213,236 research outputs found
Cascade representations for the Navier-Stokes equations
No full textWe review some “cascade representation” formulae for solutions to the Navier-Stokes equations, which are based on the interaction between modes. Rabi Bhattacharya contributed to develop this interesting approach
When No Law is Better than a Good Law
No full textThis paper argues, both theoretically and empirically, that sometimes no security law may be better than a good security law that is not enforced. The first part of the paper formalizes the sufficient conditions under which this happens for any law. The second part of the paper shows that a specific security law - the law prohibiting insider trading - may satisfy these conditions, which implies that our theory predicts that it is sometimes better not to have an insider trading law than to have an insider trading law but not enforce it. The third part of the paper takes this prediction to the data. We revisit the panel data set assembled by Bhattacharya and Daouk (2002), who showed that enforcement, not the mere existence, of insider trading laws reduced the cost of equity in a country. We find that the cost of equity actually rises when a country introduces an insider trading law, but does not enforce it.
A halide free route to the manufacture of microstructurally improved M ferrite (BaFe12O19 and SrFe12O19) fibres
No full textIn hexagonal ferrite precursor fibres halide was found to be retained up to high temperatures, delaying the formation of the BaM (BaFe12O19) and SrM (SrFe12O19) phases, and resulting in a product with a grain size of 0.5-1 μm. This paper reports a halide free route for these fibres, using a nitrate stabilised sol precursor, from which the M phases formed at lower temperatures with smaller grain sizes. This sol was characterised and compared to the halide based sol, the evolution of the crystalline phases was studied and the hysteresis loops of the M ferrite fibres assessed by VSM. It was shown that retained halide inhibited the formation of the ferrite phase, as both SrM and BaM formed at a temperature 200 °C lower than in the halide containing precursor fibres. The grain sizes were accordingly lower, the SrM grains being below 100 nm, although the crystallite sizes were only slightly smaller than those reported for the halide containing fibres fired to 1000 °C, and the magnetic properties were also similar. The BaM fibres had Ms = 58.4 kA m2 g-1 and Hc = 401 kA m-1, while the SrM fibres had Ms = 65.0 kA m2 g-1 and Hc = 440 kA m-1, comparable to small grained polycrystalline powdered samples. The M ferrite phase was formed directly from haematite, with no BaFe2O4 observed as an intermediate, and the pure ferrites were made from stoichiometric precursors. © 2002 Elsevier Science Ltd. All rights reserved
Novel aqueous sol-gel preparation and characterization of barium M ferrite, BaFe12O19 fibres
No full textGel fibres of barium M ferrite, BaFe12O19, were blow spun from an aqueous inorganic sol and calcined at temperatures up to 1200°C. The ceramic fibres were shown by X-ray diffraction to be single phase crystalline M ferrite at 1000°C, and surface area and porosity measurements indicated an unusually high degree of sintering at this temperature. The fibres also demonstrated a favourable grain structure of less than 0.1 μm at this temperature and maintained a small grain size of less than 4 μm even up to 1200°C, an im portant factor in the magnetic properties of this material
Dynamic algorithms via the primal-dual method
No full textWe develop a dynamic version of the primal-dual method for optimization problems, and apply it to obtain the following results. (1) For the dynamic set-cover problem, we maintain an O(f2)-approximately optimal solution in O(f⋅log(m+n)) amortized update time, where f is the maximum “frequency” of an element, n is the number of sets, and m is the maximum number of elements in the universe at any point in time. (2) For the dynamic b-matching problem, we maintain an O(1)-approximately optimal solution in O(log3n) amortized update time, where n is the number of nodes in the graph
The magnetic properties of aligned M hexa-ferrite fibres
