSBs such interaction among cells could be modelled as an excitatory coupling of p53 network oscillators. This study proposes a plausible coupling model of three-mode two-dimensional oscillators which models the p53-mediated cell fate selection in globally coupled DSB-induced cells. The coupled model consists of ATM and Wip1 proteins as variables. The coupling mechanism is realised through ATM variable via a mean-field modelling the bystander signal in the intercellular medium. Investigation of the model reveals that the coupling generates more sensitive DNA damage response by affecting cell fate selection. Additionally the authors search for the cause-effect relationship between coupled p53 network oscillators and bystander effect (BE) endpoints. For this they search for the possible values of uncertain parameters that may replicate BE experiments' results. At certain parametric regions there is a correlation between the outcomes of cell fate and endpoints of BE suggesting that the intercellular coupling of p53 network may manifest itself as the form of observed BEs.
Event Study Design for Modeling Early Relaxation in Turkish Public with COVID-19 Vaccine
(CAMBRIDGE UNIV PRESS, 2023) Merve Keser; Gorkem Sariyer; Serpil Kahraman
Objective:Vaccination is crucial to fighting the coronavirus disease (COVID-19) pandemic. A large body of literature investigates the effect of the initiation of the COVID-19 vaccination in case numbers in Turkey including the resistance and willingness to taking the vaccine. The effect of early relaxation in the Turkish public with the initiation of vaccination on new daily cases is unknown.Methods:This study performs an event study analysis to explore the pre-relaxation effect of vaccination on the Turkish public by using daily data of new cases stringency index and residential mobility. Two events are comparatively defined as the vaccination of the health personnel (Event 1) and the citizens age 65 and over (Event 2). The initial dates of these events are January 13 and February 12 2021 respectively. The length of the estimation window is determined as 14 days for the 2 events. To represent only the early stages of the vaccination the study period ends on April 12 2021. Thus whereas the event window of Event 1 includes 90 observations Event 2 covers 60 observations.Results:While average values of residential mobility stringency index and daily numbers of cases are 15.36 71.03 and 11 978.93 in the estimation window for Event 1 these averages are 8.89 70.88 and 17 303.20 in the event window. For Event 2 the same average values are 9.14 69.38 and 7 664.93 in the estimation window and 8.25 71.12 and 22 319.10 in the event window. When 14-day abnormal growth rates of the daily number of cases for Event 1 and Event 2 are compared it is observed that Event 1 has negative growth rates initially and reaches a 7.59% growth at most. On the other hand Event 2 starts with a 1.11% growth rate and having a steady increase it reaches a 23.70% growth in the last 14 days of the study period.Conclusion:The preliminary result shows that despite taking more strict governmental measures while residential mobility decreases the daily number of COVID-19 cases increases in the early stages of vaccination compared to short pre-periods of it. This indicates that the initiation of vaccination leads to early behavioral relaxation in public. Moreover the effect of Event 2 on the case numbers is more significant and immediate compared to that of Event 1 which may be linked to the characteristic of the Turkish culture being more sensitive to the older adult population.
How Do Cannabis and Synthetic Cannabinoids Affect Neurocognitive Functions
(TURKIYE SINIR VE RUH SAGLIGI DERNEGI, 2022) Hande Celikay Soyler; Ayse Ender Altintoprak; Ebru Ozturk Aldemir
Objective: In this study the losses of neurocognitive function caused by the use of cannabis and synthetic cannabinoids were studied on specific cognitive areas (attention and working memory executive functions visuospatial perception learning and memory planning and problem solving word naming) and were described in comparison with healthy controls (control group). Method: In this study while 52 participants who applied to Ege University Faculty of Medicine Department of Mental Health and Mental Disorders Drug Addiction Treatment Center Clinic between March 2015 - February 2017 and used cannabis at least for one year in the past and 51 participants who used synthetic cannabinoids for at least one year in the past were participant groups with a history of substance use, 57 staff/student of Ege University with no history of any substance use were participants of the control group. The research sample consisted of 160 participants. The sample group consisted of 160 men aged 18-35 and also 16 participants aged 36-54 were involved in the study in order to observe neuropsychological functions that changed with age. Stroop Test for attention area Raven Standart Progressive Matrices Test for executive functions area Line Orientation Test and Cancellation Test for visuospatial perception area Serial Digit Learning Test and Oktem Verbal Memory Progresses Scale for learning and memory area The Tower of London Test for planning and problem solving skill Boston Naming Test for word naming area were used. Results: In this study while the lowest perfomance on the ability of focused attention visuospatial cognition visual scanning orientation sustained attention general ability short-term memory learning long-term memory word naming was shown by the participants with a history of synthetic cannabis use the participants with a history of cannabis use had the lowest performance on the ability of response rate perseveration conceptualizing abstract thinking changing sets recognition. Participants' history of substance use did not affect the ability of planning and problem solving. Conclusion: In conclusion this study suggests that the addition of cognitive rehabilitation programs to medical and psychosocial improvement studies carried out in the field of addiction will increase the success.
