2,939 research outputs found
Besov's Type Embedding Theorem for Bilateral Grand Lebesgue Spaces
In this paper we obtain the non-asymptotic norm estimations of Besov's type
between the norms of a functions in different Bilateral Grand Lebesgue spaces
(BGLS). We also give some examples to show the sharpness of these inequalities
Isotope Shifts in Beryllium-, Boron-, Carbon-, and Nitrogen-like Ions from Relativistic Configuration Interaction Calculations
Energy levels, normal and specific mass shift parameters as well as
electronic densities at the nucleus are reported for numerous states along the
beryllium, boron, carbon, and nitrogen isoelectronic sequences. Combined with
nuclear data, these electronic parameters can be used to determine values of
level and transition isotope shifts. The calculation of the electronic
parameters is done using first-order perturbation theory with relativistic
configuration interaction wave functions that account for valence, core-valence
and core-core correlation effects as zero-order functions. Results are compared
with experimental and other theoretical values, when available.Comment: 56 pages, 1 figure, Atomic Data and Nuclear Data Tables (2014
Fluorine in the solar neighborhood - is it all produced in AGB-stars?
The origin of 'cosmic' fluorine is uncertain, but there are three proposed
production sites/mechanisms: AGB stars, nucleosynthesis in Type II
supernovae, and/or the winds of Wolf-Rayet stars. The relative importance of
these production sites has not been established even for the solar
neighborhood, leading to uncertainties in stellar evolution models of these
stars as well as uncertainties in the chemical evolution models of stellar
populations.
We determine the fluorine and oxygen abundances in seven bright, nearby
giants with well-determined stellar parameters. We use the 2.3 m
vibrational-rotational HF line and explore a pure rotational HF line at 12.2
m. The latter has never been used before for an abundance analysis. To be
able to do this we have calculated a line list for pure rotational HF lines. We
find that the abundances derived from the two diagnostics agree.
Our derived abundances are well reproduced by chemical evolution models only
including fluorine production in AGB-stars and therefore we draw the conclusion
that this might be the main production site of fluorine in the solar
neighborhood. Furthermore, we highlight the advantages of using the 12 m
HF lines to determine the possible contribution of the -process to the
fluorine budget at low metallicities where the difference between models
including and excluding this process is dramatic
Aging phenomena in spin glasses: theory, experiment, and simulation
We study numerically temperature-shift and field-shift aging protocols on the
3-dimensional (3D) Ising Edwards-Anderson (EA) spin-glass (SG) model focusing
on respectively the temperature-chaos nature and the stability under a static
field of the
SG phase. The results of the latter strongly support the droplet theory which
predicts the instability of the SG phase under the field. They are also
discussed in relation with the experimental studies.Comment: 6 pages, 5 figures, submitted to ICM200
Modelling meristem development in plants
Meristems continually supply new cells for post-embryonic plant development and coordinate the initiation of new organs, such as leaves and flowers. Meristem function is regulated by a large and interconnected dynamic system that includes transcription networks, intercellular protein signalling, polarized transport of hormones and a constantly changing cellular topology. Mathematical modelling, in which the dynamics of a system are simulated using explicitly defined interactions, can serve as a powerful tool for examining the expected behaviour of such a system given our present knowledge and assumptions. Modelling can also help to investigate new hypotheses in silico both to validate ideas and to obtain inspiration for new experiments. Several recent studies have used new molecular data together with modelling and computational techniques to investigate meristem function
INFLUENCE OF SOCIO-ECONOMIC FACTORS ON FARMERS’ USE OF MOBILE PHONES FOR AGRICULTURAL INFORMATION IN NIGERIA
Farmers use mobile phones to access information needed to improve their agricultural practice. However, in cases where they do maximize their mobile phone utilization, they may be hindered by some socio-economic factors which may lead to inadequate access to agricultural information. Therefore, this study investigated the influence of socio-economic factors on famers’ use of mobile phones for agricultural information in Nigeria. The research adopted a survey design. The study population was 9,650 registered farmers in Yewa South Local Government, Ogun State, Nigeria. The proportionate stratified random sampling technique was used. The instrument used was structured questionnaire. Data were collected from 363 farmers; thus the study had 93%. Data was analyzed using descriptive statistics, Regression and Multi regression analysis. Findings from this study revealed that majority of the farmers use mobile phones daily (75.5%). It was further showed that