Stellar Populations in Bulges

We present line strengths in the bulges and inner disks of 38 galaxies in the local universe, including several galaxies whose bulges were previously identified as being disk-like in their colors or kinematics, to see if their spectral properties reveal evidence for secular evolution. We find that red bulges of all Hubble types are similar to luminous ellipticals in their central stellar populations. They have large luminosity-weighted ages, metallicities, and alpha/Fe ratios. Blue bulges can be separated into a metal-poor class that is restricted to late-types with small velocity dispersion and a young, metal-rich class that includes all Hubble types and velocity dispersions. Luminosity-weighted metallicities and alpha/Fe ratios are sensitive to central velocity dispersion and maximum disk rotational velocity. Red bulges and ellipticals follow the same scaling relations. We see differences in some scaling relations between blue and red bulges and between bulges of barred and unbarred galaxies. Most bulges have decreasing metallicity with increasing radius; galaxies with larger central metallicities have steeper gradients. Where positive age gradients (with the central regions being younger) are present, they are invariably in barred galaxies. The metallicities of bulges are correlated with those of their disks. While this and the differences between barred and unbarred galaxies suggest that secular evolution cannot be ignored, our results are generally consistent with the hypothesis that mergers have been the dominant mechanism responsible for bulge formation.Comment: 30 pages, 21 figures; submitted to MNRA

Current trends in the use of Zirconium Alloys

THE development of zirconium and its alloys for use in nuclear reactors began in the United Statesin 1948 when it was found that hafnium-free zirconium had a much lower neutron-absorption crosssection than had previously been suspected. Structural materials for use in water-cooled power reactors must possess a combination of high stre-ngth, corrosion resistance and low neutron capture cross-section. Zirconium alloys alone have the required combi-nation of these. For almost a decade the standard zirconium alloy for use in water-cooled reactors has been zircalov-2. A very considerable body of experience in the fabrication and use of zirconium alloys has been built up. It has been demonstrated that zircaloy tubes can be manufactured to specifications far more exacting in their requirements than is the case for standard code specifications for heat exchanger and condenser tubes

Influence of nitrogen salts on growth and physiological responses of Rhizophora apiculata Blume in non-aerated water culture

Influence of two different forms of nitrogen on growth and physiological aspects of water-cultured seedlings of Rhizophora apiculata was studied. Of the two forms of nitrogen supplied to the growth medium, ammonium nitrogen was better than nitrate nitrogen by exhibiting increased dry matter production, shoot length, leaf area and also enhanced the contents of carotenoids, chlorophylls and their presence in photosystems and light harvesting protein complex

An Exploratory Study of Pre-service Primary Teachers’ Understanding of Uncertainty in Measurements in Singapore

This study was set in the context of a reform agenda for Singapore’s science curriculum to adopt inquiry in teaching and learning science (MOE, 2008). Teachers, including pre-service primary teachers (PSTs) who were subjects of this study, are expected to engage their students with scientific evidence including measurements taken during science investigations. The inherent nature of measurements is that they are always affected by errors that caused uncertainty. Understanding this, as well as other procedural ideas underpinning uncertainty would be important for understanding evidence before looking at data that are subjected to uncertainties in measurements. Such understandings would be important for the PSTs when they teach their future students how to obtain valid and reliable data, and to evaluate the methods of investigation or scientific conclusions based on evidence. This study, therefore, was aimed at exploring such understandings using the Concepts of Evidence (Gott, Duggan, and Roberts, 2008) as a theoretical framework. The lack of a research instrument customised to such a need motivated this study to develop one. The study was carried out in two phases. The first involved fifty-five PSTs and directed towards getting an accurate interpretation of procedural ideas underlying uncertainty by triangulating the evidence from questionnaire and interviews and iteratively refining the “probes” as the study progressed. The second phase focused on developing a questionnaire based on findings from the first and testing it on twenty PSTs. The results revealed that most PSTs could recognise uncertainties in measurements and suggest the right actions to deal with them, but they generally had difficulties explaining their actions implying shallow understanding of concepts underpinning uncertainty, and reliance on routine knowledge. This has strong implications for teacher preparatory programmes as well as the teaching of procedural understanding

Aerosol spectral optical depths over the Bay of Bengal, Arabian sea and Indian ocean

Comprehensive investigations during the last decade have clearly established that aerosols have a significant impact on the climate. No serious attempts were made to characterize the aerosols over the Bay of Bengal, despite its role in the regional climate system. This paper reports the results of the measurements of aerosol spectral optical depths made over the Bay of Bengal and compares them with those made over the equatorial Indian Ocean and the Arabian Sea, on-board the oceanographic research vessel, Sagar Kanya during its cruise #161-B in March 2001. The aerosol optical depth was found to decrease with distance from the coast with an exponential scale distance of ~1000 km for visible wavelengths and ~1600 km for near infra-red wavelengths. A significant dominance of small particle concentration near the coast is observed both over the Arabian Sea and the Bay of Bengal. The mean aerosol optical depth was higher over the Bay of Bengal compared to the Arabian Sea, at the shorter wavelengths. Over the equatorial Indian Ocean regions, aerosol optical depths were much lower compared to the Arabian Sea and the Bay of Bengal and showed lesser wavelength dependence. The relative dominance of small particles is more over the Bay of Bengal compared to the Arabian Sea. Back-trajectory analysis shows that during the cruise period, the Arabian Sea was mainly influenced by air masses from the countries lying northwest of India, the Bay of Bengal by air masses from the east coast of India and the equatorial Indian Ocean mostly by the west coast and central India. The observed features are compared with long-term climatology of aerosol optical depth observations from the east and west coast of India and an island station in the Arabian Sea

Ovarian cancer: emerging concept on cancer stem cells.

