27,484 research outputs found
The cranking formula and the spurious behaviour of the mass parameters
We discuss some aspects of the approach of the mass parameters by means of
the simple cranking model. In particular, it is well known that the numerical
application of this formula is often subject to ambiguities or contradictions.
It is found that these problems are induced by the presence of two derivatives
in the formula. To overcome these problems, we state a useful ansatz and we
develop a number of simple arguments which tend to justify the removal of these
terms. As soon as this is done, the formula becomes simpler and easier to
interpret. In this respect, it is shown how the shell effects affect the mass
parameters. A number of numerical tests help us in our conclusions.Comment: version 3 corrigendum of the ansatz of section V, corrigendum of the
  legend of Fig3. Submission = text file + 5 figure
Irrigation-Yield Production Functions and Irrigation Water Use Effciency Response of Drought-Tolerant and Non-Drought-Tolerant Maize Hybrids under Different Irrigation Levels, Population Densities, and Environments
Irrigation-yield production functions (IYPFs), irrigation water use effciency (IWUE), and grain production per unit of applied irrigation of non-drought-tolerant (NDT) and drought-tolerant (DT) maize (Zea mays L.) hybrids were quantified in four locations with different climates in Nebraska [Concord (sub-humid), Clay Center (transition zone between sub-humid and semi-arid); North Platte (semi-arid); and, Scottsbluff (semi-arid)] during three growing seasons (2010, 2011, and 2012) at three irrigation levels (fully-irrigated treatment (FIT), early cut-off (ECOT), and rainfed (RFT)) under two plant population densities (PPDs) (low-PPD; 59,300 plants ha-1; and, high-PPD, 84,000 plants ha-1). Overall, DT hybrids’ performance was superior to NDT hybrid at RFT, ECT, and FIT conditions, as confirmed by the yield response, IYPF and IWUE when all locations, years, and PPDs were averaged. The yield response to water was greater with the high-PPD than the low-PPD in most cases. The magnitude of the highest yields for DT hybrids ranged from 7.3 (low-PPD) to 8.5% (high-PPD) under RFT, 3.7 (low-PPD) to 9.6% (high-PPD) under ECOT, and 3.9% (high-PPD) under FIT higher than NDT hybrid. Relatively, DT hybrids can resist drought-stress conditions longer than NDT hybrid with fewer penalties in yield reduction and maintain comparable or even higher yield production at non-stress-water conditions
Stability, Adsorption and Diffusion of CH4, CO2 and H2 in Clathrate Hydrates
We present a study of the adsorption and diffusion of CH4, CO2 and H2
molecules in clathrate hydrates using ab initio van der Waals density
functional formalism [Dion et al. Phys. Rev. Lett. 92, 246401 (2004)]. We find
that the adsorption energy is dominated by van der Waals interactions and that,
without them, gas hydrates would not be stable. We calculate the maximum
adsorption capacity as well as the maximum hydrocarbon size that can be
adsorbed.The relaxation of the host lattice is essential for a good description
of the diffusion activation energies, which are estimated to be of the order of
0.2, 0.4, and 1.0 eV for H2, CO2, and CH4, respectively.Comment: 4 pages, 4 figures, 3 table
First evidence of anisotropic quenched disorder effects on a smectic liquid crystal confined in porous silicon
We present a neutron scattering analysis of the structure of the smectic
liquid crystal octylcyanobiphenyl (8CB) confined in one-dimensional nanopores
of porous silicon films (PS). The smectic transition is completely suppressed,
leading to the extension of a short-range ordered smectic phase aligned along
the pore axis. It evolves reversibly over an extended temperature range, down
to 50 K below the \textit{N-SmA} transition in pure 8CB. This behavior strongly
differs from previous observations of smectics in different one-dimensional
porous materials. A coherent picture of this striking behavior requires that
quenched disorder effects are invoked. The strongly disordered nature of the
inner surface of PS acts as random fields coupling to the smectic order. The
one-dimensionality of PS nano-channels offers new perspectives on quenched
disorder effects, which observation has been restricted to homogeneous random
porous materials so far.Comment: Submitted to Phys. Rev. 
The Financing Health System Problem in Algeria
The health sector in Algeria witnesses a great development, especially during the last two decades of the last century to coincide with the economic and social changes of the country. But despite the enormity of what the state spends on this sensitive sector in order to meet the growing demand for health services provided by the public or private sector, which, however, take advantage of these services was still below the required level where the sector remains vulnerable to various problems
Utilizing Satellite Based Observations and Physical Hydrological Modeling for Freshwater Ecosystem Health in the Lower Mekong River Basin
Freshwater availability is necessary to promote economic growth through agriculture, fisheries, transport, environmental health, and social equity.The National Aeronautics and Space Administration (NASA) and the Conservation International (CI) are partnering to use remote sensing Earth observations to improve regional efforts that assess natural resources for conservation and sustainable management. (Vollmer et al.,2018) have presented the social-ecological framework named the Freshwater Health Index (FHI), which takes account of the interplay between governance, stakeholders, freshwater ecosystems and the ecosystem services they provide.In this work, we develop decision support and making tools for natural resources conservation in the Lower Mekong by leveraging the FHI framework, multiple data products, and hydrological modeling capabilities (Mohammed et al., 2018). Modeling capabilities enable the integration of satellite-based daily gridded precipitation, air temperature, digital elevation model, soil characteristics, and land cover and land use information to simulate water flux framework
Variability factors in trace elements nutritional status by plasmatic indicators in camel (Camelus dromedarius) in Morocco. II. Effect of mineral supplement
Quatre lots de 5 dromadaires ont reéu respectivement une injection unique de cuivre et de zinc (lot lM), une complémentation orale pendant un mois de sulfate de cuivre (lot Cu), de sulfate de zinc (lot Zn) et aucune complémentation (lot T). L'essai a duré 111 jours et la période de complémentation est survenue entre 7e et le 37e jour. Dans le lot IM, la cuprémie et la zincémie ont significativement augmenté (maximum de 72 et de 73 µg/100 ml respectivement). Dans le lot Cu, la cuprémie a significativement augmenté ainsi que la zincémie dans le lot Zn, mais les valeurs observées ne dépassent pas les seuils admis comme limite de carence et chutent rapidement après l'arrêt de la complémentation. L'interaction cuivre-zinc se traduit par une diminution non significative de la zincémie dans le lot Cu et significative de la cuprémie dans le lot Z
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