7,140 research outputs found
Chemical and biological investigations of Delonix regia (Bojer ex Hook.) Raf.
U radu je opisana izolacija pet sastojaka petroleterske i diklormetanske frakcije metanolnog ekstrakta kore biljke Delonix regia: lupeol (1), epilupeol (2), β-sitosterol (3), stigmasterol (4) i p-metoksibenzaldehid (5). Nadalje, testirano je antimikrobno djelovanje različitih ekstrakata difuzijskom metodom na disku (15 μg mm2). Zone inhibicije za sastojke topljive u petroleteru, tetraklormetanu i diklormetanu bile su 914 mm, 1113 mm, odnosno 920 mm, dok je zona inhibicije standarda kanamicina bila 2025 mm. U biološkom pokusu smrtnosti morskih kozica najveću toksičnost pokazali su spojevi topljivi u tetraklormetanu (LC50 = 0,83 μg mL1), dok je topljivost sastojaka topljivih u petroleteru i diklormetanu bila LC50 14,94, odnosno 3,29 μg mL1, a standarda vinkristin sulfata 0,812 μg mL1. Ovo je prvo izvješće o izolaciji sastojaka, antimikrobnom djelovanju i citotoksičnosti biljke D. regia.In this study five compounds, lupeol (1), epilupeol (2), β-sitosterol (3), stigmasterol (4) and p-methoxybenzaldehyde (5) were isolated from the petroleum ether and dichloromethane fractions of a methanolic extract of the stem bark of Delonix regia. Antimicrobial screening of the different extracts (15 μg mm2) was conducted by disc diffusion method. The zones of inhibition demonstrated by the petroleum ether, carbon tetrachloride and dichloromethane fractions ranged from 914 mm, 1113 mm and 920 mm, respectively, compared to kanamycin standard with the zone of inhibition of 2025 mm. In brine shrimp lethality bioassay, the carbon tetrachloride soluble materials demonstrated the highest toxicity with LC50 of 0.83 μg mL1, while petroleum ether and dichloromethane soluble partitionates of the methanolic extract revealed LC50 of 14.94 and 3.29 μg mL1, respectively, in comparison with standard vincristine sulphate with LC50 of 0.812 μg mL1. This is the first report on compounds separation from D. regia, their antimicrobial activity and cytotoxicity
Quantum eigenstate tomography with qubit tunneling spectroscopy
Measurement of the energy eigenvalues (spectrum) of a multi-qubit system has
recently become possible by qubit tunneling spectroscopy (QTS). In the standard
QTS experiments, an incoherent probe qubit is strongly coupled to one of the
qubits of the system in such a way that its incoherent tunneling rate provides
information about the energy eigenvalues of the original (source) system. In
this paper, we generalize QTS by coupling the probe qubit to many source
qubits. We show that by properly choosing the couplings, one can perform
projective measurements of the source system energy eigenstates in an arbitrary
basis, thus performing quantum eigenstate tomography. As a practical example of
a limited tomography, we apply our scheme to probe the eigenstates of a kink in
a frustrated transverse Ising chain.Comment: 8 pages, 4 figure
Bayesian blind component separation for Cosmic Microwave Background observations
We present a technique for the blind separation of components in CMB data.
The method uses a spectral EM algorithm which recovers simultaneously component
templates, their emission law as a function of wavelength, and noise levels. We
test the method on Planck HFI simulated observations featuring 3 astrophysical
components.Comment: 15 pages, 5 figures, to appear in the Proceedings of the MAXENT 2001
international worksho
Open Wilson Lines and Chiral Condensates in Thermal Holographic QCD
We investigate various aspects of a proposal by Aharony and Kutasov
arXiv:0803.3547 [hep-th] for the gravity dual of an open Wilson line in the
Sakai-Sugimoto model or its non-compact version. In particular, we use their
proposal to determine the effect of finite temperature, as well as background
electric and magnetic fields, on the chiral symmetry breaking order parameter.
We also generalize their prescription to more complicated worldsheets and
identify the operators dual to such worldsheets.Comment: 45 pages, 18 figures; added reference
Stochastic model for nucleosome sliding in the presence of DNA ligands
Heat-induced mobility of nucleosomes along DNA is an experimentally
well-studied phenomenon. A recent experiment shows that the repositioning is
modified in the presence of minor-groove binding DNA ligands. We present here a
stochastic three-state model for the diffusion of a nucleosome along DNA in the
presence of such ligands. It allows us to describe the dynamics and the steady
state of such a motion analytically. The analytical results are in excellent
agreement with numerical simulations of this stochastic process.With this
model, we study the response of a nucleosome to an external force and how it is
affected by the presence of ligands.Comment: 10 pages, 8 figures, submitted to Eur. Phys. J.
Combretastatin A4 Disodium Phosphate Forms Aggregates In Solution Leading To Exciton Transfer
Towards a Complex Adaptive Systems Roadmap for Information Systems Research
Complex adaptive systems (CAS) theory conceptualises a system composed of heterogeneous agents, which interact with each other to adapt to the environment. CAS concepts have been applied in several Information Systems (IS) referent disciplines over the last decade to study complex phenomena in strategic management, social science and organisational research. The application of CAS theory in IS is more recent, wherein researchers have studied complex phenomena including agile processes, systems dynamics and IS alignment. Though CAS has gained some traction with IS researchers, general understanding of the potential of CAS, and its methodological and theoretical applications in IS research, is yet partial and fragmented. The aim of this study is to develop a roadmap for applying CAS in IS research, to analyse the key research objectives with CAS in extant IS research, and to identify methodological and theoretical approaches that researchers follow in conducting CAS-based IS research. To achieve this, we review IS papers published 2002-2014 inclusive in top IS outlets. We analyse the papers based on a supportive theoretical framework and identify eight main objectives of applying CAS, three methodological approaches, and two theoretical approaches related to CAS-based research in the IS discipline. The study reports several valuable observations, including the relative versatility of computational studies over other studies, the minimal use of CAS in design research, methodological triangulation, and theoretical triangulation in IS research. We propose several guidelines for future researchers
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