Quantum Key Distribution

This chapter describes the application of lasers, specifically diode lasers, in the area of quantum key distribution (QKD). First, we motivate the distribution of cryptographic keys based on quantum physical properties of light, give a brief introduction to QKD assuming the reader has no or very little knowledge about cryptography, and briefly present the state-of-the-art of QKD. In the second half of the chapter we describe, as an example of a real-world QKD system, the system deployed between the University of Calgary and SAIT Polytechnic. We conclude the chapter with a brief discussion of quantum networks and future steps.Comment: 20 pages, 12 figure

Dwarfs Gobbling Dwarfs: A Stellar Tidal Stream Around NGC 4449 and Hierarchical Galaxy Formation on Small Scales

A candidate diffuse stellar substructure was previously reported in the halo of the nearby dwarf starburst galaxy NGC 4449 by Karachentsev et al. We map and analyze this feature using a unique combination of deep integrated-light images from the Black Bird 0.5-meter telescope, and high-resolution wide-field images from the 8-meter Subaru telescope, which resolve the nebulosity into a stream of red giant branch stars, and confirm its physical association with NGC 4449. The properties of the stream imply a massive dwarf spheroidal progenitor, which after complete disruption will deposit an amount of stellar mass that is comparable to the existing stellar halo of the main galaxy. The ratio between luminosity or stellar-mass between the two galaxies is ~1:50, while the indirectly measured dynamical mass-ratio, when including dark matter, may be ~1:10-1:5. This system may thus represent a "stealth" merger, where an infalling satellite galaxy is nearly undetectable by conventional means, yet has a substantial dynamical influence on its host galaxy. This singular discovery also suggests that satellite accretion can play a significant role in building up the stellar halos of low-mass galaxies, and possibly in triggering their starbursts.Comment: ApJ Letters, in press. Minor changes. 6 pages, 3 figures. A high resolution version of the paper and Subaru image are available at http://www.cosmotography.com/images/small_ngc4449.htm

On the Gas Surrounding High Redshift Galaxy Clusters

Francis & Hewett (1993) identified two 10-Mpc scale regions of the high redshift universe that were seemingly very overdense in neutral hydrogen. Subsequent observations showed that at least one of these gas-rich regions enveloped a cluster of galaxies at redshift 2.38. We present improved observations of the three background QSOs with sightlines passing within a few Mpc of this cluster of galaxies. All three QSOs show strong neutral hydrogen absorption at the cluster redshift, suggesting that this cluster (and perhaps all high redshift clusters) may be surrounded by a ~5 Mpc scale region containing ~ 10^12 solar masses of neutral gas. If most high redshift clusters are surrounded by such regions, we show that the gas must be in the form of many small ( 0.03 cm^-3) clouds, each of mass < 10^6 solar masses. These clouds are themselves probably gathered into > 20 kpc sized clumps, which may be galaxy halos or protogalaxies. If this gas exists, it will be partially photoionised by the UV background. We predict the diffuse Ly-alpha flux from this photoionisation, and place observational limits on its intensity.Comment: 19 pages, 5 figures. Accepted for publication in PAS

