Browsing by Author "Chen, H."
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Item Open Access Almost unit-clean rings(Editura Academiei Romane, 2019) Chen, H.; Köse, H.; Kurtulmaz, YosumA ring R is almost unit-clean provided that every element in R is equivalent to the sum of an idempotent and a regular element. We investigate conditions under which a ring is almost unit-clean. We prove that every ring in which every zero-divisor is strongly _-regular is almost unit-clean and every matrix ring of elementary divisor domains is almost unit-clean. Furthermore, it is shown that the trivial extension R(M) of a commutative ring R and an R-module M is almost unit-clean if and only if each x 2 R can be written in the form ux = r+e where u 2 U(R); r 2 R (Z(R) [ Z(M)) and e 2 Id(R). We thereby construct many examples of such rings.Item Open Access The cBioPortal for cancer genomics and its application in precision oncology(American Association for Cancer Research, 2016) Gao, J.; Lindsay, J.; Watt, S.; Doğrusöz, Uğur; Lukasse, P.; Abeshouse, A.; Chen, H.; Bruijn, I.; Gross, B.; Li, D.; Kundra, R.; Heins, Z.; Reis-Filho, J.; Sumer, O.; Sun, Y.; Wang, J.; Wang, Q.; Zhang, H.; Kumari, P.; Şahin, Mehmet Furkan; Ridder, S.; Schaeffer, F.; Bochove, K.; Pugh, T.; Sander, C.; Cerami, E.; Schultz, N.; Bahçeci, İstemiAbstract The cBioPortal for Cancer Genomics provides intuitive visualization and analysis of complex cancer genomics data. The public site (http://cbioportal.org/) is accessed by more than 1,500 researchers per day, and there are now dozens of local instances of the software that host private data sets at cancer centers around the globe. We have recently released the software under an open source license, making it free to use and modify by anybody. The software and detailed documentation are available at https://github.com/cBioPortal/cbioportal. We are now establishing a multi-institutional software development network, which will coordinate and drive the future development of the software and associated data pipelines. This group will focus on four main areas: 1. New analysis and visualization features, including: a. Improved support for cross-cancer queries and cohort comparisons. b. Enhanced clinical decision support for precision oncology, including an improved patient view with knowledge base integration, patient timelines and improved tools for visualizing tumor evolution. 2. New data pipelines, including support for new genomic data types and streamlined pipelines for TCGA and the International Cancer Genome Consortium (ICGC). 3. Software architecture and performance improvements. 4. Community engagement: Documentation, user support, and training. This coordinated effort will help to further establish the cBioPortal as the software of choice in cancer genomics research, both in academia and the pharmaceutical industry. Furthermore, as the sequencing of tumor samples has entered clinical practice, we are expanding the features of the software so that it can be used for precision medicine at cancer centers. In particular, clean, web-accessible, interactive clinical reports integrating multiple sources of genome variation and clinical annotation over time has potential to improve clinical action beyond current text-based molecular reports. By making complex genomic data easily interpretable and linking it to information about drugs and clinical trials, the cBioPortal software has the potential to facilitate the use of genomic data in clinical decision making. Citation Format: Jianjiong Gao, James Lindsay, Stuart Watt, Istemi Bahceci, Pieter Lukasse, Adam Abeshouse, Hsiao-Wei Chen, Ino de Bruijn, Benjamin Gross, Dong Li, Ritika Kundra, Zachary Heins, Jorge Reis-Filho, Onur Sumer, Yichao Sun, Jiaojiao Wang, Qingguo Wang, Hongxin Zhang, Priti Kumari, M. Furkan Sahin, Sander de Ridder, Fedde Schaeffer, Kees van Bochove, Ugur Dogrusoz, Trevor Pugh, Chris Sander, Ethan Cerami, Nikolaus Schultz. The cBioPortal for cancer genomics and its application in precision oncology. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5277.Item Open Access Daylight Saving Time policy and energy consumption(Elsevier BV, 2021-11) Küfeoğlu, S.; Üçler, Ş.; Eskicioğlu, F.; Öztürk, E. Büşra; Chen, H.Daylight Saving Time is argued to be effective in saving energy. Turkey is one of the few countries that annulled the clock changes and remained in the summertime zone in 2016. Therefore, the country provides a unique natural experiment to test and confirm this policy change. This paper studies the impact of clock changes on electric energy consumption and load shift. We use historical electrical energy consumption, electricity prices, and relevant atmospheric essential climate variables data in Turkey between 2012–2020. We adopt Multiple Linear Regression, Difference in Differences and Interrupted Time Series methodologies to analyse the historical data. This paper shows that the Daylight Saving Time policy does not lead to a measurable amount of electrical energy savings. Furthermore, it does not cause a noticeable continuous daily load shift throughout the year. We also claim that our findings should apply to countries such as the United States, India, Japan, Australia or China, and continents of Africa and South America, whose latitudes are between 42.0° north and south of the equator.Item Open Access Extensions of strongly π-regular rings(Korean Mathematical Society, 2014) Chen, H.; Kose, H.; Kurtulmaz, Y.An ideal I of a ring R is strongly π -regular if for any x ∈ I there exist n ∈ ℕ and y ∈ I such that xn = xn+1y. We prove that every strongly π -regular ideal of a ring is a B-ideal. An ideal