Emerging evidence suggests that the capacity of a tumor to grow and propagate is dependent on a small subset of cells within a tumor, termed cancer stem cells. In fact, cancer cells, like stem cells, can proliferate indefinitely through a dysregulated cellular self-renewal capacity. Cancer stem cells may originate due to the distribution into self-renewal and differentiation pathways occurring in multi-potential stem cells, tissue-specific stem cells, progenitor cells and cancer cells. Recent studies have shown that ovarian cancer also contains stem cells or tumor-initiating cells. Moreover, ovarian serous adenocarcinomas were disaggregated and subjected to growth conditions to select for self-renewing, non-adherent spheroids previously shown to be derived from tissue stem cells. A recent study showed that epithelial ovarian cancer was derived from a sub population of CD44+, CD117+ and CD133+ cells. The existence of cancer stem cells would explain why only a small minority of cancer cells is capable of extensive proliferation of the tumor. In this review, we have discussed the studies on ovarian cancer stem cells along with the molecular pathways that could be involved in these cancer stem cells

Ovarian cancer: emerging concept on cancer stem cells

Emerging evidence suggests that the capacity of a tumor to grow and propagate is dependent on a small subset of cells within a tumor, termed cancer stem cells. In fact, cancer cells, like stem cells, can proliferate indefinitely through a dysregulated cellular self-renewal capacity. Cancer stem cells may originate due to the distribution into self-renewal and differentiation pathways occurring in multi-potential stem cells, tissue-specific stem cells, progenitor cells and cancer cells. Recent studies have shown that ovarian cancer also contains stem cells or tumor-initiating cells. Moreover, ovarian serous adenocarcinomas were disaggregated and subjected to growth conditions to select for self-renewing, non-adherent spheroids previously shown to be derived from tissue stem cells. A recent study showed that epithelial ovarian cancer was derived from a sub population of CD44+, CD117+ and CD133+ cells. The existence of cancer stem cells would explain why only a small minority of cancer cells is capable of extensive proliferation of the tumor. In this review, we have discussed the studies on ovarian cancer stem cells along with the molecular pathways that could be involved in these cancer stem cells

Studies on Formulation and Evaluation of Ethyl Cellulose Based Extended Release Metformin Hydrochloride Matrix Tablets

Monolithic matrix tablets of metformin hydrochloride were formulated as extended release tablets by employing ethyl cellulose polymer and the extended release characterization of the formulated tablets was investigated.  Extended release matrix tablets containing 500 mg metformin hydrochloride were developed by changing concentration of drug :  polymer (EC) in the ratio of 5:1, 5:2, 5:3 and 5:4 by direct compression.  Formulations were optimized based on the acceptable tablet properties invitro and invivo drug release.  The resulting formulations produced robust tablets with optimum hardness, weight variation, drug content and low friability.  The result of invitro and invivo drug release studies indicated that formulation (drug:polymer =5:3), is the most successful of the study and exhibited constant and extended release of metformin hydrochloride 99-100.5% release at the end of 10 h compared with reference standard.  Further, the formulation F3 was subjected to exposure at room and accelerated condition to stability studies.  A decrease in release of the drug was observed on increasing polymer ratio at certain level.  Before tablet compression, the resulting formulation blends were evaluated for angle of repose, bulk density, % porosity, % compressibility index and drug polymer compatibility study of drug and excipients.  The t25, t50 and t90 drug release values was calculated from selected formulation F3 on every month of stability studies and comparision of both room and accelerated condition by statistical t-test, there is no difference between storage temperature. The formulation F3 was showed similar invitro and invivo drug release when compared to marketed sustained release tablet (F5M)

Aerosol characteristics at a remote island: minicoy in southern Arabian sea

Extensive measurements of aerosol optical and microphysical properties made at a remote island, Minicoy in southern Arabian Sea for the period (February 2006-March 2007) are used to characterize their temporal variability and Black Carbon (BC) mass mixing ratio. Large decrease in aerosol BC (from ~800 ng m-3 to ~100 ng m-3) was observed associated with change in airmass characteristics and monsoon rains. The total aerosol mass varied between ~80 and 20 μg m-3. Though the total mass fell drastically, a slight increase in super micron mass was observed during the June-August period associated with high winds. The mass fraction of Black Carbon aerosols during the prevalence of continental airmass is found to be ~1.2% of the composite aerosols, which is much lower than the values reported earlier for this region