Approximation by Means of Fourier Trigonometric Series in Weighted Orlicz Spaces

Guven,Israfilov 장전수학회 2009 Advanced Studies in Contemporary Mathematics Vol.19 No.2

The order of approximation of Cesaro, Zygmund and Abel-Poisson means of Fourier trigonometric series were estimated by the modulus of continuity in re‡exive weighted Orlicz spaces with Muckenhoupt weights. These results were applied to estimate the rate of approximation of Cesaro, Zygmund and Abel sums of Faber series in weighted Smirnov-Orlicz classes de…ned on simply connected domains of the complex plane.

Effects of Various Inhibitors on β-galactosidase Purified from the Thermoacidophilic Alicyclobacillus acidocaldarius Subsp. Rittmannii Isolated from Antarctica

Reyhan Gul Guven,Alevcan Kaplan,Kemal Guven,Fatma Matpan,Mehmet Dogru 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.1

β-Galactosidase purified from the thermoacidophilic Alicyclobacillus acidocaldarius subsp. rittmannii isolated from Antarctica is a member of the GH42 family. The enzyme was not effected by various concentrations of its reaction product glucose, but was greatly inhibited by the other reaction product galactose using both substrates,ONPG and lactose. Linewever-Burk plot analysis derived from both ONPG and lactose hydrolysis results showed that galactose is a mixed-type inhibitor of the purified β-galactosidase. The enzyme was slightly activated by Mg^(2+)(13% at 20 mM), while inhibited at higher concentrations of Ca^(+2) (33% at 10 mM), Zn^(+2) (86% at 8 mM) and Cu^(+2)(87% at 4 mM). The enzyme activity was not significantly altered by the metal ion chelators EDTA and 1,10-phenanthroline up to 20 mM, indicating that this enzyme is not a metalloenzyme. 2-Mercaptoethanol and DTT were found to enhance β-galactosidase activity, while p-chloromercuribenzoic acid (PCMB) completely inhibited enzymatic activity (97% at 1 mM; 99.7% at 2 mM), indicating at least one essential Cys residue modified by the reagents in the active site of β-galactosidase. Iodoacetamide and Nethylmaleimide had little effect on the β-galactosidase. Phenylmethylsulfonyl fluoride (PMSF) inhibited the enzyme strongly (19.8% at 1 mM; 71.9% at 10 mM), also showing the participation of serine for enzyme activity.

MULTIPLIER THEOREMS IN WEIGHTED SMIRNOV SPACES

Guven, Ali,Israfilov, Daniyal M. Korean Mathematical Society 2008 대한수학회지 Vol.45 No.6

The analogues of Marcinkiewicz multiplier theorem and Littlewood-Paley theorem are proved for p-Faber series in weighted Smirnov spaces defined on bounded and unbounded components of a rectifiable Jordan curve.

Comparison of retention forces with various fabrication methods and materials in double crowns

Guven, Melahat Celik,Tuna, Meral,Bozdag, Ergun,Ozturk, Gizem Nur,Bayraktar, Gulsen The Korean Academy of Prosthodonitics 2017 The Journal of Advanced Prosthodontics Vol.9 No.4

PURPOSE. The purpose of this study was to analyze the retention force changes and wear behaviours of double-crown systems over long-term use. MATERIALS AND METHODS. Ten groups, each consisting of six samples, were evaluated. Specifically, casting gold alloy primary crown - casting gold alloy secondary crown (AA), laser sintering primary crown - laser sintering secondary crown (LL), casting Cr alloy primary crown - casting Cr alloy secondary crown, (CC) zirconia primary crown - electroformed secondary crown (ZA), and CAD/CAM titanium alloy primary crown - CAD/CAM titanium alloy secondary crown (TT) groups were evaluated at cone angles of $4^{\circ}$ and $6^{\circ}$. The samples were subjected to 5,000 insertion-separation cycles in artificial saliva, and the retention forces were measured every 500 cycles. The wear levels were analyzed via SEM at the beginning and end of the 5,000 cycles. RESULTS. In all samples, the retention forces increased when the conus angle decreased. The highest initial and final retention force values were found in the $LL-4^{\circ}$ group (32.89 N-32.65 N), and the lowest retention force values were found in the $ZA6^{\circ}$ group (5.41 N-6.27 N). The ZA groups' samples showed the least change in the retention force, and no wear was observed. In the other groups, wear was observed mostly in the primary crowns. CONCLUSION. More predictable, clinically relevant, and less excursive retention forces can be observed in the ZA groups. The retention force values of the LL groups were statically similar to those of the other groups, except the ZA groups.

