Compatibility of the large quasar groups with the concordance cosmological model

We study the compatibility of large quasar groups with the concordance cosmological model. Large quasar groups are very large spatial associations of quasars in the cosmic web, with sizes of 50–250 h−1 Mpc. In particular, the largest large quasar group known, named Huge-LQG, has a longest axis of ∼860 h−1 Mpc, larger than the scale of homogeneity (∼260 Mpc), which has been noted as a possible violation of the cosmological principle. Using mock catalogues constructed from the Horizon Run 2 cosmological simulation, we found that large quasar groups size, quasar member number and mean overdensity distributions in the mocks agree with observations. The Huge-LQG is found to be a rare group with a probability of 0.3 per cent of finding a group as large or larger than the observed, but an extreme value analysis shows that it is an expected maximum in the sample volume with a probability of 19 per cent of observing a largest quasar group as large or larger than Huge-LQG. The Huge-LQG is expected to be the largest structure in a volume at least 5.3 ± 1 times larger than the one currently studied

Massive MIMO for Internet of Things (IoT) Connectivity

Massive MIMO is considered to be one of the key technologies in the emerging 5G systems, but also a concept applicable to other wireless systems. Exploiting the large number of degrees of freedom (DoFs) of massive MIMO essential for achieving high spectral efficiency, high data rates and extreme spatial multiplexing of densely distributed users. On the one hand, the benefits of applying massive MIMO for broadband communication are well known and there has been a large body of research on designing communication schemes to support high rates. On the other hand, using massive MIMO for Internet-of-Things (IoT) is still a developing topic, as IoT connectivity has requirements and constraints that are significantly different from the broadband connections. In this paper we investigate the applicability of massive MIMO to IoT connectivity. Specifically, we treat the two generic types of IoT connections envisioned in 5G: massive machine-type communication (mMTC) and ultra-reliable low-latency communication (URLLC). This paper fills this important gap by identifying the opportunities and challenges in exploiting massive MIMO for IoT connectivity. We provide insights into the trade-offs that emerge when massive MIMO is applied to mMTC or URLLC and present a number of suitable communication schemes. The discussion continues to the questions of network slicing of the wireless resources and the use of massive MIMO to simultaneously support IoT connections with very heterogeneous requirements. The main conclusion is that massive MIMO can bring benefits to the scenarios with IoT connectivity, but it requires tight integration of the physical-layer techniques with the protocol design.Comment: Submitted for publicatio

32. Quality assurance for new techniques of brachytherapy

In addition to classical HDR, PDR or LDR brachytherapy, new techniques such as transperineal radioactive implantations of the prostate via template guidance, or vascular brachytherapy for the prevention of restenosis, are becoming increasingly popular. At the same time they are introduced in a department, a quality assurance program must be implemented both to minimize the risks of treatment misadministrations and to prove respect to legal liability.The authors try to point out the necessary equipments and the particularities of Q.A. programs which must cover all the steps of the treatment. They consider successively prostate and vascular brachytherapy, making for each of them, a quick review of the most current techniques (including associated accessories and imaging devices), showing the particularities of adapted computerized treatment planning systems and the characteristics of radioactive sources usually used (photon sources for prostate such as 192 Ir for temporary implants and 125I and 103 Pd for permanent implants, 192 Ir or bêta sources for vessels). Particular detectors and methods to be employed to perform quality controls of equipments and sources, or in vivo measurements, are also presented. Lastly the guidelines and recommendations for “good practice and quality assurance” concerning these particular techniques and published by different international organizations, or which are in the process of development, are summarized. It will be noted that volume definitions, dose prescription and reporting, dose planning, dosimetry, staffing and responsabilities,etc, are or should be included in a complete quality assurance program

Scanning Probe Microscopy for polymer film characterization in food packaging

Scanning probe microscopy (SPM) is a branch of microscopy allowing characterization of surfaces at the micro-scale by means of a physical probe (with a size of a few microns) raster scanning the sample. SPMs monitor the interaction between such probe and the surface and, depending on the specific physical principles causing the interaction, they allow generation of a quantitative map of topographic properties: geometrical, optical, electrical, magnetic, etc. This is of the greatest interest, in particular whenever functional surfaces have to be characterized in a quantitative manner. The present paper discusses the different applications of Scanning Probe Microscopy techniques for a thorough characterization of polymer surfaces, of specific interest in particular for the case of food packaging applications