No full textAligned and random fibres of strontium hexaferrite (SrM, Si-Fe12O19) and barium hexaferrite (BaM, BaFe12O19) were manufactured by blow spinning from an aqueous inorganic sol-gel precursor, which was then fired to give the hexagonal ferrite fibre. Their magnetic properties were studied by VSM, investigating the evolution of these properties with firing and measurement temperature, and in particular the effects of fibre alignment. It has been predicted that aligned ferrite fibres will demonstrate an enhanced magnetisation along the axis of alignment with respect to perpendicular to the axis, and this has been demonstrated here For the first time. The optimum firing temperature was 1000 degrees C, at which point they still had submicron grains. In BaM random fibres M-s=63.8emu g(-1) and H-c=428.1 kA m(-1) and in SrM random fibres M-s=63.3 emu g(-1) and H-c=452.8 kA m(-1), high values for polycrystalline materials. Fibres aligned parallel to the applied field had saturation magnetisation (M-s) values equal to those of the random fibres, whilst fibres aligned perpendicular to the field had All, values 62% and 75% lower, for BaM and SrM, respectively. There was no change in coercivity (H-c) between random or aligned fibres of any orientation, and fibres aligned 45 degrees and parallel to H appeared identical. Therefore, properties along the axis of alignment were superior when compared to measurements perpendicular to the axis of alignment, giving a directionality to the magnetisation in an otherwise randomly oriented ferrite material. (c) 2005 Elsevier B.V. All rights reserved
A comparison of sediment quality guidelines for toxicity assessment in the Sunderban wetlands (Bay of Bengal, India)
No full textThe aim of this paper was to obtain the first screening ecotoxicological risk evaluation in the Sunderban wetlands, the largest prograding delta in the estuarine phase of the River Ganges. The characterization of exposure was conducted by means of an extensive survey of several persistent organic pollutants (PAHs, PCBs, DDTs, PBDEs, HCHs, HCB) measured in seven core sediments from the Sunderban wetlands, obtaining a dataset with more than 2200 analyses. The pollutant effects were assessed by the use of three different sediment quality guidelines (SQGs) previously developed in the literature to evaluate toxicity induced in sediment-dwelling organisms. The three different approaches chosen for risk assessment of the Sunderban were the consensus SQGs obtained by TEC (threshold effect concentration), PEC (probable effect concentration) and EEC (extreme effect concentration), the threshold/probable effect level (TEL/PEL) approach and. finally, the ERL-ERM guidelines, including the m-ERM-Q(mean ERM quotient). The evaluation of the toxicity induced by a mixture of the target pollutants indicated the importance of gamma-HCH contamination in the Sunderban sediments despite the very low concentrations measured in core sediments. A different sensitivity for toxicity assessment due to quality guidelines was obtained, as the consensus SQGs based on TEC were less conservative and protective than the TEL and ERL approaches, while the use of m-ERM-Q seems to be the most powerful tool to predict the toxicity related to a contaminant mixture
Macrobrachium ramae Das & Pahari & Bhattacharya 2021, sp. nov.
No full textMacrobrachium ramae sp. nov. (Fig. 1–3) Materials examined. Measurements (in mm), HOLOTYPE (1♂, Fig.1A): total length 44.0, carapace length 10.0, rostrum length 9.0, telson length 9.0. First pereiopod: ischium (i) = 2.6, merus (m) = 4.8, carpus (c)= 5.0, propodus (p) = 3.0, dactylus (d) = 1.5. Second pereiopod: i = 5, m = 5.8, c = 8.0, p = 9.0, d = 5.0. Third pereiopod: i = 3.5, m = 6.0, c = 3.0, p = 5.5, d = 2.0. Fourth pereiopod: i = 4.0, m = 6.2, c = 3.8, p = 7.5, d = 2.0. Fifth pereiopod: i = 4.0, m = 6.5, c = 4.0, p = 7.8, d = 2.8. ALLOTYPE (1♀ Fig.1B): total length 64.0, carapace length 16.0,rostrum length 12.0, telson length 10.0. First pereiopod: ischium (i) 4.0, merus (m) 7.0,carpus (c) 9.0, propodus (p) 4.5. dactylus (d) 2.5. Second pereiopod: i = 8.0, m = 9.0, c = 12.5, p = 13.5, d = 7.0. Third pereiopod: i = 3.8, m = 9.0, c = 3.8, p = 6.8, d = 2.5. Fourth pereiopod: i = 4.0, m = 9.0, c = 4.5, p = 8.5, d = 2.8. Fifth pereiopod: i = 4.0, m = 9.5, c = 