The Neuroprotective Effect of Kefir on Spinal Cord Ischemia/Reperfusion Injury in Rats

Guven, Mustafa,Akman, Tarik,Yener, Ali Umit,Sehitoglu, Muserref Hilal,Yuksel, Yasemin,Cosar, Murat The Korean Neurosurgical Society 2015 Journal of Korean neurosurgical society Vol.57 No.5

Objective : The main causes of spinal cord ischemia are a variety of vascular pathologies causing acute arterial occlusions. We investigated neuro-protective effects of kefir on spinal cord ischemia injury in rats. Methods : Rats were divided into three groups : 1) sham operated control rats; 2) spinal cord ischemia group fed on a standard diet without kefir pretreatment; and 3) spinal cord ischemia group fed on a standard diet plus kefir. Spinal cord ischemia was performed by the infrarenal aorta cross-clamping model. The spinal cord was removed after the procedure. The biochemical and histopathological changes were observed within the samples. Functional assessment was performed for neurological deficit scores. Results : The kefir group was compared with the ischemia group, a significant decrease in malondialdehyde levels was observed (p<0.05). Catalase and superoxide dismutase levels of the kefir group were significantly higher than ischemia group (p<0.05). In histopathological samples, the kefir group is compared with ischemia group, there was a significant decrease in numbers of dead and degenerated neurons (p<0.05). In immunohistochemical staining, hipoxia-inducible factor-$1{\alpha}$ and caspase 3 immunopositive neurons were significantly decreased in kefir group compared with ischemia group (p<0.05). The neurological deficit scores of kefir group were significantly higher than ischemia group at 24 h (p<0.05). Conclusion : Our study revealed that kefir pretreatment in spinal cord ischemia/reperfusion reduced oxidative stress and neuronal degeneration as a neuroprotective agent. Ultrastructural studies are required in order for kefir to be developed as a promising therapeutic agent to be utilized for human spinal cord ischemia in the future.

Behavior and design of stainless steel tubular member welded end connections

Guven Kiymaz,Edip Seckin 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.3

Among the various alternatives to make a steel tubular member connection, making a slotted and gusset plate welded connection is one of the most frequently preferred alternatives. This type of connection is essentially an end connection that is made by slotting the tube longitudinally, inserting the gusset plate and then placing longitudinal fillet welds at the tube-to-plate interface. In this paper an experimental study on the behaviour of such connections in stainless steel is presented. 24 specimens were tested under concentrically applied axial tensile forces for varying tube-to-gusset plate weld lengths. Both circular and box section members were considered in the test program. Load-deformation curves were obtained and comparisons were made in terms of strength and ductility. The results obtained from the study were then critically examined and compared with currently available design guidance for slotted gusset plate welded tubular end connections. It is noted that no specific rules exist in international specifications on structural stainless steel which cover the design of such connections. Therefore, the results of this study are compared with the existing design rules for carbon steel.

Evaluation and comparison of the marginal adaptation of two different substructure materials

Sedat Guven,Veysel Eratilla,Ebru Sumer,Ali Ihsan Zengingul,Sabiha Zelal Ulku,Tahir Karaman 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.3

PURPOSE In this study, we aimed to evaluate the amount of marginal gap with two different substructure materials using identical margin preparations. MATERIALS AND METHODS Twenty stainless steel models with a chamfer were prepared with a CNC device. Marginal gap measurements of the galvano copings on these stainless steel models and Co-Cr copings obtained by a laser-sintering method were made with a stereomicroscope device before and after the cementation process and surface properties were evaluated by scanning electron microscopy (SEM). A dependent t-test was used to compare the mean of the two groups for normally distributed data, and two-way variance analysis was used for more than two data sets. Pearson's correlation analysis was also performed to assess relationships between variables. RESULTS According to the results obtained, the marginal gap in the galvano copings before cementation was measured as, on average, 24.47 ± 5.82 µm before and 35.11 ± 6.52 µm after cementation; in the laser-sintered Co-Cr structure, it was, on average, 60.45 ± 8.87 µm before and 69.33 ± 9.03 µm after cementation. A highly significant difference (P<.001) was found in marginal gap measurements of galvano copings and a significant difference (P<.05) was found in marginal gap measurements of the laser-sintered Co-Cr copings. According to the SEM examination, surface properties of laser sintered Co-Cr copings showed rougher structure than galvano copings. The galvano copings showed a very smooth surface. CONCLUSION Marginal gaps values of both groups before and after cementation were within the clinically acceptable level. The smallest marginal gaps occurred with the use of galvano copings.

