928 research outputs found
What does Social Distancing and Stay at Home mean to those on low incomes in Bangladesh?
No full textUnder the advice of the World Health Organization, countries around the world have implemented state messaging campaigns to ensure their populations socially distance and stay at home. Here Ranjan Saha Partha (Jahangirnagar University, Bangladesh) and Abul Kalam (Helen Keller International, Bangladesh) explain what they discovered by interviewing 30 people on low incomes in the districts of Savar and Ashulia just outside of Dhaka
Noise analysis of a suspended high power Michelson interferometer
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1997.Includes bibliographical references (p. [99]-101).by Partha Saha.Ph.D
Transition-Metal-Promoted C-N Bond-Formation Processes - Low-Spin FeIII, FeII, and NiII Complexes of 2-[(Arylamido)phenylazo]pyridine - X-ray Structure, Redox- and Spectroelectrochemistry
No full textMorpho-diversity of Oryza Sativa L. genetic cultivars from West Bengal, India
Get PDFPartha Sarathi Saha, Subhabrata Paul and Biswajit Ghosh* Plant Biotechnology Laboratory, Department of Botany, Ramakrishna Mission Vivekananda Centenary College, Rahara, Kolkata, West Bengal (700 118), India The present study was undertaken for germplasm collection, and morphological characterization of fifty Oryza sativa L. cultivars from West Bengal, India. The starch-iodine test shows that the Borapaddy variety is very sticky, indicating relatively higher amylopectin content. A positive correlation (p= 0.05; two-tailed) was observed between the number of rice grains per panicle and the leaf length or leaf width, suggesting that leaf surface area is intimately linked to photosynthetic capabilities and food storage in the grains of each panicle. The odour perceived after alkaline treatment of grains, revealed that the Tulaipanji, Tulshi bhog, Bhog dhan, Khas dhan, Chini atap, Kalojire, Phulpakri, Kalanunia, Prasad bhog, Kalojoha, Katari bhog, Badsha bhog and Danaguri varieties were aromatic. The results underscore a need for conservation strategies that optimize use of rare cultivars in breeding programs
Au(I)- and Pt(II)-N-heterocyclic carbene complexes with picoline functionalized benzimidazolin-2-ylidene ligands; synthesis, structures,electrochemistry and cytotoxicity studies
No full textNovel Au(I)-N-heterocyclic carbene complexes, 1-methyl-3-(2-pyridylmethyl)-
benzimidazolylidenegold(I)-chloride, 1; 1-benzyl-3-(2-pyridylmethyl)-
benzimidazolylidenegold(I)chloride, 2; and Pt(II)-N-heterocyclic carbene complexes 1-methyl-3-(2-
pyridylmethyl) benzimidazolylidene platinum(II)chloride, 3; and 1-benzyl-3-(2-pyridylmethyl)
benzimidazolylidene platinum-(II)chloride, 4, have been synthesized, based on CN-donor proligands
1-alkyl-3-(2-pyridylmeth-yl)-benzimidazoliumchloride L1 and L2 [alkyl, R = –CH3 = L1;
R = –CH2Ph = L2]. All the compounds have been synthesized and characterized by different
spectroscopic methods. The Au(I) complexes 1 and 2 have been synthesized by a silver carbene
transfer method. The solid-state structures of 1 and 3 have been determined by single crystal
X-ray diffraction studies. The square planar Pt(II) complexes 3 and 4 show a reversible
Pt(II)/Pt(IV) couple at 0.69 eV and 0.67 eV respectively. Among the complexes 1–4, complexes 1
and 3 have been used for cytotoxicity studies on the cell lines B16F10 (mouse melanoma), HepG2
(human hepatocarcinoma) and HeLa (human cervical carcinoma). IC50 values are compared with
cisplatin, among 1 and 3, the Au(I) complex 1 is more effective than Pt(II) complex 3
Photo-responsive Schottky Diode Behavior of a Donor-Acceptor Co-crystal with Violet Blue Light Emission
No full textHerein, we report the crystal structure, supramolecular structure, electronic
transport property and optoelectronic behaviour of a co-crystal made of
tetrabromoterephthalic acid (TBTA) and quinoxaline (QUIN) (1:1). The sample has been
characterized by thermogravimetric analysis and spectral techniques. Moreover, the
theoretical analysis on noncovalent interactions, optical properties and band structure of the
co-crystal has been performed. The co-crystal has been crystallized in orthorhombic system
with P nma space group and the constituent molecules assemble in the solid state by using O-
H···N hydrogen bonding, π···π, Br···π and Br···O interactions. The ground state geometry
optimization over the hydrogen bonded dimer by DFT method indicates that TBTA acts as
the donor and QUIN as the acceptor within the self-assembled co-crystal. According to UV-
vis spectroscopic study the bandgap of the co-crystal is ~ 3.18 eV. In solid state it exhibits a
broad emission band with maxima at 405 nm while in aqueous medium its
photoluminescence emission peaks are obtained at 350 and 403 nm. The values of average
fluorescence lifetime of the sample in aqueous medium are 3.38 ns at 352 nm and 4.94 ns at
403 nm. Under UV-irradiation, the co-crystal emits violet-blue light. The emission spectra in
solution phase shows relative quantum yield of 0.018. Band structure calculation indicates
that the co-crystal is a p-type semiconductor with bandgap of 2.835 eV. Due to its
semiconducting character, the ITO/Co-crystal/Al sandwiched structured device acts as a Schottky barrier diode with rectification ratio, ideality factor, barrier height and series
resistance of 41, 1.36, 0.70 eV, and 26.97 KΩ, respectively. The current through the device
increases substantially under visible light exposure. Upon visible light illumination the values
of electrical conductivity, mobility, carrier concentration increases by 35 (± 0.5), 54 (± 0.5)
and 6 (± 0.5) %, respectively, with respect to dark condition. It has been shown that π···π and
