Comments on the Refractive Index of Tin Sulphide Nano-crystalline Thin Films

The refractive indices of nano-crystalline thin films of Tin (IV) Sulphide (SnS) were investigated here. The experimental data conformed well with the single oscillator model for refractive indices. Based on the this, we explain the increasing trend of refractive index to the improvement in crystal ordering with increasing grain size.Comment: Nine figure

Breakup length on Urea Water Solution jet in hot cross flow

[EN] Selective Catalytic Reduction (SCR) using Urea-Water Solution (UWS) as an ammonia precursor is considered as one of the best choices to meet the current stringent emission norms for reduction of NOX in diesel engines. UWS sprayed in the engine exhaust line forms ammonia, and this ammonia reduces NOX into nitrogen. The NOX reduction efficiency depends on the mixing and evaporation behavior of the UWS spray in the hot exhaust gas. Spray characteristics decide the evaporation rate and hence the NOX reduction efficiency. The spray structure is closely related to the breakup point and breakup mode of the jet. Hence, in this study, breakup length and breakup mode were investigated by injecting UWS (32.5 % by weight) through a nozzle in a hot air cross flow. A CCD camera and pulsed Nd:Yag laser were used for capturing the images. Experiments were conducted with varying nozzle size (150, 250 and 400 micron), injection pressure (0.5 to 3 bar), temperature (32 °C,150 °C and 200 °C) and air flow rate. The effect of operating parameters (nozzle size, injection pressure, air temperature and velocity) in terms of dimensionless numbers (Weber number and momentum flux ratio) on jet breakup mode and jet breakup length was studied. It was observed that the breakup length for UWS was close to that of water. The jet breakup length increases with momentum flux ratio since a jet having a higher momentum is able to penetrate a larger distance in the cross flow. Increasing the air temperature increases the velocity of the cross flow and hence reduces the breakup length. A correlation for jet breakup length was developed. The effect of inclusion of Weber number in the breakup length correlation, in addition to the momentum flux ratio, was studied. Visual observation shows that droplet sizes obtained from the plain orifice injector without preheating is large. Preheating the UWS before injection is recommended to reduce the droplet size.P, S.; Bakshi, S.; T.n.c, A. (2017). Breakup length on Urea Water Solution jet in hot cross flow. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 838-845. https://doi.org/10.4995/ILASS2017.2017.4982OCS83884

Parallel algorithm with spectral convergence for nonlinear integro-differential equations

We discuss a numerical algorithm for solving nonlinear integro-differential equations, and illustrate our findings for the particular case of Volterra type equations. The algorithm combines a perturbation approach meant to render a linearized version of the problem and a spectral method where unknown functions are expanded in terms of Chebyshev polynomials (El-gendi's method). This approach is shown to be suitable for the calculation of two-point Green functions required in next to leading order studies of time-dependent quantum field theory.Comment: 15 pages, 9 figure

Weighted Maximum Independent Set of Geometric Objects in Turnstile Streams

We study the Maximum Independent Set problem for geometric objects given in the data stream model. A set of geometric objects is said to be independent if the objects are pairwise disjoint. We consider geometric objects in one and two dimensions, i.e., intervals and disks. Let $\alpha$ be the cardinality of the largest independent set. Our goal is to estimate $\alpha$ in a small amount of space, given that the input is received as a one-pass stream. We also consider a generalization of this problem by assigning weights to each object and estimating $\beta$, the largest value of a weighted independent set. We initialize the study of this problem in the turnstile streaming model (insertions and deletions) and provide the first algorithms for estimating $\alpha$ and $\beta$. For unit-length intervals, we obtain a $(2+\epsilon)$-approximation to $\alpha$ and $\beta$ in poly$(\frac{\log(n)}{\epsilon})$ space. We also show a matching lower bound. Combined with the $3/2$-approximation for insertion-only streams by Cabello and Perez-Lanterno [CP15], our result implies a separation between the insertion-only and turnstile model. For unit-radius disks, we obtain a $\left(\frac{8\sqrt{3}}{\pi}\right)$-approximation to $\alpha$ and $\beta$ in poly$(\log(n), \epsilon^{-1})$ space, which is closely related to the hexagonal circle packing constant. We provide algorithms for estimating $\alpha$ for arbitrary-length intervals under a bounded intersection assumption and study the parameterized space complexity of estimating $\alpha$ and $\beta$, where the parameter is the ratio of maximum to minimum interval length.Comment: The lower bound for arbitrary length intervals in the previous version contains a bug, we are updating the submission to reflect thi

External Factors Affecting Gastrointestinal Barrier and Mucosal Immunity at High Altitude

High altitude regions above 2,700 meters pose unique physiological challenges to travellers, including hypoxia caused by decreased oxygen levels. Gastrointestinal issues such as nausea, vomiting, and anorexia are common in high altitude sojourners. The gastrointestinal barrier is composed of epithelial cells connected with tight junctions, desmosomes, and covered with a thick layer of mucous. The mucosal and immunological barriers work together to regulate intestinal homeostasis and prevent harmful pathogens from entering the system. Any damage to the gastrointestinal barrier can lead to an increase in permeability which can cause harmful microbial toxins and unwanted substances to enter the bloodstream, triggering an inflammatory response. External factors such as hypoxia and intense physical workouts at high altitude can disrupt the barrier and lead to inflammation and microbial dysbiosis, which changes the normal population of gut microbiota and can cause gastrointestinal discomfort. This review aims to examine the effects of these external factors on the gastrointestinal barrier and highlights the importance of therapeutic and dietary interventions to manage high altitude induced mucosal barrier dysfunction and restore immunological homeostasis of the gut

1+1 Dimensional Compactifications of String Theory

We argue that stable, maximally symmetric compactifications of string theory to 1+1 dimensions are in conflict with holography. In particular, the finite horizon entropies of the Rindler wedge in 1+1 dimensional Minkowski and anti de Sitter space, and of the de Sitter horizon in any dimension, are inconsistent with the symmetries of these spaces. The argument parallels one made recently by the same authors, in which we demonstrated the incompatibility of the finiteness of the entropy and the symmetries of de Sitter space in any dimension. If the horizon entropy is either infinite or zero the conflict is resolved.Comment: 11 pages, 2 figures v2: added discussion of AdS_2 and comment