2,681 research outputs found
Elliptical Galaxies with Emission Lines from the Sloan Digital Sky Survey
We present the results of 11 elliptical galaxies with strong nebular emission
lines during our study of star formation history along the Hubble sequence.
After removing the dilution from the underlying old stellar populations by use
of stellar population synthesis model, we derive the accurate fluxes of all
emission lines for these objects, which are later classified with emission line
ratios into one Seyfert 2, six LINERs and four HII galaxies. We also identify
one HII galaxy (A1216+04) as a hitherto unknown Wolf-Rayet galaxy from the
presence of the Wolf-Rayet broad bump at 4650 \AA. We propose that the
star-forming activities in elliptical galaxies are triggered by either
galaxy-galaxy interaction or the merging of a small satellite/a massive star
cluster, as already suggested by recent numerical simulations
Intercellular Trafficking of Gold Nanostars in Uveal Melanoma Cells for Plasmonic Photothermal Therapy
Efficient plasmonic photothermal therapies (PPTTs) using non-harmful pulse laser irradiation at the near-infrared (NIR) are a highly sought goal in nanomedicine. These therapies rely on the use of plasmonic nanostructures to kill cancer cells while minimizing the applied laser power density. Cancer cells have an unsettled capacity to uptake, retain, release, and re-uptake gold nanoparticles, thus offering enormous versatility for research. In this work, we have studied such cell capabilities for nanoparticle trafficking and its impact on the effect of photothermal treatments. As our model system, we chose uveal (eye) melanoma cells, since laser-assisted eye surgery is routinely used to treat glaucoma and cataracts, or vision correction in refractive surgery. As nanostructure, we selected gold nanostars (Au NSs) due to their high photothermal efficiency at the near-infrared (NIR) region of the electromagnetic spectrum. We first investigated the photothermal effect on the basis of the dilution of Au NSs induced by cell division. Using this approach, we obtained high PPTT efficiency after several cell division cycles at an initial low Au NS concentration (pM regime). Subsequently, we evaluated the photothermal effect on account of cell division upon mixing Au NS-loaded and non-loaded cells. Upon such mixing, we observed trafficking of Au NSs between loaded and non-loaded cells, thus achieving effective PPTT after several division cycles under low irradiation conditions (below the maximum permissible exposure threshold of skin). Our study reveals the ability of uveal melanoma cells to release and re-uptake Au NSs that maintain their plasmonic photothermal properties throughout several cell division cycles and re-uptake. This approach may be readily extrapolated to real tissue and even to treat in situ the eye tumor itself. We believe that our method can potentially be used as co-therapy to disperse plasmonic gold nanostructures across affected tissues, thus increasing the effectiveness of classic PPTT
Qualitative properties of scalar-tensor theories of Gravity
The qualitative properties of spatially homogeneous stiff perfect fluid and
minimally coupled massless scalar field models within general relativity are
discussed. Consequently, by exploiting the formal equivalence under conformal
transformations and field redefinitions of certain classes of theories of
gravity, the asymptotic properties of spatially homogeneous models in a class
of scalar-tensor theories of gravity that includes the Brans-Dicke theory can
be determined. For example, exact solutions are presented, which are analogues
of the general relativistic Jacobs stiff perfect fluid solutions and vacuum
plane wave solutions, which act as past and future attractors in the class of
spatially homogeneous models in Brans-Dicke theory.Comment: 19 page
Highly Diastereo- and Enantioselective Allylboration of Aldehydes using alpha-Substituted Allyl/Crotyl Pinacol Boronic Esters via in Situ Generated Borinic Esters
Insulin Restores Gestational Diabetes Mellitus–Reduced Adenosine Transport Involving Differential Expression of Insulin Receptor Isoforms in Human Umbilical Vein Endothelium
Carbonaceous molecules in the oxygen-rich circumstellar environment of binary post-AGB stars: C_{60} fullerenes and polycyclic aromatic hydrocarbons
Context. The circumstellar environment of evolved stars is generally rich in
molecular gas and dust. Typically, the entire environment is either oxygen-rich
or carbon-rich, depending on the evolution of the central star. Aims. In this
paper we discuss three evolved disc sources with evidence of atypical emission
lines in their infrared spectra. The stars were taken from a larger sample of
post-AGB binaries for which we have Spitzer infrared spectra, characterised by
the presence of a stable oxygen-rich circumbinary disc. Our previous studies
have shown that the infrared spectra of post-AGB disc sources are dominated by
silicate dust emission, often with an extremely high crystallinity fraction.
However, the three sources described here are selected because they show a
peculiar molecular chemistry. Methods. Using Spitzer infrared spectroscopy, we
study in detail the peculiar mineralogy of the three sample stars. Using the
observed emission features, we identify the different observed dust, molecular
and gas species. Results. The infrared spectra show emission features due to
various oxygen-rich dust components, as well as CO2 gas. All three sources show
the strong infrared bands generally ascribed to polycyclic aromatic
hydrocarbons. Furthermore, two sample sources show C60 fullerene bands.
Conclusions. Even though the majority of post-AGB disc sources are dominated by
silicate dust in their circumstellar environment, we do find evidence that, for
some sources at least, additional processing must occur to explain the presence
of large carbonaceous molecules. There is evidence that some of these sources
are still oxygen-rich, which makes the detection of these molecules even more
surprising.Comment: Accepted for publication in Astronomy and Astrophysics, 10 pages, 7
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Preoperative spinal tumor embolization: an institutional experience with Onyx.
BACKGROUND: Preoperative embolization has the potential to decrease intraoperative blood loss and facilitate spinal cord decompression and tumor resection.
OBJECTIVE: We report our institutional experience with the embolization of hypervascular extradural spinal tumors with Onyx as well as earlier embolic agents in a series of 28 patients.
METHODS: A retrospective case review was conducted on patients undergoing preoperative transarterial embolization of a spinal tumor between 1995 and 2012 at our institution.
RESULTS: Twenty-eight patients met the inclusion criteria, with a mean age of 60.6 years. Twenty-eight patients had metastatic tumors. In 14 (50%) patients the metastases were from renal cell carcinomas. Fifty-four vessels were embolized using PVA, NBCA, Onyx, coils, or embospheres. Sixteen patients were treated with Onyx, 6 patients with PVA, 3 patients with embospheres, 2 patients with NBCA, and 3 patients with a combination of embolic agents. The average decrease in tumor blush was 97.8% with Onyx versus 92.7% with the rest of the embolic agents (p=0.08). The estimated blood loss was 1616ml (range 350-5000ml). Blood loss was 750cm(3) on average with Onyx versus 1844 with the rest of the embolic agents (p=0.14). The mean length of stay was 16 days. The mortality rate was zero. Pre- and post-operative modified Rankin Score (mRS) did not differ significantly in the series (3.12 versus 3.10, respectively, p=0.9).
CONCLUSION: In our experience, the use of transarterial tumor embolization as an adjunct for spinal surgery is a safe and feasible option
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