691 research outputs found

    TEX: The New Insensitive High Explosive

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    Insensitive high explosive 4, 10-dinitro-2,6,8, 12-tetraoxa-4, 10-diazatetracyclo (5.5.0.0.5,9 03,11) dodecane (TEX) has been synthesised by an improved laboratory-scale process using 93 per cent to 96 per cent nitric acid as nitrating agent. Characterisation of the product was done based on its physical constants, infrared, differential thermal analysis, and mass spectral studies. Explosive and ballistic parameters of TEX containing formulations were computed using Becker-Kistiakowsky-Wilson (BKW) code and NASA Chemical Equilibrium Composition- 71 programme, respectively. Semi-empirical quantum mechanical calculations using the parametric model 3 (PM3) method have been carried out for the TEX molecule. The optimised geometrical parameters and heats of formation were obtained from semi-empirical PM3

    Self-sorting of nonmuscle myosins IIA and IIB polarizes the cytoskeleton and modulates cell motility

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    Nonmuscle myosin II (NMII) is uniquely responsible for cell contractility and thus defines multiple aspects of cell behavior. To generate contraction, NMII molecules polymerize into bipolar minifilaments. Different NMII paralogs are often coexpressed in cells and can copolymerize, suggesting that they may cooperate to facilitate cell motility. However, whether such cooperation exists and how it may work remain unknown. We show that copolymerization of NMIIA and NMIIB followed by their differential turnover leads to self-sorting of NMIIA and NMIIB along the front–rear axis, thus producing a polarized actin–NMII cytoskeleton. Stress fibers newly formed near the leading edge are enriched in NMIIA, but over time, they become progressively enriched with NMIIB because of faster NMIIA turnover. In combination with retrograde flow, this process results in posterior accumulation of more stable NMIIB-rich stress fibers, thus strengthening cell polarity. By copolymerizing with NMIIB, NMIIA accelerates the intrinsically slow NMIIB dynamics, thus increasing cell motility and traction and enabling chemotaxis

    Probing the single-particle character of rotational states in 19^{19}F using a short-lived isomeric beam

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    A beam containing a substantial component of both the JÏ€=5+J^{\pi}=5^+, T1/2=162T_{1/2}=162 ns isomeric state of 18^{18}F and its 1+1^+, 109.77-min ground state has been utilized to study members of the ground-state rotational band in 19^{19}F through the neutron transfer reaction (d(d,p)p) in inverse kinematics. The resulting spectroscopic strengths confirm the single-particle nature of the 13/2+^+ band-terminating state. The agreement between shell-model calculations, using an interaction constructed within the sdsd shell, and our experimental results reinforces the idea of a single-particle/collective duality in the descriptions of the structure of atomic nuclei

    Stability analysis for yield and its attributing traits in advanced breeding lines of rabi sorghum (Sorghum bicolor (L.) Moench)

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    An experiment was carried out involving twenty three advanced breeding lines along with two checks M 35-1 and Muguthi during rabi season 2012-13 at four locations. Observations were recorded on 10 different characters viz., plant height (cm), stem diameter (cm), ear head length (cm), ear head diameter (cm), days to 50 per cent flowering, days to maturity, 100 seed weight (g), fodder yield per plot (kg), seed yield per plot (kg), and lodging percentage. The pooled analysis of variance revealed that mean sum of squares due to genotypes was significant for ear head diameter, days to 50 per cent flowering, days to maturity and fodder yield, indicating presence of considerable amount of variability in the genotypes. The mean sum of square due to environment + (genotypes x environment) was significant for plant height, ear head length (cm), ear head diameter (cm), days to 50 per cent flowering, fodder yield per plot (kg), seed yield per plot (kg), and lodging percentage characters except stem diameter, days to maturity and 100 seed yield. On the basis of stability parameters a four genotypes viz., GS-6 (2364 kg/ha), GS-16 (2454 kg/ha), GS-22(2775 kg/ha) and GS-23(2978 kg/ha) were found most stable over Gulbarga, Raichur, Bellary and Malnoor environments of Hyderabad Karnataka region

    Character association and path analysis in advanced breeding lines of rabi sorghum [Sorghum bicolor (L.) Moench]

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    The field experiment was carried out using advanced breeding lines of rabi sorghum to study association among the yield and its component traits, direct and indirect effects of traits on the yield. Association studies indicated that seed yield per plot showed significant positive correlation with traits viz., plant height (rp=+0.7243, rg=+0.7409), ear head length (rp=+0.6002, rg=+0.6021), 100 seed weight (rp=+0.1593, rg=+0.1880), fodder yield (rp=+0.9434, rg=+0.9476) and lodging percentage (rp=+0.5263, rg=+0.5646) at both phenotypic and genotypic level.Genotypic correlation was higher magnitude than phenotypic correlation. Revealed increase in ear head length will increase the seed yield. Partitioning of yield and yield components both at phenotypic and genotypic levels into direct and indirect effects revealed that positive direct effects of ear head length (Ppi=+0.2533, Pgi=+0.5241), ear head diameter (Ppi=+0.0669, Pgi=+0.2580), days to maturity (Ppi=+0.0338, Pgi=+0.1193), fodder yield (Ppi=+0.6484, Pgi=+0.7461) were relatively high and followed by less lodging percentage (Ppi=+0.1751, Pgi=+0.2263). Residual effects were Pr=0.1303 and Gr=0.0624 at phenotypic and genotypic levels. Indicating importance of these characters and can be strategically used to improve the seed yield of sorghum

