Ideal cell-decompositions for a hyperbolic surface and Euler characteristic

Yasar Sozen 대한수학회 2008 대한수학회지 Vol.45 No.4

In this article, we constructively prove that on a surface S with genus g ≥ 2, there exit maximal geodesic laminations with 7g - 7,..., 9g - 9 leaves. Thus, S can have ideal cell-decompositions (i.e., S can be (ideally) triangulated by maximal geodesic laminations) with 7g - 7,..., 9g - 9 (ideal) 1-cells. Once there is a triangulation for a compact surface, the Euler characteristic for the surface can be calculated as the alternating sum F - E+V, where F,E, and V denote the number of faces, edges, and vertices, respectively. We also prove that the same formula holds for the ideal celldecompositions. In this article, we constructively prove that on a surface S with genus g ≥ 2, there exit maximal geodesic laminations with 7g - 7,..., 9g - 9 leaves. Thus, S can have ideal cell-decompositions (i.e., S can be (ideally) triangulated by maximal geodesic laminations) with 7g - 7,..., 9g - 9 (ideal) 1-cells. Once there is a triangulation for a compact surface, the Euler characteristic for the surface can be calculated as the alternating sum F - E+V, where F,E, and V denote the number of faces, edges, and vertices, respectively. We also prove that the same formula holds for the ideal celldecompositions.

Impaired Gallbladder Motility and Increased Gallbladder Wall Thickness in Patients with Nonalcoholic Fatty Liver Disease

( Yasar Colak ),( Gulcin Bozbey ),( Tolga Erim ),( Ozge Telci Caklili ),( Celal Ulasoglu ),( Ebubekir Senates ),( Hasan Huseyin Mutlu ),( Banu Mesci ),( Mehmet Sait Dogan ),( Guralp Tasan ),( Feruze Y 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2016 Journal of Neurogastroenterology and Motility (JNM Vol.22 No.3

Background/Aims Nonalcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease worldwide. Along with the increase in the incidence of NAFLD and associated obesity, an increase in gallbladder disease (GD) has been noted. This has led to the identification of a new disease entity called fatty GD. There is a gap in the literature on the dynamics of gallbladder function in patients with NAFLD. Methods An observational case-control study, a total of 50 patients with biopsy proven NAFLD without gallbladder stone/sludge and 38 healthy comparison subjects were enrolled. Fasting, postprandial gallbladder volumes (PGV), gallbladder ejection fraction (GEF), and fasting gallbladder wall thickness (FGWT) were measured by real-time 2-dimensional ultrasonography. Results Fasting gallbladder wall thickness, fasting gallbladder volumes and PGV were significantly higher in patients with NAFLD than control subjects (P < 0.001, P = 0.006, and P < 0.001, respectively). Gallbladder ejection fraction was significantly lower in the NAFLD group than the controls (P = 0.008). The presence of NAFLD was an independent predictor for GEF, PGV, and FGWT. Also, steatosis grade was an independent predictor for GEF, and GEF was significantly lower in the nonalcoholic steatohepatitis (NASH) subgroup than the controls. Conclusions Gallbladder dysfunction and increase in gallbladder wall thickness exists in asymptomatic (without stone/sludge and related symptoms) patients with NAFLD and are useful in identifying fatty GD. Measurement of these variables in NAFLD patients may be useful in identifying those at higher risk for GD. (J Neurogastroenterol Motil 2016;22:470-476)

The association of reproductive hormones, thyroid function, and vitamin levels with premature ejaculation: A prospective case-control study

Yasar Pazır,Haydar Guler,Taha Burak Bulut,Emre Ari,Semih Aktas,Mustafa Kadıhasanoglu 대한비뇨의학회 2024 Investigative and Clinical Urology Vol.65 No.2

Purpose: To investigate whether serum hormone (testosterone, prolactin, gonadotropins, and thyroid hormones) and vitamin (vitamin B12, folic acid, and vitamin D) levels are associated with premature ejaculation (PE). Materials and Methods: This prospective case-control study included 126 patients with PE (lifelong PE [LPE] in 94 and acquired PE [APE] in 32) who presented to the urology outpatient clinic between April 2016 and January 2023 and 92 healthy men as a control group. The diagnosis of PE was based on the criteria defined by the International Society for Sexual Medicine. Serum total testosterone (TT), free and bioavailable testosterone, follicle-stimulating hormone, luteinizing hormone, prolactin, thyroid-stimulating hormone, free triiodothyronine, thyroxine (fT4), vitamin B12, folic acid, and vitamin D levels were measured. Results: Serum TT, fT4, and vitamin D levels were significantly higher in patients with PE than in the control group (p=0.022, p=0.002, and p=0.044, respectively). However, the serum vitamin B12 level was significantly lower in the PE group (p=0.021). In the multivariate logistic regression analysis, only vitamin B12 was found to be an independent risk factor for PE, with an estimated odds ratio of 0.997 (95% confidence interval 0.994–0.999, p=0.036). Conclusions: This study demonstrated that lower vitamin B12 levels are associated with the presence of PE. Therefore, we believe that it would be beneficial to consider vitamin B12 levels in the evaluation of patients with PE.

