Lämmermast mit verschiedenen Rassen auf extensivem Grünland: erste Ergebnisse

Ziel dieser Studie ist es, die mögliche Nutzung von extensivem Grünland für die Mast von Merino-Lämmern und reinrassigen Waldschaf-Lämmern unter verschiedenen Besatzraten zu untersuchen. Während der ersten Weidemonate im Jahr 2017 wurden Merino-Lämmer unter Ausnutzung der hohen Graswachstumsintensität geweidet. Die Waldschaf-Lämmer wurden in der zweiten Hälfte der Vegetationsperiode im Jahr 2017 mit geringerer Wachstumsintensität der Weide bis zum Ende dieser Weidezeit geweidet. Beide Rassen wurden in zwei getrennten Paddocks mit unterschiedlichen Besatzraten und Graswachstumshöhen beweidet. Das gleiche Verfahren wird im Jahr 2018 wiederholt. Ergebnisse des ersten Jahres 2017 werden vorgestellt

Pisces VII: Discovery of a possible satellite of Messier 33 in the DESI Legacy Imaging Surveys

We report deep imaging observations with DOLoRes@TNG of an ultra-faint dwarf satellite candidate of the Triangulum galaxy (M33) found by visual inspection of the public imaging data release of the DESI Legacy Imaging Surveys. Pisces VII/Triangulum (Tri) III is found at a projected distance of 72 kpc from M33, and using the tip of the red giant branch method we estimate a distance of D=1.0 +0.3,-0.2 Mpc, meaning the galaxy could either be an isolated ultra-faint or the second known satellite of M33. We estimate an absolute magnitude of M_V=-6.1+/-0.2 if Pisces VII/Tri II is at the distance of M33, or as bright as M_V=-6.8+/-0.2 if the galaxy is isolated. At the isolated distance, it has a physical half-light radius of r_h=131+/-61 pc consistent with similarly faint galaxies around the Milky Way. As the tip of the red giant branch is sparsely populated, constraining a precision distance is not possible, but if Pisces VII/Tri III can be confirmed as a true satellite of M33 it is a significant finding. With only one potential satellite detected around M33 previously (Andromeda XXII/Tri I), it lacks a significant satellite population in stark contrast to the similarly massive Large Magellanic Cloud. The detection of more satellites in the outskirts of M33 could help to better illuminate if this discrepancy between expectation and observations is due to a poor understanding of the galaxy formation process, or if it is due to the low luminosity and surface brightness of the M33 satellite population which has thus far fallen below the detection limits of previous surveys. If it is truly isolated, it would be the faintest known field dwarf detected to date.Comment: 10 pages, 9 figures, 2 tables, accepted for publication in MNRAS. This final version includes a moderate revision after the referee's comments and a correct titl

Pegasus V -- a newly discovered ultra-faint dwarf galaxy on the outskirts of Andromeda

We report the discovery of an ultra-faint dwarf in the constellation of Pegasus. Pegasus~V (Peg~V) was initially identified in the public imaging data release of the DESI Legacy Imaging Surveys and confirmed with deep imaging from Gemini/GMOS-N. The colour-magnitude diagram shows a sparse red giant branch (RGB) population and a strong over-density of blue horizontal branch stars. We measure a distance to Peg~V of $D=692^{+33}_{-31}$~kpc, making it a distant satellite of Andromeda with $M_V=-6.3\pm0.2$ and a half-light radius of $r_{\rm half}=89\pm41$~pc. It is located $\sim260$~kpc from Andromeda in the outskirts of its halo. The RGB is well-fit by a metal-poor isochrone with [Fe/H]$=-3.2$, suggesting it is very metal poor. This, combined with its blue horizontal branch could imply that it is a reionisation fossil. This is the first detection of an ultra-faint dwarf outside the deep Pan-Andromeda Archaeological Survey area, and points to a rich, faint satellite population in the outskirts of our nearest neighbour.Comment: Submitted to MNRAS Letters. 6 pages, 4 figures. Comments welcom

Flying ad-hoc network application scenarios and mobility models

[EN] Flying ad-hoc networks are becoming a promising solution for different application scenarios involving unmanned aerial vehicles, like urban surveillance or search and rescue missions. However, such networks present various and very specific communication issues. As a consequence, there are several research studies focused on analyzing their performance via simulation. Correctly modeling mobility is crucial in this context and although many mobility models are already available to reproduce the behavior of mobile nodes in an ad-hoc network, most of these models cannot be used to reliably simulate the motion of unmanned aerial vehicles. In this article, we list the existing mobility models and provide guidance to understand whether they could be actually adopted depending on the specific flying ad-hoc network application scenarios, while discussing their advantages and disadvantages.Bujari, A.; Tavares De Araujo Cesariny Calafate, CM.; Cano, J.; Manzoni, P.; Palazzi, CE.; Ronzani, D. (2017). Flying ad-hoc network application scenarios and mobility models. International Journal of Distributed Sensor Networks. 13(10):1-17. doi:10.1177/1550147717738192S117131

