9,076 research outputs found
Photolysis of cellulose
The paper reviews in brief the salient features of the work under study at T.D.E.L., Kanpur. The requisite historical background is provided. The results are reported under two main heads- (i) Fundamental studies on the action of light on cellulose, and (ii) Barriers for the prevention of light attack on cellulose. Extensive investigations, on barriers which will minimize the extent of photolysis have shown that urea-formal-dehyde resin and hydrated manganese oxide are outstanding. The mechanism of protection has been investigated
Recent applications of the transonic wing analysis computer code, TWING
An evaluation of the transonic-wing-analysis computer code TWING is given. TWING utilizes a fully implicit approximate factorization iteration scheme to solve the full potential equation in conservative form. A numerical elliptic-solver grid-generation scheme is used to generate the required finite-difference mesh. Several wing configurations were analyzed, and the limits of applicability of this code was evaluated. Comparisons of computed results were made with available experimental data. Results indicate that the code is robust, accurate (when significant viscous effects are not present), and efficient. TWING generally produces solutions an order of magnitude faster than other conservative full potential codes using successive-line overrelaxation. The present method is applicable to a wide range of isolated wing configurations including high-aspect-ratio transport wings and low-aspect-ratio, high-sweep, fighter configurations
GM crops and gender issues
Correspondence in the December issue by Jonathan Gressel not only states that gender issues in rural settings have not been adequately addressed with respect to weed control biotech but also asserts that such technology can increase the quality of life of rural women in developing countries. Improved weed control is a labor-saving technology that can result in less employment in a labor surplus rural economy. Often in rural areas, wage income is the main source of income and an important determinant of the quality of life, particularly where employment opportunities are generally limited. Apart from soil preparation, planting and weeding, harvesting is also 'femanual' work that can generate more employment if yields are higher. Biotech can enhance the quality of life of women but only if the technology is associated with overall generation of rural employment
The structure of dark matter halos in hierarchical clustering theories
During hierarchical clustering, smaller masses generally collapse earlier
than larger masses and so are denser on the average. The core of a small mass
halo could be dense enough to resist disruption and survive undigested, when it
is incorporated into a bigger object. We explore the possibility that a nested
sequence of undigested cores in the center of the halo, which have survived the
hierarchical, inhomogeneous collapse to form larger and larger objects,
determines the halo structure in the inner regions. For a flat universe with
, scaling arguments then suggest that the core density
profile is, with . But
whether such behaviour obtains depends on detailed dynamics. We first examine
the dynamics using a fluid approach to the self-similar collapse solutions for
the dark matter phase space density, including the effect of velocity
dispersions. We highlight the importance of tangential velocity dispersions to
obtain density profiles shallower than in the core regions. If
tangential velocity dispersions in the core are constrained to be less than the
radial dispersion, a cuspy core density profile shallower than 1/r cannot
obtain, in self-similar collapse. We then briefly look at the profiles of the
outer halos in low density cosmological models where the total halo mass is
convergent. Finally, we analyze a suite of dark halo density and velocity
dispersion profiles obtained in cosmological N-body simulations of models with
n= 0, -1 and -2. We find that the core-density profiles of dark halos, show
considerable scatter in their properties, but nevertheless do appear to reflect
a memory of the initial power spectrum, with steeper initial spectra producing
flatter core profiles. (Abridged)Comment: 31 pages, 7 figures, submitted to Ap
Mortality Burden and Socioeconomic Status in India
Background: The dimensions along which mortality is patterned in India remains unclear. We examined the specific contribution of social castes, household income, assets, and monthly per capita consumption to mortality differentials in India. Methods and Findings: Cross-sectional data on 217 363 individuals from 41 554 households from the 2004–2005 India Human Development Survey was analyzed using multiple logistic regressions. Mortality differentials across social castes were attenuated after adjusting for household economic factors such as income and assets. Individuals living in the lowest income and assets quintiles had an increased risk of mortality with odds ratio (OR) of 1.66 (95 % CI = 1.23–2.24) in the bottom income quintile and OR of 2.94 (95 % CI = 1.66–5.22) in the bottom asset quintile. Counter-intuitively, individuals living in households with lowest monthly consumption per capita had significantly lower probability of death (OR = 0.27, 95 % CI = 0.20–0.38). Conclusions: Mortality burden in India is largely patterned on economic dimensions as opposed to caste dimensions, though caste may play an important role in predicting economic opportunities
A novel heavy-fermion state in CaCu_3Ru_4O12
We have measured susceptibility, specific heat, resistivity, and thermopower
of CaCuTiRuO and CaCuMnRuO, and
have found that CaCuRuO can be regarded as a heavy-fermion oxide
in d-electron systems. The Kondo temperature is near 200 K, and the
susceptibility (1.4 emu/Cu mol) and the electron specific heat
coefficient (28 mJ/Cu molK) are moderately enhanced. The resistivity is
proportional to at low temperatures, and satisfies the Kadowaki-Woods
relation. The heavy-fermion state comes from the interaction between the
localized moment of Cu 3d and the conduction electron of Ru 4d. An
insulator-metal transition occurs between and 4 in
CaCuTiRuO, which can be regarded as a transition from
magnetic insulator to heavy-fermion metal.Comment: 4 pages, 5 figures, submitted to J. Phys. Soc. Jp
Physical phenomena in containerless glass processing
Experiments were conducted on bubble migration in rotating liquid bodies contained in a sphere. Experiments were initiated on the migration of a drop in a slightly less dense continuous phase contained in a rotating sphere. A refined apparatus for the study of thermocapillar flow in a glass melt was built, and data were acquired on surface velocities in the melt. Similar data also were obtained from an ambient temperature fluid model. The data were analyzed and correlated with the aid of theory. Data were obtained on flow velocities in a pendant drop heated from above. The motion in this system was driven principally by thermocapillarity. An apparatus was designed for the study of volatilization from a glass melt
Cosmic Microwave Background Trispectrum and Primordial Magnetic Field Limits
Primordial magnetic fields will generate non-Gaussian signals in the cosmic
microwave background (CMB) as magnetic stresses and the temperature anisotropy
they induce depend quadratically on the magnetic field. We compute a new
measure of magnetic non-Gaussianity, the CMB trispectrum, on large angular
scales, sourced via the Sachs-Wolfe effect. The trispectra induced by magnetic
energy density and by magnetic scalar anisotropic stress are found to have
typical magnitudes of approximately a few times 10^{-29} and 10^{-19},
respectively. Observational limits on CMB non-Gaussianity from WMAP data allow
us to conservatively set upper limits of a nG, and plausibly sub-nG, on the
present value of the primordial cosmic magnetic field. This represents the
tightest limit so far on the strength of primordial magnetic fields, on Mpc
scales, and is better than limits from the CMB bispectrum and all modes in the
CMB power spectrum. Thus, the CMB trispectrum is a new and more sensitive probe
of primordial magnetic fields on large scales.Comment: Published in Physical Review Letters on 5 June 201
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