4.8, p = 10.0, d = 3.0. PARATYPES: (based on 4 ♂) Total length 38–44, carapace length 9–10, rostrum length 8–14,telson length 6–9.5. First pereiopod: ischium (i) 2.0 –2.5; merus (m) 4.0–4.8, carpus (c) 6,0–7.5, propodus (p) 2.5–3.0; dactylus (d) 1.0–1.5. Second pereiopod: i = 4.5–5.0, m = 4.8–5.8, c = 7.2–8.0, p = 8.5–9.2, d = 4.75–5.0. Third pereiopod: i = 2.8–3.0, m = 5.5–6.0, c = 2.2–2.5, p = 4.5–5.5, d = 1.8–2.0. Fourth pereiopod: i = 3.0–3.5, m =5.0– 6.0, c = 2.5–3.0, p = 6.2–7.0, d = 1.5– 2.0. Fifth pereiopod: i = 3.5–3.8, m = 6.2–6.8, c = 3.75–4.5, p = 7.0–7.8, d = 2.0–2.8. (Based on 4 ♀) Total length 59.0–69.5, carapace length 16.0–18.0, rostrum length 11.5–14.0,telson length 8.5–10.0. First pereiopod: ischium (i) 4.5–4.8, merus (m) 6.8–7.0, carpus (c) 8.5–10.0, propodus (p) 4.25–5.0, dactylus (d)1.5–2.75. Second pereiopod: i = 6.75–8.0, m = 9.0–9.5, c = 12.0–14.0, p = 15.5–17.0, d = 7.5–8.2. Third pereiopod: i = 3.8–4.2, m = 8.0–10.0, c = 3.5–4.5, p = 7.0–8.0, d = 2.5–3.0. Fourth pereiopod: i = 4.0–4.5, m =9.0– 9.25, c = 4.0–4.5, p = 8.0–8.5, d = 2.5–3.0. Fifth pereiopod: i = 3.8–4.5, m = 9.0–10.0, c = 4.5–5.8, p = 9.5–10.0, d = 3.0–3.5. Description. Rostrum broad, overreaching antennal scale, tip directed slightly upwards. Rostral formula 9– 12/3–5 with 2 postorbitals; wide gap between 1 st and 2 nd post orbital tooth, 1 st post orbital and rest of the dorsals closely packed; 1 st ventral is located at half length of rostrum and last one at the level of 9/10 dorsal tooth. Carapace smooth, 6–8 mm in males, 17–19 mm in females; both antennal and hepatic spine present, latter situated below and behind the former (Fig.1C). Abdomen glabrous, pleurae of somites I–III typical, IV and V directed backwards, VI ending in spine. Telson broad, stout. conical with a median projection and two pairs of dorsal spines and two pairs of distal spines;1 st dorsal pair situated at 45–50%, 2 nd pair at 66–70% distance; inner pair of distal spines very long, overreaching tip of telson;3 pairs of plumose setae present between inner pair of spines. Eyes and cornea well developed, broader than eye stalk, slightly pigmented. Length of three segments of antennular peduncle, 5.5(proximal): 2(middle): 3(distal); lateral spine of basal segment not reaching middle segment. Tip of antennal scale round, outer spine subdistal, length 3 times as long as breadth. Mandible three segmented, middle segment shortest,apical one longest with one apical and one subapical row of setae (Fig.3F). Maxillula, maxilla,1 st maxilliped, 2 nd maxilliped typical of Macrobrachium. 3 rd maxilliped overreaching antennular peduncle, reaching nearly basal 1/3 rd of carpus of 1 st pereiopod.(Fig.2.a,b,c,d,e) 1 st pereiopod slender; chela overreaching antennal scale; ischium slightly shorter than propodus,0.61 to 0.66 times as long as merus,0.50 to 0.57 times as long as carpus; dactylus and palm equal (Fig.1D). 2 nd pereiopods exhibit sexual dimorphism. Male chelipeds equal,0.5 to 0.62 times of total body length; carpus longer than merus, ischum, shorter than propodus, podomere longest; dactylus equal or slightly longer than ischium; fingers distinctly longer than inflated palm with sharp ridge along the cutting edge (Fig.1E, 2 Ai,2D). Ratio (in %) of ischium, merus, carpus, propodus, dactylus, palm are 18(i):20.9(m):28.8(c):32.3(p):18(d):14.3(palm). Female chelipeds subequal, 0.59 to 0.63 times of body length (Fig.1F); carpus stout, conical near palm, longer than merus and ischium, shorter than propodus, podomere largest; dactylus equal to merus,0.50 to 0.62 times as long as propodus; palm inflated, equal to or longer than slender fingers,1 minute and 2 blunt denticles at the base of immovable finger and movable finger respectively. Ratio (in %) of ischium, merus, carpus, propodus, dactylus, palm are 16.0(i):22.5(m):29.7(c): [32.1(p)]:16.0(d): 15.4(palm). 3 rd to 5 th pereiopods simple, 5 th one longest. 1 st pleopod typical of Macrobrachium (Fig.1G). 