Distributed Information Object Resolution

The established host-centric networking paradigm is chal-lenged due to handicaps related with disconnected opera-tion, mobility, and broken locator/identifier semantics. This paper soberly examines another topic of great interest: distributed information object resolution. After recapping the notion of an information object, we review object resolution in today’s Internet which is based on Uniform Resource Identifiers (URIs). We revisit the implications of DNS involvement in URI resolution and discuss how two different types of content distribution networks work with respect to name resolution. Then we evaluate proposals championing the replacement of DNS with alternatives based on distributed hash tables. We present the pros and cons and highlight the importance of latency in resolution. The paper positions these issues in the context of a Network of Information (NetInf) and concludes with open research topics in the area. 1

Study of a quasi-microscope design for planetary landers

The Viking Lander fascimile camera, in its present form, provides for a minimum object distance of 1.9 meters, at which distance its resolution of 0.0007 radian provides an object resolution of 1.33 millimeters. It was deemed desirable, especially for follow-on Viking missions, to provide means for examing Martian terrain at resolutions considerably higher than that now provided. This led to the concept of quasi-microscope, an attachment to be used in conjunction with the fascimile camera to convert it to a low power microscope. The results are reported of an investigation to consider alternate optical configurations for the quasi-microscope and to develop optical designs for the selected system or systems. Initial requirements included consideration of object resolutions in the range of 2 to 50 micrometers, an available field of view of the order of 500 pixels, and no significant modifications to the fascimile camera

Alternative methods for top-quark mass determination at the Tevatron and LHC

I am summarizing here the determination of the top-quark mass from the CDF and D0 Collaborations at the Tevatron and the ATLAS and CMS Collaborations at the LHC using non-conventional methods. I am concentrating on the extraction of the top-quark mass from the top-antitop cross-section, on the mass measurement using the so-called endpoint method and on the top-quark mass determination from the b-lifetime. Other alternative methods are described in another articleComment: proceedings for the 6th international workshop on top quark physics (Top2013, Durbach, Germany), 10 pages, 7 figure

Fault-tolerant and finite-error localization for point emitters within the diffraction limit

We implement an estimator for determining the separation between two incoherent point sources. This estimator relies on image inversion interferometry and when used with the appropriate data analytics, it yields an estimate of the separation with finite-error, even when the sources come arbitrarily close together. The experimental results show that the technique has a good tolerance to noise and misalignment, making it an interesting consideration for high resolution instruments

On the Probability Distributions of Ellipticity

In this paper we derive an exact full expression for the 2D probability distribution of the ellipticity of an object measured from data, only assuming Gaussian noise in pixel values. This is a generalisation of the probability distribution for the ratio of single random variables, that is well-known, to the multivariate case. This expression is derived within the context of the measurement of weak gravitational lensing from noisy galaxy images. We find that the third flattening, or epsilon-ellipticity, has a biased maximum likelihood but an unbiased mean; and that the third eccentricity, or normalised polarisation chi, has both a biased maximum likelihood and a biased mean. The very fact that the bias in the ellipticity is itself a function of the ellipticity requires an accurate knowledge of the intrinsic ellipticity distribution of the galaxies in order to properly calibrate shear measurements. We use this expression to explore strategies for calibration of biases caused by measurement processes in weak gravitational lensing. We find that upcoming weak lensing surveys like KiDS or DES require calibration fields of order of several square degrees and 1.2 magnitude deeper than the wide survey in order to correct for the noise bias. Future surveys like Euclid will require calibration fields of order 40 square degree and several magnitude deeper than the wide survey. We also investigate the use of the Stokes parameters to estimate the shear as an alternative to the ellipticity. We find that they can provide unbiased shear estimates at the cost of a very large variance in the measurement. The python code used to compute the distributions presented in the paper and to perform the numerical calculations are available on request.Comment: 24 pages, 18 figures, 2 Tables. Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journa