17,993 research outputs found
Mapping the star formation history of Mrk86: I. Data and models
We have obtained optical (BVR, [OIII]5007 and Halpha), near infrared (JHK)
imaging and long-slit optical spectroscopy for the Blue Compact Dwarf galaxy
Mrk86 (NGC2537). In this paper, the first of two, we present optical-near-
infrared colors and emission-line fluxes for the currently star-forming
regions, intemediate aged starburst and underlying stellar population. We also
describe the evolutionary synthesis models used in Paper II. The R and Halpha
luminosity distributions of the galaxy star-forming regions show maxima at
M_R=-9.5 and L_Halpha=10^37.3 erg s^-1. The underlying stellar population shows
an exponential surface brigthness profile with central value, mu_E,0=21.5 mag
arcsec^-2, and scale, alpha=0.88 kpc, both measured in the R-band image. In the
galaxy outer regions, dominated by this component, no significant color
gradients are observed. Finally, a set of evolutionary synthesis models have
been developed, covering a wide range in metallicity and burst strength.Comment: 21 pages, 14 figures, 2 landscape tables, accepted for publication in
Astronomy & Astrophysics Supplement Series, for higher resolution images see
ftp://cutrex.fis.ucm.es/pub/OUT/gil/PAPERS/aa00_I.ps.g
XMM-Newton Observations of Radio Pulsars B0834+06 and B0826-34 and Implications for Pulsar Inner Accelerator
We report the X-ray observations of two radio pulsars with drifting
subpulses: B0834 + 06 and B0826 - 34 using \xmm\. PSR B0834 + 06 was detected
with a total of 70 counts from the three EPIC instruments over 50 ks exposure
time. Its spectrum was best described as that of a blackbody (BB) with
temperature K and bolometric luminosity
of erg s. As it is typical in
pulsars with BB thermal components in their X-ray spectra, the hot spot surface
area is much smaller than that of the canonical polar cap, implying a
non-dipolar surface magnetic field much stronger than the dipolar component
derived from the pulsar spin-down (in this case about 50 times smaller and
stronger, respectively). The second pulsar PSR B0826 - 34 was not detected over
50 ks exposure time, giving an upper limit for the bolometric luminosity erg s. We use these data as well as the radio
emission data concerned with drifting subpulses to test the Partially Screened
Gap (PSG) model of the inner accelerator in pulsars.Comment: Accepted for publication by The Astrophysical Journa
The braking indices in pulsar emission models
Using the method proposed in a previous paper, we calculate pulsar braking
indices in the models with torque contributions from both inner and outer
accelerating regions, assuming that the interaction between them is negligible.
We suggest that it is likely that the inverse Compton scattering induced polar
vacuum gap and the outer gap coexist in the pulsar magnetosphere. We include
the new near threshold vacuum gap models with curvature-radiation and inverse
Compton scattering induced cascades, respectively; and find that these models
can well reproduce the measured values of the braking indices.Comment: A&Ap accepted, or at
http://vega.bac.pku.edu.cn/~rxxu/publications/index_P.ht
Seeing Star Formation Regions with Gravitational Microlensing
We qualitatively study the effects of gravitational microlensing on our view
of unresolved extragalactic star formation regions. Using a general
gravitational microlensing configuration, we perform a number of simulations
that reveal that specific imprints of the star forming region are imprinted,
both photometrically and spectroscopically, upon observations. Such
observations have the potential to reveal the nature and size of these star
forming regions, through the degree of variability observed in a monitoring
campaign, and hence resolve the star formation regions in distant galaxies
which are too small to be probed via more standard techniques.Comment: 7 pages, 8 figures, ApJ accepte
Magnetic composite biomaterials for tissue engineering
Magnetic nanoparticles (MNPs) have been increasingly used in tissue engineering and regenerative medicine. These particles have been mainly employed as elements directly incorporated into cells or interacting with cell membranes; however, MNPs are now being combined with biomaterials to create other functionalities of the structural framework used to support cells, namely for controlling cellular responses and for enhancing drug delivery and release. This mini-review summarizes and highlights the latest developments and applications of polymeric/ceramic biomimetic scaffolds and hydrogels that contain MNPs for such purposes, also addressing future perspectives for the use of these magnetic composite biomaterials in biomedicine
Lamotrigine treatment of aggression in female borderline patients, Part II: an 18-month follow-up
Borderline patients often display pathological aggression. We previously tested lamotrigine, an anti-convulsant, in therapy for aggression in women with borderline personality disorder (BPD) (J Psychopharmacol 2005; 19: 287–291), and found significant changes on most scales of the State-Trait Anger Expression Inventory (STAXI) after eight weeks. To assess the longerterm efficacy of lamotrigine in therapy for aggression in women with BPD, this 18-month follow-up observation was carried out, in which patients (treated with lamotrigine: n = 18; former placebo group: n = 9) were tested every six months. According to the intent-to-treat principle, significant changes on all scales of the STAXI were observed in the lamotrigine-treated subjects. All subjects tolerated lamotrigine relatively well. Lamotrigine appears to be an effective and relatively safe agent in the longer-term treatment of aggression in women with BPD
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