Poster Session : Structural characterizations of RGS11

( Yasar Saleem ),( Key Sun Kim ) 한국생화학분자생물학회 (구 한국생화학회) 2006 생화학분자생물학회 춘계학술발표논문집 Vol.2006 No.-

The Challenges of Internationalization from Foreign and Local Students' Perspectives: The Case of Management School

Yasar Kondakci 서울대학교 교육연구소 2008 Asia Pacific Education Review Vol.9 No.4

The Purpose of this qualitative case study is to discern the issues pertaining to different dimensions of internationalization from the perspectives of both foreign and local students. Semi-structured interviews were conducted with 22 foreign, and 13 local students. The results show that there is a dissonance between policy makers and implementers, and the students themselves on "what a truly international higher education organization" in fact is. Moreover, the results suggest that asymmetrical aims of local and foreign students endanger fulfillment of the academic, social, and Cultural rationales behind internationalization. Fulfilling the rationales of internationalization depends not only the adaptability of foreign students to local conditions but also on the priorities, choices and level of commitment of local Students, administrative staff, and faculty members to the imperatives of internationalization.

Foliar Application of Growth Bioregulators Influences Floral Traits, Cormassociated Traits and Chemical Constituents in Gladiolus grandiflorus L.

Yasar Sajjad,Muhammad Jafar Jaskani,Muhammad Qasim,Gulzar Akhtar,Asim Mehmood 한국원예학회 2015 원예과학기술지 Vol.33 No.6

Gladiolus is one of the most popular cut flowers in the world floral market and is highly attractive to consumers. The production of poor-quality gladiolus spikes is one of the most important hurdles to obtaining high prices for this crop. The main objectives of this study were to improve the quantitative characteristics of gladiolus spikes, to increase propagule production and to enhance chemical constituent levels in leaves to help improve plant growth. We performed foliar application of bioregulators, including polyamines (putrescine and spermine) and vitamins (ascorbic acid and thiamine), at different concentrations (0, 0.1, 0.4, 0.7 and 1 mM) to gladiolus plants at the three leaf, five leaf and slipping stages. Application of 1 mM putrescine was the most effective treatment, with prominent effects on economically important spike traits including spike length (55.53 ㎝), spike diameter (7.53 ㎜), florets per spike (13.99), first floret diameter (9.66 ㎝) and first floret weight (4.90 g), followed by spermine treatment. The 1 mM putrescine treatment also had positive effects on corm-associated traits including corm diameter and corm weight, with values of 4.57 ㎝ and 26.16 g compared to 3.47 ㎝ and 17.16 g in control plants, respectively. The contents of chemical constituents in leaves, including total chlorophylls (8.06 ㎎·g<SUP>-1</SUP>), total carotenoids (1.66 ㎎·g<SUP>-1</SUP>), total soluble sugars (4.75 ㎎·g<SUP>-1</SUP>) and phenolics (0.89 ㎎·g<SUP>-1</SUP>) increased in response to foliar application of 1 mM putrescine compared to the control. Ascorbic acid and thiamine also had positive effects on various plant morphological traits and chemical constituents in leaves compared to control plants, but the growth-promoting effects of polyamines were more pronounced. Hence, applying polyamines to gladiolus leaves will help improve spike production and increasing propagule (cormel) yields.

The Velvet Family of Fungal Regulators Contains a DNA-Binding Domain Structurally Similar to NF-κB

Ahmed, Yasar Luqman,Gerke, Jennifer,Park, Hee-Soo,Bayram, Ö,zgü,r,Neumann, Piotr,Ni, Min,Dickmanns, Achim,Kim, Sun Chang,Yu, Jae-Hyuk,Braus, Gerhard H.,Ficner, Ralf Public Library of Science 2013 PLoS biology Vol.11 No.12

