Atılım Akademik Arşivi
Atılım Academic Archive
Atılım Akademik Arşivi; hakemli makaleleri, teknik raporları, çalışma raporlarını, yüksek lisans / doktora tezlerini ve daha fazlasını içeren Atılım Üniversitesi araştırma ekosistemi için oluşturulmuş bir dijital açık arşivdir.
Atılım Academic Archive; It is a digital open archive created for the Atılım University research ecosystem, which includes peer-reviewed articles, technical reports, study reports, master's / doctoral theses and more.
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Recent Submissions
A new extended δ-shock model with the consideration of shock magnitude
(Applied Stochastic Models in Business and Industry, 2024-07-14) Lorvand, Hamed; Eryılmaz, Serkan
In this article, a new -shock model that takes into account the magnitude of shocks is introduced and studied from reliability perspective. According to the new model, the system breaks down if either a shock after non-critical shock occurs in a time length less than or a shock after a critical shock occurs in a time length less than where . The distribution of the system's lifetime is studied for both discrete and continuous intershock time distributions. It is shown that a new model is useful to describe a certain cold standby repairable system.
Reliability and performance evaluation of weighted k-out-of-n:G system consisting of components with discrete lifetimes
(Reliability Engineering and System Safety, 2024-08-31) Eryılmaz, Serkan
For the k-out-of-n system consisting of components that have di§erent weights, the system is in a good state if the total weight of working components is at least k.
Such a system is known to be weighted k-out-of-n:G system. Although the weighted k-out-of-n system that has continuously distributed componentsílifetimes has been extensively studied, the discrete weighted k-out-of-n:G system has not been consid ered yet. The present paper Ölls this gap by modelling and analyzing the weighted k-out-of-n:G system that consists of discretely distributed componentsílifetimes. In particular, the behavior of the total capacity/weight of the system with respect to the component failures is evaluated. An optimization problem that is concerned with the determination of optimal number of spare components is also formulated by utilizing the mean lost capacity of the system.
Editorial: Biofabricated materials for tissue engineering
(Frontiers in Bioengineering and Biotechnology, 2024-05-08) Şaşmazel, Hilal Türkoğlu; Gündüz, Oğuzhan; Ramalingam, Murugan; Ulağ, Songül
Editorial on the Research Topic Biofabricated materials for tissue engineering
On 𝜹-shock model with a change point in intershock time distribution
(Statistics & Probability Letters, 2024-06-25) Chadjiconstantinidis, Stathis; Eryılmaz, Serkan
In this paper, we study the reliability of a system that works under 𝛿-shock model. That is, the
system failure occurs when the time between two successive shocks is less than a given thresh old 𝛿. In a traditional setup of the 𝛿 shock model, the intershock times are assumed to have the
same distribution. In the present setup, a change occurs in the distribution of the intershock
times due to an environmental effect. Thus, the distribution of the intershock times changes
after a random number of shocks. The reliability of the system is studied under this change
point setup.
Complete characterization of a class of permutation trinomials in characteristic five
(Cryptography and Communications, 2024-02-21) Grassl, Markus; Özbudak, Ferruh; Özkaya, Buket; Gülmez Temür, Burcu
In this paper, we address an open problem posed by Bai and Xia in [2].We study polynomials of the form f (x) = x^4q+1 + λ_1x^5q + λ_2x^q+4 over the finite field F_5^k , which are not quasimultiplicative equivalent to any of the known permutation polynomials in the literature. We find necessary and sufficient conditions on λ1, λ2 ∈ F_5^k so that f (x) is a permutation monomial, binomial, or trinomial of F_5^2k .
Effect of Knee Hyperextension on Femoral Cartilage Thickness in Stroke Patients
(American Journal of Physical Medicine & Rehabilitation, 2024-05) Korkusuz, Süleyman; Kibar, Sibel; Özgören, Nihat; Arıtan, Serdar; Seçkinoğulları, Büşra; Fil Balkan, Ayla
Objective
Knee hyperextension is one of the most common compensatory mechanisms in stroke patients. The first aim of the study was to measure knee hyperextension and femoral cartilage thickness in stroke patients. The second aim was to compare the femoral cartilage thickness of the paretic and nonparetic limbs in stroke patients with and without knee hyperextension.
Design
Forty stroke patients were included in the study. The patients were divided into two groups according to the presence of knee hyperextension based on kinematic analyses performed during walking with a three-dimensional motion analysis system. The medial femoral cartilage, lateral femoral cartilage, and intercondylar cartilage thicknesses of the paretic and nonparetic sides of the patients were measured by ultrasonography.
Results
In the study group, medial femoral cartilage, intercondylar, and lateral femoral cartilage thicknesses were less on the paretic side than on the nonparetic side, while the femoral cartilage thicknesses on the paretic and nonparetic sides were similar in the control group. Paretic side medial femoral cartilage and intercondylar thicknesses were less in the study group compared with the control group, and lateral femoral cartilage thickness was similar between the two groups.
Conclusions
Knee hyperextension during walking causes femoral cartilage degeneration in stroke patients.
Clinical Trial code: NCT05513157
Balance and gait in individuals with diabetic peripheral neuropathy
(Neurological Research, 2023-03-04) Korkusuz, Süleyman; Seçkinoğulları, Büşra; Yürük, Zeliha Özlem; Uluğ, Naime; Kibar, Sibel
Background
Diabetic Peripheral Neuropathy (DPN) causes various physical problems such as the increased risk of falling, loss of balance and coordination while standing or walking, susceptibility to injuries due to sensory loss.
