RXJ1716.6+6708: a young cluster at z=0.81

Clusters of galaxies at redshifts nearing one are of special importance since they may be caught at the epoch of formation. At these high redshifts there are very few known clusters. We present follow-up ASCA, ROSAT HRI and Keck LRIS observations of the cluster RXJ1716.6+6708 which was discovered during the optical identification of X-ray sources in the North Ecliptic Pole region of the ROSAT All-Sky Survey. At z=0.809, RXJ1716.6+6708 is the second most distant X-ray selected cluster so far published and the only one with a large number of spectroscopically determined cluster member velocities. The optical morphology of RXJ1716.6+6708 resembles an inverted S-shape filament with the X-rays coming from the midpoint of the filament. The X-ray contours have an elongated shape that roughly coincide with the weak lensing contours. The cluster has a low temperature, kT=5.66{+1.37 -0.58} keV, and a very high velocity dispersion sigma_{los}=1522{+215 -150} km s^{-1}. While the temperature is commensurate with its X-ray luminosity of (8.19 +/- 0.43)x10^{44} h_{50}^{-2} erg s^{-1} (2-10 keV rest frame), its velocity dispersion is much higher than expected from the sigma-T_X relationship of present-day clusters with comparable X-ray luminosity. RXJ1716.6+6708 could be an example of a protocluster, where matter is flowing along filaments and the X-ray flux is maximum at the impact point of the colliding streams of matter.Comment: Latex file, 18 pages, 4 figures, accepted for publication in the Astronomical Journa

Evidence of unrelaxed IGM around IC1262

AIMS: A peculiar morphology of the hot gas was discovered at the center of IC1262 with the ROSAT HRI. Sensitive Chandra and XMM-Newton data were requested to investigate the characteristics of this structure to understand its nature. METHODS: We have exploited the high resolution and sensitivity of Chandra's ACIS-S to investigate the peculiar morphology and spectral characteristics of hot gas in the group around IC1262. XMM-Newton data are only partially usable due to very heavy high background contamination, but they are useful to confirm and strengthen the results from Chandra. RESULTS: The Chandra data show a quite dramatic view of the \object{IC1262} system: a sharp discontinuity east of the central galaxy, with steep drops and a relatively narrow feature over 100 kpc long, plus an arc/loop to the N, are all indicative of a turmoil in the high energy component. Their morphologies could suggest them to be tracers of shocked material caused either by peculiar motions in the system or by a recent merger process, but the spectral characteristics indicate that the structure is cooler than its surroundings. The lack of evidence of significant structures in the velocity distribution of the group members and the estimated scale of the phenomenon make the interpretation of its physical nature challenging. We review a few possible interpretations, in light of similar phenomena observed in clusters and groups. The ram pressure stripping of a bright spiral galaxy, now near the center of the group, is a promising interpretation for most of the features observed. The relation with the radio activity requires a better sampling of the radio parameters that can only be achieved with deeper and higher resolution observations.Comment: Accepted for pubblication in Astronomy & Astrophysics. Figs 1, 2, 3 and 9-12 are given as JPEG files due to the restrictions on space available on astro-p

Energy Consumption Of Visual Sensor Networks: Impact Of Spatio-Temporal Coverage

Wireless visual sensor networks (VSNs) are expected to play a major role in future IEEE 802.15.4 personal area networks (PAN) under recently-established collision-free medium access control (MAC) protocols, such as the IEEE 802.15.4e-2012 MAC. In such environments, the VSN energy consumption is affected by the number of camera sensors deployed (spatial coverage), as well as the number of captured video frames out of which each node processes and transmits data (temporal coverage). In this paper, we explore this aspect for uniformly-formed VSNs, i.e., networks comprising identical wireless visual sensor nodes connected to a collection node via a balanced cluster-tree topology, with each node producing independent identically-distributed bitstream sizes after processing the video frames captured within each network activation interval. We derive analytic results for the energy-optimal spatio-temporal coverage parameters of such VSNs under a-priori known bounds for the number of frames to process per sensor and the number of nodes to deploy within each tier of the VSN. Our results are parametric to the probability density function characterizing the bitstream size produced by each node and the energy consumption rates of the system of interest. Experimental results reveal that our analytic results are always within 7% of the energy consumption measurements for a wide range of settings. In addition, results obtained via a multimedia subsystem show that the optimal spatio-temporal settings derived by the proposed framework allow for substantial reduction of energy consumption in comparison to ad-hoc settings. As such, our analytic modeling is useful for early-stage studies of possible VSN deployments under collision-free MAC protocols prior to costly and time-consuming experiments in the field.Comment: to appear in IEEE Transactions on Circuits and Systems for Video Technology, 201