    Measurement of the 58Ni(α, γ) 62Zn reaction and its astrophysical impact

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    Funding Details: PHY 08-22648, NSF, National Science Foundation; PHY 0969058, NSF, National Science Foundation; PHY 1102511, NSF, National Science FoundationCross section measurements of the 58Ni(α,γ)62Zn reaction were performed in the energy range Eα=5.5to9.5 MeV at the Nuclear Science Laboratory of the University of Notre Dame, using the NSCL Summing NaI(Tl) detector and the γ-summing technique. The measurements are compared to predictions in the statistical Hauser-Feshbach model of nuclear reactions using the SMARAGD code. It is found that the energy dependence of the cross section is reproduced well but the absolute value is overestimated by the prediction. This can be remedied by rescaling the α width by a factor of 0.45. Stellar reactivities were calculated with the rescaled α width and their impact on nucleosynthesis in type Ia supernovae has been studied. It is found that the resulting abundances change by up to 5% when using the new reactivities. © 2014 American Physical Society.Peer reviewe

    Stellar 36,38^{36,38}Ar(n,γ)37,39(n,\gamma)^{37,39}Ar reactions and their effect on light neutron-rich nuclide synthesis

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    The 36^{36}Ar(n,γ)37(n,\gamma)^{37}Ar (t1/2t_{1/2} = 35 d) and 38^{38}Ar(n,γ)39(n,\gamma)^{39}Ar (269 y) reactions were studied for the first time with a quasi-Maxwellian (kT∼47kT \sim 47 keV) neutron flux for Maxwellian Average Cross Section (MACS) measurements at stellar energies. Gas samples were irradiated at the high-intensity Soreq applied research accelerator facility-liquid-lithium target neutron source and the 37^{37}Ar/36^{36}Ar and 39^{39}Ar/38^{38}Ar ratios in the activated samples were determined by accelerator mass spectrometry at the ATLAS facility (Argonne National Laboratory). The 37^{37}Ar activity was also measured by low-level counting at the University of Bern. Experimental MACS of 36^{36}Ar and 38^{38}Ar, corrected to the standard 30 keV thermal energy, are 1.9(3) mb and 1.3(2) mb, respectively, differing from the theoretical and evaluated values published to date by up to an order of magnitude. The neutron capture cross sections of 36,38^{36,38}Ar are relevant to the stellar nucleosynthesis of light neutron-rich nuclides; the two experimental values are shown to affect the calculated mass fraction of nuclides in the region A=36-48 during the weak ss-process. The new production cross sections have implications also for the use of 37^{37}Ar and 39^{39}Ar as environmental tracers in the atmosphere and hydrosphere.Comment: 18 pages + Supp. Mat. (13 pages) Accepted for publication in Phys. Rev. Let

    Independent measurement of the Hoyle state β\beta feeding from 12B using Gammasphere

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    Using an array of high-purity Compton-suppressed germanium detectors, we performed an independent measurement of the β\beta-decay branching ratio from 12B^{12}\mathrm{B} to the second-excited (Hoyle) state in 12C^{12}\mathrm{C}. Our result is 0.64(11)%0.64(11)\%, which is a factor ∼2\sim 2 smaller than the previously established literature value, but is in agreement with another recent measurement. This could indicate that the Hoyle state is more clustered than previously believed. The angular correlation of the Hoyle state γ\gamma cascade has also been measured for the first time. It is consistent with theoretical predictions

    The Traveling Salesman Problem: Low-Dimensionality Implies a Polynomial Time Approximation Scheme

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    The Traveling Salesman Problem (TSP) is among the most famous NP-hard optimization problems. We design for this problem a randomized polynomial-time algorithm that computes a (1+eps)-approximation to the optimal tour, for any fixed eps>0, in TSP instances that form an arbitrary metric space with bounded intrinsic dimension. The celebrated results of Arora (A-98) and Mitchell (M-99) prove that the above result holds in the special case of TSP in a fixed-dimensional Euclidean space. Thus, our algorithm demonstrates that the algorithmic tractability of metric TSP depends on the dimensionality of the space and not on its specific geometry. This result resolves a problem that has been open since the quasi-polynomial time algorithm of Talwar (T-04)
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