hydrogen bonding interaction can play crucial role in producing donor-acceptor (D-A) type
co-crystal, semiconducting behaviour can be incorporated in organic co-crystal utilizing π···π
and hydrogen bonding interactions and weak intermolecular π···π, Br···π and Br···O
interactions can act as the pathway for electrical conduction
Depth-4 Lower Bounds, Determinantal Complexity: A Unified Approach
Get PDFTavenas has recently proved that any n^{O(1)}-variate and degree n polynomial in VP can be computed by a depth-4 SigmaPi^[O(sqrt{n})]SigmaPi^{[sqrt{n}]} circuit of size 2^{O(n^{1/2}.log(n))} [Tavenas, 2013]. So, to prove that VP is not equal to VNP it is sufficient to show that an explicit polynomial in VNP of degree n requires 2^{omega(n^{1/2}.log(n))} size depth-4 circuits. Soon after Tavenas' result, for two different explicit polynomials, depth-4 circuit size lower bounds of 2^{Omega(n^{1/2}.log(n))} have been proved (see [Kayal, Saha, and Saptharishi, 2013] and [Fournier et al., 2013]). In particular, using combinatorial design [Kayal et al., 2013] construct an explicit polynomial in VNP that requires depth-4 circuits of size 2^{Omega(n^{1/2}.log(n))} and [Fournier et al., 2013] show that the iterated matrix multiplication polynomial (which is in VP) also requires 2^{Omega(n^{1/2}.log(n))} size depth-4 circuits.
In this paper, we identify a simple combinatorial property such that any polynomial f that satisfies this property would achieve a similar depth-4 circuit size lower bound. In particular, it does not matter whether f is in VP or in VNP. As a result, we get a simple unified lower bound analysis for the above mentioned polynomials.
Another goal of this paper is to compare our current knowledge of the depth-4 circuit size lower bounds and the determinantal complexity lower bounds. Currently the best known determinantal complexity lower bound is Omega(n^2) for Permanent of a nxn matrix (which is a n^2-variate and degree n polynomial) [Cai, Chen, and Li, 2008]. We prove that the determinantal complexity of the iterated matrix multiplication polynomial is Omega(dn) where d is the number of matrices and n is the dimension of the matrices. So for d=n, we get that the iterated matrix multiplication polynomial achieves the current best known lower bounds in both fronts: depth-4 circuit size and determinantal complexity. Our result also settles the determinantal complexity of the iterated matrix multiplication polynomial to Theta(dn).
To the best of our knowledge, a Theta(n) bound for the determinantal complexity for the iterated matrix multiplication polynomial was known only for any constant d>1 [Jansen, 2011]
Different in vitro activation methods for latent transforming growth factors (TGF)–β : considerable exogenous factors to promote higher mesenchymal-origin cell proliferation in a bioprocessing platform
No full textRegenerative medicine includes two efficient techniques, namely tissue-engineering and cell-based therapy in order to repair tissue damage efficiently. Most importantly, huge numbers of autologous cells are required to deal these practices. Nevertheless, primary cells, from autologous tissue, grow very slowly while culturing in vitro; moreover, they lose their natural characteristics over prolonged culturing period. Transforming growth factors-beta (TGF-β) is a ubiquitous protein found biologically in its latent form, which prevents it from eliciting a response until conversion to its active form. In active form, TGF-β acts as a proliferative agent in many cell lines of mesenchymal origin in vitro. This article reviews on some of the important activation methods-physiochemical, enzyme-mediated, non-specific protein interaction mediated, and drug-induced- of TGF-β, which may be established as exogenous factors to be used in culturing medium to obtain extensive proliferation of primary cells
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Art and Nationalism in Colonial India 1850 - 1922
No full textPartha Mitter's book is a pioneering study of the history of modern art on the Indian subcontinent from 1850 to 1922. The author tells the story of Indian art during the Raj, set against the interplay of colonialism and nationalism. The work addresses the tensions and contradictions that attended the advent of European naturalism in India, as part of the imperial design for the westernisation of the elite, and traces the artistic evolution from unquestioning westernisation to the construction of Hindu national identity. Through a wide range of literary and pictorial sources, Art and Nationalism in Colonial India balances the study of colonial cultural institutions and networks with the ideologies of the nationalist and intellectual movements which followed. The result is a book of immense significance, both in the context of South Asian history and in the wider context of art history
New methods and strategies towards total synthesis of (9S)-dihydroerythronolide A
No full textDisclosed are studies directed towards the total synthesis of (9S)-dihydroerythronolide A. Towards this goal an advanced intermediate, 14 member bis[allene] macrolactone was synthesized. A general method of cuprate-mediated carbon nucleophile delivery to spirodiepoxides was developed. An unprecedented macrolactonization to form bis[allene] macrolactone and macrocyclic stereocontroled epoxidation of this system was achieved. In a separate study, the highly stereocontroled formation of spirodiepoxides and excellent regiocontroled spirodiepoxide opening was developed. This method relies upon the presence of a silyl substituent on the allene. This finding was applied to the total synthesis of epicitreodiol.Ph.D.Includes bibliographical references
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