Hasil untuk "physics.atm-clus"

Prasit Jiyapanichkul

Abstract In this paper, a network optimization model has been proposed as a tool that finds a VP pool which provides the maximum possible objective value. In the model, both virtual path connection (VPC) topology and VPC capacity allocation are solved at the same time, but also the current state of the network (number of connections in progress) is taken into an account to place constraints on the VP pool. The solution from the model automatically provides a set of VPCs and a capacity assignment which maximizes objective function value subject to the current network condition. As an application example, the model is used to manage the VP pool for a sample network subject to a major link failure. This illustrates the ability of the model to adapt rapidly and optimally to changing network conditions.

Azzeddine Zeraib, Lamia Boudjedjou, Naziha Suici et al.

Antibiotic resistance has been called one of the world’s most pressing public health threats. The combination of essential oils with conventional antibiotics is one of the emerging approaches that could help prevent this problem. In light of this, this study aimed to investigate the impact of combination of Ruta montana essential oil with conventional antibiotics on some pathogenic bacteria. The essential oil isolated by steam-hydrodistillation was first analyzed using GC-MS then tested alone and in combination with five recommended antibiotics against three bacterial strains by the agar disc diffusion and broth micro-dilution methods. Out of forty-nine peaks, thirty-eight components were identified representing 98.17% of the total oil composition. The major components were 2-Undecanone (63.39%), 2-Nonanone (5.65%), 2-Acetoxytetradecane (4.94%), 2-Decanone (4.47%) and 2-Dodecanone (3.35%). While R. montana essential oil showed only weak antibacterial activity compared to the antibiotics tested alone, unexpectedly, the combination of RM essential oil with antibiotics remarkably increased the antibacterial activity of the antibiotics through synergistic effects in up to 70% of cases. These results suggest that combining antibiotics with essential oils, even those with low antibacterial activity, may be effective in overcoming problems caused by increasing bacterial resistance.

R. K. Scott, A.-S. Tissier

The development of zonal flows on a midlatitude β-plane subject to a time-varying topographic forcing is investigated in a series of numerical integrations in which the forcing is concentrated at large scales, and in which the usual two-dimensional inverse energy cascade is absent. In contrast to the case of small-scale forcing, where mixing of potential vorticity occurs largely through the action of small-scale eddies, mixing of potential vorticity in this case occurs predominantly in latitudinally localized Rossby wave critical layer regions, whose width grows continuously in time due to the entrainment of background fluid. The potential vorticity is found to organize into a piecewise constant staircase-like profile, monotonic in latitude, provided the ratio \documentclass[12pt]{minimal}\begin{document}$L_\text{Rh}/L_f\gtrsim 1$\end{document}LRh/Lf≳1, where \documentclass[12pt]{minimal}\begin{document}$L_\text{Rh}$\end{document}LRh is the usual Rhines scale and Lf is the scale of the forcing; this may be regarded as supplemental to the condition \documentclass[12pt]{minimal}\begin{document}$L_\text{Rh}/L_{\varepsilon }\gtrsim 6$\end{document}LRh/Lɛ≳6, where Lɛ = (ɛ/β3)1/5 and ɛ is the rate of energy input, obtained recently [R. K. Scott and D. G. Dritschel, “The structure of zonal jets in geostrophic turbulence,” J. Fluid Mech. 711, 576–598 (2012)10.1017/jfm.2012.410] for the case of small-scale forcing. The numerical results further suggest that the nature of the potential vorticity mixing is controlled by the ratio Lɛ/Lf, and occurs predominantly in critical layers when Lɛ/Lf ≲ 1/6. A combined condition for staircase formation may therefore be expressed as \documentclass[12pt]{minimal}\begin{document}$L_\text{Rh}/L_{\varepsilon }\gtrsim \max \lbrace 6,L_f/L_{\varepsilon }\rbrace$\end{document}LRh/Lɛ≳max{6,Lf/Lɛ}. Finally, in a separate set of experiments it is shown that when forcing is represented by an additive source term in the evolution equation, as is common practice in numerical investigations of two-dimensional turbulence, the effect of non-conservation of potential vorticity may obscure the development of the staircase profile in the critical layer mixing dominated regime.

E. Oki, N. Yamanaka

C.H. Tse, B. Bensaou, K.C. Chua

A. Kassler, A. Lupper

I. Papaefstathiou

H.S. Yoon

F. Vakil

C.-M. Wu

T. Ludwig

D.J. Thorne

D.J. Shorrock

A. Rouz

Zhi Cui, Arne A. Nilsson

H. Kusano, T. Ohba, K. Miyake