This paper offers an explanation for some evidence that intergenerational earnings mobility is higher in more developed economies and that mobility is positively correlated with wage equality. In the ...model mobility promotes economic growth via its effect on the accumulation and allocation of human capital. Growth influences mobility via its effect on incentives to acquire education and its effect on liquidity constraints upon such acquisition. In the process of development mobility increases and the distribution of education becomes better correlated with ability. Redistributive policy has a negative effect on growth in developed economies and a positive effect in developing economies.
We have observed four low-luminosity active galactic nuclei (AGNs) classified as type 1 Low-Ionization Nuclear Emission-Line Regions (LINERs) with the X-Ray Telescope (XRT) and the ...Ultraviolet–Optical Telescope (UVOT) onboard Swift, in an attempt to clarify the main powering mechanism of this class of nearby sources. Among our targets, we detect X-ray variability in NGC 3998 for the first time. The light curves of this object reveal variations of up to 30 per cent amplitude in half a day, with no significant spectral variability on this time-scale. We also observe a decrease of ∼30 per cent over 9 d, with significant spectral softening. Moreover, the X-ray flux is ∼40 per cent lower than observed in previous years. Variability is detected in M81 as well, at levels comparable to those reported previously: a flux increase in the hard X-rays (1–10 keV) of 30 per cent in ∼3 h and variations by up to a factor of 2 within a few years. This X-ray behaviour is similar to that of higher luminosity, Seyfert-type objects. Using previous high-angular-resolution imaging data from the Hubble Space Telescope (HST), we evaluate the diffuse UV emission due to the host galaxy and isolate the nuclear flux in our UVOT observations. All sources are detected in the UV band, at levels similar to those of the previous observations with HST. The XRT (0.2–10 keV) spectra are well described by single power laws and the UV-to-X-ray flux ratios are again consistent with those of Seyferts and radio-loud AGNs of higher luminosity. The similarity in X-ray variability and broad-band energy distributions suggests the presence of similar accretion and radiation processes in low- and high-luminosity AGNs.
The iron mass in galaxy clusters is about six times larger than could have been produced by core-collapse supernovae (SNe), assuming the stars in the cluster formed with a standard initial mass ...function (IMF). SNe Ia have been proposed as the alternative dominant iron source. Different SN Ia progenitor models predict different ‘delay functions’, between the formation of a stellar population and the explosion of some of its members as SNe Ia. We use our previous measurements of the cluster SN Ia rate at high redshift to constrain SN Ia progenitor models and the star-formation epoch in clusters. The low observed rate of cluster SNe Ia at z∼ 0–1 means that, if SNe Ia produced the observed amount of iron, they must have exploded at even higher z. This puts a >95 per cent upper limit on the mean SN Ia delay time of τ < 2 Gyr (< 5 Gyr) if the stars in clusters formed at zf < 2 (zf < 3), assuming H0= 70 km s−1 Mpc−1. In a companion paper, we show that, for some current versions of cosmic (field) star-formation history (SFH), observations of field SNe Ia place a lower bound on the delay time, τ > 3 Gyr. If these SFHs are confirmed, the entire range of τ will be ruled out. Cluster enrichment by core-collapse SNe from a top-heavy IMF will then remain the only viable option.
We present 426 epochs of optical monitoring data spanning 1000 days from 2003 December to 2006 June for the gravitationally lensed quasar SDSS J1004+4112. The time delay between the A and B images is ...Delta t sub(BA) = 38.4 plus or minus 2.0 days ( Delta chi super(2) = 4) in the expected sense that B leads A and the overall time ordering is C-B-A-D-E. The measured delay invalidates all published models. The models probably failed because they neglected the perturbations from cluster member galaxies. Models including the galaxies can fit the data well, but conclusions about the cluster mass distribution should await the measurement of the longer, and less substructure sensitive, delays of the C and D images. For these images, a delay of Delta t sub(CB) unk 681 plus or minus 15 days is plausible but requires confirmation, while delays of Delta t sub(CB) > 560 days and Delta t sub(AD) > 800 days are required. We clearly detect microiensing of the A/B images, with the delay-corrected flux ratios changing from m sub(B) -m sub(A) = 0.44 plus or minus 0.01 mag in the first season to 0.29 plus or minus 0.01 mag in the second season and 0.32 plus or minus 0.01 mag in the third season.
