Cognitive Backoff Mechanism for IEEE802.11ax High-Efficiency WLANs

Nurullah Shahin,Rashid Ali,김성원,김영탁 한국통신학회 2019 Journal of communications and networks Vol.21 No.2

Carrier sense multiple access with collision avoidance(CSMA/CA) in current IEEE 802.11 wireless local area networks(WLANs) uses a uniformly distributed binary exponentialbackoff (BEB) mechanism that is mainly based upon exponentialincreases of the contention window (CW) to avoid repeated collisions. After each consecutive collision, the CW is doubled untilit reaches the maximum value. Under dense conditions, however,the blind selection of the CW greatly reduces throughput, whereasunder sparse conditions with smaller number of contending stations,the blind exponential increase of the CW for collision avoidancecauses unnecessarily long delays. Therefore, it fails to achievehigh efficiency in both dense and sparse environments with the currentBEB mechanism. In this paper, we propose a cognitive backoff(CB) mechanism that adaptively determines the CW to provide efficientcollision avoidance with high throughput and low delay underboth dense and sparse conditions. In the proposed CB mechanism,the measured conditional collision probability and the numberof backoff stages determine the CW. A performance analysiswith an event-driven simulator, NS3, reveals that the proposed CBcan achieve higher throughput and lower delay than the BEB, withoutmuch implementation complexity while preserving fairness.

Serum Inflammatory Biomarkers in Patients with Nonarteritic Anterior Ischemic Optic Neuropathy

Nurullah Koç,ak,Bilge Eraydın,Mustafa Turunç,,Volkan Yeter,İ,nci Gü,ngö,r 대한안과학회 2020 Korean Journal of Ophthalmology Vol.34 No.6

Purpose: To evaluate the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyteratio (PLR), and systemic immune-inflammation index (SII) in patients with non-arteritic anterior ischemic optic neuropathy(NAION). Methods: Fifty-six patients with NAION and 60 age-sex matched healthy controls were included in the study. Demographiccharacteristics and laboratory findings of the patients and the controls were obtained from the electronic medical records. NLR, PLR, MLR, and SII were calculated and compared between the groups. Cutoff values were also determined. Results: Neutrophil, monocyte and platelet counts were higher in the NAION group than in the control group, but the differencewas not statistically significant (p > 0.05). The mean NLR and SII were higher in the NAION group than in the controlgroup (p = 0.004 and p = 0.011, respectively). In the receiver operating characteristic curve analysis, the areas under thecurve for NLR were 0.67, and NLR >1.79 predicted NAION with a sensitivity of 71% and specificity of 59%. The areas under thecurve for SII was 0.66, and SII of >417 predicted NAION with a sensitivity of 71% and specificity of 49%. There was no significantdifference in PLR and MLR between the groups (p = 0.105 and p = 0.347, respectively). Conclusions: The current study demonstrated that NAION patients had increased NLR and SII levels compared with controlsubjects. Elevated NLR and SII might serve as readily available inflammatory predictors in NAION patients.

An Investigation Into the Degree of Sinus Mucosal Delivery of Inhaled Black Cumin Volatile and Peppermint Essential Oils

Nurullah Türe,Cafer Yıldırım,Özgür Pınarbaşlı,Erkan Özüdoğru,Cemal Cingi,Fatih Demirci,Nursenem Karaca 한국식품영양과학회 2021 Journal of medicinal food Vol.24 No.11

