Motion and Teleportation of Polar Bubbles in Low-dimensional Ferroelectrics

Electric bubbles are sub-10nm spherical vortices of electric dipoles that can spontaneously form in ultra-thin ferroelectrics. While the static properties of electric bubbles are well established, little to nothing is known about the dynamics of these particle-like structures. Here, we reveal pathways to realizing both the spontaneous and controlled dynamics of electric bubbles in ultra-thin Pb(Zr0.4Ti0.6)O3 films. In low screening conditions, we find that electric bubbles exhibit thermally-driven chaotic motion giving rise to a liquid-like state. In the high screening regime, we show that bubbles remain static but can be continuously displaced by a local electric field. Additionally, we predict and experimentally demonstrate the possibility of bubble teleportation - a process wherein a bubble is transferred to a new location via a single electric field pulse of a PFM tip. Finally, we attribute the discovered phenomena to the hierarchical structure of the energy landscape

Detection of somaclonal variation in micropropagated Hibiscus sabdariffa L. using RAPD markers

The main objective of micropropagation is to produce clones i.e. plants which arephenotypically and genetically identical to the mother plants. The culture of organized meristems usually guarantees the production of true-to-type plants but variations in the progenies have been widely reported. Hibiscus sabdariffa L. plants were regenerated on MS (Murashige and Skoog) medium containing BAP (Benzyl amino purine) and IBA (Indole 3 butyric acid) and were propagated in vitro on hormone-free MS medium. The aim of this study was to detect variation in micropropagated plantlets of Hibiscus sabdariffa using RAPD amplification. DNA extraction from Hibiscus sabdariffa L. plants was optimized using CTAB buffer supplemented with 5M NaCl to eliminate polysaccharides and the isolated DNA proved amenable to PCR amplification. RAPD analysis was carried out on DNA samples to compare the mother plant with 10 randomly selected regenerated plants. Out of 30 primers screened, primers OPB-01, OPX-06 and DK-02 produced polymorphic bands. These results show that RAPD is a suitable technique which can be used to detect genetic change caused by somaclonal variation and could be promising for the selection of desirable traits or transformation systems.Keywords: Hibiscus sabdariffa L. In vitro culture. RAPD, SomaclonalVariatio

Topology and Control of Self-assembled Domain Patterns in Low-dimensional Ferroelectrics

Whilst often discussed as non-trivial phases of low-dimensional ferroelectrics, modulated polar phases such as the dipolar maze and the nano-bubble state have been appraised as essentially distinct. Here we emphasize their topological nature and show that these self-patterned polar states, but also additional mesophases such as the disconnected labyrinthine phase and the mixed bimeron-skyrmion phase, can be fathomed in their plurality through the unifying canvas of phase separation kinetics. Under compressive strain, varying the control parameter, i.e., the external electric field, conditions the nonequilibrium self-assembly of domains, and bridges nucleation and spinodal decomposition via the sequential onset of topological transitions. The evolutive topology of these polar textures is driven by the (re)combination of the elementary topological defects, merons and antimerons, into a plethora of composite topological defects such as the fourfold junctions, the bimeron and the target skyrmion. Moreover, we demonstrate that these manipulable defects are stable at room temperature and feature enhanced functionalities, appealing for devising future topological-based nanoelectronics

Controlling topological defect transitions in nanoscale lead zirconate titanate heterostructures

Varying thickness in ferroelectric heterostructures systematically changes both the strain and the electrical boundary conditions and thus the polarization screening. This has a direct result on the observed ferroelectric nanotopologies, from polar vortices, skyrmions, and bubbles to Kittel type stripe/labyrinthine domains. Here, a control of the topological defect transitions is reported in epitaxial (001)-oriented PbZr0.4Ti0.6O3/SrTiO3/PbZr0.4Ti0.6O3 (PZT/STO/PZT) heterostructures. Piezoresponse force microscopy is exploited to capture various topological defect states, such as merons, skyrmions, dislocations, bimerons, and three- or fourfold junctions and hence to understand their transition pathways. The thickness of the dielectric spacer and/or ferroelectric layer is tuned during growth to manipulate the strength of the residual depolarization field; this consequently leads to a range of the abovementioned topological defect structures. This is further corroborated by effective Hamiltonian-based Monte Carlo simulations that provide insight into why and how altering the thickness of ferroelectric or dielectric layers triggers topological phase transitions. This controlled design of nanoscale ferroic topologies opens possibilities of engineering emergent transitions

