19,750 research outputs found
Brudno's theorem for Z(d) (or Z(+)(d)) subshifts
No full textWe generalize Brudno's theorem of 1-dimensional shift dynamical system to Z(d) (or Z(+)(d)) subshifts. That is to say, in Zd (or Z(+)(d) subshift, the Kolmogorov-Sinai entropy is equivalent to the Kolmogorov complexity density almost everywhere for an ergodic shift-invariant measure. (C) 2017 Elsevier Inc. All rights reserved
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Z(c)(3900) as a (D)over-barD* molecule from the pole counting rule
No full textA comprehensive study on the nature of the Zc(3900) resonant structure is carried out in this work. By constructing the pertinent effective Lagrangians and considering the important final-state-interaction effects, we first give a unified description to all the relevant experimental data available, including the J/psi pi and pi invariant mass distributions from the e(+)e(-) -> J/psi pi process, the h(c)pi distribution from e(+)e(-) -> h(c)pi pi, and also the D (D) over bar* spectrum in the e(+)e(-) -> D (D) over bar*pi process. After fitting the unknown parameters to the previous data, we search the pole in the complex energy plane and find only one pole in the nearby energy region in different Riemann sheets. Therefore, we conclude that Z(c)(3900) is of D (D) over bar* molecular nature, according to the pole counting rule method [Nucl. Phys. A543, 632 (1992); Phys. Rev. D 35, 1633 (1987)]. We emphasize that the conclusion based upon the pole counting method is not trivial, since both the D (D) over bar* contact interactions and the explicit Z(c) exchanges are introduced in our analyses andNational Nature Science Foundations of China (NSFC) [10925522, 11021092, 11575052, 11105038]; Natural Science Foundation of Hebei Province [A2015205205]; inoGerman Collaborative Research Center "Symmetries and the Emergence of Structure in QCD" [CRC 110]; DFG; NSFCSCI(E)ARTICLE119
Two-body open charm decays of Z(+)(4430)
No full textThe two-body open charm decays Z(+)(4430)-> D(+)(D) over bar*(0), D*(+)(D) over bar (0), D*(+)(D) over bar*(0) occur through the rescattering mechanism and their branching ratios are strongly suppressed if Z(+)(4430) is a D(1)(D) over bar* molecular state. In contrast, Z(+)(4430) falls apart into these modes easily with large phase space and they become the main decay modes if Z(+)(4430) is a tetraquark state. Experimental search of these two-body open charm modes and the hidden charm mode chi(cJ)rho will help distinguish different theoretical schemes.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)0ARTICLE11null7
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Statistics of the subgrid scales after the shock-turbulence interaction
No full textThe interaction of a normal shock with isotropic turbulence (IT) represents a basic problem for studying some of the phenomena associated with high speed flows, such as hypersonic flight, supersonic combustion and Inertial Confinement Fusion (ICF). In general, in practical applications, the shock width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J. Fluid Mech., 756, R1, 2014) show that the interaction can be described by the Linear Interaction Approximation (LIA). By using LIA to alleviate the need to solve the shock, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number around are used to investigate the properties of the subgrid scales (SGS). In particular, it is shown that the shock interaction decreases the asymmetry of the SGS dissipation PDF as the shock Mach number increases, with a significant enhancement in size of the regions and magnitude of backscatter
Working Paper 37 - The Formation of Human Capital and the Economic Development of Africa: Returns to Health and Schooling Investments
No full textThis paper first outlines a framework within which to assess the contribution of health and schooling to increasing individual and aggregate income, as well as the possible feedback of increasing income on the demand for human resources. It then evaluates how African countries have fared from 1970 to 1985 in terms of survival and schooling, compared with other countries, to place in perspective areas of achievement and the aggregate composition of human capital formation in the African region. Several microeconomic studies are then described in more detail that illustrate the magnitudes of private returns to health and schooling in West Africa, some of the consequences of the rationed supply of schooling in South Africa, and evidence of returns to the quality of schooling. The concluding section extracts lessons as to how to conduct country-specific research based on merged household and community surveys to estimate the key parameters describing the private and social returns to marginal investments in health, education, and mobility.
Positron beam study of annealed silicon nitride films
No full textPositron annihilation spectroscopy has been used to study silicon nitride films grown by plasma-enhanced chemical vapor deposition and annealed at different temperatures. For both silicon-rich and nitrogen-rich films, the positron line shape (S) parameter increases after annealing for 15 min at temperatures up to 700-800 degrees C. This is understood in terms of the fact that removal of the hydrogen by annealing leads to the presence of unpassivated silicon dangling bond sites and vacancy complexes. Annealing at higher temperatures leads to a reduction in the S parameter, consistent with further hydrogen removal producing unpassivated N- sites. (C) 1996 American Institute of Physics.PT: J; CR: ASOKAKUMAR P, 1994, J APPL PHYS, V76, P4935 GOLDBERG RD, 1995, APPL SURF SCI, V85, P287 GOSSMANN HJ, 1992, APPL PHYS LETT, V61, P540 HABRAKEN FHP, 1991, LPCVD SILICON NITRID, P118 HAKVOORT RA, 1991, APPL PHYS LETT, V59, P1687 HAKVOORT RA, 1993, THESIS DELFT U TECHN HEYNS M, 1991, LPCVD SILICON NITRID, P82 LANDFORD WA, 1978, J APPL PHYS, V49, P2473 LANDFORD WA, 1992, NUCL INSTRUM METH B, V66, P65 LANDHEER D, 1995, J APPL PHYS, V78, P2568 LU Z, 1995, J VAC SCI TECHNOL 1, V13, P607 LYNN KG, 1989, CAN J PHYS, V67, P618 MITCHELL LV, 1990, AIP C P, V218, P121 PEROVIC DD, 1991, PHYS REV B, V43, P14257 RUBLOFF GW, 1990, VACUUM, V41, P790 SCHULTZ PJ, 1988, NUCL INSTRUM METH B, V30, P94 SCHULTZ PJ, 1988, PHYS REV LETT, V61, P187 SCHULTZ PJ, 1988, REV MOD PHYS, V60, P701 SIMPSON PJ, 1991, PHYS REV B, V44, P12180 SMITH DL, 1990, J ELECTROCHEM SOC, V137, P614 SMITH DL, 1990, MATER RES SOC S P, V165, P69; NR: 21; TC: 1; J9: J APPL PHYS; PG: 5; GA: TY119Source type: Electronic(1
Hidden-charm tetraquarks and charged Z(c) states
No full textExperimentally several charged axial-vector hidden-charm states were reported. Within the framework of the color-magnetic interaction, we have systematically considered the mass spectrum of the hidden-charm and hidden-bottom tetraquark states. It is impossible to accommodate all of the three charged states Z(c)(3900), Z(c)(4025), and Z(c)(4200) within the axial-vector tetraquark spectrum simultaneously. Not all of these three states are tetraquark candidates. Moreover, the eigenvector of the chromomagnetic interaction contains valuable information of the decay pattern of the tetraquark states. The dominant decay mode of the lowest axial-vector tetraquark state is J/psi pi while its D*(D) over bar and (D) over bar *D* modes are strongly suppressed, which is in contrast with the fact that the dominant decay mode of Z(c)(3900) and Z(c)(4025) is (D) over barD* and (D) over bar *D*, respectively. We emphasize that all the available experimental information indicates that Z(c)(4200) is a very promising candidate of the lowest axial-vector hidden-charm tetraquark state.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000345662400003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)[email protected]; [email protected]; [email protected]
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