The aim of this study was to investigate the quantity of volatile components reaching the sinus mucosa (SM) by inhalation, which is responsible for the therapeutic effect, as a first step toward targeted drug design. In this study, 18 Wistar-Albino female rats with an average weight between 200 and 250 g were used. The rats to be used in the study were randomized: Black cumin (BC) essential oil group (group 1) (n = 6), Peppermint essential oil (PEO) group (group 2) (n = 6), and Control (group 3) (n = 6). Volatile oils were inhaled in group 1 and 2; in the control group volatile oils were not inhaled. In all groups, SM was removed and essential volatile oil composition was determined. In group 1, α-pinene was identified as the principal component in the gas phase from five different glass bottles containing SM. The data obtained were evaluated using the single sample T-test and results show that the α-pinene component in the group of inhaled BC essential oil reached significance (P < .001) when compared with the control group. The active component of the BC essential oil could not be identified as thymoquinone. In group 2, eucalyptol (1,8-cineole) was identified as the principal component in the gas phase from five different glass bottles containing SM. The data obtained were evaluated using the single sample T-test and it was found that the eucalyptol component in the group which inhaled PEO reached statistical significance (P < .001) compared with the control group. In group 3, no volatile oil compounds were detected. We have demonstrated that both oils (BC and peppermint) are delivered to the SM. There is a need for the optimum dose to be clarified by different methods of measurement than those used in the spectrometric data we have obtained. We are convinced that our work will lead to pharmacological, toxicological, and subsequent clinical trials in this area.

The effects of different surface treatments on the shear bond strengths of two dual-cure resin cements to CAD/CAM restorative materials

Turker, Nurullah,Buyukkaplan, Ulviye Sebnem,Basar, Ebru Kaya,Ozarslan, Mehmet Mustafa The Korean Academy of Prosthodonitics 2020 The Journal of Advanced Prosthodontics Vol.12 No.4

PURPOSE. The aim of the present study was to investigate the effects of surface treatments on the bond strengths between polymer-containing restorative materials and two dual-cure resin cements. MATERIALS AND METHODS. In the present study, rectangular samples prepared from Lava Ultimate (LU) and Vita Enamic (VE) blocks were used. The specimen surfaces were treated using CoJet sandblasting, 50 ㎛ Al₂O₃ sandblasting, % 9 HF (hydrofluoric) acid, ER,Cr:YSGG laser treatment, and Z-Prime. Dual-cure resin cements (TheraCem and 3M RelyX U 200) were applied on each specimen's treated surface. A micro-tensile device was used to evaluate shear bond strength. Statistical analysis was performed using the SAS 9.4v3. RESULTS. While the bond strength using TheraCem with LU or VE was not statistically significant (P=.164), the bond strength using U200 with VE was statistically significant (P=.006). In the TheraCem applied VE groups, Z-Prime and HF acid were statistically different from CoJet, Laser, and Sandblast groups. In comparison of TheraCem used LU group, there was a statistically significant difference between HF acid and other surface treatments. CONCLUSION. The bonding performance between the restorative materials and cements were material type-dependent and surface treatment had a large effect on the bond strength. Within the limitations of the study, the use of both U200 and TheraCem may be suggested if Z-prime was applied to intaglio surfaces of VE. The cementation of LU using TheraCem is suitable after HF acid conditioning of the restoration surfaces.

Effects of overdenture attachment systems with different working principles on stress transmission: A three-dimensional finite element study

Turker, Nurullah,Buyukkaplan, Ulviye Sebnem The Korean Academy of Prosthodonitics 2020 The Journal of Advanced Prosthodontics Vol.12 No.6

PURPOSE. The aim of the present study was to compare the stress distributions on the dental implants, abutments, and bone caused by different overdenture attachment types under functional chewing forces. MATERIALS AND METHODS. The 3D finite element models of the mandible, dental implants, attachment types, and prostheses were prepared. In accordance with a conventional dental implant supported overdenture design, the dental implants were positioned at the bone level in the canine teeth region bilaterally. A total of eight models using eight different attachment systems were used in this study. All the models were loaded to simulate chewing forces generated during the centric relationship (450 N), lateral movement (400 N), protrusive movement (400 N), and also in the presence of a food mass unilaterally (200 N). Stress outputs were obtained as the maximum principal stress and the equivalent von-Mises stress. RESULTS. In all attachment types, higher stress values were observed in the abutments, dental implants, and bone in the magnet attachments in different loading conditions. The highest stress values were observed among the magnet systems in the components of the Titanmagnetics model in all loading conditions (stresses were 15.4, 17.7, and 33.1 MPa on abutment, dental implant, and bone, respectively). The lowest stress value was observed in the models of Zest and O-Ring attachments. CONCLUSION. The results of the present study implied that attachment types permitting rotation and tolerating various angles created lower stresses on the bone, dental implants, and abutments.

