OAO/ISLE Near-IR Spectroscopy of IRAS Galaxies

We present the results of the near-infrared (IR) spectroscopy of nine IRAS galaxies (NGC 1266, NGC 1320, NGC 2633, NGC 2903, NGC 3034, Mrk 33, NGC 7331, NGC 7625, NGC 7714) with the ISLE imager and spectrograph mounted on the Okayama Astrophysical Observatory 1.88 m telescope. [Fe II] 1.257 um and Pa beta emission lines were observed for the whole sample while H2 2.121 um and Br gamma lines were additionally obtained for two sources, whose flux ratios are used as a diagnostic tool of dominant energy sources of the galaxies. We find that the nucleus of NGC 1266 is most likely a low ionization nuclear emission-line region (LINER), while NGC 2633 and NGC 2903 possibly harbor active galactic nuclei (AGNs). No AGN or LINER signal is found for other objects. In addition, we find the spectral features which is indicative of some unusual phenomena occurring in the galaxies, such as the large [Fe II] line widths compared to the local escape velocity in NGC 1266. The present work shows the potential ability of the ISLE to shed new light on the nature of infrared galaxies, either through a statistical survey of galaxies or an exploration of spectral features found in individual objects.Comment: Accepted for publication in PAS

Iron-Based Heavy Quasiparticles in SrFe4_{4}Sb12_{12}: An Infrared Spectroscopic Study

Temperature-dependent infrared reflectivity spectra of SrFe$_{4}$Sb$_{12}$ has been measured. A renormalized Drude peak with a heavy effective mass and a pronounced pseudogap of 10 meV develops in the optical conductivity spectra at low temperatures. As the temperature decreases below 100 K, the effective mass ($m^{*}$) rapidly increases, and the scattering rate ($1/\tau$) is quenched. The temperature dependence of $m^{*}$ and $1/\tau$ indicates that the hybridization between the Fe 3d spins and the charge carriers plays an important role in determining the physical properties of SrFe$_{4}$Sb$_{12}$ at low temperatures. This result is the clear evidence of the iron-based heavy quasiparticles.Comment: 5 pages, 5 figure

An investigation of star formation and dust attenuation in major mergers using ultraviolet and infrared data

Merger processes play an important role in galaxy formation and evolution. To study the influence of merger processes on the evolution of dust properties and cosmic star formation rate, we investigate a local sample of major merger galaxies and a control sample of isolated galaxies using GALEX ultraviolet (UV) and Spitzer infrared (IR) images. Through a statistical study, we find that dust attenuation in merger galaxies is enhanced with respect to isolated galaxies. We find this enhancement is contributed mainly by spiral galaxies in spiral-spiral (S-S) pairs, and increases with the increasing stellar mass of a galaxy. Combining the IR and UV parts of star formation rates (SFRs), we then calculated the total SFRs and specific star formation rates (SSFRs). We find the SSFRs to be enhanced in merger galaxies. This enhancement depends on galaxy stellar mass and the companion's morphology, but depends little on whether the galaxy is a primary or secondary component or on the separation between two components. These results are consistent with a previous study based only on IR images. In addition, we investigate the nuclear contributions to SFRs. SFRs in paired galaxies are more concentrated in the central part of the galaxies than in isolate galaxies. Our studies of dust attenuation show that the nuclear parts of pairs most resemble ULIRGs. Including UV data in the present work not only provides reliable information on dust attenuation, but also refines analyses of SFRs.Comment: 21 pages, 21 figure

Relationship of electroencephalographic and cardiovascular changes to plasma nicotine levels in tobacco smokers

