On stability of stiffened cylindrical shells with varying material properties

The static stability analysis of stiffened functionally graded cylindrical shells by isotropic rings and stringers subjected to axial compression is presented in this paper. The Young's modulus of the shell is taken to be function of the thickness coordinate. The fundamental relations, the equilibrium and stability equations are derived using the Sander's assumption. Resulting equations are employed to obtain the closed-form solution for the critical axial loads. The effects of material properties, geometric size and different material coefficient on the critical axial loads are examined. The analytical results are compared and validated using the finite element model

The correlation between biofilm formation capability and antibiotic resistance pattern in Pseudomonas aeruginosa

The infections caused by Pseudomonas aeruginosa are life-threatening, due to high intrinsic antimicrobial resistance of this microorganism. The integrons and biofilm formation of P. aeruginosa have a significant role in antibiotic resistance. Therefore, this study aimed to evaluate antibiotic resistance pattern in Pseudomonas aeruginosa isolates with biofilm formation ability. This cross-sectional study from January 2017 to December 2017 was conducted on 78 isolates (58 clinical and 20 environmental) of P. aeruginosa recovered from the 547 samples (439 of clinical and 108 of environmental samples). The isolates were identified by phenotypic and genotypic tests. Kirby-Bauer disk diffusion method was used for susceptibility testing. The prevalence of class 1, 2 and 3 Integrons, rhlA, and lasB genes were determined using Polymerase Chain Reaction (PCR). Biofilm formation was determined using the microtiter plate method. Data analyzed using Stata 14 software and Chi-Square test. The most prevalent resistance was observed against Ticarcillin/Clavulanic Acid (55). Generally, 56.4 of isolates were producers of strong biofilm in both environmental and clinical isolates. The prevalence of strong biofilm producers in clinical isolates was more than environmental. A significant correlation was observed between Int1, Int2, and rhlA genes with biofilm formation capability (P = 0.02). Regarding >50 of both environmental and clinical isolates were producers of strong biofilm and because the source of clinical isolates may be from the environment, the necessary hygiene measurements should be taken. No significant correlation was observed between lasB gene with biofilm formation capability. © 2019 Elsevier Inc

Growth factor in f(T) gravity

We derive the evolution equation of growth factor for the matter over-dense perturbation in $f(T)$ gravity. For instance, we investigate its behavior in power law model at small redshift and compare it to the prediction of $\Lambda$CDM and dark energy with the same equation of state in the framework of Einstein general relativity. We find that the perturbation in $f(T)$ gravity grows slower than that in Einstein general relativity if \p f/\p T>0 due to the effectively weakened gravity.Comment: 15 pages,1 figure; v2,typos corrected; v3, discussions added, accepted by JCA

Interacting entropy-corrected new agegraphic dark energy in Brans-Dicke cosmology

Motivated by a recent work of one of us [1], we extend it by using quantum (or entropy) corrected new agegraphic dark energy in the Brans-Dicke cosmology. The correction terms are motivated from the loop quantum gravity which is one of the competitive theories of quantum gravity. Taking the non-flat background spacetime along with the conformal age of the universe as the length scale, we derive the dynamical equation of state of dark energy and the deceleration parameter. An important consequence of this study is the phantom divide scenario with entropy-corrected new agegraphic dark energy. Moreover, we assume a system of dark matter, radiation and dark energy, while the later interacts only with dark matter. We obtain some essential expressions related with dark energy dynamics. The cosmic coincidence problem is also resolved in our model.Comment: 16 pages, no figure, accepted for publication in Gen. Relativ. Gra

Genotypes performance in relation to drought tolerance in barley using multi-environment trials

ArticleThe selection of stable and superior genotypes, with the aim of improving grain yield in breeding programs, requires the evaluation of genotypes under different environments. In this study, the yields of 10 barley genotypes were evaluated in eight different environments using a graphical method (GGE biplot). These experiments were conducted from 2011 to 2015. There were irrigated and rain-fed conditions, as a randomized complete block design (RCBD) with three replications. Results indicated that the two components of PC1 and PC2 explained 62.9% and 14.9% of the total variation observed in the yield, respectively. Genotypes with a positive value for PC1 (i.e., PC1 > 0) had the adaptable and the highest performance, whereas genotypes with a negative value for the first component (i.e., PC1 < 0) were non-adaptable and had the lowest performance. Likewise, among the genotypes, some had their second component scores near zero, and they exhibited the greatest stability compared to other genotypes. Specifically, genotype 3 had the highest grain yield and stability, while genotypes 2 and 8 showed relatively high yields

