Impact of Inter-Country Distances on International Tourism

Tourism is a worldwide practice with international tourism revenues increasing from US\$495 billion in 2000 to US\$1340 billion in 2017. Its relevance to the economy of many countries is obvious. Even though the World Airline Network (WAN) is global and has a peculiar construction, the International Tourism Network (ITN) is very similar to a random network and barely global in its reach. To understand the impact of global distances on local flows, we map the flow of tourists around the world onto a complex network and study its topological and dynamical balance. We find that although the WAN serves as infrastructural support for the ITN, the flow of tourism does not correlate strongly with the extent of flight connections worldwide. Instead, unidirectional flows appear locally forming communities that shed light on global travelling behaviour inasmuch as there is only a 15% probability of finding bidirectional tourism between a pair of countries. We conjecture that this is a consequence of one-way cyclic tourism by analyzing the triangles that are formed by the network of flows in the ITN. Finally, we find that most tourists travel to neighbouring countries and mainly cover larger distances when there is a direct flight, irrespective of the time it takes

Goertler instability in compressible boundary layers along curved surfaces with suction and cooling

The Goertler instability of the laminar compressible boundary layer flows along concave surfaces is investigated. The linearized disturbance equations for the three-dimensional, counter-rotating streamwise vortices in two-dimensional boundary layers are presented in an orthogonal curvilinear coordinate. The basic approximation of the disturbance equations, that includes the effect of the growth of the boundary layer, is considered and solved numerically. The effect of compressibility on critical stability limits, growth rates, and amplitude ratios of the vortices is evaluated for a range of Mach numbers for 0 to 5. The effect of wall cooling and suction of the boundary layer on the development of Goertler vortices is investigated for different Mach numbers

Surgical technique for arthroscopic onlay suprapectoral biceps tenodesis with an all-suture anchor.

The long head of the biceps is a frequent pain generator in the shoulder. Tendinopathy of the long head of the biceps may be treated with biceps tenodesis. There has been great debate about the optimal technique for biceps tenodesis, without a clear distinction between different techniques. Biceps tenodesis fixation may include interference fixation, suspensory fixation, all-suture anchors, and soft tissue fixation. In this technical note, we describe an all-arthroscopic onlay suprapectoral biceps tenodesis with an all-suture anchor

Computation of Kolmogorov's Constant in Magnetohydrodynamic Turbulence

In this paper we calculate Kolmogorov's constant for magnetohydrodynamic turbulence to one loop order in perturbation theory using the direct interaction approximation technique of Kraichnan. We have computed the constants for various $E^u(k)/E^b(k)$, i.e., fluid to magnetic energy ratios when the normalized cross helicity is zero. We find that $K$ increases from 1.47 to 4.12 as we go from fully fluid case $(E^b=0)$ to a situation when $E^u/E^b=0.5$, then it decreases to 3.55 in a fully magnetic limit $(E^u=0)$. When $E^u/E^b=1$, we find that $K=3.43$.Comment: Latex, 10 pages, no figures, To appear in Euro. Phys. Lett., 199

Interval structure of the Pieri formula for Grothendieck polynomials

We give a combinatorial interpretation of a Pieri formula for double Grothendieck polynomials in terms of an interval of the Bruhat order. Another description had been given by Lenart and Postnikov in terms of chain enumerations. We use Lascoux's interpretation of a product of Grothendieck polynomials as a product of two kinds of generators of the 0-Hecke algebra, or sorting operators. In this way we obtain a direct proof of the result of Lenart and Postnikov and then prove that the set of permutations occuring in the result is actually an interval of the Bruhat order.Comment: 27 page

Photoluminescence, photoredox properties and crystal structures of rhenium(v)-benzylidyne complex with phosphine ligands.

Several rhenium(v)-benzylidyne complexes [Re(CR)(pdpp)2Cl]+[R=C6H2Me3-2,4,6,pdpp= o-phenylenebis(diphenylphosphine)], [Re(CR)L2(CO)(H2O)Cl]+ [L=PPh3, P(C6H4OMe-p)3 or PMe2Ph] and trans-[Re(CR)(dppe)(CO)2Cl]+ [dppe= 1,2-bis(diphenylphosphino)ethane] have been prepared. The structures of trans-Re(CR)(pdpp)2Cl]ClO4.CHCl3.0.25MeOH and [Re(CR)(PPh3)2 (CO)(H2O)Cl]ClO4. 1.5MeOH have been determined by X-ray analyses. The Re≡C distances are 1.802(5) and 1.784(8) Å respectively. In acetonitrile and dichloromethane the complexes show intense absorption bands at 318-330 nm and weak ones at 405-450 nm, the latter being tentatively assigned to dxy → dn* (dxz,dyz) transitions. Photoexcitation in the solution, solid or glassy state gives intense orange to red emissions, and the emitting states are tentatively assigned to 3[(dxy)1](dπ*)1]. The variation in non-radiative decay rate constants for the emissions of the rhenium(v)-benzylidyne complexes are consistent with a predication from the energy-gap law. The excited states are better oxidants and reductants than the grounds states. The values of E°(Rev*-ReIV ) and E° (ReVI-ReV*) in acetonitrile have been determined using spectroscopic and electrochemical data as well as by Stern-Volmer  quenching experiments