Registration of Groundnut Cultivar Venus (ICGV 87853)

Released in 1998, the virginia bunch new variety Venus was developed by bulk selection from the cross of Kadiri 3 (ICG 799) with a stable, interspecific derivative CS-9. Venus has a decumbent habit, and matures in 120-125 days during the rainy season and in 135-140 days during the post-rainy season. It has two-seeded pods which have a small beak, a slight constriction and moderate reticulation. Mean pod size is 34 mm × 10 mm. Shelling percentage averages 68% while 100-seed weight ranges from 32 to 52 g depending on season and location. Seeds are tan coloured. Pod yield in trials conducted at Patancheru during kharif 1990 and 1991 gave mean yields of 1.58 t/ha outyielding ICGS 76 by 43.7% and Kadiri 3 by 64.6%. Venus is resistant to rust (Puccinia arachidis) and is moderately tolerant of late leaf spot (Mycosphaerella berkeleyi)

Registration of groundnut cultivar Sylvia (ICGV 93207)

ICGV 93207 as Sylvia is a high-yielding improved spanish groundnut genotype developed at ICRISAT, Patancheru, India, and released by the Mauritius Sugar Industry Research Institute, in 1998 for commercial plantation in pure stand and in sugarcane interrows in Mauritius. It was derived from a cross between 2 advanced breeding lines, ICGV 86594 and ICGV 86672. Sylvia significantly outyielded the popular control cultivar Cabri by 38.8% with more stable yields than the control. It is adapted to all soils and regions in Mauritius where groundnut is grown. It is resistant to rust (caused by Puccinia arachidis). The yield performance and other characteristics of ICGV 93207 are given

Registration of ICGV-SM 85048 Peanut Germplasm

ICGV-SM 85048 (Reg. no. GP-90, PI 598134), an improved Spanish peanut (Arachis hypogaea L. subsp.fastigiata var. vitlgaris) germplasm, was developed at the SADC/ICRISAT (Southern African Development Community/International Crops Research Institute for the Semi-Arid Tropics) Groundnut Project in Malawi. It was first tested at the Mauritius Sugar Industry Research Institute (MSIRI), Mauritius, in 1988. After evaluations in on-station and on-farm trials, it was released in 1992 as 'Stella' in Mauritius (8). It is suitable for cultivation both in sugarcane (Sacchanim officinarum L.) interrows and in pure stand

Registration of ICGV-SM 86715 Peanut Germplasm

ICGV-SM 86715 (Reg. no. GP-89, PI 598133), an improved Virginia peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) germplasm line, was developed by the SADC/ICRISAT (Southern African Development Community/International Crops Research Institute for the Semi-Arid Tropics) Groundnut Project in Malawi. It was released in 1992 as 'Veronica' for pure stand cultivation in Mauritius by the Mauritius Sugar Industry Research Institute (MSIRI), Reduit, Mauritius (5). It has resistance to rust (caused by Puccinia arachidis Speg.), late leafspot [caused by Phaeoisariopsis personata (Berk. & M.A. Curtis) Arx; syn. Cercosporidium personatum (Berk. & M.A. Curtis) Deighton], and pepper spot [caused by Leptosphaerulina crassiasca (Sechet) C.R. Jackson & D.K. Bell]. It was also found free from early leafspot (caused by Cercospora arachidicola S. Hori) in Mauritiu

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency–Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe