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.

Collusive behaviour in finite repeated games with bonding

In finite repeated games, it is not possible to enforce collusive behaviour using deterrent strategies because of the "unraveling" of cooperative behaviour in the last period. This paper demonstrates that under certain conditions collusion among the players can be maintained if they can post a bond which they must forfeit if they defect from the cooperative mode. We show that the incentives to cooperate increase as the period of interaction grows in that the size of the bond required to deter defection becomes arbitrarily small as the number of periods in the game increases

Elucidation of genetic diversity through Multivariate analysis in brinjal (Solanum melongena L.) landraces for varietal improvement

Genetic diversity plays a crucial role in harnessing the potential of crop genotypes for genetic improvement. It helps to identify, preserve, and utilize diverse landraces effectively. This research aimed to assess the level of genetic diversity and traits enhancing genetic variation among 46 brinjal genotypes (Solanum melongena L.) in preparation for a special breeding programme to utilize the potential landraces. Genetic divergence among 46 genotypes of brinjal for eleven characters was assessed using the D2 method. The studied genotypes were categorized into eight clusters. Cluster I with 15 genotypes was the largest followed by Cluster IV (14 genotypes), Cluster V (7 genotypes), Cluster VII (4 genotypes), Cluster III (3 genotypes), Clusters II, VI, and VIII with one genotype each. The intra-cluster D2 values ranged from 0.00 (Cluster II, VI and VII) to 103.53 (Cluster III). The inter-cluster distances varied from 117.00 to 791.17. Cluster II and Cluster VII had the greatest inter-cluster distance (791.17), followed by Cluster II and VIII (673.41), and Cluster VII and Cluster V had the smallest inter-cluster distance (117.00). Crossing genotypes in clusters with wide inter-cluster distances improves recombinant isolation in segregating generations. The three traits- number of flowers per inflorescence (23.8%), average fruit weight (17.68%) and days to first flowering (16.81%) altogether contribute to 57.8% of the total divergence. The combination of these traits could be useful to produce high-yielding climate resilient varieties from valuable landraces

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

Collusive behaviour in finite repeated games with bonding

In finite repeated games, it is not possible to enforce collusive behaviour using deterrent strategies because of the "unraveling" of cooperative behaviour in the last period. This paper demonstrates that under certain conditions collusion among the players can be maintained if they can post a bond which they must forfeit if they defect from the cooperative mode. We show that the incentives to cooperate increase as the period of interaction grows in that the size of the bond required to deter defection becomes arbitrarily small as the number of periods in the game increases

Effects of suppression of bone turnover on cortical and trabecular load sharing in the canine vertebral body

The relative biomechanical effects of antiresorptive treatment on cortical thickness vs. trabecular bone microarchitecture in the spine are not well understood. To address this, T-10 vertebral bodies were analyzed from skeletally mature female beagle dogs that had been treated with oral saline (n=8 control) or a high dose of oral risedronate (0.5 mg/kg/day, n=9 RIS-suppressed) for 1 year. Two linearly elastic finite element models (36-μm voxel size) were generated for each vertebral body—a whole-vertebra model and a trabecular-compartment model—and subjected to uniform compressive loading. Tissue-level material properties were kept constant to isolate the effects of changes in microstructure alone. Suppression of bone turnover resulted in increased stiffness of the whole vertebra (20.9%, p=0.02) and the trabecular compartment (26.0%, p=0.01), while the computed stiffness of the cortical shell (difference between whole-vertebra and trabecular-compartment stiffnesses, 11.7%, p=0.15) was statistically unaltered. Regression analyses indicated subtle but significant changes in the relative structural roles of the cortical shell and the trabecular compartment. Despite higher average cortical shell thickness in RIS-suppressed vertebrae (23.1%, p=0.002), the maximum load taken by the shell for a given value of shell mass fraction was lower (p=0.005) for the RIS-suppressed group. Taken together, our results suggest that—in this canine model—the overall changes in the compressive stiffness of the vertebral body due to suppression of bone turnover were attributable more to the changes in the trabecular compartment than in the cortical shell. Such biomechanical studies provide an unique insight into higher-scale effects such as the biomechanical responses of the whole vertebra

Dust in Brown Dwarfs IV. Dust formation and driven turbulence on mesoscopic scales

Dust formation in brown dwarf atmospheres is studied by utilising a model for driven turbulence in the mesoscopic scale regime. We apply a pseudo-spectral method where waves are created and superimposed within a limited wavenumber interval. The turbulent kinetic energy distribution follows the Kolmogoroff spectrum which is assumed to be the most likely value. Such superimposed, stochastic waves may occur in a convectively active environment. They cause nucleation fronts and nucleation events and thereby initiate the dust formation process which continues until all condensible material is consumed. Small disturbances are found to have a large impact on the dust forming system. An initially dust-hostile region, which may originally be optically thin, becomes optically thick in a patchy way showing considerable variations in the dust properties during the formation process. The dust appears in lanes and curls as a result of the interaction with waves, i.e. turbulence, which form larger and larger structures with time. Aiming on a physical understanding of the variability of brown dwarfs, related to structure formation in substellar atmospheres, we work out first necessary criteria for small-scale closure models to be applied in macroscopic simulations of dust forming astrophysical systems.Comment: A&A accepted, 20 page