Penetración de fosfomicina en explantes intestinales

Fosfomycin (FOS) is an antibiotic used in pig farms for treatment and prevention of infections caused by resistant bacteria during post-weaning period. Antibiotics and non-toxic concentrations of such mycotoxins as deoxynivalenol (DON) are frequently found in the diet of animals. These compounds can establish interactions in the intestinal tract which affect and/or modify the penetration of FOS to enterocytes. The aim of this study was to culture intestinal explants from jejuna of pigs and to apply this model to the study of intracellular penetration of FOS in presence or absence of DON. The use of intestinal explants reduces the number of animals sacrificed per experiment and preserves normal intestinal histological structure in vitro. The results showed that there was no statistically significant difference in the intracellular concentration of FOS between explants incubated with 580 ppm FOS and explants incubated with 580 ppm FOS and 1 ppm DON. The Cmax was 12 ppm and the tmax was 2 h. Our study proved that only the 2% of the antibiotic is intracellularly accumulated and that the intracellular concentration of FOS is not affected by the presence of non-toxic concentrations of DON.Fosfomicina (FOS) es un antibiótico utilizado en producción porcina para el tratamiento y prevención de infecciones causadas por bacterias resistentes durante el post destete. En la dieta de los animales es frecuente encontrar antibióticos y concentraciones subtóxicas de micotoxinas como el deoxinivalenol (DON). Estos compuestos pueden establecer interacciones en el tracto intestinal afectando y/o modificando la penetración de FOS a los enterocitos. El objetivo de este trabajo fue desarrollar un cultivo de explantes de intestino procedentes de yeyuno de cerdos y aplicar este modelo para estudiar la penetración intracelular de FOS en presencia o ausencia de DON. El uso de explantes intestinales disminuye el sacrificio de animales por experimento y preservan la estructura histológica intestinal normal en condiciones in vitro. Los resultados mostraron que no existieron diferencias estadísticamente significativas en la concentración intracelular de FOS entre los explantes incubados con 580 ppm FOS y los explantes incubados con 580 ppm FOS y 1 ppm DON. Se obtuvo un Cmax de 12 ppm y tmax de 2 h. Nuestro estudio demostró que solo el 2% del antibiótico se acumula intracelularmente y que la concentración intracelular de FOS no es afectada por la presencia de concentraciones subtóxicas de DON

Colour Dependence of the Distribution of IRAS Galaxies revealed by Multifractal Measures

Multifractal measures are applied to three IRAS galaxy subsamples selected by colour from the PSCz catalogue. As shown by generalised dimension spectrum, hot IRAS galaxies are found less clustered than cold galaxies, but the difference is very weak. An alternative tool, the conditional multifractal dimension spectrum reveals apparent peculiarity of the distribution of hot galaxies, especially at high orders. The conditional multifractal measure is basically measuring the environment of selected galaxies. A detailed analysis of the distribution of galaxies with their number of neighbours turns out that cold galaxies are more likely living in over dense regions than hot galaxies. Further studies suggest that, since the colour of IRAS galaxies is a good trace of star formation rate, it is possible that we have statistical evidence here for enhanced star formation rate due to galaxy interactionsComment: minor revision; accepted by A&

Semantic models and knowledge graphs as manufacturing system reconfiguration enablers

Reconfigurable Manufacturing System (RMS) provides a cost-effective approach for manufacturers to adapt to fluctuating market demands by reconfiguring assets through automated analysis of asset utilization and resource allocation. Achieving this automation necessitates a clear understanding, formalization, and documentation of asset capabilities and capacity utilization. This paper introduces a unified model employing semantic modeling to delineate the manufacturing sector's capabilities, capacity, and reconfiguration potential. The model illustrates the integration of these three components to facilitate efficient system reconfiguration. Additionally, semantic modeling allows for the capture of historical experiences, thus enhancing long-term system reconfiguration through a knowledge graph. Two use cases are presented: capability matching and reconfiguration solution recommendation based on the proposed model. A thorough explication of the methodology and outcomes is provided, underscoring the advantages of this approach in terms of heightened efficiency, diminished costs, and augmented productivity

Biological and functional analysis of interactions among tetraspanin-associated proteins in human T lymphocites by high-throuchput methods using second generation proteomics techniques

Comunicaciones a congreso

Multimodality in galaxy clusters from SDSS DR8: substructure and velocity distribution