2 nd pleopod in male with appendix masculina bearing 1 short, 2 long stiff distal setae and two lateral rows of 12-14 spinous setae (Fig.2C,2B), 2 nd pleopod in female simple.3 rd to 5 th pleopod simple in both the sexes (Fig.1I). Colouration. Body transluscent; Carapace, rostrum, antennal scale, antennular peduncle, first three abdominal pleurae without pigmentation, ventrolateral margin of 4 th,5 th, 6 th abdominal pleurae and uropod with dark brown pigmentation; 2 nd chelate leg has reddish brown pigmentation in entire carpus,outer margin of palm and fingers, half of merus close to carpus; red pigmentation in antennular flagella and at distal end of propodus; podomere joints of 3 rd,4 th & 5 th pereiopods with yellow bands.(Fig.2E). Discussion. A comparison of morphological characters (Table.2) shows that M. ramae sp. nov. shares several characters with M. gurudeve, M. jayasreei, M. kunjuramani and M. saengphani. However the new species can easily be distinguished from these species by the structure of rostrum, telson, appendix masculina and in presence of bigger proximal antennular peduncle segment as compared to middle and distal segments.A key is given below for distinctive identification of the five species. I dentification key: 1. Carapace shorter than rostrum........................................................................... 2 - Carapace longer than rostrum............................................................................ 3 2. Uropodal exopod with accessory spine; telson slender........................................................ 4 - Uropodal exopod without accessory spine;telson broad............................................... M.gurudeve 3. Uropodal exopod without accessory spine; telson slender.............................................. M.jayasreei - Uropodal exopod with accessory spine; telson broad............................................. M.ramae sp.nov. 4. Antennal spine with carina,males longer than females............................................ M.kunjuramani - Antennal spine without carina,males smaller than females........................................... M.saengphani Different haplotypes of M. ramae sp. nov. generated using both COI and 16S rRNA gene sequences of 3 males and 3 females cluster together in molecular phylogenetic trees, strongly suggests that the specimens belong to same species. Neither 16s rRNA nor COI gene sequences of M. gurudeve, M. jayasreei, M. kunjuramani are available in NCBI, except COI gene sequence of M. Saengphani, which forms a very distant clade from M. ramae sp. nov. (Fig. 4). Neighbor-joining tree of COI gene sequences of different Macrobrachium species shows that, M. ramae sp. nov. forms cluster with M. lamarrei and M. rude remains as separate clade. However, Neighbor-joining tree using 16S rRNA gene sequences shows that M. ramae sp. nov. forms a cluster with M. rude whereas M. lamarrei belongs to a separate clade. It is well established that morphologically M. lamarrei and M. rude are very easily distinguishable species and could be identified easily. M.rude differs hugely from M.ramae sp. nov. in having larger males than females measuring upto 130 mm of total length,2 nd cheliped 1.5 times longer than total body length.Moreover, all the sengments of 2 nd cheliped bear velvety pubescence, hence known as ‘hairy river prawn’. M. lamarrei also differs significantly from M.ramae sp. nov. in having longer rostrum with characteristic edentate gap, non-hairy appendix masculina longer than 2 nd pleopodal endopod and absence of subapical spine in uropodal exopod. If the sequences submitted to NCBI for M. lamarrei and M. rude are accurate in terms of species identification, then the sequences generated during the current study using COI and 16S rRNA genes should show similarity with any one of the species for both the gene fragments. This indicates that the samples for M. lamarrei and M. rude were collected and sequences were submitted without proper confirmation of the taxonomic status of those species, making their identification done rather doubtful. The sequences of M. lamarrei and M. rude retrieved from NCBI were submitted by three different research groups from two different countries. COI gene sequences MT483220 and MT483221, submitted as M. lamarrei were collected from Bhairab river, Bangladesh which is a coastal river carrying estuarine water. 