Theory of coupled resonator optical waveguides exhibiting high-order exceptional points of degeneracy

We present an approach and a theoretical framework for generating high-order exceptional points of degeneracy (EPDs) in photonic structures based on periodic coupled resonator optical waveguides (CROWs). Such EPDs involve the coalescence of Floquet-Bloch eigenwaves in CROWs, without the presence of gain and loss, which contrasts with the parity-time symmetry required to develop exceptional points based on gain and loss balance. The EPDs arise here by introducing symmetry breaking in a conventional chain of coupled resonators through periodic coupling to an adjacent uniform optical waveguide, which leads to unique modal characteristics that cannot be realized in conventional CROWs. Such remarkable characteristics include high quality factors (Q factors) and strong field enhancement, even without any mirrors at the two ends of a cavity. We show for the first time the capability of CROWs to exhibit EPDs of various orders, including the degenerate band edge (DBE) and the stationary inflection point. The proposed CROW of finite length shows an enhanced quality factor when operating near the DBE, and the Q factor exhibits an unconventional scaling with the CROW's length. We develop the theory of EPDs in such unconventional CROW using coupled-wave equations, and we derive an analytical expression for the dispersion relation. The proposed unconventional CROW concepts have various potential applications including Q switching, nonlinear devices, lasers, and extremely sensitive sensors

Exceptional points of degeneracy and branch points for coupled transmission lines - Linear-algebra and bifurcation theory perspectives

We provide a new angle to investigate exceptional points of degeneracy (EPD) relating the current linear-algebra point of view to bifurcation theory. We apply these concepts to EPDs related to propagation in waveguides supporting two modes (in each direction), described as a coupled transmission line. We show that EPDs are singular points of the dispersion function associated with the fold bifurcation connecting multiple branches of dispersion spectra. This provides an important connection between various modal interaction phenomena known in guided-wave structures with recent interesting effects observed in quantum mechanics, photonics, and metamaterials systems described in terms of the algebraic EPD formalism. Since bifurcation theory involves only eigenvalues, we also establish the connection to the linear-algebra point of view by casting the system eigenvectors in terms of eigenvalues, analytically showing that the coalescence of two eigenvalues results automatically in the coalescence of the two respective eigenvectors. Therefore, for the studied two-coupled transmission-line problem, the eigenvalue degeneracy explicitly implies an EPD. Furthermore, we discuss in some detail the fact that EPDs define branch points in the complex frequency plane, we provide simple formulas for these points, and we show that parity-time (PT) symmetry leads to real-valued EPDs occurring on the real-frequency axis

PLOJDY ANALYSIS AND DNA CONTENT OF MUTANT BANANA "PISANG BERANGAN" USING FLOW CYTOMETRY

Mutagens cause random changes in the nuclear DNA or cytoplasmic organelles, resulting in gene, chromosomal or genomic mutations and hence, create variability. In this study, flow cytometry (FCM) was used to determine ploidy levels and DNA content in gamma-irradiated variants of mutated Pisang Berangan (cv. Intan, AAA) - a local banana genotype. Induced variants such as short plant stature (stunted growth), late flowering plants (late maturity) and abnormalities in bunch characters were selected to study possible changes at the DNA level. The study showed that DNA content of mutated plants differed from non-irradiated control and that irradiation had the most effect at high doses (40 and 60 Gy). The increase of DNA content in 20 Gy and 30 Gy treated plants was not more than that of the control plants. The values of genomic DNA content of gamma-irradiation variants decreased as the dose of irradiation increased from 20 to 60 Gy, indicating that the high dose of gamma-irradiation had a significant effect on the genome of the plants. The analysis further showed that phenotypic variation due to mutagenesis was reflected in the DNA content of the plants. The results also showed that ploidy levels were not affected by gamma-irradiation even at high doses. Keywords: Musa spp./mutation breeding/ flow cytometry/  ploidy level/ DNA conten

CHARACTERIZATION OF MALAYSIAN WILD BANANAS BASED ON ANTHOCYANINS

The male buds of 16 Musa species (Musaceae) populations were investigated by HPLC for the occurrence of anthocyanins. The investigation was based on the presence of 6 anthocyanins. The 16 Musa samples could be classified into three distinct species i.e. Musa acuminata, Musa violascens and Musa balbisiana. Musa acuminata could be divided into two subspecies : malaccensis (lowland) and tmncata (highland) according to their constituents and content of major anthocyanins. No variation was observed in the composition of the anthocyanins of Kedah type ssp. siamea and Selangor types ssp. malaccensis. The classification of M. acuminata into two subspecies based on anthocyanin data further supported the current taxonomic grouping of the species. Key words: Musa acuminata/Musa violascens/Musa balbisiana/Musaceae /HPLC /chemotaxonom

Plojdy Analysis and Dna Content of Mutant Banana "Pisang Berangan" Using Flow Cytometry