EQUITY OWNERSHIP PATTERNS AND IMPACT ON OPERATIONS: EVIDENCE FROM U.S. FIRMS IN CHINA

Turgut Guvenli,Rajib Sanyal People&Global Business Association 2002 Global Business and Finance Review Vol.7 No.2

This study examines how variations in equity ownership among U.S. firms in China translate into actual organizational practices and experiences. Four levels of equity ownership-minority, equal, majority, and wholly foreign owned-are tested against three sets of variables-finance. government relations, and human resource management. There is no clear-cut advantage for one level of equity ownership over another. On some issues, wholly owned firms appear to enjoy certain freedoms and advantages while on other issues, there are benefits to being a minority or equal partner, or a majority owner in a joint venture. Majority and wholly owned ventures are able to introduce distinct human resource practices in their Chinese operations but are less likely to develop good relationships with the Chinese government and bureaucracy. Joint ventures are more likely to exhibit patterns typical of Chinese enterprises and less able to resist meddling by government authorities. Consequently, firms contemplating entry into China would have to examine their own unique circumstances and industry specific factors to determine whether they should form a minority, equal, majority or wholly owned enterprise.

Predictive factors associated with successful response to utrasound guided genicular radiofrequency ablation

Selin Guven Kose,Halil Cihan Kose,Feyza Celikel,Omer Taylan Akkaya 대한통증학회 2022 The Korean Journal of Pain Vol.35 No.4

Background: Ultrasound-guided genicular nerve radiofrequency (RF) procedures are of interest in the management of chronic knee pain. A wide variety of demographic, clinical, and procedural characteristics can affect treatment success. This study aimed to determine predictive factors to provide superior treatment outcomes. Methods: The demographic, clinical, and technical data of patients who received genicular nerve RF for knee pain between September 2016 and September 2021 were evaluated. A positive outcome was defined as at least 50% pain relief on a pain score for at least 6 months. Logistic regression analysis was performed to determine the factors associated with a successful response to genicular RF. Results: Among 206 patients who underwent genicular RF, 62% of the patients reported successful outcomes at 6 months. In the multivariate model, targeting 5 nerves (odds ratio [OR], 6.184; 95% confidence interval [CI], 2.291–16.690; P < 0.001) was the most significant predictor of successful outcomes. Multivariable logistic regression analysis showed that prognostic genicular nerve block with a 50% cut-off value (OR, 2.109; 95% CI, 1.038–4.287; P = 0.039), no opioid use (OR, 2.753; 95% CI, 1.405–5.393; P = 0.003), and depression (OR, 0.297; 95% CI, 0.124–0.713; P = 0.007) were the predictive factors significantly associated with response to genicular RF. Conclusions: Clinical and technical factors associated with better treatment outcomes were ultimately targeting more nerves, performing prognostic block, no opioid use, and no depression. These results are expected to be considered when selecting patients for genicular RF.

Equality in degrees of compactness: Schauder's theorem and $s$-numbers

Asuman Guven Aksoy,Daniel Akech Thiong 대한수학회 2023 대한수학회논문집 Vol.38 No.4

We investigate an extension of Schauder's theorem by studying the relationship between various $s$-numbers of an operator $T$ and its adjoint $T^*$. We have three main results. First, we present a new proof that the approximation number of $T$ and $T^*$ are equal for compact operators. Second, for non-compact, bounded linear operators from $X$ to $Y$, we obtain a relationship between certain $s$-numbers of $T$ and $T^*$ under natural conditions on $X$ and $Y$. Lastly, for non-compact operators that are compact with respect to certain approximation schemes, we prove results for comparing the degree of compactness of $T$ with that of its adjoint $T^*$.