16S rRNA sequences AY858836 and MG283139, submitted as M. rude were collected from Tamil Nadu and Orissa states of India respectively. These sequences rather indicate the presence of M. ramae sp. nov. in those locations and often be misidentified as other species of Macrobrachium and hence providing a hint of distribution of M. ramae sp. nov. spanning from coast of Bangladesh to entire East coast of India. Conclusion. The results of phylogenetic analysis have clearly pointed out that M. ramae sp. nov. is a new species as indicated through detail morphological study conducted during the present study. The results show the importance of both morphological and molecular data for accurate identification of any species and would surely help future taxonomists to figure out species level identification of the genus Macrobrachium in India with more clarity. Etymology. This new species is named in loving memory of the grandmother of the corresponding author (MD), late Rama Sengupta, who was a constant inspiration to her.The species name is a noun in the genitive singular.Published as part of Das, Mitali, Pahari, Priti Ranjan & Bhattacharya, Tanmay, 2021, A new species of palaemonid prawn Macrobrachium ramae sp. nov. (Malacostraca Decapoda: Palaemonidae) from Rupnarayana River, West Bengal, India with its molecular profiles, pp. 540-550 in Zootaxa 4952 (3) on pages 542-549, DOI: 10.11646/zootaxa.4952.3.6, http://zenodo.org/record/469064
Imprints of Archean to Neoproterozoic crustal processes in the Madurai Block, Southern India
No full textAbstract not availableShrema Bhattacharya, M. Santosh, Zhaochong Zhang, He Huang, Amlan Banerjee, P.M. George, K. Sajee
Gli ellagitannini di Punica granatum antagonizzano la risposta immune innata nella malaria
No full textIl pericarpo del frutto immaturo di Punica granatum (P.g.) L. è usato in una formulazione per la terapia e la profilassi malarica in Orissa, una regione dell’India. La malaria cerebrale è una complicanza grave dovuta alla citoaderenza di Plasmodium falciparum ai vasi cerebrali e all’eccesso di risposta infiammatoria, associata ad una sovraproduzione di mediatori tra cui metalloproteasi-9 (MMP-9) e TNF. Studi recenti hanno dimostrato l’attività antiplasmodio di P.g. in vitro [1]. Lo scopo del presente studio è stato di esplorare se oltre all’effetto antimalarico, P.g. potesse modulare la risposta immune dell’ospite. A tal fine si è preparata una frazione arricchita in tannini (P.g.-FRT) dall’estratto metanolico del pericarpo. L’espressione genica e la secrezione di MMP-9 sono state valutate in cellule THP-1 stimolate con il pigmento malarico (emozoina, 6 μg/ml). Per valutare se i meccanismi molecolari alla base dell’effetto coinvolgessero il fattore nucleare di trascrizione NF-kB, abbiamo valutato l’effetto delle molecole sul promotore di NF-kB in seguito a stimolo con emozoina. I saggi sono stati condotti su P.g.-FRT e sui costituenti principali della frazione: acido ellagico e punicalagina. Inoltre, è stato valutato anche l’effetto delle urolitine, i metaboliti intestinali degli ellagitannini. P.g.-FRT (50 e 100 μg/ml) inibisce la secrezione di MMP-9 indotta da emozoina rispettivamente del 78% e 95%; l’effetto osservato è ascrivibile alla presenza di punicalagina e acido ellagico poichè tali sostanze riducono la secrezione dell’enzima rispettivamente del 79% e 66% a 10 μM. L’effetto osservato sulla secrezione di MMP-9 sembra essere dovuto ad una diminuzione dell’espressione genica in quanto FRT e i composti puri, alle medesime concentrazioni, diminuiscono i livelli di mRNA di MMP-9 e inibiscono l’attività del promotore di MMP-9. Anche le urolitine (25 μM) inibiscono l’espressione e la secrezione di MMP-9. FRT, acido ellagico e punicalagina riducono l’attività del promotore di NF-kB, suggerendo un coinvolgimento di questo fattore di trascrizione nei meccanismi alla base dell’attività biologica osservata.
Gli effetti benefici del pericarpo di P.g. nel trattamento della malaria sono quindi in relazione sia all’attività diretta sul parassita sia all’inibizione di uno dei meccanismi pro-infiammatori coinvolti nell’insorgenza della malaria cerebrale. Riferimenti [1] M. Dell’Agli, G.V. Galli, Y. Corbett, D. Taramelli, L. Lucantoni, A. Habluetzel, O. Maschi, D. Caruso, S. Giavarini, S. Romeo, D. Bhattacharya, E. Bosisio Journal of Ethnopharmacology, 2009, 125, pag. 27
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