Dynamics of Dark-Bright Solitons in Cigar-Shaped Bose-Einstein Condensates

We explore the stability and dynamics of dark-bright solitons in two-component elongated Bose-Einstein condensates by developing effective 1D vector equations as well as solving the corresponding 3D Gross-Pitaevskii equations. A strong dependence of the oscillation frequency and of the stability of the dark-bright (DB) soliton on the atom number of its components is found. Spontaneous symmetry breaking leads to oscillatory dynamics in the transverse degrees of freedom for a large occupation of the component supporting the dark soliton. Moreover, the interactions of two DB solitons are investigated with special emphasis on the importance of their relative phases. Experimental results showcasing dark-bright soliton dynamics and collisions in a BEC consisting of two hyperfine states of $^{87}$Rb confined in an elongated optical dipole trap are presented.Comment: 4 pages, 5 figure

A hybrid organic–inorganic polariton LED

Polaritons are quasi-particles composed of a superposition of excitons and photons that can be created within a strongly coupled optical microcavity. Here, we describe a structure in which a strongly coupled microcavity containing an organic semiconductor is coupled to a second microcavity containing a series of weakly coupled inorganic quantum wells. We show that optical hybridisation occurs between the optical modes of the two cavities, creating a delocalised polaritonic state. By electrically injecting electron–hole pairs into the inorganic quantum-well system, we are able to transfer energy between the cavities and populate organic-exciton polaritons. Our approach represents a new strategy to create highly efficient devices for emerging ‘polaritonic’ technologies

Recent progress in cassava varietal improvement in India

In India cassava breeding is done mainly at the Central Tuber Crops Research Institute (CTCRI) in Trivandrum, as well as in the State Agricultural Universities through the All India Co-ordinating Centres. CTCRI maintains 786 exotic and 848 indigenous accessions of cassava and 8 wild species in its germplasm bank. Coordinating Centres maintain about 280 indigenous accessions. Seedling progenies of 158 and 19 CIAT cassava accessions were screened at the Regional Centre of CTCRI in Bhubaneswar during 1985 and 1990, respectively. High root yields of more than 4 kg/plant were recorded in seedling progenies of CM3426, CM4046 and CM4229. Selection of promising germplasm and hybridization among selected accessions have been the principal strategies in cassava breeding. The most popular eating variety in Kerala, M-4, was introduced from Malaysia in the 1950s. Three high yielding hybrids, H-165, H-226 and H-97 were released in 1971 by CTCRI, of which H-165 and H-226 have become popular in Tamil Nadu for starch production. In 1983, 'Sree Sahya' and 'Sree Vishakam' were released at the national level. 'Sree Prakash' is a short duration cultivar released by CTCRI in 1987. In 1993 the Tamil Nadu Agricultural University released a high yielding, short-duration cultivar, called 'Co-3', which is reported to be tolerant to CMD. Recently, the Kerala Agricultural University also released a short-duration cultivar, called 'Nidhi', which can be harvested in 5 1 /2 - 6 months and has been recommended for paddy fallows of central Kerala. Two high yielding high quality short-duration cultivars, which can be harvested at six months, have been identified from the germplasm of CTCRI and are now being evaluated in advanced yield trials. A study on hybrid vigor in cassava indicated the predominance of non-additive gene action for root yield and yield components, indicating the possibility of exploiting hybrid vigor. Seven elite top-cross selections have been identified with high root yield, starch and dry matter contents and with low HCN content. By successive cycles of recurrent selection among germplasm accessions, the carotene content of roots could be raised significantly. Induction of triploidy has been found to be very effective for the development of high yielding, high starch and high dry matter cassava cultivars. A promising triploid, 2/14, is being considered for release for starch processing. Recently, successful induction of mutation has been reported in M-4. A few useful mutants, having higher root yields (20-25%) and high dry matter and starch contents, have been selected from single node cuttings of gamma-irradiated stakes. Studies on the use of true seed revealed the possibility of enhancing the multiplication rate more than 15 fold compared to the traditional method of vegetative propagation. A few promising seedling families have been identified, which give seedling yields comparable to clonal yields. Cassava mosaic disease is considerably reduced in seedling families

Breeding and varietal improvement of cassava in India

An analysis of the recent trend in cassava area, production and yield during 1993-96 revealed an impressive increase in Tamil Nadu, which is the predominant state where cassava is grown as an industrial crop. Its present yield of 29 t/ha is the highest in the world. Even though the overall national trend in cassava area and production is declining, India's current average yield of 21 t/ha is also the world's highest. In India, cassava breeding is mainly carried out at CTCRI in Thiruvananthapuram and at its regional centre at Bhubaneswar. The All India Co-ordinated Research Project on Tuber Crops, with eleven centres in the country, is also engaged in cassava improvement in a limited way. The Tamil Nadu centre has recently identified a high yielding short duration variety, H-1 19, while the Assam centre has identified two varieties, i.e. H-165 and Sree Prakash, suitable for the region. The co-ordinating centres in Madhya Pradesh and Andhra Pradesh, along with the CTCRI regional centre at Bhubaneswar, have been evaluating the promising exotic germplasm received from the Thai-CIAT program. High root yields of more than 35 t/ha were recorded for some of the CIAT selections, i.e. CMR33-67, CMR36-32, SM2077 and SM2090. Attention is currently being given to the development of early maturing, good cooking quality varieties, which can be harvested at sixth months, so that they can effectively be utilized in cassava-rice double cropping systems as practised in Kerala. Three short-duration indigenous clones, i.e. CI-649, CI-731 and CI-732, were identified, which are now in the pre-release stage. These varieties are also included in the initial evaluation trial of the All India Co-ordinated Research Project on Tuber Crops. Breeding efforts are also focused on developing high yielding, high starch varieties for areas like Tamil Nadu, Andhra Pradesh and Madhya Pradesh. A unique approach in this direction is the production of "triploids". The triploids, possessing high yield combined with high starch recovery, hold much promise to become popular in regions like Salem district of Tamil Nadu, where the crop is grown for the starch industry. A triploid, 2/14, has already been proposed for release under the name 'Sree Harsha' by the State Varietal Release Committee. Studies are also in progress on the possibility of using sexual seed for the rapid propagation and spread of cassava. Results indicate that even unselected first clonal progenies of promising parents have a comparable root yield and dry matter production capacity as those of the high yielding released varieties of cassava. Cassava mosaic disease is still posing great problems in germplasm conservation. Use of a nursery technique with three noded cuttings coupled with thorough screening and roguing of CMD affected plants in the nursery and field was effective in the recovery and quicker multiplication of symptom-free plants

Seasonal influence on phenolic-mediated antihyperglycemic properties of Canadian sugar and red maple leaves using in vitro assay models

Red and sugar maple leaves collected in the summer and fall from Canada, were evaluated for phenolic content, antioxidant, α-glucosidase, and α-amylase inhibitory activities variation. The phenolic contents of summer red maple leaves (RML-S) and summer sugar maple leaves (SML-S) were higher than red and sugar maple leaves collected in fall (RML-F and SML-F, respectively). HPLC analyses showed differences in phenolic compounds present in the SML samples compared to the RML samples. The extracts were assayed for yeast and rat α-glucosidase inhibitory activities. Both results showed that SML-S extracts had the highest inhibitory activity which could possibly be attributed to the unique phenolics present therein. Milder effects were observed in terms of α-amylase inhibitory activity, with RML-F having the highest inhibitory activity. These results suggest that maple tree leaf extracts may have potential for phenolic-mediated α-glucosidase inhibition, relevant to type 2 diabetes management, with SML-S extract having the highest bioactivity