I is periodic provided that for any x ∈ I there exist two distinct m, n ∈ N such that xm = xn. Furthermore, we prove that an ideal I of a ring R is periodic if and only if I is strongly π -regular and for any u ∈ U(I), u-1 ∈ ℤ[u]. © 2014 Korean Mathematical Society.Item Open Access Factorizations of matrices over projective-free Rings(World Scientific Publishing Co. Pte Ltd, 2016) Chen, H.; Kose, H.; Kurtulmaz, Y.An element of a ring R is called strongly J#-clean provided that it can be written as the sum of an idempotent and an element in J#(R) that commute. In this paper, we characterize the strong J#-cleanness of matrices over projective-free rings. This extends many known results on strongly clean matrices over commutative local rings. © 2016 Academy of Mathematics and Systems Science, Chinese Academy of Sciences, and Suzhou University.Item Open Access Local comparability of exchange ideals(Hacettepe University, 2019) Köse, H.; Kurtulmaz, Yosum; Chen, H.An exchange ideal I of a ring R is locally comparable if for every regular x ∈ I there exists a right or left invertible u ∈ 1+I such that x = xux. We prove that every matrix extension of an exchange locally comparable ideal is locally comparable. We thereby prove that every square regular matrix over such ideal admits a diagonal reduction.Item Open Access On feckly clean rings(World Scientific Publishing, 2015) Chen, H.; Kose, H.; Kurtulmaz, Y.A ring R is feckly clean provided that for any a R there exists an element e R and a full element u R such that a = e + u, eR(1 - e) J(R). We prove that a ring R is feckly clean if and only if for any a R, there exists an element e R such that V(a) V(e), V(1 - a) V(1 - e) and eR(1 - e) J(R), if and only if for any distinct maximal ideals M and N, there exists an element e R such that e M, 1 - e N and eR(1 - e) J(R), if and only if J-spec(R) is strongly zero-dimensional, if and only if Max(R) is strongly zero-dimensional and every prime ideal containing J(R) is contained in a unique maximal ideal. More explicit characterizations are also discussed for commutative feckly clean rings. © 2015 World Scientific Publishing Company.Item Open Access Resonant cavity based compact efficient antireflection structures for photonic crystals(Institute of Physics Publishing Ltd., 2007) Li, Z.; Özbay, Ekmel; Chen, H.; Chen, J.; Yang, F.; Zheng, H.We propose an effective admittance (EA) method to design antireflection structures for two-dimensional photonic crystals (PCs). We demonstrate that a compact and efficient antireflection structure, which is difficult to obtain by the conventional admittance matching method, can be readily designed by the EA method. The antireflection structure consists of an air slot resonant cavity that is constructed only with the materials that constitute the PC. Compared with a bare PC, the reflection from a PC with an antireflection structure is reduced by two orders of magnitude over a wide bandwidth. To confirm the presented EA method, finite-difference time-domain (FDTD) simulations are performed, and the results from the FDTD and the EA method are in good agreement.Item Open Access Rings in which elements are a sum of a central and a unit element(The Belgian Mathematical Society, 2019) Kurtulmaz, Yosum; Halıcıoğlu, S.; Harmancı, A.; Chen, H.In this paper we introduce a new class of rings whose elements are a sum of a central and a unit element, namely a ring RR is called CUCU if each element a∈Ra∈R has a decomposition a=c+ua=c+u where cc is central and uu is unit. One of the main results in this paper is that if FF is a field which is not isomorphic to Z2Z2, then M2(F)M2(F) is a CUCU ring. This implies, in particular, that any square matrix over a field which is not isomorphic to Z2Z2 is the sum of a central matrix and a unit matrix.Item Open Access Strongly clean matrices over power series(Kyungpook National University, 2016) Chen, H.; Kose, H.; Kurtulmaz, Y.An n × n matrix A over a commutative ring is strongly clean provided that it can be written as the sum of an idempotent matrix and an invertible matrix that commute. Let R be an arbitrary commutative ring, and let A(x) ∈ Mn ( R[[x]]) . We prove, in this note, that A(x) ∈ Mn ( R[[x]]) is strongly clean if and only if A(0) ∈ Mn(R) is strongly clean. Strongly clean matrices over quotient rings of power series are also determined.Item Open Access Strongly clean triangular matrix rings with endomorphisms(Springer, 2015) Chen, H.; Kose, H.; Kurtulmaz, Y.A ring R is strongly clean provided that every element in R is the sum of an idempotent and a unit that commutate. Let Tn(R; σ) be the skew triangular matrix ring over a local ring R where σ is an endomorphism of R. We show that T2(R; σ) is strongly clean if and only if for any aϵ 1+J(R); b ϵ J(R), la -rσ (b): R→ R is surjective. Further, T3(R; σ) is strongly clean if la-rσ (b); la-rσ2 (b) and lb-rσ (a)are surjective for any a ϵ U(R); b ϵ J(R). The necessary condition for T3(R; σ) to be strongly clean is also obtained. © 2015 Iranian Mathematical Society.Item Open Access Sytongly P-clean Rings and Matrices(Elsevier, 2014) Chen, H.; Kose, H.; Kurtulmaz, Y.Abstract. An element of a ring R is strongly P-clean provided that it can be written as the sum of an idempotent and a strongly nilpotent element that commute. A ring R is strongly P-clean in case each of its elements is strongly P-clean. We investigate, in this article, the necessary and sufficient conditions under which a ring R is strongly P-clean. Many characterizations of such rings are obtained. The criteria on strong P-cleanness of 2 × 2 matrices over commutative projective-free rings are also determined.