A GEOMETRIC APPROACH TO TIMELIKE FLOWS IN TERMS OF ANHOLONOMIC COORDINATES

Ays¸e Yavuz,Melek Erdogdu 호남수학회 2022 호남수학학술지 Vol.44 No.2

This paper is devoted to the geometry of vector fields and timelike flows in terms of anholonomic coordinates in three dimensional Lorentzian space. We discuss eight parameters which are related by three partial differential equations. Then, it is seen that the curl of tangent vector field does not include any component in the direction of principal normal vector field. This implies the existence of a surface which contains both s − lines and b − lines. Moreover, we examine a normal congruence of timelike surfaces containing the s − lines and b − lines. Considering the compatibility conditions, we obtain the Gauss-Mainardi-Codazzi equations for this normal congruence of timelike surfaces in the case of the abnormality of normal vector field is zero. Intrinsic geometric properties of these normal congruence of timelike surfaces are obtained. We have dealt with important results on these geometric properties.

Characteristics of nanocomposite films deposited by atmospheric pressure uniform RF glow plasma

Aysegul Uygun,Lutfi Oksuz,Ayse Gul Yavuz,Ali Guleç,Songul Sen 한국물리학회 2011 Current Applied Physics Vol.11 No.2

Characteristics of nanocomposite films synthesized and deposited by atmospheric pressure Radio-Frequency (RF) (13.56 MHz) uniform glow discharge are examined. The nanocomposite thin film deposition is carried out in the presence of titanium dioxide (TiO_2) with polymerization of pyrrole,thiophene and furan monomers in acetonitrile medium containing lithium perchlorate (LiClO_4). The chemical, morphological, thermal and electrical characteristics of polypyrrole/TiO_2 (PPy/TiO_2), polythiophene/TiO_2 (PT/TiO_2) and polyfuran/TiO_2 (PF/TiO_2) composites are examined by FTIR spectroscopy,scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), atomic force microscopy (AFM), thermogravimetry (TGA) and four-probe conductivity measurements. The presence of PT bands in the FTIR spectra of PT/TiO_2 indicates that plasma polymerization did not cause thiophene ring opening as was reported in the literature. The thermograms indicate that the PPy/TiO_2 composite has the best thermal stability, whereas PT/TiO_2 has the best electrical conductivity. Morphology studies reveal that the composite film deposition occurs uniformly through polymerization of the monomer onto TiO_2nanoparticles.

BETCHOV-DA RIOS EQUATION BY NULL CARTAN, PSEUDO NULL AND PARTIALLY NULL CURVE IN MINKOWSKI SPACETIME

Melek Erdogdu,Yanlin Li,Ayse Yavuz 대한수학회 2023 대한수학회보 Vol.60 No.5

The aim of this paper is to investigate Betchov-Da Rios equation by using null Cartan, pseudo null and partially null curve in Minkowski spacetime. Time derivative formulas of frame of $s$ parameter null Cartan, pseudo null and partially null curve are examined, respectively. By using the obtained derivative formulas, new results are given about the solution of Betchov-Da Rios equation. The differential geometric properties of these solutions are obtained with respect to Lorentzian causal character of $s$ parameter curve. For a solution of Betchov-Da Rios equation, it is seen that null Cartan $s$ parameter curves are space curves in three-dimensional Minkowski space. Then all points of the soliton surface are flat points of the surface for null Cartan and partially null curve. Thus, it is seen from the results obtained that there is no surface corresponding to the solution of Betchov-Da Rios equation by using the pseudo null $s$ parameter curve.

Internalized Stigma in Pediatric Psoriasis: A Comparative Multicenter Study

( Erkan Alpsoy Mualla Polat ),( Ibrahim Halil Yavuz ),( Pelin Kartal ),( Didem Didar Balci ),( Ayse Serap Karadag ),( Asli Bilgic Ercan Arca ),( Bilge Fettahlioglu Karaman ),( Selma Emre ),( Esra Adis 대한피부과학회 2020 Annals of Dermatology Vol.32 No.3

