Spectral Variations in Early-Type Galaxies as a Function of Mass

We report on the strengths of three spectral indicators - Mg_2, Hbeta, and Hn/Fe - in the integrated light of a sample of 100 field and cluster E/S0 galaxies. The measured indices are sensitive to age and/or and metallicity variations within the galaxy sample. Using linear regression analysis for data with non-uniform errors, we determine the intrinsic scatter present among the spectral indices of our galaxy sample as a function of internal velocity dispersion. Our analysis indicates that there is significantly more intrinsic scatter in the two Balmer line indices than in the Mg_2 index, indicating that the Balmer indices provide more dynamic range in determining the age of a stellar population than does the Mg_2 index. Furthermore, the scatter is much larger for the low velocity dispersion galaxies, indicating that star formation has occurred more recently in the lower mass galaxies.Comment: 4 pages, 1 figure, 1 table, to appear in the Astrophysical Journal Letter

HST and Spitzer point source detection and optical extinction in powerful narrow-line radio galaxies

We present the analysis of infrared HST and Spitzer data for a sample of 13 FRII radio galaxies at 0.03<z<0.11 that are classified as narrow-line radio galaxies (NLRG). In the context of the unified schemes for active galactic nuclei (AGN), our direct view of the AGN in NLRG is impeded by a parsec-scale dusty torus structure. Our high resolution infrared observations provide new information about the degree of extinction induced by the torus, and the incidence of obscured AGN in NLRG. We find that the point-like nucleus detection rate increases from 25 per cent at 1.025$\mu$m, to 80 per cent at 2.05$\mu$m, and to 100 per cent at 8.0$\mu$m. This supports the idea that most NLRG host an obscured AGN in their centre. We estimate the extinction from the obscuring structures using X-ray, near-IR and mid-IR data. We find that the optical extinction derived from the 9.7$\mu$m silicate absorption feature is consistently lower than the extinction derived using other techniques. This discrepancy challenges the assumption that all the mid-infrared emission of NLRG is extinguished by a simple screen of dust at larger radii. This disagreement can be explained in terms of either weakening of the silicate absorption feature by (i) thermal mid-IR emission from the narrow-line region, (ii) non-thermal emission from the base of the radio jets, or (iii) by direct warm dust emission that leaks through a clumpy torus without suffering major attenuation.Comment: 18 pages, 7 figures, 8 tables, accepted for publication in MNRA

Time evolution of the Partridge-Barton Model

The time evolution of the Partridge-Barton model in the presence of the pleiotropic constraint and deleterious somatic mutations is exactly solved for arbitrary fecundity in the context of a matricial formalism. Analytical expressions for the time dependence of the mean survival probabilities are derived. Using the fact that the asymptotic behavior for large time $t$ is controlled by the largest matrix eigenvalue, we obtain the steady state values for the mean survival probabilities and the Malthusian growth exponent. The mean age of the population exhibits a $t^{-1}$ power law decayment. Some Monte Carlo simulations were also performed and they corroborated our theoretical results.Comment: 10 pages, Latex, 1 postscript figure, published in Phys. Rev. E 61, 5664 (2000

Nonlinearity in a dynamo

Using a rotating flat layer heated from below as an example, we consider effects which lead to stabilizing an exponentially growing magnetic field in magnetostrophic convection in transition from the kinematic dynamo to the full non-linear dynamo. We present estimates of the energy redistribution over the spectrum and helicity quenching by the magnetic field. We also study the alignment of the velocity and magnetic fields. These regimes are similar to those in planetary dynamo simulations.Comment: Accepted to Geophys. Astrophys. Fluid Dyna

Inclusive Education and Sustainable Peace in Africa

Inclusive education is an innovative approach to education by which all children, youths and adults on the globe have equal opportunities to learn comfortably in the same academic environment regardless their intellectual and physical ability/disability and irrespective of their political, ethnic and socio-economic background. It is a brain child of UNESCO (the United Nations Educational Scientific and Cultural Organization); part of its Education For All (EFA) initiative which seeks to overcome the global challenges of marginalization, discrimination and exclusion. In this light, this paper examines the concept of inclusive education as a means of attaining long-lasting peace in Africa, which in turn will rekindle socio-economic and political progress. The paper provides copious evidence of the fact that socio-economic and political exclusion and marginalization are major sources of conflict and instability in Africa. Its underlying assumption is that inclusive education is a sure means of attaining optimum integral development and sustainable peace in Africa. Keywords: Inclusive education, sustainable peace in Afric

ANTIPROLIFERATIVE EFFECTS OF PSIDIUM GUAJAVA LEAF EXTRACT ON ORAL SQUAMOUS CARCINOMA CELLS

Objective: Cancer is the major cause of mortality affecting population irrespective of age. Oral cancer is one among the various cancers affecting major population in India. To overcome toxicity of chemotherapy and disfiguration by surgical procedures, researchers are targeting phytochemicals for their anticancer properties. This study evaluates the antiproliferative effects of Psidium guajava leaf extract against OSC cells. Methods: KB cells were purchased from NCCS, Pune. Extract from leaves of P. guajava was prepared with ethanol and evaluated with high-performance thin-layer chromatography (HPTLC). Antiproliferative effects of the extract were assessed with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl--tetrazolium bromide (MTT) assay and flow cytometry. Results: HPTLC revealed the presence of quercetin in the extract. MTT assay showed decreasing pattern in cell viability with the increasing dose of extract. Flow cytometry revealed the seizing of cycle by the extract. Conclusion: The study results conclude the presence of antiproliferative properties in the leaf extract of P. guajava

Religious Education in Context: Evangelization of the Igbo People and Culture

The context, content and process, by which the Church brings the good news of Christ into all aspects of human life and endeavors, influencing its transformation from within, constitute what is known as evangelization. Evangelization is about people and their way of life, that is their culture. It is a process of religious education which seeks to transform adherents of the Christian faith, whether new or old members, into persons who are Christ-like. In this regard, this paper grapples with the question: ‘what will it take to produce the kind of Christians, today and in the future, who are Christ-like in mentality, behavior, and attitudes?’ Using case stories from the mission fields in conjunction with available literature, including various post-synodal apostolic exhortations, the paper proposes ‘integral evangelization as inculturation,’ coupled with a prophetic stance, which keeps Christ central to the entire process. Key words: religious education, context, Igbo culture, evangelization, inculturatio