The Nearby Field Galaxy Survey: a spectrophotometric and photometric study of nearby galaxies

We report on our observing program to obtain integrated spectrophotometry, intermediate and high resolution major axis spectra, and U,B,R surface photo- metry of a representative sample of ~200 galaxies in the nearby field. The main goal of this program is to provide a comparison sample for high redshift studies and to study the variation in star formation rates (SFR), star forma- tion history (SFH), excitation, metallicity, and internal kinematics over a large range in galaxy luminosity and morphological type. In particular, we extend the work of Kennicutt (1992) to lower luminosity systems. We present the main results of our analysis sofar. In these proceedings, we condense the presented two atlases of (1) images and radial surface brightness profiles and color profiles, and (2) of images and integrated spectra into several example images, profiles and spectra, showing the general trends observed. For the original atlasses we refer to the electronic version, available at http://www.astro.rug.nl/~nfgs/ .Comment: 9 pages, LateX, 6 figures, to appear in the forthcoming issue of Astrophysics and Space Science: "The Evolution of Galaxies on Cosmological Timescales

Ultrasonic and Spectral Studies on Hydrogen Bonded Complexes of Aromatic Aldehydes and N-Methylaniline in n-Hexane

Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formation constants is discussed based on structures of the component molecules and correlate with computed molecular propertie

A Broad Search for Counterrotating Gas and Stars: Evidence for Mergers and Accretion

We measure the frequency of bulk gas-stellar counterrotation in a sample of 67 galaxies drawn from the Nearby Field Galaxy Survey, a broadly representative survey of the local galaxy population down to M_B-15. We detect 4 counterrotators among 17 E/S0's with extended gas emission (24% +8 -6). In contrast, we find no clear examples of bulk counterrotation among 38 Sa-Sbc spirals, although one Sa does show peculiar gas kinematics. This result implies that, at 95% confidence, no more than 8% of Sa-Sbc spirals are bulk counterrotators. Among types Sc and later, we identify only one possible counterrotator, a Magellanic irregular. We use these results together with the physical properties of the counterrotators to constrain possible origins for this phenomenon.Comment: 19 pages, 4 figures, AJ, accepte

Synthesis, crystal structure and magnetic properties of a polymeric copper(II) schiff-base complex having binuclear units covalently linked by isonicotinate ligands

The polynuclear copper(II) complex [{Cu2L(O2CC5H4N)}·C2H5OH]x (1), where H3L is a 1:2 Schiff base derived from 1,3-diaminopropan-2-ol and salicylaldehyde, has been prepared and structurally characterized. The structure consists of a one-dimensional zigzag chain in which the binuclear [Cu2L]+ units are covalently linked by isonicotinate ligands to give a syndiotactic arrangement of the copper ions protruding outside the chain. In the basic unit, the copper(II) centres are bridged by an alkoxo and a carboxylato ligand, giving a Cu···Cu distance of 3.492(3) Å and a Cu-O-Cu angle of 130.9(2)° . While one copper centre has a square-planar geometry, the other copper is squarepyramidal with the pyridine nitrogen being the axial ligand. The visible electronic spectrum of 1 shows a broad d-d band at 615 nm. The complex shows a rhombic X-band EPR spectral pattern in the polycrystalline phase at 77 K. Magnetic susceptibility measurements in the temperature range 22 to 295 K demonstrate the antiferromagnetic behaviour of 1. A theoretical fit to the magnetic data is based on a model assuming 1 as an equimolar mixture of copper atoms belonging to an antiferromagnetically coupled one-dimensional Heisenberg chain with the other copper atoms outside the chain behaving like paramagnetic centres

Physical Sources of Scatter in the Tully-Fisher Relation

We analyze residuals from the Tully-Fisher relation for the emission-line galaxies in the Nearby Field Galaxy Survey, a broadly representative survey designed to fairly sample the variety of galaxy morphologies and environments in the local universe. For spirals brighter than M_R^i=-18, we find strong correlations between Tully-Fisher residuals and both B-R color and EW(Halpha). The extremes of the correlations are populated by Sa galaxies, which show consistently red colors, and spirals with morphological peculiarities, which are often blue. If we apply an EW(Halpha)-dependent or B-R color-dependent correction term to the Tully-Fisher relation, the scatter in the relation no longer increases from R to B to U but instead drops to a nearly constant level close to the scatter we expect from measurement errors. We argue that these results probably reflect correlated offsets in luminosity and color as a function of star formation history. Broadening the sample in morphology and luminosity, we find that most non-spirals brighter than M_R^i=-18 follow the same correlations as do spirals, albeit with greater scatter. However, the color and EW(Halpha) correlations do not apply to galaxies fainter than M_R^i=-18 or to emission-line S0 galaxies with anomalous gas kinematics. For the dwarf galaxy population, the parameters controlling Tully-Fisher residuals are instead related to the degree of recent disturbance: overluminous dwarfs have higher rotation curve asymmetries, brighter U-band effective surface brightnesses, and shorter gas consumption timescales than their underluminous counterparts. As a result, sample selection strongly affects the measured faint-end slope of the Tully-Fisher relation. Passively evolving, rotationally supported galaxies display a break toward steeper slope at low luminosities.Comment: 58 pages including 21 figures, AJ, accepte