Blood Count-derived Immunoinflammatory Markers in Thyroidassociated Ophthalmopathy

Volkan Yeter,Nurullah Koç,ak,Mehmet Tayfun Arslan,Elif Kiliç, Kan 대한안과학회 2021 Korean Journal of Ophthalmology Vol.35 No.3

Purpose: To investigate the diagnostic and prognostic significance of the blood-count derived systemic immunoinflammatory parameters in patients with thyroid-associated ophthalmopathy (TAO). Methods: In this retrospective case-control study, the blood-count parameters and neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio, and systemic immune-inflammatory index (SII), thyroid peroxidase antibody, and anti-thyroglobulin antibody were evaluated in 46 patients with TAO and 46 matched controls. The associations of the immunoinflammatory parameters with clinical outcomes were analyzed among TAO patients. Results: Significant differences were found in NLR, PLR, SII, and lymphocyte count between the controls and the TAO group (p < 0.05 for all). In logistic regression analysis, these inflammatory parameters did not have any prognostic effect on the clinical outcomes of the TAO (p > 0.05 for all). The patients, who needed systemic treatment due to any ocular involvement of TAO during the follow-up period, had significantly lower platelet count (p = 0.001) and PLR (p = 0.02) at the time of initial diagnosis when compared to the no treatment-needed group of the TAO patients. The initial platelet count was significantly associated with the subsequent steroid need due to TAO during the follow-up period (β = -0.02, p = 0.03). Conclusions: NLR, PLR, and SII may serve as potential inflammatory markers in the identification of the TAO, although they have no evident prognostic significance in TAO. However, the relatively lower platelet count at initial diagnosis may be associated with the need for systemic therapy during the follow-up in patients with TAO.

ORiginal Article : Ischemia-Modified Albumin: Could It Be a New Oxidative Stress Biomarker for Colorectal Carcinoma?

( Hamit Yasar Ellidag ),( Nurullah Bulbuller ),( Esin Eren ),( Sedat Abusoglu ),( Evren Akgol ),( Mustafa Cetiner ),( Necat Yilma ) The Editorial Office of Gut and Liver 2013 Gut and Liver Vol.7 No.6

Background/Aims: An impaired oxidative/antioxidative status plays an important role in the pathogenesis of many diseases, including cancer. The aim of this study was to evaluate the levels of the novel marker ischemia-modified al-bumin (IMA) and albumin-adjusted IMA (Adj-IMA) in patients with colorectal cancer (CRC) and look for the associations of these with the total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI). Methods: Forty patients with CRC (19 females and 21 males; mean age, 56.5±2.1 years) and 39 age- and sex-matched healthy peo-ple (22 females and 17 males; mean age, 56.0±1.7 years) were included in this study. Serum levels of IMA, TAS, and TOS were analyzed, and the OSI was calculated. Results: Serum IMA, TOS, and OSI levels were significantly higher in patients with CRC than in controls (p<0.0001), whereas TAS levels were significantly lower in CRC patients (p=0.03). There was no significant difference in serum Adj-IMA levels between groups (p=0.32). Conclusions: In this study, the oxidative/antioxidant status was impaired in favor of oxida-tive stress in CRC patients. This observation was not con-firmed by IMA measurement. Further studies are needed to establish the relationship between IMA and oxidative stress parameters in CRC and other cancers. (Gut Liver 2013;7:675-680)

Is it Time to Change the Control Placebo Arms in Phase III Trials of Metastatic Castration Resistant Prostate Cancer?