Mutagens cause random changes in the nuclear DNA or cytoplasmic organelles, resulting in gene, chromosomal or genomic mutations and hence, create variability. In this study, flow cytometry (FCM) was used to determine ploidy levels and DNA content in gamma-irradiated variants of mutated Pisang Berangan (cv. Intan, AAA) - a local banana genotype. Induced variants such as short plant stature (stunted growth), late flowering plants (late maturity) and abnormalities in bunch characters were selected to study possible changes at the DNA level. The study showed that DNA content of mutated plants differed from non-irradiated control and that irradiation had the most effect at high doses (40 and 60 Gy). The increase of DNA content in 20 Gy and 30 Gy treated plants was not more than that of the control plants. The values of genomic DNA content of gamma-irradiation variants decreased as the dose of irradiation increased from 20 to 60 Gy, indicating that the high dose of gamma-irradiation had a significant effect on the genome of the plants. The analysis further showed that phenotypic variation due to mutagenesis was reflected in the DNA content of the plants. The results also showed that ploidy levels were not affected by gamma-irradiation even at high doses

Morphological Characterization of Malaysian Wild Banana Musa Acuminata

Fourteen populations of Musa acuminata ranging from populations in the lowlands of northern (ssp. siamea) to central Malaysian region (ssp. malaccensis) and highland banana (ssp. truncata) were characterized based on chromosome number and 46 morphological characters. A large amount of variation was observed within the populations. However, only highland bananas appeared morphologically distinct. Lowland populations both from northern and central Malaysia were found to be overlapping and no distinguishing pattern was observed. The morphological characters found variable within these populations were related to developmental changes and mutations. The results obtained in this study were not revolutionary. However, the survey of a large number of characters treated with multivariate techniques further sharpened the existing groupings of the Musa acuminata subspecies

Characterization of Malaysian Wild Bananas Based on Anthocyanins

The male buds of 16 Musa species (Musaceae) populations were investigated by HPLC for the occurrence of anthocyanins. The investigation was based on the presence of 6 anthocyanins. The 16 Musa samples could be classified into three distinct species i.e. Musa acuminata, Musa violascens and Musa balbisiana. Musa acuminata could be divided into two subspecies : malaccensis (lowland) and tmncata (highland) according to their constituents and content of major anthocyanins. No variation was observed in the composition of the anthocyanins of Kedah type ssp. siamea and Selangor types ssp. malaccensis. The classification of M. acuminata into two subspecies based on anthocyanin data further supported the current taxonomic grouping of the species

Pembentukan etos nasional belia Malaysia: wadah pembinaan negara-bangsa

Persoalan etos nasional sebagai suatu wadah dalam pembinaan negara-bangsa kurang dibahaskan dalam kalangan sarjana. Dari itu, makalah ini akan mengupas perspektif pembinaan negara-bangsa dari sudut etos nasional sebagai suatu dimensi yang perlu diteliti dalam mencorak pembentukan sesebuah bangsa. Etos nasional merujuk kepada watak, karakter, sikap, etika, keperibadian dan keyakinan atas sesuatu perkara yang dapat menggambarkan ciri-ciri semangat yang dikongsi bersama oleh ahli-ahli masyarakat. Dengan wujudnya etos nasional dalam diri individu, maka ia dapat menggambarkan tentang sentimen kenegaraan yang berpaksikan kepada platform nasional. Sehubungan itu, secara spesifiknya makalah ini mengaplikasikan takrif etos nasional sebagai ciri-ciri unik masyarakat setempat yang mengikat seseorang individu dengan individu yang lain, dan yang mengikat individu dengan negara. Ciri-ciri unik tersebut merangkumi empat dimensi utama iaitu nilai, perasaan dan semangat, kepercayaan dan identiti. Ciri-ciri unik etos nasional tersebut menjadi wadah utama dalam proses pembinaan negara-bangsa Malaysia yang terdiri dari pelbagai etnik. Golongan yang seringkali mendapat tumpuan apabila membahaskan tentang proses pembinaan negara-bangsa ialah golongan belia. Ini kerana mereka adalah tulang belakang dan tunjang bangsa pada masa hadapan. Kejayaan membangunkan golongan belia menjadi penanda aras utama kejayaan pembangunan negara-bangsa pada hari muka. Kajian ini mendapati empat dimensi utama iaitu nilai, perasaan dan semangat, kepercayaan serta identiti telah membentuk suatu ikatan yang kuat antara individu dengan individu yang lain, dan di antara individu dengan negara khususnya dalam kalangan belia yang dikaji. Oleh yang demikian, dalam merealisasikan pembinaan negara-bangsa Malaysia, etos nasional menjadi wadah yang perlu dipupuk dalam diri setiap individu khususnya golongan belia yang masih tercari-cari jati diri mereka