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109893/1/cptclpt199444.pd

The variable OVIII Warm Absorber in MCG-6-30-15

We present the results of a 4 day ASCA observation of the Seyfert galaxy MCG-6-30-15, focussing on the nature of the X-ray absorption by the warm absorber, characterizd by the K-edges of the intermediately ionized oxygen, OVII and OVIII. We confirm that the column density of OVIII changes on a timescale of $\sim 10^4$~s when the X-ray continuum flux decreases. The significant anti-correlation of column density with continuum flux gives direct evidence that the warm absorber is photoionized by the X-ray continuum. From the timescale of the variation of the OVIII column density, we estimate that it originates from gas within a radius of about 10^{17}\cm of the central engine. In contrast, the depth of the OVII edge shows no response to the continuum flux, which indicates that it originates in gas at larger radii. Our results strongly suggest that there are two warm absorbing regions; one located near or within the Broad Line Region, the other associated with the outer molecular torus, scattering medium or Narrow Line Region.Comment: 8 pages (including figures) uuencoded gziped PS file. Submitted to Publications of the Astronomical Society of Japa

Comparative American and Japanese tobacco smoke uptake parameters after overnight tobacco deprivation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109819/1/cptclpt2004281.pd

Cholinergic modulation of single lateral geniculate neurons in the cat

The effects of physostigmine, nicotine and scopolamine were studied on the activity of single lateral geniculate neurons in the acute cat. Most of the lateral geniculate neurons selected were P-cells. These increased their responses to ipsilateral optic tract and midbrain reticular formation stimulation.Nicotine and physostigmine in doses of 25 [mu]g/kg i.v. significantly increased the spontaneous firing rate of single geniculate neurons. Scopolamine in a dose of 0.5 mg/kg i.v. depressed their firing rates to control levels. Physostigmine enhanced their post-stimulus discharge rate to optic nerve stimulation. This enhancement was depressed by scopolamine. The effects of midbrain reticular formation stimulation were further enhanced by physostigmine and reduced by scopolamine in about 86% of lateral geniculate neurons studied. Generally, the effects of trains of pulses to the reticular formation (250 Hz/sec, 50 msec train duration, 0.05-0.1 msec pulses) were more marked than single stimuli.It is concluded that a major cholinergic facilitatory system exists which influences lateral geniculate neurons. It is postulated that this involves the reticular formation. Evidence is presented for a predominant muscarinic cholinergic mechanism.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34147/1/0000432.pd

Effects of tobacco smoking on the topographic EEG I

1. 1. The EEG and cardiovascular effects of smoking tobacco cigarettes of varying nicotine content were studied in Japanese chronic tobacco smokers.2. 2. Thirteen female and fifteen male adult normal volunteers were recruited for this study.3. 3. Each subject was asked to stop smoking the evening before coming to the laboratory the next morning, so they were approximately 10-12 hr deprived of cigarettes.4. 4. The objectives of this study were: a) To compare the mean differences in total activity in the alpha1, alpha2, beta, delta, and theta frequency bands before and after smoking a cigarette with 0, 0.27, 2.0, and 2.16 mg nicotine content in these 10-12 hr deprived tobacco smokers, b) To compare the topographic EEG patterns in such volunteers before and after smoking each of the above cigarettes, c) To compare the cardiovascular effects of smoking each of the above cigarettes in the same volunteers.5. 5. Smoking any of the four different types of cigarettes increased the total alpha EEG activity, although there were marked individual differences. Only after smoking nicotine containing cigarettes was there a mean decrease in alpha1 (8.0-9.8 Hz) and an increase in alpha2 (10-11.8 Hz) activity in the EEG, not only in the occipital areas but also more diffusely throughout the cerebral cortex. There were no consistent mean changes in EEG delta, theta, or beta activity. Individual differences were marked, irrespective of the nicotine content of the cigarette smoked. Baseline state, individual subject variation, and nicotine content of the cigarette smoked determine the EEG effects observed. Zero nicotine cigarette smoking also caused EEG changes, including an increase in alpha1 and alpha2 activity.6. 6. In contrast to smoking a zero nicotine cigarette, the cardiovascular effects of tobacco smoking include a slight increase in heart rate, systolic, and diastolic blood pressure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31374/1/0000287.pd

Anomalously-dense firn in an ice-shelf channel revealed by wide-angle radar

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