<P>Morphological development of fungi and their combined production of secondary metabolites are both acting in defence and protection. These processes are mainly coordinated by <I>velvet</I> regulators, which contain a yet functionally and structurally uncharacterized <I>velvet</I> domain. Here we demonstrate that the <I>velvet</I> domain of VosA is a novel DNA-binding motif that specifically recognizes an 11-nucleotide consensus sequence consisting of two motifs in the promoters of key developmental regulatory genes. The crystal structure analysis of the VosA <I>velvet</I> domain revealed an unforeseen structural similarity with the Rel homology domain (RHD) of the mammalian transcription factor NF-κB. Based on this structural similarity several conserved amino acid residues present in all <I>velvet</I> domains have been identified and shown to be essential for the DNA binding ability of VosA. The <I>velvet</I> domain is also involved in dimer formation as seen in the solved crystal structures of the VosA homodimer and the VosA-VelB heterodimer. These findings suggest that defence mechanisms of both fungi and animals might be governed by structurally related DNA-binding transcription factors.</P><P><B>Author Summary</B></P><P>In many fungi, developmental processes and the synthesis of nonessential chemicals (secondary metabolites) are regulated by various external stimuli, such as light. Although fungi employ them for defensive purposes, secondary metabolites range from useful antibiotics to powerful toxins, so understanding the molecular processes that regulate their synthesis is of particular interest to us. In the mold <I>Aspergillus nidulans</I> the main regulators of these processes are the so-called “<I>velvet</I>” proteins VeA, VelB, and VosA, which share a 150-amino acid region known as the <I>velvet</I> domain. <I>Velvet</I> proteins interact with each other, alone (“homodimers”), in various combinations (“heterodimers”), and also with other proteins, but the molecular mechanism by which these proteins exert their regulatory function has been unclear. In this work we show that <I>velvet</I> proteins form a family of fungus-specific transcription factors that directly bind to target DNA, even though analysis of their amino acid sequence does not reveal any known DNA-binding domains or motifs. We determined the three-dimensional structure of the VosA-VosA homodimer and the VosA-VelB heterodimer and found that the structure of the <I>velvet</I> domain is strongly reminiscent of the N-terminal immunoglobulin-like domain found in the mammalian transcription factor NFκB-p50, despite the very low sequence similarity. We propose that, like NFκB, various homo- or heterodimers of <I>velvet</I> proteins modulate gene expression to drive development and defensive pathways in fungi.</P>

Case Reports : A Case of Lichen Sclerosus et Atrophicus Accompanying Bullous Morphea

( Sirin Yasar ),( Ceyda Tanzer Mumcuoglu ),( Zehra Asiran Serdar ),( Pembegul Gunes ) 대한피부과학회 2011 Annals of Dermatology Vol.23 No.3s

Bullous morphea is a rare form of morphea characterized with bullae on or around atrophic morphea plaques. Whereas lichen sclerosus et atrophicus (LSA) is a disease the etiology of which is not fully known, and which is characterized with sclerosis. Coexistence of morphea and LSA has been identified in some cases. Some authors believe that these two diseases are different manifestations which are on the same spectrum. The 70-year-old patient stated herein, presented to us for 6 months with annular, atrophic plaques, ivory color in the middle, surrounded by living erythema, on the front and back of the trunk. Occasionally bulla formation on the plaques on the trunk lateral was identified. Fibrotic and atrophic plaques of ligneous hardness were present on the front side of tibia of both legs. In the histopathologic examination, the lesions were found concordant with bullous morphea and LSA. With colchicine 1.5 mg/day, pentoxifylline 1,200 mg/day, topical calcipotriol ointment and clobetasol propionate cream, the erythema in the patient`s lesions faded and softening in the fibrotic plaques was observed. Concomitance of bullous morphea and LSA is a rarely seen, interesting coexistence which suggests a common, as yet unknown, underlying pathogenesis. (Ann Dermatol 23(S3) S354~S359, 2011)

IDEAL CELL-DECOMPOSITIONS FOR A HYPERBOLIC SURFACE AND EULER CHARACTERISTIC

Sozen, Yasar Korean Mathematical Society 2008 대한수학회지 Vol.45 No.4

In this article, we constructively prove that on a surface S with genus g$\geq$2, there exit maximal geodesic laminations with 7g-7,...,9g-9 leaves. Thus, S can have ideal cell-decompositions (i.e., S can be (ideally) triangulated by maximal geodesic laminations) with 7g-7,...,9g-9 (ideal) 1-cells. Once there is a triangulation for a compact surface, the Euler characteristic for the surface can be calculated as the alternating sum F-E+V, where F, E, and V denote the number of faces, edges, and vertices, respectively. We also prove that the same formula holds for the ideal cell decompositions.

On geomerty of half-lightlike submanifolds with a semi-symmetric non-metric connection

E. Yasar 장전수학회 2013 Advanced Studies in Contemporary Mathematics Vol.23 No.4

On geomerty of half-lightlike submanifolds with a semi-symmetric non-metric connection