1,846 research outputs found
FIGURE 2. Aristolochia gurinderii K in Aristolochia gurinderii (Aristolochiaceae): a new species from Great Nicobar Island, India
No full textFIGURE 2. Aristolochia gurinderii K. Ravikumar, Umeshkumar Tiwari and N. Balachandran, sp. nov.: A. Leaf with fruit; B. Inflorescence; C. Flower patterns; D. Close up of Flower; E. Dry Fruits and F. Green Fruit (Type: FRLH).Published as part of Ravikumar, K., Tiwari, Umeshkumar & Balachandran, N., 2014, Aristolochia gurinderii (Aristolochiaceae): a new species from Great Nicobar Island, India, pp. 117-122 in Phytotaxa 172 (2) on page 120, DOI: 10.11646/phytotaxa.172.2.7, http://zenodo.org/record/514244
Bauhinia bassacensis var. nicobarica Tiwari U. L., K. Ravikumar & N. Balachandran 2013, var. nov.
No full textBauhinia bassacensis var. nicobarica Tiwari U.L., K. Ravikumar & N. Balachandran, var. nov. (Figs. 1 & 2) Differs from the typical variety in having exstipulate leaves, lobes of leaves obtuse at apex, bract rusty tomentose and ovate, bracteoles 2, lanceolate, rusty tomentose; fertile stamens always 2; filaments hairy, anther lobes brown. Type:— INDIA. Great Nicobar Island: Near Army land, Campbell Bay, 20 February 2013, N- 71 o 2’ 2.9’’, E 93 o 55’ 2.9’’, 16 m ASL, K . Ravikumar, N. Balachandran and Umeshkumar Tiwari 115533 (holotype FRLH!; isotypes FRLH!, PBL!). Large, woody, climbers; tendrils coiled stout, glabrous; young branches rusty tomentose, mature grooved and lenticellate. Leaves exstipulate; petioles glabrescent, 2 7 cm long; lamina ovate-cordate, ca. 19 × 13 cm, 9 13-nerved, bifid, down to 3.5 4.8 cm length with narrow sinus, apex of lobes obtuse, base cordate, upper surface glabrous, lower brownish tomentose to glabrescent, base of the lamina with two distinct glands expanding up to pulvinous base. Inflorescences lateral or terminal, many-flowered, racemes or panicles; peduncles rusty tomentose; pedicels ca. 3.5 cm long in flower and ca. 7 cm long in fruit; bracts ovate, rusty tomentose, ca. 0.5 mm long; bracteoles 2, lanceolate, inserted near the middle of the pedicels, rusty tomentose, 1–1.5 mm long. Buds ovoid, rusty tomentose, 4–6 mm long. Hypanthium c. 1 mm long. Calyx during anthesis splitting into 2 segments forming right angles with the pedicels, 5–7 mm long, sometime persistent with fruit. Petals 2 above and three below, pubescent, creamish with purplish-red veins prominent on both sides, blade deltoid, crumpled, subequal, narrowly ovate to suborbicular with undulate margin, ca. 6 × 5 mm; claw 1.5–2 cm long, soft hairy. Stamens 9 (2 + 7); fertile stamens 2, staminodes absent sometime 1; filaments 1.2–1.6cm long, hairy; anthers 1–2 mm long, lobes brown; reduced stamens 7 in number, unequal, 3–9 mm long, filiform, white. Carpels densely brownish pilose, distinctly stalked, styles 6-8 mm, hairy with a small capitate stigma. Pods rusty tomentose, 8–13 × 3–4 cm with persistent style, stalks c. 3 mm long; styles persistent in fruit. Seeds, 2–5, dark brown, flattened, oblong-orbicular, c. 1.5 × 2 cm, smooth, glabrous. Flowering & Fruiting:— From February to March. Distribution:— India: Campbell Bay, Great Nicobar Island, Andaman and Nicobar Islands. Habitat:— Liana in mixed semi-evergreen forests. Ecological status:— About three individuals confined to an area of 1 km 2 were observed during field survey. Though it qualifies to be kept under Critically Endangered (CR) category, further studies and explorations in adjacent areas are required to ascertain its actual status. Etymology:— The varietal epithet refers to the place of its collection. This new variety is allied to typical var. bassacensis and var. backeri, but differs from both markedly in having exstipulate leaves, lobes of leaves obtuse at apex, bract rusty tomentose and ovate, bracteoles 2, lanceolate, rusty tomentose; fertile stamens always 2; filaments hairy, anther lobes brown (see table 1).Published as part of Tiwari, Umeshkumar, Ravikumar, Kaliamoorthy & Balachandran, Natesan, 2013, A new variety of Bauhinia bassacensis (Leguminosae: Caesalpinioideae) from Great Nicobar Island, India, pp. 12-18 in Phytotaxa 149 (1) on pages 13-16, DOI: 10.11646/phytotaxa.149.1.2, http://zenodo.org/record/510042
Aristolochia gurinderii (Aristolochiaceae): a new species from Great Nicobar Island, India
No full textRavikumar, K., Tiwari, Umeshkumar, Balachandran, N. (2014): Aristolochia gurinderii (Aristolochiaceae): a new species from Great Nicobar Island, India. Phytotaxa 172 (2): 117-122, DOI: 10.11646/phytotaxa.172.2.7, URL: http://dx.doi.org/10.11646/phytotaxa.172.2.