Hypoglycemic effect of Lentinus strigosus (Schwein.) fr. crude exopolysaccharide in streptozotocin-induced diabetic rats
(MARY ANN LIEBERT INC, 2008-09) Mustafa Yamac; Gungor Kanbak; Melih Zeytinoglu; Gokhan Bayramoglu; Hakan Senturk; Mustafa Uyanoglu
This study reports the hypoglycemic effects of the crude exopolysaccharide (EPS) produced from submerged mycelial culture of Lentinus strigosus (Schwein.) Fr. (Family Polyporaceae) in streptozotocin (STZ)-induced diabetic rats. In a dose-dependent study diabetic rats were treated with EPS at doses of 50-150 mg/kg of body weight for 7 days. Serum glucose and plasma insulin levels were measured in normal STZ-induced diabetic and EPS-treated diabetic rats. Following oral administration of FPS dosages for 7 days the serum glucose levels in the STZ-induced diabetic rats were reduced up to 21.1% at the dose of 150 mg/kg of body weight. The results revealed that orally administered L. strigosus EPS at the dose of 150 mg/kg exhibited a considerable hypoglycemic effect in STZ-induced diabetic rats. Plasma insulin levels of STZ-induced diabetic rats decreased as compared to control group rats (P <.05). Although insulin levels slightly increased in the EPS-treated groups the increase was not statistically significant. The hypoglycemic potential of the EPS was further supported by histological observations of pancreatic islets of Langerhans.
Multiple genetic programming: a new approach to improve genetic-based month ahead rainfall forecasts
(SPRINGER, 2019-12-10) Ali Danandeh Mehr; Mir Jafar Sadegh Safari
It is well documented that standalone machine learning methods are not suitable for rainfall forecasting in long lead-time horizons. The task is more difficult in arid and semiarid regions. Addressing these issues the present paper introduces a hybrid machine learning model namely multiple genetic programming (MGP) that improves the predictive accuracy of the standalone genetic programming (GP) technique when used for 1-month ahead rainfall forecasting. The new model uses a multi-step evolutionary search algorithm in which high-performance rain-borne genes from a multigene GP solution are recombined through a classic GP engine. The model is demonstrated using rainfall measurements from two meteorology stations in Lake Urmia Basin Iran. The efficiency of the MGP was cross-validated against the benchmark models namely standard GP and autoregressive state-space. The results indicated that the MGP statistically outperforms the benchmarks at both rain gauge stations. It may reduce the absolute and relative errors by approximately up to 15% and 40% respectively. This significant improvement over standalone GP together with the explicit structure of the MGP model endorse its application for 1-month ahead rainfall forecasting in practice.
Citation - WoS: 26
Citation - Scopus: 30
Negotiators' profit predicted by cognitive reappraisal suppression of emotions misrepresentation of information and tolerance of ambiguity
(SAGE Publications Inc, 2008-04) Gülçimen Yurtsever; Yurtsever, Golcimen
This study examined the relationship between negative emotions and variables that affect negotiators' profit. Based on a simulated negotiation this study induced emotions by providing negative feedback on how negotiating partners perceived and evaluated each other's behavior. Then relationships were examined between negative emotions and emotional regulation strategies misrepresentation of information tolerance of ambiguity and negotiators' profit. A total of 228 undergraduate students enrolled in an economics course in the Faculty of Law and the Faculty of Management at a university in Ankara participated. There were 130 students in the experimental group and 98 students in the control group, 102 were men and 126 were women ages 17 to 35 years (M = 22.6 yr. SD = 2.3). A simulated negotiation process was used. Regression coefficients suggested positive relation between Emotional Reaction and the use of a Suppression strategy and Misrepresentation of Information. Negative coefficients were obtained from scores between Emotional Reaction and Cognitive Reappraisal and Tolerance of Ambiguity. The regression also suggested there were negative regression coefficients linking Misrepresentation of Information and Suppression strategies to Negotiators' Profit. Positive regression coefficients linked Tolerance of Ambiguity to Negotiators' Profit. Mediating variables explained 55% of variance in Negotiators' Profit, the majority (43%) was explained by Cognitive Reappraisal. © Perceptual and Motor Skills 2008. © 2008 Elsevier B.V. All rights reserved., MEDLINE® is the source for the MeSH terms of this document.
Citation - WoS: 1
Citation - Scopus: 1
New dimension of slow food movement using supercritical fluid technology and methods to influence society by effective marketing strategies
(SAGE Publications Inc. claims@sagepub.com, 2015-09-02) Ruhan Askin-Uzel; Uzel, Ruhan Aşkin
Although slow food movement is a well-known movement nowadays in order to make it more widespread to the society necessity to develop and to adapt new techniques has become inevitable for healthier consumption age. For this purpose possibility of increased usage of healthy foods with addition of natural extracts using new techniques came out from relevant questionaries applied to people of different age groups. In this study specific properties of supercritical carbon dioxide at distinct temperatures and water in subcritical conditions were used to obtain extracts rich in water-soluble organic compounds. Experiments were carried out at pressures of 10 20 30 and 40 MPa and temperatures ranging from 40 to 200 ° with and without modifier for 2 h of extraction time. The flow rate was kept at 4 and 1 ml/min for CO2 and water respectively. The highest water-soluble organic compound recovery yield was 78.10%. Results were supported by marketing strategies to announce this new application and products to the society. Group of sample questions was prepared to investigate (a) frequency of staple food usage (b) the brand names and relevant reasons that bring up consumers to buy specifically same branded products (c) knowledge about the ingredients and how advertising effects purchasing decision etc. Finally efficiency increase in slow food consumption was proved with supercritical fluid technology to draw attention to the health of consumers with newer and functional healthy foods. © 2017 Elsevier B.V. All rights reserved.
