3,012 research outputs found
An Integrated Content and Metadata based Retrieval System for Art
In this paper we describe aspects of the Artiste project to develop a distributed content and metadata based analysis, retrieval and navigation system for a number of major European Museums. In particular, after a brief overview of the complete system, we describe the design and evaluation of some of the image analysis algorithms developed to meet the specific requirements of the users from the museums. These include a method for retrievals based on sub images, retrievals based on very low quality images and retrieval using craquelure type
Lensed quasar search via time variability with the HSC transient survey
Gravitationally lensed quasars are useful for studying astrophysics and
cosmology, and enlarging the sample size of lensed quasars is important for
multiple studies. In this work, we develop a lens search algorithm for
four-image (quad) lensed quasars based on their time variability. In the
development of the lens search algorithm, we constructed a pipeline simulating
multi-epoch images of lensed quasars in cadenced surveys, accounting for quasar
variabilities, quasar hosts, lens galaxies, and the PSF variation. Applying the
simulation pipeline to the Hyper Suprime-Cam (HSC) transient survey, we
generated HSC-like difference images of the mock lensed quasars from Oguri &
Marshall's lens catalog. We further developed a lens search algorithm that
picks out variable objects as lensed quasar candidates based on their spatial
extent in the difference images. We tested our lens search algorithm with the
mock lensed quasars and variable objects from the HSC transient survey. Using
difference images from multiple epochs, our lens search algorithm achieves a
high true-positive rate (TPR) of 90.1% and a low false-positive rate (FPR) of
2.3% for the bright quads with wide separation. With a preselection of the
number of blobs in the difference image, we obtain a TPR of 97.6% and a FPR of
2.6% for the bright quads with wide separation. Even when difference images are
only available in one single epoch, our lens search algorithm can still detect
the bright quads with wide separation at high TPR of 97.6% and low FPR of 2.4%
in the optimal seeing scenario, and at TPR of and FPR of in
typical scenarios. Therefore, our lens search algorithm is promising and is
applicable to ongoing and upcoming cadenced surveys, particularly the HSC
transient survey and the Rubin Observatory Legacy Survey of Space and Time, for
finding new lensed quasar systems. [abridged]Comment: 15 pages, 11 figure
Search for the Lepton-Number-Violating Decay
A sensitive search for the lepton-number-violating decay has been performed using a sample of hyperons
produced in 800 GeV/ -Cu collisions. We obtain at 90% confidence, improving on the best
previous limit by four orders of magnitude.Comment: 9 pages, 5 figures, to be published in Phys. Rev. Let
Advances in lung bioengineering: Where we are, where we need to go, and how to get there
Lung transplantation is the only potentially curative treatment for end-stage lung failure and successfully improves both long-term survival and quality of life. However, lung transplantation is limited by the shortage of suitable donor lungs. This discrepancy in organ supply and demand has prompted researchers to seek alternative therapies for end-stage lung failure. Tissue engineering (bioengineering) organs has become an attractive and promising avenue of research, allowing for the customized production of organs on demand, with potentially perfect biocompatibility. While breakthroughs in tissue engineering have shown feasibility in practice, they have also uncovered challenges in solid organ applications due to the need not only for structural support, but also vascular membrane integrity and gas exchange. This requires a complex engineered interaction of multiple cell types in precise anatomical locations. In this article, we discuss the process of creating bioengineered lungs and the challenges inherent therein. We summarize the relevant literature for selecting appropriate lung scaffolds, creating decellularization protocols, and using bioreactors. The development of completely artificial lung substitutes will also be reviewed. Lastly, we describe the state of current research, as well as future studies required for bioengineered lungs to become a realistic therapeutic modality for end-stage lung disease. Applications of bioengineering may allow for earlier intervention in end-stage lung disease and have the potential to not only halt organ failure, but also significantly reverse disease progression
Influence of diffraction on the spectrum and wavefunctions of an open system
In this paper, we demonstrate the existence and significance of diffractive
orbits in an open microwave billiard, both experimentally and theoretically.
Orbits that diffract off of a sharp edge of the system are found to have a
strong influence on the transmission spectrum of the system, especially in the
regime where there are no stable classical orbits. On resonance, the
wavefunctions are influenced by both classical and diffractive orbits. Off
resonance, the wavefunctions are determined by the constructive interference of
multiple transient, nonperiodic orbits. Experimental, numerical, and
semiclassical results are presented.Comment: 27 pages, 29 figures, and 3 tables. Submitted to Physical Review E. A
copy with higher resolution figures is available at
http://monsoon.harvard.edu/~hersch/papers.htm
Hmox1 (Heme Oxygenase-1) Protects Against Ischemia-Mediated Injury via Stabilization of HIF-1α (Hypoxia-Inducible Factor-1α)
Complement-Mediated Virus Infectivity Neutralisation by HLA Antibodies Is Associated with Sterilising Immunity to SIV Challenge in the Macaque Model for HIV/AIDS.
Sterilising immunity is a desired outcome for vaccination against human immunodeficiency virus (HIV) and has been observed in the macaque model using inactivated simian immunodeficiency virus (SIV). This protection was attributed to antibodies specific for cell proteins including human leucocyte antigens (HLA) class I and II incorporated into virions during vaccine and challenge virus preparation. We show here, using HLA bead arrays, that vaccinated macaques protected from virus challenge had higher serum antibody reactivity compared with non-protected animals. Moreover, reactivity was shown to be directed against HLA framework determinants. Previous studies failed to correlate serum antibody mediated virus neutralisation with protection and were confounded by cytotoxic effects. Using a virus entry assay based on TZM-bl cells we now report that, in the presence of complement, serum antibody titres that neutralise virus infectivity were higher in protected animals. We propose that complement-augmented virus neutralisation is a key factor in inducing sterilising immunity and may be difficult to achieve with HIV/SIV Env-based vaccines. Understanding how to overcome the apparent block of inactivated SIV vaccines to elicit anti-envelope protein antibodies that effectively engage the complement system could enable novel anti-HIV antibody vaccines that induce potent, virolytic serological response to be developed
Measurement of the Alpha Asymmetry Parameter for the Omega- to Lambda K- Decay
We have measured the alpha parameter of the Omega- to Lambda K- decay using
data collected with the HyperCP spectrometer during the 1997 fixed-target run
at Fermilab. Analyzing a sample of 0.96 million Omega- to Lambda K^-, Lambda to
p pi- decays, we obtain alpha_Omega*alpha_Lambda =
[1.33+/-0.33(stat)+/-0.52(syst)] x 10^{-2}. With the accepted value of
alpha_Lambda, alpha_Omega is found to be [2.07+/-0.51(stat)+/-0.81(syst)] x
10^{-2}.Comment: 5 pages, 4 figures, to be appeared as a Rapid Communication in Phys.
Rev.
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