Mobility and Migrations in the Rural Areas of Mediterranean EU Countries

AbstractThis chapter focuses on the ambivalent nature of contemporary migrations in European rural areas. The growing presence of immigrants in these areas is a direct result of the restructuring of agriculture and global agri-food chains. Evidence indicates that while agricultural work and rural settings are decreasingly attractive to local populations, they represent a favourable environment to international newcomers, due to the higher chances to access livelihood resources. The non-visibility and informality that characterise rural settings and agricultural work arrangements provide on the one side opportunities for employment, while also fostering illegal labour practices and situations of harsh exploitation

Protective intraoperative ventilation with higher versus lower levels of positive end-expiratory pressure in obese patients (PROBESE): study protocol for a randomized controlled trial

Background: Postoperative pulmonary complications (PPCs) increase the morbidity and mortality of surgery in obese patients. High levels of positive end-expiratory pressure (PEEP) with lung recruitment maneuvers may improve intraoperative respiratory function, but they can also compromise hemodynamics, and the effects on PPCs are uncertain. We hypothesized that intraoperative mechanical ventilation using high PEEP with periodic recruitment maneuvers, as compared with low PEEP without recruitment maneuvers, prevents PPCs in obese patients. Methods/design The PRotective Ventilation with Higher versus Lower PEEP during General Anesthesia for Surgery in OBESE Patients (PROBESE) study is a multicenter, two-arm, international randomized controlled trial. In total, 2013 obese patients with body mass index ≥35 kg/m2 scheduled for at least 2 h of surgery under general anesthesia and at intermediate to high risk for PPCs will be included. Patients are ventilated intraoperatively with a low tidal volume of 7 ml/kg (predicted body weight) and randomly assigned to PEEP of 12 cmH2O with lung recruitment maneuvers (high PEEP) or PEEP of 4 cmH2O without recruitment maneuvers (low PEEP). The occurrence of PPCs will be recorded as collapsed composite of single adverse pulmonary events and represents the primary endpoint. Discussion To our knowledge, the PROBESE trial is the first multicenter, international randomized controlled trial to compare the effects of two different levels of intraoperative PEEP during protective low tidal volume ventilation on PPCs in obese patients. The results of the PROBESE trial will support anesthesiologists in their decision to choose a certain PEEP level during general anesthesia for surgery in obese patients in an attempt to prevent PPCs. Trial registration ClinicalTrials.gov identifier: NCT02148692. Registered on 23 May 2014; last updated 7 June 2016. Electronic supplementary material The online version of this article (doi:10.1186/s13063-017-1929-0) contains supplementary material, which is available to authorized users

The Distributed Contention in the Medium Access Control of IEEE 802.11 Wireless LANs: a Space and Time Perspective

This chapter will illustrate the new space and time perspective of the contention problem for the class of distributed random-access MAC protocols. This class of MAC protocol is fundamental because it is the basic access scheme in today\u2019s Standard IEEE 802.11 MAC, the most widely deployed WLAN technology, and also the basis for new protocol enhancements aimed at obtaining higher performance (such as IEEE 802.11b and IEEE 802.11a) and QoS support (such as IEEE 802.11e). Many solutions and guidelines that have been inherited from the wired scenarios, and the preliminary wireless solutions proposed to overcome the distributed contention problem in both the time and space domains of wireless channels, will be illustrated in this chapter. Additionally, the resource-oriented design of the distributed contention-based MAC protocols will be emphasized. This is required, given the resource bottlenecks of wireless systems (as an example, limited channel bandwidth and battery energy), and given the challenging resource requirements of user applications that would make no concessions to the wireless Internet

Collision Avoidance, Contention Control and Power Saving in IEEE 802.11 Wireless LANs

In recent years the proliferation of portable and laptop computers required LAN technology to support wireless connectivity. Mobile and wireless solutions for communication have been designed to allowmobile users to access information anywhere and at anytime. A variety of networking solutions, services, protocols, standards, technologies, and new applications have been proposed to meet the wireless Internet goals. One of the most successful technologies in recent years is based on the IEEE 802.11 Standard. The IEEE 802.11 Standard defines the Physical, the medium access control (MAC), and link layer control (LLC) sub-layers of the wireless technology that is widely deployed in today\u2019s wireless LANs. The aim of this chapter is to illustrate the evolution in the design and the main issues originating and characterizing the protocols as the basis of the distributed, random-access implementation of the IEEE 802.11 DCF MAC protocol. In general, it is interesting to determine the motivations for a consistent redesign work and the leading role of protocols in the resolution of many peculiar issues for the wireless scenario. Basically, this chapter will introduce and analyze the problems considered in the protocol design that are determined by the wireless scenarios and, more specifically, the evolution of protocols that inherited most of the design concepts from their wired counterpart. The chapter describes the new protocol-adaptation solutions proposed to control new critical system factors and limitations such as time- and space-contention under distributed control, channel bandwidth limitation, host mobility and variable hosts density, battery energy limitation, and power control