Representational Context Modulates the Direction and Transiency of Practice Effects on SNARC
(SAGE Publications Ltd, 2025-09-30) Palaz, Ezgi; Cetinkaya, Hakan; Dural, Seda
The Spatial-Numerical Association of Response Codes (SNARC) effect typically results in faster left-hand responses for small numbers and right-hand responses for large numbers, aligning with the concept of the mental number line (MNL). It is a robust but a flexible phenomenon that can reverse direction depending on the spatial-numerical mappings employed. This study investigates the potential modulatory effects of two contrasting representational contexts (ruler vs. clockface) on the emergence and persistence of the SNARC effect under two opposing spatial-numerical practices (MNL-compatible vs. MNL-incompatible). In Experiment 1, a magnitude classification task was employed as a practice session including either MNL-compatible or MNL-incompatible stimulus-response mappings, and the transfer and transiency of practice effects were examined by engaging participants in three test parity judgment tasks administered 5 min, 1 day, and 1 week after the practice session. In Experiment 2, different representational contexts were introduced during practice sessions. Experiment 2a utilized an image of a ruler as the context consistent with the MNL, while Experiment 2b employed a clockface image as an inconsistent context. Participants underwent testing three times to assess changes in performance over time. Results revealed that MNL-compatible practice effects did not transfer while MNL-incompatible practice effects resulted in a reverse SNARC effect persisting for up to 1 day. However, introducing the ruler context eliminated this transfer, while the clockface context reduced the persistence of the practice effect.
Revealing determinants of two-phase dynamics of P53 network under gamma irradiation based on a reduced 2D relaxation oscillator model
(INST ENGINEERING TECHNOLOGY-IET, 2018-02) Gokhan Demirkiran; Guleser Kalayci Demir; Cuneyt Guzelis
This study proposes a two-dimensional (2D) oscillator model of p53 network which is derived via reducing the multidimensional two-phase dynamics model into a model of ataxia telangiectasia mutated (ATM) and Wip1 variables and studies the impact of p53-regulators on cell fate decision. First the authors identify a 6D core oscillator module then reduce this module into a 2D oscillator model while preserving the qualitative behaviours. The introduced 2D model is shown to be an excitable relaxation oscillator. This oscillator provides a mechanism that leads diverse modes underpinning cell fate each corresponding to a cell state. To investigate the effects of p53 inhibitors and the intrinsic time delay of Wip1 on the characteristics of oscillations they introduce also a delay differential equation version of the 2D oscillator. They observe that the suppression of p53 inhibitors decreases the amplitudes of p53 oscillation though the suppression increases the sustained level of p53. They identify Wip1 and P53DINP1 as possible targets for cancer therapies considering their impact on the oscillator supported by biological findings. They model some mutations as critical changes of the phase space characteristics. Possible cancer therapeutic strategies are then proposed for preventing these mutations' effects using the phase space approach.
Two-dimensional polynomial type canonical relaxation oscillator model for p53 dynamics
(INST ENGINEERING TECHNOLOGY-IET, 2018-08) Gokhan Demirkiran; Guleser Kalayci Demir; Cuneyt Guzelis
p53 network which is responsible for DNA damage response of cells exhibits three distinct qualitative behaviours, low state oscillation and high state which are associated with normal cell cycle progression cell cycle arrest and apoptosis respectively. The experimental studies demonstrate that these dynamics of p53 are due to the ATM and Wip1 interaction. This paper proposes a simple two-dimensional canonical relaxation oscillator model based on the identified topological structure of ATM and Wip1 interaction underlying these qualitative behaviours of p53 network. The model includes only polynomial terms that have the interpretability of known ATM and Wip1 interaction. The introduced model is useful for understanding relaxation oscillations in gene regulatory networks. Through mathematical analysis we investigate the roles of ATM and Wip1 in forming of these three essential behaviours and show that ATM and Wip1 constitute the core mechanism of p53 dynamics. In agreement with biological findings we show that Wip1 degradation term is a highly sensitive parameter possibly related to mutations. By perturbing the corresponding parameters our model characterizes some mutations such as ATM deficiency and Wip1 overexpression. Finally we provide intervention strategies considering our observation that Wip1 seems to be an important target to conduct therapies for these mutations.

Browse

Browsing PubMed İndeksli Yayınlar Koleksiyonu by WoS Q "Q3"