Background: Internalized stigma, adoption of negative attitudes and stereotypes of the society regarding persons’ illness, has not been studied previously in pediatric psoriasis patients. Objective: We aimed to investigate the internalized stigma in pediatric psoriasis patients and to determine differences according to factors affecting internalized stigma compared to adult psoriasis patients. Methods: This multicenter, cross-sectional, comparative study included 125 pediatric (55 female, 70 male; mean age±standard deviation [SD], 14.59±2.87 years) and 1,235 adult psoriasis patients (577 female, 658 male; mean age±SD, 43.3±13.7 years). Psoriasis Internalized Stigma Scale (PISS), Dermatology Life Quality Index (DLQI), Perceived Health Status (PHS), and the General Health Questionnaire (GHQ)-12 were the scales used in the study. Results: The mean PISS was 58.48±14.9 in pediatric group. When PISS subscales of groups were compared, the pediatric group had significantly higher stigma resistance (p=0.01) whereas adult group had higher scores of alienation (p=0.01) and stereotype endorsement (p=0.04). There was a strong correlation between mean values of PISS and DLQI (r=0.423, p=0.001). High internalized stigma scores had no relation to either the severity or localization of disease in pediatric group. However, poor PHS (p=0.007) and low-income levels (p=0.03) in both groups, and body mass index (r=0.181, p=0.04) in the pediatric group were related to high PISS scores. Conclusion: Internalized stigma in pediatric patients is as high as adults and is related to poor quality of life, general health, and psychological illnesses. Unlike adults, internalized stigma was mainly determined by psoriasis per se, rather than disease severity or involvement of visible body parts, genitalia or folds. (Ann Dermatol 32(3) 181∼188, 2020)

A practical method for accurate coordination between the plastic surgeon and the pathologist: The clockwork technique

Sezgin, Billur,Kapucu, Irem,Yenidunya, Guliz,Bulutay, Pinar,Armutlu, Ayse,Ozmen, Selahattin,Yavuzer, Reha Korean Society of Plastic and Reconstructive Surge 2018 Archives of Plastic Surgery Vol.45 No.1

The electrical conductivity properties of polythiophene/TiO2 nanocomposites prepared in the presence of surfactants

Aysegul Uygun,Orhan Turkoglu,Songul Sen,Ersay Ersoy,Ayse Gul Yavuz,Gokhan Guven Batir 한국물리학회 2009 Current Applied Physics Vol.9 No.4

A composite of polythiophene (PT) and nano-titanium dioxide (TiO2), possessing core–shell structure, was synthesized via oxidative polymerization of thiophene using FeCl3 in the presence of three different surfactants: anionic, cationic, and nonionic. The morphology of the obtained composite materials was investigated by SEM, proving the core–shell structure of the prepared nanocomposite. The formation and thermal stability of the PT onto TiO2 nanoparticles were confirmed by FTIR and TGA analyses, respectively. XRD data show all of composite materials were amorphous structures. The electrical properties of the nanocomposites were investigated in the presence of surfactant materials, and the best semiconductor property was observed for PT/TiO2-anionic system. This difference in the conductivity has been attributed to differences in the stability of the composites. A composite of polythiophene (PT) and nano-titanium dioxide (TiO2), possessing core–shell structure, was synthesized via oxidative polymerization of thiophene using FeCl3 in the presence of three different surfactants: anionic, cationic, and nonionic. The morphology of the obtained composite materials was investigated by SEM, proving the core–shell structure of the prepared nanocomposite. The formation and thermal stability of the PT onto TiO2 nanoparticles were confirmed by FTIR and TGA analyses, respectively. XRD data show all of composite materials were amorphous structures. The electrical properties of the nanocomposites were investigated in the presence of surfactant materials, and the best semiconductor property was observed for PT/TiO2-anionic system. This difference in the conductivity has been attributed to differences in the stability of the composites.

Case Report : Subcutaneous Sarcoidosis with Plantar Involvement

( Gokhan Celik ),( Aydin Ciledag ),( Pinar Akin ),( Yasin Simsek ),( Akin Kaya ),( Numan Numanoglu ),( Yavuz Yener Saglik ),( Ayse Boyvat ),( Selim Erekul ) 대한피부과학회 2010 Annals of Dermatology Vol.22 No.4

Sarcoidosis is a multisystem granulomatous disorder of an unknown etiology. Subcutaneous sarcoidosis is a rare manifestation of sarcoidosis, and plantar involvement is extremely rare and there is only one such case report in the medical literature. Herein we present an interesting case of a patient who was diagnosed as having subcutaneous sarcoidosis at a plantar localization because plantar involvement is extremely rare and also because of the successful outcome after performing intralesional corticosteroid therapy. (Ann Dermatol 22(4) 435~438, 2010)