We search for the presence of substructure, a non-Gaussian, asymmetrical velocity distribution of galaxies, and large peculiar velocities of the main galaxies in galaxy clusters with at least 50 member galaxies, drawn from the SDSS DR8. We employ a number of 3D, 2D, and 1D tests to analyse the distribution of galaxies in clusters: 3D normal mixture modelling, the Dressler-Shectman test, the Anderson-Darling and Shapiro-Wilk tests and others. We find the peculiar velocities of the main galaxies, and use principal component analysis to characterise our results. More than 80% of the clusters in our sample have substructure according to 3D normal mixture modelling, the Dressler-Shectman (DS) test shows substructure in about 70% of the clusters. The median value of the peculiar velocities of the main galaxies in clusters is 206 km/s (41% of the rms velocity). The velocities of galaxies in more than 20% of the clusters show significant non-Gaussianity. While multidimensional normal mixture modelling is more sensitive than the DS test in resolving substructure in the sky distribution of cluster galaxies, the DS test determines better substructure expressed as tails in the velocity distribution of galaxies. Richer, larger, and more luminous clusters have larger amount of substructure and larger (compared to the rms velocity) peculiar velocities of the main galaxies. Principal component analysis of both the substructure indicators and the physical parameters of clusters shows that galaxy clusters are complicated objects, the properties of which cannot be explained with a small number of parameters or delimited by one single test. The presence of substructure, the non-Gaussian velocity distributions, as well as the large peculiar velocities of the main galaxies, shows that most of the clusters in our sample are dynamically young.Comment: 15 pages, 11 figures, 2 online tables, accepted for publication in Astronomy and Astrophysic

Multimodality of rich clusters from the SDSS DR8 within the supercluster-void network

We study the relations between the multimodality of galaxy clusters drawn from the SDSS DR8 and the environment where they reside. As cluster environment we consider the global luminosity density field, supercluster membership, and supercluster morphology. We use 3D normal mixture modelling, the Dressler-Shectman test, and the peculiar velocity of cluster main galaxies as signatures of multimodality of clusters. We calculate the luminosity density field to study the environmental densities around clusters, and to find superclusters where clusters reside. We determine the morphology of superclusters with the Minkowski functionals and compare the properties of clusters in superclusters of different morphology. We apply principal component analysis to study the relations between the multimodality parametres of clusters and their environment simultaneously. We find that multimodal clusters reside in higher density environment than unimodal clusters. Clusters in superclusters have higher probability to have substructure than isolated clusters. The superclusters can be divided into two main morphological types, spiders and filaments. Clusters in superclusters of spider morphology have higher probabilities to have substructure and larger peculiar velocities of their main galaxies than clusters in superclusters of filament morphology. The most luminous clusters are located in the high-density cores of rich superclusters. Five of seven most luminous clusters, and five of seven most multimodal clusters reside in spider-type superclusters; four of seven most unimodal clusters reside in filament-type superclusters. Our study shows the importance of the role of superclusters as high density environment which affects the properties of galaxy systems in them.Comment: 16 pages, 12 figures, 2 online tables, accepted for publication in Astronomy and Astrophysic

Accretion, Growth of Supermassive Black Holes, and Feedback in Galaxy Mergers

Super-Eddington accretion is very efficient in growing the mass of a black hole: in a fraction of the Eddington time its mass can grow to an arbitrary large value if the feedback effect is not taken into account. However, since super-Eddington accretion has a very low radiation efficiency, people have argued against it as a major process for the growth of the black holes in quasars since observations have constrained the average accretion efficiency of the black holes in quasars to be \ga 0.1. In this paper we show that the observational constraint does not need to be violated if the black holes in quasars have undergone a two-phase growing process: with a short super-Eddington accretion process they get their masses inflated by a very large factor until the feedback process becomes important, then with a prolonged sub-Eddington accretion process they have their masses increased by a factor \ga 2. The overall average efficiency of this two-phase process is then \ga 0.1, and the existence of black holes of $10^9 M_\odot$ by redshift 6 is easily explained. Observational test of the existence of the super-Eddington accretion phase is briefly discussed.Comment: 11 pages, 4 figures. Submitted to MNRA