An Evaluation of Popular Copy-Move Forgery Detection Approaches

A copy-move forgery is created by copying and pasting content within the same image, and potentially post-processing it. In recent years, the detection of copy-move forgeries has become one of the most actively researched topics in blind image forensics. A considerable number of different algorithms have been proposed focusing on different types of postprocessed copies. In this paper, we aim to answer which copy-move forgery detection algorithms and processing steps (e.g., matching, filtering, outlier detection, affine transformation estimation) perform best in various postprocessing scenarios. The focus of our analysis is to evaluate the performance of previously proposed feature sets. We achieve this by casting existing algorithms in a common pipeline. In this paper, we examined the 15 most prominent feature sets. We analyzed the detection performance on a per-image basis and on a per-pixel basis. We created a challenging real-world copy-move dataset, and a software framework for systematic image manipulation. Experiments show, that the keypoint-based features SIFT and SURF, as well as the block-based DCT, DWT, KPCA, PCA and Zernike features perform very well. These feature sets exhibit the best robustness against various noise sources and downsampling, while reliably identifying the copied regions.Comment: Main paper: 14 pages, supplemental material: 12 pages, main paper appeared in IEEE Transaction on Information Forensics and Securit

High-Mass Proto-Stellar Candidates - II : Density structure from dust continuum and CS emission

We present a detailed 1.2 mm continuum and CS spectral line study of a large sample of 69 massive star forming regions in very early stages of evolution, most of them prior to building up an ultracompact HII region. The continuum data show a zoo of different morphologies and give detailed information on the spatial distributions, the masses, column densities and average densities of the whole sample. Fitting the radial intensity profiles shows that three parameters are needed to describe the spatial distribution of the sources: constant emission from the center out to a few arcsec radius followed by a first power law intensity distribution which steepens further outside into a second power law distribution. The mean inner power law intensity index mi (I~r^(-mi)) is 1.2 corresponding to density indices p (n~r^(-p)) of 1.6. In total the density distribution of our massive star formations sites seem to be not too different from their low-mass counterparts, but we show that setting tight constrains on the density indices is very difficult and subject to many possible errors. The local densities we derive from CS calculations are higher (up to one order of magnitude) than the mean densities we find via the mm-continuum. Such inhomogeneous density distribution reflects most likely the ubiquitous phenomenon of clumping and fragmentation in molecular clouds. Linewidth-mass relations show a departure from virial equilibrium in the stages of strongly collapsing cores.Comment: 15 pages, 13 jpeg-figures. Astrophysical Journal, in pres

Development of a new automated method for the quantification of nuclear immunohistochemical markers

Antecedentes: La evaluación de marcadores inmunohistoquímicos se realiza con fines diagnósticos, terapéuticos e investigadores de forma manual. La utilización del análisis informatizado de imágenes digitales para evaluar estos marcadores aún no es suficientemente eficaz. Objetivos: Diseñar un nuevo procedimiento informatizado para cuantificar marcadores inmunohistoquímicos nucleares y evaluar los efectos de la compresión de imágenes. Métodos: El procedimiento desarrollado consta de diferentes etapas, donde se evalúan diferentes marcadores immunohistoquímicos utilizados en cáncer de mama y en linfoma. Resultados: El análisis estadístico demostró una gran validez del método automatizado. La redondez fue el único parámetro morfológico afectado por la compresión. Unos factores correctores fueron desarrollados para corregir esta afectación y la variabilidad en la cuantificación producida por esta afectación. Conclusiones: Este nuevo procedimiento automatizado es un método objetivo, más rápido y reproducible que tiene un excelente nivel de precisión, incluso con imágenes digitales de elevada complejidad y también en imágenes comprimidas. Background: The evaluation of immunohistochemical markers is carried out manually for diagnostic, therapeutic and research purposes. The use of a computerized digital image analysis to evaluate these markers is not sufficiently effective yet.Objectives: To design a new computerized procedure to quantify nuclear immunohistochemical markers and evaluate the effects of image compression.Methods: The procedure developed consists of several stages which evaluate different immunohistochemical markers used in breast cancer and lymphoma.Results: Statistical analysis demonstrated a high validity of the automated method. The roundness was the only morphological parameter affected by compression. Some correction factors were developed to correct this disorder and the variability in the measurement caused by this disorder.Conclusions: This new automated process is objective, faster and it has also an excellent level of accuracy, even with highly complex digital images and compressed images

Carving contiguous and fragmented files with fast object validation

http://dx.doi.org/10.1016/j.dlin.2007.06.017"File carving" reconstructs files based on their content, rather than using metadata that points to the content. Carving is widely used for forensics and data recovery, but no file carvers can automatically reassemble fragmented files. We survey files from more than 300 hard drives acquired on the secondary market and show that the ability to reassemble fragmented files is an important requirement for forensic work. Next we analyze the file carving problem, arguing that rapid, accurate carving is best performed by a multi-tier decision problem that seeks to quickly validate or discard candidate byte strings -- "object" -- from the media to be carved. Validators for the JPEG, Microsoft OLE (MSOLE) and ZIP file formats are discussed. Finally, we show how high speed validators can be used to reassemble fragmented files