sj-docx-1-pie-10.1177_09544089221112162 - Supplemental material for Study on tribological behaviour of aluminium hybrid composites strengthened with novel groundnut shell ash and boron carbide
No full textSupplemental material, sj-docx-1-pie-10.1177_09544089221112162 for Study on tribological behaviour of aluminium hybrid composites strengthened with novel groundnut shell ash and boron carbide by L. Venkatesh, T.V. Arjunan, M. Arulraj and K. Ravikumar in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
In situ Ru K-edge EXAFS of CO adsorption on a Ru modified Pt/C fuel cell catalyst
No full textThe Ru–CO bond of CO adsorbed on a Ru modified Pt/C fuel cell catalyst has been directly probed by in situ EXAFS at the Ru K-edge, providing evidence of a CO:metal surface atom ratio greater than 1:1 and that CO is adsorbed at bridging sites associated with Ru atoms at the surface of the catalyst nanoparticles. This result illustrates the limitations of single crystal models as representations of the bonding of adsorbed species at nanoparticle surfaces.<br/
Synthesis of meso-substituted core modified expanded porphyrins; Effect of acid catalysts on the cyclization
No full text[3+2] condensation between modified tripyrromethane and bithiophene or bifurandiol leads to the formation of 18π, 22π, 26π macrocycles under Lewis acid conditions while only 22π macrocycle is formed under protic acid conditions
Ambiguity and communication
No full textThe ambiguity of a nondeterministic finite automaton (NFA) N for input size n is the maximal number of accepting computations of N for an input of size n. For all k, r 2 N we construct languages Lr,k which can be recognized by NFA's with size k poly(r) and ambiguity O(nk), but Lr,k has only NFA's with exponential size, if ambiguity o(nk) is required. In particular, a hierarchy for polynomial ambiguity is obtained, solving a long standing open problem (Ravikumar and Ibarra, 1989, Leung, 1998)
A neo-clerodane diterpene from Teucrium tomentosum. Corrigendum
No full textThe chemical name of the title compound in the paper by Devi, Malathi, Rajan, Aravind, Krishnakumari &amp; Ravikumar [Acta Cryst. (2004), E60, o117&#8211;o119] is corrected and the structural diagram is updated
Combinatorics of K-Theoretic Jeu de Taquin
No full textThomas and Yong [5] introduced a theory of jeu de taquin which extended Schutzenberger's [4] for Young tableaux. The extended theory computes structure constants for the K-theory of (type A) Grassmannians using combinatorial machinery similar to that for cohomology. This rule naturally generalizes to give a conjectural root-system uniform rule for any minuscule flag variety G/P.
In this dissertation, we see that the root-system uniform rule is well-defined for certain G/P other than the Grassmannian. This gives rise to combinatorially defined rings which are conjecturally isomorphic to K(G/P). Although we do not prove that these rings are isomorphic to K(G/P), we do produce a ``Pieri rule" for computing the product of a general class with a generating class in the type B combinatorial case. We also investigate some symmetries which support the conjectural isomorphism. Moreover, our results combined with recent work of Buch and Ravikumar [1] imply that this conjecture is in fact true.
Lenart [2] gave a Pieri rule for the type A K-theory, demonstrating that the Pieri structure constants are binomial coefficients. In contrast, using techniques of [3], we show that type B Pieri structure constants have no such simple closed forms.
References:
[1] A. Buch and V. Ravikumar: Pieri rules for the K-theory of cominuscule Grassmannians, arXiv:1005.2605, 2010.
[2] C. Lenart: Combinatorial aspects of K-theory of Grassmannians. Ann. Combin. 4 (2000), 67--82.
[3] M. Petkovsek and H. Wilf and D. Zeilberger: A=B. A K Peters, Ltd. (1996).
[4] M.-P. Schutzenberger: Combinatoire et representation du groupe symetrique. Springer-Verlag Berlin, Lec. Notes in Math. 579 (1977), 59--113.
[5] H. Thomas and A. Yong: A jeu de taquin theory for increasing tableaux, with applications to K-theoretic Schubert calculus. Algebra Number Theory 3 (2009), no. 2, 121--148
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