1,001 research outputs found
Small-scale Interaction of Turbulence with Thermonuclear Flames in Type Ia Supernovae
Microscopic turbulence-flame interactions of thermonuclear fusion flames
occuring in Type Ia Supernovae were studied by means of incompressible direct
numerical simulations with a highly simplified flame description. The flame is
treated as a single diffusive scalar field with a nonlinear source term. It is
characterized by its Prandtl number, Pr << 1, and laminar flame speed, S_L. We
find that if S_L ~ u', where u' is the rms amplitude of turbulent velocity
fluctuations, the local flame propagation speed does not significantly deviate
from S_L even in the presence of velocity fluctuations on scales below the
laminar flame thickness. This result is interpreted in the context of
subgrid-scale modeling of supernova explosions and the mechanism for
deflagration-detonation-transitions.Comment: 8 pages, 6 figures, accepted by Astrophys.
A Scale to Measure Attitude of Farmers towards Agricultural Schemes for Sustainable Livelihood
Agriculture schemes are formulated to induce the agricultural growth of the nation and also improve the sustainable livelihood of the farming community. The study aims to develop a scale to measure the attitude of farmers towards agricultural schemes for sustainable livelihood of agrarians. Thurstone and Chave’s (1929) equal appearing intervals scale method was adopted to develop the scale. The final scale comprised ten statements which are having universe of content, uniform distribution of scale values along the psychological continuum and high “scale values” and lower “Q” values and more or less equal number of favourable and unfavourable attitude items
Initial Condition Sensitivity of Global Quantities in Magnetohydrodynamic Turbulence
In this paper we study the effect of subtle changes in initial conditions on
the evolution of global quantities in two-dimensional Magnetohydrodynamic (MHD)
turbulence. We find that a change in the initial phases of complex Fourier
modes of the Els\"{a}sser variables, while keeping the initial values of total
energy, cross helicity and Alfv\'{e}n ratio unchanged, has a significant effect
on the evolution of cross helicity. On the contrary, the total energy and
Alfv\'{e}n ratio are insensitive to the initial phases. Our simulations are
based on direct numerical simulation using the pseudo-spectral method.Comment: 12 pages LateX, 11 ps figures. Accepted for publication by Physics of
Plasma
Cubic Augmentation of Planar Graphs
In this paper we study the problem of augmenting a planar graph such that it
becomes 3-regular and remains planar. We show that it is NP-hard to decide
whether such an augmentation exists. On the other hand, we give an efficient
algorithm for the variant of the problem where the input graph has a fixed
planar (topological) embedding that has to be preserved by the augmentation. We
further generalize this algorithm to test efficiently whether a 3-regular
planar augmentation exists that additionally makes the input graph connected or
biconnected. If the input graph should become even triconnected, we show that
the existence of a 3-regular planar augmentation is again NP-hard to decide.Comment: accepted at ISAAC 201
Combined Classifier versus Combined Feature Space in Scale Space Texture Classification
Using combined classifiers alleviates the problem of generating a large feature space, as the features generated from each scale/derivative are directly fed to a base classifier. In this approach, instead of concatenating features generated from each scale/derivative, the decision made by the base classifiers are combined in a two-stage combined classifier.In this paper, the performance of the proposed classification system is first compared against the combined feature space for only the zeroth order Gaussian derivative at multiple scales. The results clearly show that the proposed system using combined classifiers outperforms the classical approach of the combined feature space. The significance of the parameters, especially the fraction of variance maintained after applying PCA (principal component analysis) is also discussed
DCP vs LCDCP in forearm fractures: a comparative study of functional outcomes
Background: Forearm fractures in general, and diaphyseal fractures in specific, are one of the most common fractures which accounts for about 31% of upper limb fractures seen in emergency. Early reduction and fixation is necessary in order to restore the function of forearm so as to be able to carry out their daily activities. The objective of this study was to compare the functional outcomes of forearm fractures fixed with DCP and LC DCP.Methods: The present study was a hospital based study, and a prospective, comparative study. A total of 40 patients with fracture of both bones forearm were taken up for the study, and randomly divided into 2 groups of 20 patients each. They were followed up for a period of 1 year.Results: The majority of patients were males (31 males and 9 females), involving age group 21-30. The left side was more common than right in both groups. The site of fracture was middle one-third of forearm in both groups (60% in group A and 65% in group B). The time for union was on average 4 weeks for LC DCP and DCP. ROM was full in 85% in DCP group and 90% in LC DCP group. Overall results were comparable in both groups. Excellent in 34 cases (18 in LC DCP, 16 in DCP), satisfactory in 5 cases (2 in LC DCP, 3 in DCP) and unsatisfactory in one case treated with DCP.Conclusions: LC DCP provides slightly better functional outcome in terms of time taken for union, early mobilisation and range of motion. However, it is more expensive than DCP.
A computational assessment of the independent contribution of changes in canine trabecular bone volume fraction and microarchitecture to increased bone strength with suppression of bone turnover
This study addressed the effects of changes in trabecular microarchitecture induced by suppressed bone turnover—including changes to the remodeling space—on the trabecular bone strength–volume fraction characteristics independent of changes in tissue material properties. Twenty female beagle dogs, aged 1–2 years, were treated daily with either oral saline (n=10 control) or high doses of oral risedronate (0.5 mg/kg/day, n=10 suppressed) for a period of 1 year, the latter designed (and confirmed) to substantially suppress bone turnover. High-resolution micro-CT-based finite element models (18-μm voxel size) of canine trabecular bone cores (n=2 per vertebral body) extracted from the T-10 vertebrae were analyzed in both compressive and torsional loading cases. The same tissue-level material properties were used in all models, thus providing measures of tissue-normalized strength due only to changes in the microarchitecture. Suppressed bone turnover resulted in more plate-like architecture with a thicker and more dense trabecular structure, but the relationship between the microarchitectural parameters and volume fraction was unaltered (p>0.05). Though the suppressed group had a greater tissue-normalized strength as compared to the control group (p0.13) or torsion (p>0.09). In this high-density, non-osteoporotic animal model, the increases in tissue-normalized strength seen with suppression of bone turnover were entirely commensurate with increases in bone volume fraction and thus, no evidence of microarchitecture-related or “stress-riser” effects which may disproportionately affect strength were found
Diethyl 2-{[2-(trifluoromethyl)anilino]methylidene}propanedioate
The title compound, C15H16F3NO4, is an N-substituted derivative of ortho-trifluoromethylaniline featuring a twofold Michael system. The least-squares planes defined by the atoms of the phenyl ring and the atoms of the Michael system enclose an angle of 15.52 (5)°. Apart from classical intramolecular N—H⋯O and N—H⋯F hydrogen bonds, intermolecular C—H⋯O contacts are observed, the latter connecting the molecules into chains along [110]. The shortest intercentroid distance between two aromatic systems is 3.6875 (9) Å
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