Aims
The aim of the study was to evaluate and compare the effects of neuropathic pain (NP) in individuals with DPN on balance and gait.
Methods
This prospective controlled study was conducted on 42 adults aged between 40–65 years. The participants were divided into three groups; individuals with DPN and NP (DPN+NP/n = 14), individuals with DPN without NP (DPN-NP/n = 14), and the control group (n = 14), respectively. The Force Plate system and Core Balance System measured static and dynamic postural balance and stability limits. Gait and dynamic plantar pressure distribution analyses were performed with a computerized gait evaluation system.
Results
The score of LANSS, and VAS during gait were higher in DPN+NP group than in DPN-NP (p < 0.05). No significant difference was observed between the groups in balance parameters (p > 0.05). The right-left heel maximum forces were lower in both groups with DPN compared to the control group (p < 0.05). In terms of spatiotemporal parameters of the gait, there was a difference between the groups only in step width and left single support line parameters (p < 0.05).
Conclusions
The results of this study indicate that the individuals with DPN have an increased step width, their left single support line was shortened, and the maximum force on the heel decreased. The NP did not cause any change in balance and gait parameters.
The Effect of a Light-Dark Cycle on Premature Infants in the Neonatal Intensive Care Unit: A Randomized Controlled Study
(Journal of Pediatric Nursing, 2024-05-09) Olgun, Ayşe Betül; Yüksel, Didem; Yardımcı, Figen
Purpose
To investigate potential differences in discharge time, feeding methods and amounts, daily weight gain, vital signs, pain, and comfort levels among preterm infants born at 28–32 weeks' gestation who were hospitalized in the neonatal intensive care unit during long-term follow-up while implementing a light-dark cycle.
Design and methods
This is a randomized controlled study conducted with the support of a day-night cycle in premature infants born at 28–32 weeks' gestation and admitted to the neonatal intensive care unit of a teaching and research hospital affiliated with the Ministry of Health. The study compared the follow-up results from hospitalization to discharge over a period of 8 weeks.
Results
50% of premature infants admitted to the unit are multiple pregnancies. There was no significant difference in discharge weight, comfort level, pain level, vital signs of the infants included in the study (p > 0.05). The optimal development of infant feeding patterns was examinedand it was observed that the study group had significantly improved before the control group in terms of the time to switch to full enteral feeding and oral feeding (p < 0,05). The daily weight gain of the babies was examined, it was seen that the weight gain was higher in the study group compared to the control group (p < 0,05). The mean duration of hospitalization was compared, it was seen that the babies in the study group were discharged significantly earlier (p < 0,05).
Conclusion
The study compared the long-term outcomes of premature babies hospitalized in neonatal intensive care and babies exposed to a light-dark cycle and regularly monitored in standard care. The results showed that the babies in the study group had higher daily weight gain and were discharged earlier than the control group. There were also no statistically significant differences in comfort and pain scores, vital signs or oxygen saturation between the study and control groups.
Practice implications
A light-dark cycle was found to be a feasible and promising intervention for infants at 28–32 weeks' gestation. It was a nurse-led management of care that could be integrated into the usual care of 28–32-week-old babies in neonatal units.
Revealing Defect Centers in PbWO4 Single Crystals Using Thermally Stimulated Current Measurements
(Journal of Applied Physics, 2024-02-28) Işık, Mehmet; Gasanly, Nizami Mamed
The trap centers have a significant impact on the electronic properties of lead tungstate (PbWO4), suggesting their crucial role in optoelectronic applications. In the present study, we investigated and revealed the presence of shallow trap centers in PbWO4 crystals through the utilization of the thermally stimulated current (TSC) method. TSC experiments were performed in the 10–280 K range by applying a constant heating rate. The TSC spectrum showed the presence of a total of four peaks, two of which were overlapped. As a result of analyzing the TSC spectrum using the curve fit method, the activation energies of revealed centers were found as 0.03, 0.11, 0.16, and 0.35 eV. The trapping centers were associated with hole centers according to the comparison of TSC peak intensities recorded by illuminating the opposite polarity contacts. Our findings not only contribute to the fundamental understanding of the charge transport mechanisms in PbWO4 crystals but also hold great promise for enhancing their optoelectronic device performance. The identification and characterization of these shallow trap centers provide valuable insights for optimizing the design and fabrication of future optoelectronic devices based on PbWO4.
Investigation of Λ (1405)as a molecular pentaquark state
(The European Physical Journal C, 2024-04-30) Azizi, Kazım; Saraç Oymak, Yasemin; Sundu, Hayriye
Λ(1405) is one of the interesting particles with its unclear structure and distinct properties. It has a light mass compared to its non-strange counterpart, despite the strange quark it carries. This situation puts the investigation of this resonance among the hot topics in hadron physics and collects attention to clarify its properties. In this study, we focus on the calculation of the mass and residue of the Λ(1405) resonance within the framework of QCD sum rules. We assign a structure in the form of a molecular pentaquark composed from admixture of K− meson-proton and K¯ 0 meson neutron. Using an interpolating current in this form, the masses and the current coupling constant are attained as m = 1406±128 MeV and λ = (3.35±0.35)×10−5 GeV6 for /q and m = 1402±141 MeV and λ = (4.08 ± 1.08) × 10−5 GeV6 for I Lorentz structures entering the calculations, respectively. The obtained mass values agree well with the experimental data supporting the plausibility of the considered structure.