13,301 research outputs found
Southern Sky Redshift Survey: Clustering of Local Galaxies
We use the two-point correlation function to calculate the clustering
properties of the recently completed SSRS2 survey. The redshift space
correlation function for the magnitude-limited SSRS2 is given by xi(s)=(s/5.85
h-1 Mpc)^{-1.60} for separations between 2 < s < 11 h-1 Mpc, while our best
estimate for the real space correlation function is xi(r) = (r/5.36 h-1
Mpc)^{-1.86}. Both are comparable to previous measurements using surveys of
optical galaxies over much larger and independent volumes. By comparing the
correlation function calculated in redshift and real space we find that the
redshift distortion on intermediate scales is small. This result implies that
the observed redshift-space distribution of galaxies is close to that in real
space, and that beta = Omega^{0.6}/b < 1, where Omega is the cosmological
density parameter and b is the linear biasing factor for optical galaxies. We
also use the SSRS2 to study the dependence of xi on the internal properties of
galaxies. We confirm earlier results that luminous galaxies (L>L*) are more
clustered than sub-L* galaxies and that the luminosity segregation is
scale-independent. We find that early types are more clustered than late types,
but that in the absence of rich clusters, the relative bias between early and
late types in real space, is not as strong as previously estimated.
Furthermore, both morphologies present a luminosity-dependent bias, with the
early types showing a slightly stronger dependence on luminosity. We also find
that red galaxies are significantly more clustered than blue ones, with a mean
relative bias stronger than that seen for morphology. Finally, we find that the
relative bias between optical and iras galaxies in real space is b_o/b_I
1.4.Comment: 43 pages, uses AASTeX 4.0 macros. Includes 8 tables and 16 Postscript
figures, updated reference
First Order Phase Transition in the 3-dimensional Blume-Capel Model on a Cellular Automaton
The first order phase transition of the three-dimensional Blume Capel are
investigated using cooling algorithm which improved from Creutz Cellular
Automaton for the parameter value in the first order phase transition
region. The analysis of the data using the finite-size effect and the histogram
technique indicate that the magnetic susceptibility maxima and the specific
heat maxima increase with the system volume () at .Comment: 13 pages, 4 figure
Pressure of thermal excitations in superfluid helium
We find the pressure, due to the thermal excitations of superfluid helium, at
the interface with a solid. The separate contributions of phonons, rotons
and rotons are derived. The pressure due to rotons is shown to be
negative and partially compensates the positive contribution of rotons,
so the total roton pressure is positive but several times less than the
separate and roton contributions. The pressure of the quasiparticle
gas is shown to account for the fountain effect in . An experiment is
proposed to observe the negative pressure due to rotons.Comment: 14 pages, 4 figure
Group-work: does it have to be that bad?
Many accreditation bodies and universities require the graduate attribute of "an ability to work in teams" or to "effectively collaborate". Students invariably dislike working in groups maintaining that "malingerers ride on the back" of those students who work hard and contribute effectively to the outcomes of the group or team. This is the context in which an ALTC/OLT project was established, the project is to consider ways of enhancing group-work in Architecture and design related disciplines. The project has identified the issues associated with group-work, from the perspective of student and lecturer, and has begun to develop strategies to overcome the issues. This paper reports on an assessment intervention made in a subject that involved significant levels of group-work, the initiative gained interesting responses from the students involved. Interestingly the class was multi-disciplinary and with a large percentage of international students. The students articulated during the focus group at the end of the experience were positive about the experience of having to collaborate. This paper reports on the assessment initiative as well as providing some insights into the students\u27 experiences of working in groups
Ultra-high energy cosmic rays may come from clustered sources
Clustering of cosmic-ray sources affects the flux observed beyond the cutoff
imposed by the cosmic microwave background and may be important in interpreting
the AGASA, Fly's Eye, and HiRes data. The standard deviation, sigma, in the
predicted number, N, of events above 10^{20} eV is sigma/N = 0.9(r_0/10
Mpc)^{0.9}, where r_0 is the unknown scale length of the correlation function
(r_0 = 10 Mpc for field galaxies). Future experiments will allow the
determination of r_0 through the detection of anisotropies in arrival
directions of ~ 10^{20} eV cosmic-rays over angular scales of Theta ~ r_0/30
Mpc.Comment: Accepted for publication in Astrophysical Journa
Parental Involvement\u27s Effects on Academic Performance: Evidence From the YouthSave Ghana Experiment
Research in developed countries suggests that parental involvement is associated with youth academic success, but little is known about this relationship in developing countries. Further, it is unclear which type of parental involvement may impact the academic performance of youth from developing countries. This study examines whether (a) parental involvement at home and in school are meaningfully different constructs in a population of Ghanaian youth and their parents and (b) parental involvement predicts academic performance. Results suggest that parental involvement is a bidimensional construct consists of home and school involvement. The effect of parental involvement on youth academic performance appears to be a function of the type of involvement. Home-based parental involvement is associated positively with academic performance, while school-based parental involvement has a negative association. Parents can model positive attitudes and behaviors toward school and convey the importance of school
Isomorphism between Non-Riemannian gravity and Einstein-Proca-Weyl theories extended to a class of Scalar gravity theories
We extend the recently proved relation between certain models of
Non-Riemannian gravitation and Einstein- Proca-Weyl theories to a class of
Scalar gravity theories. This is used to present a Black-Hole Dilaton solution
with non-Riemannian connection.Comment: 13 pages, tex file, accepted in Class. Quant. Gra
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