71 research outputs found
Laser-controlled fluorescence in two-level systems
The ability to modify the character of fluorescent emission by a laser-controlled, optically nonlinear process has recently been shown theoretically feasible, and several possible applications have already been identified. In operation, a pulse of off-resonant probe laser beam, of sufficient intensity, is applied to a system exhibiting fluorescence, during the interval of excited- state decay following the initial excitation. The result is a rate of decay that can be controllably modified, the associated changes in fluorescence behavior affording new, chemically specific information. In this paper, a two-level emission model is employed in the further analysis of this all-optical process; the results should prove especially relevant to the analysis and imaging of physical systems employing fluorescent markers, these ranging from quantum dots to green fluorescence protein. Expressions are presented for the laser-controlled fluorescence anisotropy exhibited by samples in which the fluorophores are randomly oriented. It is also shown that, in systems with suitably configured electronic levels and symmetry properties, fluorescence emission can be produced from energy levels that would normally decay nonradiatively. © 2010 American Chemical Society
Radio polarization from the inner Galaxy at arcminute resolution
The Southern Galactic Plane Survey (SGPS) is an HI and 1.4-GHz continuum
survey of the 4th quadrant of the Galaxy at arcmin resolution. We present here
results on linearly polarized continuum emission from an initial
28-square-degree Test Region for the SGPS, consisting of 190 mosaiced pointings
of the Australia Telescope Compact Array, and covering the range 325.5 < l <
332.5, -0.5 < b < +3.5. Complicated extended structure is seen in linear
polarization throughout the Test Region, almost all of which has no correlation
with total intensity. We interpret the brightest regions of polarized emission
as representing intrinsic structure in extended polarization, most likely
originating in the Crux spiral arm at a distance of 3.5 kpc; fainter polarized
structure is imposed by Faraday rotation in foreground material. Two large
areas in the field are devoid of polarization. We argue that these voids are
produced by foreground HII regions in which the magnetic field is disordered on
scales of ~0.1-0.2 pc. We also identify a depolarized halo around the HII
region RCW 94, which we suggest results from the interaction of the HII region
with a surrounding molecular cloud.Comment: 21 pages, 5 embedded EPS figures, 9 jpeg figures, uses emulateapj
apjfonts. Accepted to the Astrophysical Journal. Version with all 14 figures
in embedded EPS format available at http://space.mit.edu/~bmg/sgps
Transglutaminases (TGs) in Ocular and Periocular Tissues: Effect of Muscarinic Agents on TGs in Scleral Fibroblasts
10.1371/journal.pone.0018326PLoS ONE64
Distinct gene subsets in pterygia formation and recurrence: dissecting complex biological phenomenon using genome wide expression data
<p>Abstract</p> <p>Background</p> <p>Pterygium is a common ocular surface disease characterized by fibrovascular invasion of the cornea and is sight-threatening due to astigmatism, tear film disturbance, or occlusion of the visual axis. However, the mechanisms for formation and post-surgical recurrence of pterygium are not understood, and a valid animal model does not exist. Here, we investigated the possible mechanisms of pterygium pathogenesis and recurrence.</p> <p>Methods</p> <p>First we performed a genome wide expression analysis (human Affymetrix Genechip, >22000 genes) with principal component analysis and clustering techniques, and validated expression of key molecules with PCR. The controls for this study were the un-involved conjunctival tissue of the same eye obtained during the surgical resection of the lesions. Interesting molecules were further investigated with immunohistochemistry, Western blots, and comparison with tear proteins from pterygium patients.</p> <p>Results</p> <p>Principal component analysis in pterygium indicated a signature of matrix-related structural proteins, including fibronectin-1 (both splice-forms), collagen-1A2, keratin-12 and small proline rich protein-1. Immunofluorescence showed strong expression of keratin-6A in all layers, especially the superficial layers, of pterygium epithelium, but absent in the control, with up-regulation and nuclear accumulation of the cell adhesion molecule CD24 in the pterygium epithelium. Western blot shows increased protein expression of beta-microseminoprotein, a protein up-regulated in human cutaneous squamous cell carcinoma. Gene products of 22 up-regulated genes in pterygium have also been found by us in human tears using nano-electrospray-liquid chromatography/mass spectrometry after pterygium surgery. Recurrent disease was associated with up-regulation of sialophorin, a negative regulator of cell adhesion, and <it>never in mitosis a</it>-5, known to be involved in cell motility.</p> <p>Conclusion</p> <p>Aberrant wound healing is therefore a key process in this disease, and strategies in wound remodeling may be appropriate in halting pterygium or its recurrence. For patients demonstrating a profile of 'recurrence', it may be necessary to manage as a poorer prognostic case and perhaps, more adjunctive treatment after resection of the primary lesion.</p
Developments in the Photonic Theory of Fluorescence
Conventional fluorescence commonly arises when excited molecules relax to their ground electronic state, and most of the surplus energy dissipates in the form of photon emission. The consolidation and full development of theory based on this concept has paved the way for the discovery of several mechanistic variants that can come into play with the involvement of laser input – most notably the phenomenon of multiphoton-induced fluorescence. However, other effects can become apparent when off-resonant laser input is applied during the lifetime of the initial excited state. Examples include a recently identified scheme for laser-controlled fluorescence. Other systems of interest are those in which fluorescence is emitted from a set of two or more coupled nanoemitters. This chapter develops a quantum theoretical outlook to identify and describe these processes, leading to a discussion of potential applications ranging from all-optical switching to the generation of optical vortices
Meta-analysis of gene-environment-wide association scans accounting for education level identifies additional loci for refractive error
Myopia is the most common human eye disorder and it results from complex genetic and environmental causes. The rapidly increasing prevalence of myopia poses a major public health challenge. Here, the CREAM consortium performs a joint meta-analysis to test single-nucleotide polymorphism (SNP) main effects and SNP x education interaction effects on refractive error in 40,036 adults from 25 studies of European ancestry and 10,315 adults from 9 studies of Asian ancestry. In European ancestry individuals, we identify six novel loci (FAM150B-ACP1, LINC00340, FBN1, DIS3L-MAP2K1, ARID2-SNAT1 and SLC14A2) associated with refractive error. In Asian populations, three genome-wide significant loci AREG, GABRR1 and PDE10A also exhibit strong interactions with education (P <8.5 x 10(-5)), whereas the interactions are less evident in Europeans. The discovery of these loci represents an important advance in understanding how gene and environment interactions contribute to the heterogeneity of myopia.Peer reviewe
Human limbal progenitor cell characteristics are maintained in tissue culture
Annals of the Academy of Medicine Singapore35280-8
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