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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Transactions on Combinatorics
- نوع مقاله: Journal Article
- کلمات کلیدی: diameter,Reversible rings,Zero-divisor graphs,Noetherian rings,Skew power series rings
- چکیده:
- چکیده انگلیسی: Let $R$ be an associative ring with identity and $Z^{ast}(R)$ be its set of non-zero zero-divisors. Zero-divisor graphs of rings are well represented in the literature of commutative and non-commutative rings. The directed zero-divisor graph of $R$, denoted by $Gamma{(R)}$, is the directed graph whose vertices are the set of non-zero zero-divisors of $R$ and for distinct non-zero zero-divisors $x,y$, $xrightarrow y$ is an directed edge if and only if $xy=0$. In this paper, we connect some graph-theoretic concepts with algebraic notions, and investigate the interplay between the ring-theoretical properties of a skew power series ring $R[[x;alpha]]$ and the graph-theoretical properties of its directed zero-divisor graph $Gamma(R[[x;alpha]])$. In doing so, we give a characterization of the possible diameters of $Gamma(R[[x;alpha]])$ in terms of the diameter of $Gamma(R)$, when the base ring $R$ is reversible and right Noetherian with an $alpha$-condition, namely $alpha$-compatible property. We also provide many examples for showing the necessity of our assumptions.
- انتشار مقاله: 20-10-1396
- نویسندگان: Ebrahim Hashemi,Marzieh Yazdanfar,Abdollah Alhevaz
- مشاهده
- جایگاه : پژوهشی
- مجله: Current Medical Mycology
- نوع مقاله: Journal Article
- کلمات کلیدی: PCR-RFLP,Candida species,Vulvovaginal candidiasis,Antifungal Susceptibility testing,C. lusitaniae
- چکیده:
- چکیده انگلیسی: Background and Purpose: The aim of the current study was to investigate the epidemiology of vulvovaginal candidiasis (VVC) and recurrent VVC (RVVC), as well as the antifungal susceptibility patterns of Candida species isolates.
Materials and Methods: A cross-sectional study was carried out on 260 women suspected of VVC from February 2017 to January 2018. In order to identify Candida species isolated from the genital tracts, the isolates were subjected to polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) using enzymes Msp I and sequencing. Moreover, antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute guidelines (M27-A3).
Results: Out of 250 subjects, 75 (28.8%) patients were affected by VVC, out of whom 15 (20%) cases had RVVC. Among the Candida species, C. albicans was the most common species (42/95; 44.21%), followed by C. lusitaniae (18/95; 18.95%), C. parapsilosis (13/95; 13.69%), C. glabrata (8/95; 8.42%), C. kefyr (6/95; 6.31%), C. famata (5/95; 5.26%), C. africana (2/95; 2.11%), and C. orthopsilosis (1/95; 1.05%), respectively. Multiple Candida species were observed in 28% (21/75) of the patients. Nystatin showed the narrowest range of minimum inhibitory concentration (MIC) (0.25-16 μg/ml) against all Candida strains, whereas fluconazole (0.063-64 μg/ml) demonstrated the widest MIC range. In the current study, C. lusitaniae, as the second most common causative agent of VVC, was susceptible to all antifungal agents. Furthermore, 61.1% of C. lusitaniae isolates were inhibited at a concentration of ≤ 2 μg/ml, while38.9% (n=7)of them exhibited fluconazole MICs above the epidemiologic cutoff values (ECV). Candida species showed the highest overall resistance against fluconazole (61.3%), followed by itraconazole (45.2%) and caspofungin (23.7%). All of C. albicans strains were resistant to itraconazole with a MIC value of ≥ 1 μg/ml; in addition, 87.5% of them were resistant to fluconazole. Moreover, 100% and 87.5% of C. glabrata strains were resistant to caspofungin and fluconazole, respectively.
Conclusion: As the findings revealed, the majority of VVC cases were caused by non-albicans Candida species which were often more resistant to antifungal agents. Candida lusitaniae generally had fluconazole MICs above the ECV. Given the propensity of C. lusitaniae to develop resistance under drug pressure, antifungals should be administered with caution. The emergence of these species justify the epidemiological surveillance surveys to watch out the distribution of yeast species.- انتشار مقاله: 24-03-1398
- نویسندگان: Seyedebrahim Hashemi,Tahereh Shokohi,Mahdi Abastabar,Narges Aslani,Mahbobeh Ghadamzadeh,Iman Haghani
- مشاهده
- جایگاه : پژوهشی
- مجله: Categories and General Algebraic Structures with Applications
- نوع مقاله: Journal Article
- کلمات کلیدی: Minimal ideal,Socle,real-valued functions ring,ring with property $(A)$
- چکیده:
- چکیده انگلیسی: For a frame $L$, consider the $f$-ring $ mathcal{F}_{mathcal P}L=Frm(mathcal{P}(mathbb R), L)$. In this paper, first we show that each minimal ideal of $ mathcal{F}_{mathcal P}L$ is a principal ideal generated by $f_a$, where $a$ is an atom of $L$. Then we show that if $L$ is an $mathcal{F}_{mathcal P}$-completely regular frame, then the socle of $ mathcal{F}_{mathcal P}L$ consists of those $f$ for which $coz (f)$ is a join of finitely many atoms. Also it is shown that not only $ mathcal{F}_{mathcal P}L$ has Property (A) but also if $L$ has a finite number of atoms then the residue class ring $ mathcal{F}_{mathcal P}L/mathrm{Soc}( mathcal{F}_{mathcal P}L)$ has Property (A).
- انتشار مقاله: 22-09-1395
- نویسندگان: Ali Asghar Estaji,Ebrahim Hashemi,Ali Akbar Estaji
- مشاهده
- جایگاه : پژوهشی
- مجله: Algebraic Structures and Their Applications
- نوع مقاله: Journal Article
- کلمات کلیدی: zero-divisor graph,quasi-zero-divisor graph,reversible ring,reduced ring,diameter
- چکیده:
- چکیده انگلیسی: Let $R$ be an associative ring with identity. A ring $R$ is called reversible if $ab=0$, then $ba=0$ for $a,bin R$.
The quasi-zero-divisor graph of $R$, denoted by $Gamma^*(R)$ is an undirected graph with all nonzero zero-divisors of $R$ as vertex set and two distinct vertices $x$ and $y$ are adjacent if and only if there exists $0neq rin R setminus (mathrm{ann}(x) cup mathrm{ann}(y))$ such that $xry=0$ or $yrx=0$. In this paper, we determine the diameter and girth of $Gamma^*(R)$. We show that the zero-divisor graph of $R$ denoted by $Gamma(R)$, is an induced subgraph of $Gamma^*(R)$. Also, we investigate when $Gamma^*(R)$ is identical to $Gamma(R)$. Moreover, for a reversible ring $R$, we study the diameter and girth of $Gamma^*(R[x])$ and we investigate when $Gamma^*(R[x])$ is identical to $Gamma(R[x])$.- انتشار مقاله: 23-04-1397
- نویسندگان: Raziyeh Amirjan,Ebrahim Hashemi
- مشاهده