Dogan, Mutlu,Erdem, Gokmen Umut,Zengin, Nurullah Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.14

Prostate cancer is common all around the world. Hormonal therapy is the mainstay of therapy, however castration-resistant prostate cancer (CRPC) becomes a serious problem and needs further clinical trials with novel agents. Novel agents like cabazitaxel, abireterone acetate or enzalutamide are encouraging but we do not know which one is the best in metastatic CRPC. In here, treatment modalities for metastatic CRPC are discussed witha mini-review of the literature.

Free-floating Vitreous Cyst in an Adult Male

Yasin Toklu,Sabri Raza,Hasan Basri Cakmak,Nurullah Cagil 대한안과학회 2013 Korean Journal of Ophthalmology Vol.27 No.6

A 50 year-old male patient was referred to our clinic due to a floating mass in the right eye. The uncorrectedvisual aquity was 10 / 10 in both eyes.The patient did not have any systemic disorder and trauma history. Hisophthalmological examination revealed an unremarkable anterior segment with no signs of inflammation. Indirect opthalmoscopy and posterior segment biomicroscopy performed with 90D lens was unremarkablein the left eye, while in the right eye a single oval cyst was identified floating freely in the vitreous. The cystwas partially masking the underlying retinal vasculature. B-scan ultrasound revealed an echo-free, roundshapedcyst that was free from surrounding vitreous strands or retina localised at the posterior vitreous. Fluorescein angiography (FA) ruled out the presence of intra and overlying vascularisation of the cyst. Indeed,FA showed a clear-edged hypofluorescence due to a pre-retinal masking effect. The indirect hemaglutinintests of the patient for ecinococcus and cysticercosis were negative. Eosinophilia was not detected in thepreripheral blood smear. Based on these findings the patient was diagnosed as primary vitreal cyst. Thepresented case was mild symptomatic so the patient was decided to be followed up without any treatment.

Radiation Exposure to Premature Infants in a Neonatal Intensive Care Unit in Turkey

Turan Olgar,Esra Onal,Dogan Bor,Nurullah Okumus,Yildiz Atalay,Canan Turkyilmaz,Ebru Ergenekon,Esin Koc 대한영상의학회 2008 Korean Journal of Radiology Vol.9 No.5

Objective: The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. Materials and Methods: We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESDTO) (n = 23) and from the use of thermoluminescent dosimetry (ESDTLD) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESDTO by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESDTO and ESDTLD were correlated using linear regression analysis. Results: The mean ESDTO for the chest and abdomen were 67 μGy and 65 μGy per procedure, respectively. The mean ESDTLD per radiograph was 70 μGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 μGy) per radiograph. Mean effective doses were 16 and 27 μSv per procedure for the chest and abdomen, respectively. ESDTLD was well correlated with ESDTO obtained from the total chest and abdomen radiographs for each infant (R2 = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 × 10-6 to 2 × 10-6 and 0.6 × 10-6 to 2.9 × 10-6 for chest and abdomen radiographs, respectively. Conclusion: The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other. Objective: The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. Materials and Methods: We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESDTO) (n = 23) and from the use of thermoluminescent dosimetry (ESDTLD) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESDTO by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESDTO and ESDTLD were correlated using linear regression analysis. Results: The mean ESDTO for the chest and abdomen were 67 μGy and 65 μGy per procedure, respectively. The mean ESDTLD per radiograph was 70 μGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 μGy) per radiograph. Mean effective doses were 16 and 27 μSv per procedure for the chest and abdomen, respectively. ESDTLD was well correlated with ESDTO obtained from the total chest and abdomen radiographs for each infant (R2 = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 × 10-6 to 2 × 10-6 and 0.6 × 10-6 to 2.9 × 10-6 for chest and abdomen radiographs, respectively. Conclusion: The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other.