To report the outcomes of repeat endothelial keratoplasty (EK) in patients with failed Descemet stripping endothelial keratoplasty (DSEK).
The clinical records of patients with failed DSEK who ...underwent repeat EK surgery at a single institution were reviewed.
A total of 20 eyes of 20 patients (8 men and 12 women) were included. The mean age at initial DSEK surgery was 69.9 ± 11.9 years (range, 41-83 years). The causes of DSEK failure included progressive endothelial failure (8 eyes; 40%), primary graft failure (8 eyes; 40%), and endothelial rejection (4 eyes; 20%). The mean duration from primary DSEK to repeat EK was 13.1 ± 10.3 months (range, 2-33 months). Removal of the failed DSEK donor disc was performed in all eyes. Mean preoperative corrected distance visual acuity (logMAR) before repeat EK surgery was 1.76, and this improved to 0.5 (P < 0.001) at the final follow-up at 27 months. Three eyes had limited corrected distance visual acuity secondary to ocular comorbidities (age-related macular degeneration and advanced glaucomatous optic neuropathy).
Repeat EK in patients with DSEK failure is an effective treatment modality. This is the preferred management option compared with penetrating keratoplasty because the advantages of EK surgery are maintained with repeat EK surgery.
Mid-Infrared Diagnostics of LINERS Sturm, E; Rupke, D; Contursi, A ...
The Astrophysical journal,
12/2006, Letnik:
653, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We report results from the first mid-infrared spectroscopic study of a comprehensive sample of 33 LINERs, observed with the Spitzer Space Telescope. We compare the properties of two different LINER ...populations: infrared-faint LINERs, with LINER emission arising mostly in compact nuclear regions, and infrared-luminous LINERs, which often show spatially extended (non-AGN) LINER emission. We show that these two populations can be easily distinguished by their mid-infrared spectra in three different ways: (1) their mid-IR spectral energy distributions (SEDs), (2) the emission features of polycyclic aromatic hydrocarbons (PAHs), and (3) various combinations of IR fine-structure line ratios. IR-luminous LINERs show mid-IR SEDs typical of starburst galaxies, while the mid-IR SEDs of IR-faint LINERs are much bluer. PAH flux ratios are significantly different in the two groups. Fine-structure emission lines from highly excited gas, such as O IV, are detected in both populations, suggesting the presence of an additional AGN in a large fraction of IR-bright LINERs as well, which contributes little to the combined mid-IR light. The two LINER groups occupy different regions of mid-infrared emission-line excitation diagrams. The positions of the various LINER types in our diagnostic diagrams provide important clues regarding the power source of each LINER type. Most of these mid-infrared diagnostics can be applied at low spectral resolution, making AGN- and starburst-excited LINERs distinguishable at high redshifts as well.
The pattern of joining the labor force only at an advanced stage of the life-cycle was widespread among American women in the 1960s and 1970s, but not since the 1980s. To explain this change we ...conduct a theoretical analysis of the interrelation between women’s lifetime labor supply choices and the dynamic macroeconomic environment. In our model women choose the late-entry pattern only at early stages of the growth process when wages are sufficiently low and grow sufficiently rapidly. As the economy grows, this lifetime labor profile vanishes and women either join the labor force either early in life or not at all.
A 45-year-old woman developed a spontaneous flap-margin-related corneal ulcer 11 years after the original laser in situ keratomileusis (LASIK) procedure. Two enhancements had been performed; the most ...recent was 3 years prior to presentation. Cultures were positive for a heavy growth of Klebsiella oxytoca. The ulcer responded clinically to topical treatment with fortified cefazolin. Eighteen days after presentation, the infiltrate had resolved and the cornea had fully epithelialized. To our knowledge, this is the first report of post-LASIK infectious keratitis caused by K oxytoca.
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