On the climatological probability of the vertical propagation of stationary planetary waves

We introduce a diagnostic tool to assess a climatological framework of the optimal propagation conditions for stationary planetary waves. Analyzing 50 winters using NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) reanalysis data we derive probability density functions (PDFs) of positive vertical wave number as a function of zonal and meridional wave numbers. We contrast this quantity with classical climatological means of the vertical wave number. Introducing a membership value function (MVF) based on fuzzy logic, we objectively generate a modified set of PDFs (mPDFs) and demonstrate their superior performance compared to the climatological mean of vertical wave number and the original PDFs. We argue that mPDFs allow an even better understanding of how background conditions impact wave propagation in a climatological sense. As expected, probabilities are decreasing with increasing zonal wave numbers. In addition we discuss the meridional wave number dependency of the PDFs which is usually neglected, highlighting the contribution of meridional wave numbers 2 and 3 in the stratosphere. We also describe how mPDFs change in response to strong vortex regime (SVR) and weak vortex regime (WVR) conditions, with increased probabilities of the wave propagation during WVR than SVR in the stratosphere. We conclude that the mPDFs are a convenient way to summarize climatological information about planetary wave propagation in reanalysis and climate model data

Reconstructing interacting new agegraphic polytropic gas model in non-flat FRW universe

We study the correspondence between the interacting new agegraphic dark energy and the polytropic gas model of dark energy in the non-flat FRW universe. This correspondence allows to reconstruct the potential and the dynamics for the scalar field of the polytropic model, which describe accelerated expansion of the universe.Comment: 9 page

Restoring New Agegraphic Dark Energy in RS II Braneworld

Motivated by recent works [1,2], we investigate new agegraphic model of dark energy in the framework of RS II braneworld. We also include the case of variable gravitational constant in our model. Furthermore, we establish correspondence between the new agegraphic dark energy with other dark energy candidates based on scalar fields.Comment: 13 pages, accepted for publication in IJT

Modelled thermal and dynamical responses of the middle atmosphere to EPP-induced ozone changes

Energetic particles including protons, electrons and heavier ions, enter the Earth\u27s atmosphere over the polar regions of both hemispheres, where they can greatly disturb the chemical composition of the upper and middle atmosphere and contribute to ozone depletion in the stratosphere and mesosphere. The chemistry–climate general circulation model EMAC is used to investigate the impact of changed ozone concentration due to Energetic Particle Precipitation (EPP) on temperature and wind fields. The results of our simulations show that ozone perturbation is a starting point for a chain of processes resulting in temperature and circulation changes over a wide range of latitudes and altitudes. In both hemispheres, as winter progresses the temperature and wind anomalies move downward with time from the mesosphere/upper stratosphere to the lower stratosphere. In the Northern Hemisphere (NH), once anomalies of temperature and zonal wind reach the lower stratosphere, another signal develops in mesospheric heights and moves downward. Analyses of Eliassen and Palm (EP) flux divergence show that accelerating or decelerating of the stratospheric zonal flow is in harmony with positive and negative anomalies of the EP flux divergences, respectively. This results suggest that the oscillatory mode in the downwelling signal of temperature and zonal wind in our simulations are the consequence of interaction between the resolved waves in the model and the mean stratospheric flow. Therefore, any changes in the EP flux divergence lead to anomalies in the zonal mean zonal wind which in turn feed back on the propagation of Rossby waves from the troposphere to higher altitudes. The analyses of Rossby waves refractive index show that the EPP-induced ozone anomalies are capable of altering the propagation condition of the planetary-scale Rossby waves in both hemispheres. It is also found that while ozone depletion was confined to mesospheric and stratospheric heights, but it is capable to alter Rossby wave propagation down to tropospheric heights. In response to an accelerated polar vortex in the Southern Hemisphere (SH) late wintertime, we found almost two weeks delay in the occurrence of mean dates of Stratospheric Final Warming (SFW). These results suggest that the stratosphere is not merely a passive sink of wave activity from below, but it plays an active role in determining its own budget of wave activity