2,438 research outputs found
Length-weight relationships of coral reef fishes from the Alacran Reef, Yucatan, Mexico
Length-weight relationships were computed for 42 species of coral reef fishes from 14 families from the Alacran Reef (Yucatan, Mexico). A total of 1 892 individuals was used for this purpose. The fish species were caught by different fishing techniques such as fishhooks, harpoons, gill and trawl nets. The sampling period was from March 1998 to January 2000
Viscosity and tribology of copper oxide nanofluids
Nanofluids, a term proposed by Choi in 1995 [1], are composites consisting of solid nanoparticles with sizes varying generally from 1 to 100 nm dispersed in a liquid. Numerous nanoparticles used as oil additives have been investigated in recent years [2-7]. Results show that they deposit on the rubbing surface and improve the tribological properties of the base oil, displaying good friction and wear reduction characteristics even at concentrations below 2%wt. Although the viscosity of the nanofluids is a property of crucial importance for film forming, and hence friction and wear reduction, which are characteristic of lubricants, only Hwang et al. [8] have studied thermal characteristics, kinematic viscosity and tribological properties of nanofluids simultaneously. In this paper, we present measurements of dynamic viscosity of nanofluids formed by copper oxide nanoparticles dispersed in a polyalphaolefin, for temperatures and concentrations varying from 20 to 60ÂșC and 0.5 to 2% wt., respectively. Dependence of the nanofluid viscosity to the solid fraction and temperature was compared with existing models and its influence on lubrication was also analysed
The New Contact Binary GSC 2414-0797
Original article can be found at: http://www.konkoly.hu/ibvs/GSC 2414-0797 has a contact binary star type light curve, a 0.4 magnitude brightness variation with a period 0.3406 days.Peer reviewe
Geometric Integration of Hamiltonian Systems Perturbed by Rayleigh Damping
Explicit and semi-explicit geometric integration schemes for dissipative
perturbations of Hamiltonian systems are analyzed. The dissipation is
characterized by a small parameter , and the schemes under study
preserve the symplectic structure in the case . In the case
the energy dissipation rate is shown to be asymptotically
correct by backward error analysis. Theoretical results on monotone decrease of
the modified Hamiltonian function for small enough step sizes are given.
Further, an analysis proving near conservation of relative equilibria for small
enough step sizes is conducted.
Numerical examples, verifying the analyses, are given for a planar pendulum
and an elastic 3--D pendulum. The results are superior in comparison with a
conventional explicit Runge-Kutta method of the same order
Fermi Liquid Properties of a Two Dimensional Electron System With the Fermi Level Near a van Hove Singularity
We use a diagrammatic approach to study low energy physics of a two
dimensional electron system where the Fermi level is near van-Hove singularies
in the energy spectrum. We find that in most regions of the
phase diagram the system behaves as a normal Fermi liquid rather than a
marginal Fermi liquid. Particularly, the imaginary part of the self energy is
much smaller than the excitation energy, which implies well defined
quasiparticle excitations, and single particle properties are only weakly
affected by the presence of the van-Hove singularities. The relevance to high
temperature superconductivity is also discussed.Comment: 10 pages, 4 postscript figure
Larvae of the blue crab Callinectes sapidus Rathbun, 1896 (Decapoda: Brachyura: Portunidae) in the Balearic Archipelago (NW Mediterranean Sea)
The invasive blue crab Callinectes sapidus has been frequently recorded during the last years along the NW Mediterranean Sea, leading to established populations. Two megalopae of C. sapidus were found during two different oceanographic surveys in open waters of the Balearic Archipelago, in July 2005 and October 2011, previous to the first reference of adult specimens documented in the Balearic sub-basin. The analyzed environmental conditions of the sampling periods allowed us to hypothesize the likely introduction pathways, namely by maritime transport and surface currents. Furthermore, the recorded megalopae seem to enlarge the life history of C. sapidus in regard to its native area, where spawning peaks occur in late July and early August.VersiĂłn del editor
RVB Contribution to Superconductivity in
We view as electronically equivalent to (non-staggered) graphite
( layer) that has undergone a zero gap semiconductor to a superconductor
phase transition by a large c-axis (chemical) pressure due to layers.
Further, like the \ppi bonded planar organic molecules, graphite is an old
resonating valence bond (RVB) system. The RVB's are the `preexisting cooper
pairs' in the `parental' zero gap semiconducting (graphite) sheets that
manifests themselves as a superconducting ground state of the transformed
metal. Some consequences are pointed out.Comment: 4 pages, 2 figure, RevTex. Based on a talk given at the Institute
Seminar Week, IMSc, Madras (12-16, Feb. 2001
Assessment of CD-105 as an Angiogenic Modulator in Odontogenic Myxomas and Dental Follicles
Aim. Odontogenic myxoma is a benign intraosseous neoplasm of the jaws, with a locally aggressive behavior and a high
recurrence rate. CD-105 is a homodimeric cell membrane glycoprotein and is a component of the TGF-ÎČ1 growth factor
receptor complex that modulates angiogenesis by regulating the proliferation, differentiation and cellular migration.
The aim of this study is to quantify the microvascular density of the odontogenic myxoma based on the expression of
CD-105. Materials and Methods. The analysis included 18 odontogenic myxoma and 18 dental follicles as controls. A
standard immunohistochemical procedure was performed with the CD-105 antibody. Five representative fields (40Ă)
of the odontogenic myxoma and the dental follicles were selected to determine the microvascular density, which was
then followed by a descriptive and comparative statistical analysis. Results. Dental follicles presented a significantly higher
microvascular density compared with odontogenic myxoma (P = .001). The odontogenic myxoma smaller than 3 cm
showed a greater microvascular density than those larger than 3 cm in size (P > .05), and the microvascular density was
lower in large odontogenic myxomas as compared with the dental follicles (P = .003). Conclusion. A weaker expression
of CD-105 in odontogenic myxoma might indicate a lower angiogenic activity, suggesting that vascular proliferation has
a limited role in the growth mechanisms and in the aggressive behavior of this neoplasm.peer-reviewe
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