1,721,239 research outputs found
A Deep Space Challenge for Future Human Communications: Achieving Mars through Light
No full textWith the increasing investments and initiatives aimed at human landings on Mars, there arises a critical necessity for swift and dependable communication between Earth and Mars. While traditional radio communications have historically been employed, it is recognized that optical signals offer the potential for higher transmission speeds. However, challenges such as overcoming communication hurdles and mitigating in-terference, particularly from the Sun's position, remain to be addressed. This discussion delves into evaluating the strengths and weaknesses of various communication architectures, empha-sizing the necessary advancements to establish reliable and rapid communication links between Earth and Mars. One prospective solution for ensuring continuous communication could involve utilizing non-Keplerian orbits for satellite relays, thus circum-venting potential disruptions during Earth-Mars conjunctions
In vitro synergistic effect of 5-pyrrolidone-2-carboxylic acid (PCA) and copper sulphate pentahydrate (CS) against Staphylococcus aureus and Staphylococcus epidermidis
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The importance of the phytocomplex: The inspiring and illuminating example of Cannabis sativa L
No full textInterference Mitigation and Decoding Through Gateway Diversity in LoRaWAN
No full textLong Range (LoRa) represents an efficient low power solution for the Internet of Things. Specifically, LoRa defines a physical layer technology, while access control and network issues are handled by the LoRaWAN protocol. Channel access is essentially unslotted ALOHA, so LoRaWAN performance suffer from packet collision events. Such problem becomes more penalizing in dense network scenarios, where the large number of devices simultaneously connected makes the collision probability significantly grow. The largest part of solutions proposed to overcome LoRaWAN inefficiency is oriented to collision avoidance. Differently, we firstly present an algorithm for mitigating the interference among superposing LoRa signals, allowing collided packets to be detected anyway. Then, we propose a novel combining mechanism, implemented at the LoRaWAN network server, that exploits the information carried by the same packet, but received by different gateways, to achieve a more robust decoding. Hence, packet detection is reliably performed even in the presence of interference, thus reducing the need of retransmission and providing energy saving for end devices. Furthermore, simulation results show that the proposed solutions allow the end users to transmit exploiting low spreading factors, thus reducing the channel use that will be fundamental when dealing with larger scale network scenarios
On the Convenience of Perfect Channel Knowledge for Spatial Equalization of Correlated MIMO-VLC Links: Is it Really Worth it?
No full textVisible Light Communication has risen as a promising technology to support indoor wireless connectivity and provide illumination services as well. Moreover, high communication performance can be achieved by implementing Multiple-Input Multiple-Output architectures. However, the crosstalk characterizing spatially correlated channels scenarios may significantly impact on reliability. Such issue is commonly addressed by means of spatial equalization, with zero forcing and minimum mean square error representing the most widespread approaches. These methods allow the mitigation of crosstalk, even though they may cause undesired noise amplification as side effect, inducing errors during signal detection and decoding. In this regard, by focusing on a more realistic approach with respect to the literature, this work overturns the belief that having perfect channel knowledge is always better. Hence, we show that, when applying spatial equalization, imperfect channel knowledge is sometimes preferable to ideal channel state information. As a result, noise amplification is reduced at the expense of a reasonably less accurate crosstalk mitigation, with better communication performance being achieved
A Time-Frequency Geometric Detection Approach for LoRa Chirp Signals
No full textLong Range (LoRa) defines a particular chirp spread spectrum modulation employed for signaling in the LoRaWAN network. LoRa is recognized as one of the most effective technologies for the Internet of Things communication scenario, providing high reliability, wide coverage and low energy consumption for devices. The achievement of such performance is tied to the capability of LoRa receivers to accurately detect the signal even at low signal-to-noise ratio conditions. Dealing with signal demodulation, coherent and non-coherent detection represent the most widespread approaches. In this contribution, we present a new detection mechanism that exploits the geometrical properties of linear chirp to perform symbol demodulation, without requiring the energy consuming operations related to coherent and non-coherent detection. Furthermore, we demonstrate how the proposed approach can be fruitfully exploited not only for symbol demodulation, but also for LoRa packet synchronization and spreading factor recognition. By showing some numerical results, we compare the reliability level of the presented scheme through bit error rate with respect to the one offered by conventional detection methods
Copaifera langsdorffii Desf.: in vitro investigation on anti-Helicobacter pylori and anti-inflammatory activities of oleoresin and fruit methanolic extract
No full textCopaifera langsdorffii Desf. has been used in the traditional medicine of Brazil for centuries to treat a wide range of conditions, including infections, wounds and inflammation. The aim of this study is to compare the effects of C. langsdorffii bark oleoresin and a methanolic extract of the fruit for their anti-Helicobacter pylori (HP) activity and gastroprotective effects. We analyzed the in vitro anti-HP activity against three HP strains: CCUG 39500 (cagA+) and two clinical isolates, G21 and 10 K (cagA + and cagA–, respectively). The effect of C. langsdorffii products on IL-6 release in lipopolysaccharide-stimulated human peripheral blood mononuclear cells was also evaluated. Finally, the toxicity of the samples was evaluated in vitro and in vivo. Both the samples showed an interesting anti-HP activity, acting on different virulence strains, with the oleoresin reaching a minimum bactericidal concentration of 98 μg/ml against cagA– strain. Moreover, an interesting reduction in IL-6 release was observed, which could be helpful for reducing HP-induced inflammation, thus, preventing complications such as ulcer and irritation of the gastric mucosa. Toxicity was not observed up to 2000 μg/ml. Even if more studies must be conducted, this work supports the use of C. langsdorffii in the management of HP-related gastric disorders
Weaving as Traditional and Innovative Human-Centred Activity
No full textIt is a question of how physical and theoretical knowledge are deeply connected and how the learning of elementary gestures is the necessary basis for the development of highly refined artistic and artisan skills. The textile processes express single passages that many of us fortunately learn at a young age and that allow the development not only of manual skills but also of the control of thought and actions. The study is verified through a survey of a population sample on the skills of textile processing that do not produce income and that are not a job but which are part of our life also for the mere fact that everyone comes into daily physical contact with their clothes, your second skin
LIBERO: LIght Bias as effective countermeasure against EavesdROpper attacks
No full textVisible Light Communication (VLC) is expected to enable a wide range of applications in the next generation wireless networks. These applications are recognized as sensitive and prone to dangerous threats. So far, VLC research activities have been more focused on developing high data rate solutions and more robust systems for both indoor and outdoor applications, with a reduced focus on the security aspects. This is mostly due to the fact that VLC systems are based on short range and occurs in line of sight and it is then considered inherently secure by design. The specific characteristics of VLC systems make the traditional countermeasures adopted in radio-frequency-based systems not applicable, with a concrete need to conceive ad hoc solutions. Basing on these premises, in this work we consider a physical layer perspective by analyzing the intrinsic properties of visible light signals so as to develop a secure by design VLC system to be used in downlink. By exploiting the light bias, we guarantee an improved security level in respect of eavesdropper attack by granting also a good illumination level. A key aspect of this work is that the proposed solution does not rely on external devices or extra hardware
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