Forming Young Bulges within Existing Disks: Statistical Evidence for External Drivers

Contrary to traditional models of galaxy formation, recent observations suggest that some bulges form within preexisting disk galaxies. Such late-epoch bulge formation within disks seems to be linked to disk gas inflow and central star formation, caused by either internal secular processes or galaxy mergers and interactions. We identify a population of galaxies likely to be experiencing active bulge growth within disks, using the criterion that the color within the half-light radius is bluer than the outer disk color. Such blue-centered galaxies make up >10% of star-forming disk galaxies within the Nearby Field Galaxy Survey, a broad survey designed to represent the natural diversity of the low-z galaxy population over a wide range of luminosities and environments. Blue-centered galaxies correlate at 99% confidence with morphological peculiarities suggestive of minor mergers and interactions. From this and other evidence, we argue that external drivers rather than internal secular processes probably account for the majority of blue-centered galaxies. We go on to discuss quantitative plausibility arguments indicating that blue-centered evolutionary phases may represent an important mode of bulge growth for most disk galaxies, leading to significant changes in bulge-to-disk ratio without destroying disks. If this view is correct, bulge growth within disks may be a natural consequence of the repeated galaxy mergers and interactions inherent in hierarchical galaxy formation.Comment: 18 pages including 12 figures, AJ, accepte

A characterization of quadratic-multiplicative mappings

In the spirit of some earlier studies of Jean Dhombres, Roman Ger and Ludwig Reich we discuss the alienation problem for quadratic and multiplicative mappings

Targeting Inflammatory Pathways by Triterpenoids for Prevention and Treatment of Cancer

Traditional medicine and diet has served mankind through the ages for prevention and treatment of most chronic diseases. Mounting evidence suggests that chronic inflammation mediates most chronic diseases, including cancer. More than other transcription factors, nuclear factor-kappaB (NF-κB) and STAT3 have emerged as major regulators of inflammation, cellular transformation, and tumor cell survival, proliferation, invasion, angiogenesis, and metastasis. Thus, agents that can inhibit NF-κB and STAT3 activation pathways have the potential to both prevent and treat cancer. In this review, we examine the potential of one group of compounds called triterpenes, derived from traditional medicine and diet for their ability to suppress inflammatory pathways linked to tumorigenesis. These triterpenes include avicins, betulinic acid, boswellic acid, celastrol, diosgenin, madecassic acid, maslinic acid, momordin, saikosaponins, platycodon, pristimerin, ursolic acid, and withanolide. This review thus supports the famous adage of Hippocrates, “Let food be thy medicine and medicine be thy food”

PERFORMANCE EVALUATION OF A THREE-PHASE EMULSION OF JATROPHA BIODIESEL PRODUCED BY PEROXIDATION. 48 1 2 3 4

Abstract Keywords: Indiscriminate extraction and lavish consumption of fossil fuels have led to reduction in underground based carbon resources. The search for an alternative fuel, which promises a harmonious correlation with sustainable development, energy conservation, management, efficiency and environmental preservation, has become highly pronounced from the refined edible vegetable oil such as Jatropha seed oil by alkaline catalyzed transesterification process. In the study reported herein, Jatropha oil was used as raw oil to produce biodiesel by transesterification reaction accompanied by peroxidation to further improve the fuel properties of the biodiesel. By means of high-speed mechanical homogenizer, the biodiesel product was then emulisified with distilled water and emulsifying surfactant to produce a three phase oil droplets in-water-droplets-in-oil(ie.O/W/O) biodiesel emulsion and an O/W/O emulsion that contained aqeous ammonia, which is a NO inhibitor agent. The prepared x biodiesel was then subjected to performance and emission tests in order to evaluate its actual performance, when used as a diesel engine fuel. A single cylinder direct injection diesel engine was used for this work to investigate the engine performance and emission characteristics of the biodiesel, the O/W/O biodiesel emulsion, the O/W/O biodiesel emulsion that contained aqeous ammonia. The brake specifc fuel consumption (BSFC) and brake thermal efficiency (BTE) were calculated from the recorded data. Moreover, the existence of aqeous ammonia in the O/W/O biodiesel emulsion curtails NO formation, thus X resulting in the lowest NO emissions among the four tested fuels in burning the O/W/O biodiesel emulsion that contained X aqeous ammonia