farmers use mobile phones for specific purposes such as making phone calls (mean= 3.47), and receiving text messages (mean= 2.90). The findings also revealed that farmers use mobile phones to acquire different types of Agricultural information such as fertilizer and pesticide information (mean=2.52), and market information (mean=2.31). High tariff deductions from telecommunication companies (mean=3.53) was a major constrain. Findings further revealed that family size (β= .173; P˂.05), and Farm Size (β= .168; P˂.05) had positive significant influence on farmers’ use of mobile phones for agricultural information while Age range (β= -.031; P˂.05), Gender (β= -.027; P˂.05), Marital status (β= -.18; P˂.05), Educational qualification (β= -.031; P˂.05), Years of farming (β= -.126; P˂.05), Farm income per month (β= -.021; P˂.05) had negative influence respectively. Finally, socio-economic factors jointly influenced farmers’ use of mobile phones for agricultural information (F = 3.81; R² = .58, p \u3c .05). The study concluded that, socio-economic factors collectively contribute to farmers’ use of mobile phones for agricultural information. Therefore, it is recommended that telecommunication companies in Nigeria, in conjunction with the Federal Government, should provide a low tariff plans for farmers. This would enable them to adequately utilize their mobile phones for agricultural information
A Variational Approach for Minimizing Lennard-Jones Energies
A variational method for computing conformational properties of molecules
with Lennard-Jones potentials for the monomer-monomer interactions is
presented. The approach is tailored to deal with angular degrees of freedom,
{\it rotors}, and consists in the iterative solution of a set of deterministic
equations with annealing in temperature. The singular short-distance behaviour
of the Lennard-Jones potential is adiabatically switched on in order to obtain
stable convergence. As testbeds for the approach two distinct ensembles of
molecules are used, characterized by a roughly dense-packed ore a more
elongated ground state. For the latter, problems are generated from natural
frequencies of occurrence of amino acids and phenomenologically determined
potential parameters; they seem to represent less disorder than was previously
assumed in synthetic protein studies. For the dense-packed problems in
particular, the variational algorithm clearly outperforms a gradient descent
method in terms of minimal energies. Although it cannot compete with a careful
simulating annealing algorithm, the variational approach requires only a tiny
fraction of the computer time. Issues and results when applying the method to
polyelectrolytes at a finite temperature are also briefly discussed.Comment: 14 pages, uuencoded compressed postscript fil
Interaction effects and transport properties of Pt capped Co nanoparticles
We studied the magnetic and transport properties of Co nanoparticles (NPs)
being capped with varying amounts of Pt. Beside field and temperature dependent
magnetization measurements we performed delta-M measurements to study the
magnetic interactions between the Co NPs. We observe a transition from
demagnetizing towards magnetizing interactions between the particles for an
increasing amount of Pt capping. Resistivity measurements show a crossover from
giant magnetoresistance towards anisotropic magnetoresistance
Natural radiative lifetimes in the 3 sns 1S0 and 3 snd 1D2 sequences of magnesium
Natural radiative lifetimes have been determined in the determined in the 3 sns 1S0 (n=4-15) and the 3 snd 1D2 (n=3-15) sequences of Mg I employing a pulsed-laser system. The radiative lifetimes in the 1S0 sequence and of the higher members in the 1D2 sequence are unperturbed and scale as (n*)2.6 (where n* is the effective principal quantum number), while the lifetimes of the lower members in the 1D2 sequence are perturbed by the doubly excited 3p2 configuration. The measured lifetimes are compared with available theoretical calculations, and a very good agreement is obtained
Проблемы преподавания дисциплины "Охраны труда" для студентов первого курса лечебного и фармацевтического профиля
The characterization of nonmetallic inclusions is of importance for the production of clean steel in order to improve the mechanical properties. In this respect, a three-dimensional (3D) investigation is considered to be useful for an accurate evaluation of size, number, morphology of inclusions, and elementary distribution in each inclusion particle. In this study, the application of various extraction methods (chemical extraction/etching by acid or halogen-alcohol solutions, electrolysis, sputtering with glow discharge, and so on) for 3D estimation of nonmetallic Al2O3 inclusions and clusters in high-alloyed steels was examined and discussed using an Fe-10 mass% Ni alloy and an 18/8 stainless steel deoxidized with Al. Advantages and limitations of different extraction methods for 3D investigations of inclusions and clusters were discussed in comparison to conventional two-dimensional (2D) observations on a polished cross section of metal samples.QC 20140227</p
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