Search results for "Spreading"
showing 10 items of 91 documents
A systematic review on external ear melanoma
2014
Summary Background External ear melanoma accounts for only 1% of all cutaneous melanomas, and data on its optimal management and prognosis are limited. Aim We aim to review the literature on external ear melanoma to guide surgeons in the treatment of this uncommon and peculiar pathology. Materials and methods A systematic review of English language studies on ear melanoma published from 1993 to 2013 was performed using the PubMed electronic database. Data on epidemiology, oncological treatment (tumor resection and regional lymph nodes management), and reconstruction were extrapolated from selected papers. Results The total number of patients was 858 (30 studies). The helix was the most comm…
Capture Aware Sequential Waterfilling for LoraWAN Adaptive Data Rate
2020
LoRaWAN (Long Range Wide Area Network) is emerging as an attractive network infrastructure for ultra low power Internet of Things devices. Even if the technology itself is quite mature and specified, the currently deployed wireless resource allocation strategies are still coarse and based on rough heuristics. This paper proposes an innovative "sequential waterfilling" strategy for assigning Spreading Factors (SF) to End-Devices (ED). Our design relies on three complementary approaches: i) equalize the Time-on-Air of the packets transmitted by the system's EDs in each spreading factor's group; ii) balance the spreading factors across multiple access gateways, and iii) keep into account the c…
Epidemic spreading and aging in temporal networks with memory
2018
Time-varying network topologies can deeply influence dynamical processes mediated by them. Memory effects in the pattern of interactions among individuals are also known to affect how diffusive and spreading phenomena take place. In this paper we analyze the combined effect of these two ingredients on epidemic dynamics on networks. We study the susceptible-infected-susceptible (SIS) and the susceptible-infected-removed (SIR) models on the recently introduced activity-driven networks with memory. By means of an activity-based mean-field approach we derive, in the long time limit, analytical predictions for the epidemic threshold as a function of the parameters describing the distribution of …
Interference Cancellation for LoRa Gateways and Impact on Network Capacity
2021
In this paper we propose LoRaSyNc (LoRa receiver with SyNchronization and Cancellation), a second generation LoRa receiver that implements Successive Interference Cancellation (SIC) and time synchronization to improve the performance of LoRa gateways. Indeed, the chirp spread spectrum modulation employed in LoRa experiences very high capture probability, and cancelling the strongest signal in case of collisions can significantly improve the cell capacity. An important feature of LoRaSyNc is the ability to track the frequency and clock drifts between the transmitter and receiver, during the whole demodulation of the interfered frame. Due to the use of low-cost oscillators on end-devices, a s…
Heavy metals in coastal water systems. A case study from the northwestern Gulf of Thailand.
2005
A geochemical survey of the northwestern part of the Thailand Gulf (Inner Gulf) was carried out in order to define concentrations and distribution patterns of selected heavy metals (V, Cr, Co, Ni, Cu, Zn, and U) in the coastal system and estuarine area of the Mae Klong river. The results indicate the presence of two different sources of heavy metals in the studied environment and allowed us to identify a lithogenic component that significantly influences the composition of coastal waters and suspended particulate matter (SPM). Comparison of the normalized heavy metals concentrations both in the studied samples and in those reported for the Sn–W ores present in the surrounding areas suggests…
Sclerochronological evidence of pronounced seasonality from the late Pliocene of the southern North Sea basin and its implications
2022
Oxygen isotope (δ18O) sclerochronology of benthic marine molluscs provides a means of reconstructing the seasonal range in seafloor temperature, subject to use of an appropriate equation relating shell δ18O to temperature and water δ18O, a reasonably accurate estimation of water δ18O, and due consideration of growth-rate effects. Taking these factors into account, δ18O data from late Pliocene bivalves of the southern North Sea basin (Belgium and the Netherlands) indicate a seasonal seafloor range a little smaller than now in the area. Microgrowth-increment data from Aequipecten opercularis, together with the species composition of the bivalve assemblage and aspects of preservation, suggest …
Universidad Politécnica Radiotelevisión. Creación y primera etapa (2000-2008)
2012
En el artículo se trata la historia de los canales UPVRadio y Universidad Politécnica Televisión desde el año 2000 a 2008, incluyendo el proceso de estudio, diseño y puesta en marcha de ambos y una descripción de los objetivos, el modelo de gestión, la plantilla, los canales de emisión, la programación, la audiencia y las fuentes de financiación alternativa en el régimen permanente. Se comenta también la infraestructura de soporte de ambos canales, con apartados para las dependencias de la cadena, el equipamiento de la radio y el de la televisión. The article narrates the story of UPVRadio and Universidad Politecnica Television University from 2000 to 2008, including the process of study, d…
Large deep-seated slump structure off Ischia volcanic island, Eastern Tyrrhenian sea (Italy)
2012
Ischia island is located over the Campania sector of Eastern Tyrrhenian margin and represents the sub-aerial section of a larger, E-W trending volcanic ridge including others submerged or buried volcanic edifices. The island itself result from the coalescence of a multitude of small to medium scale eruptions leading to the emplacement of domes, lava flow and pyroclastic deposits and ignimbrites (VEZZOLI et al., 1988) ranging from alkali basalts to trachytes. The oldest basement dates back to 150 ky and crops out along the perimeter of the island especially to the south. Latest eruption occurred in 1302 A.D. and together with strong hydrothermal activity, ground uplift and seismic shaking in…
L'ensenyament del català a la ràdio durant el tardofranquisme : 'cursos de catalán' (1969) de Ràdio Barcelona
2018
En el context dels intents de recuperació de l'ensenyament del català que van succeir-se durant la dècada dels seixanta, el 1969 Ràdio Barcelona va posar en antena el programa Cursos de catalán, ideat i escrit pel poeta, gramàtic i editor Miquel Arimany, al qual posaven veu ell mateix i els locutors Isidre Sola, Enriqueta Teixidó i Xavier Ubach, dirigits per Armand Blanch. El programa, que es va estroncar a la trenta-tresena emissió, tenia com a objectiu fonamental l'extensió del coneixement del català entre el col·lectiu immigrant, condició imprescindible per a eixamplar-ne l'ús. El present article analitza les característiques del curs: l'alternança de castellà i català com a llengües veh…
Impact of LoRa Imperfect Orthogonality: Analysis of Link-Level Performance
2018
In this letter, we focus on the evaluation of link-level performance of LoRa technology, in the usual network scenario with a central gateway and high-density deployment of end-devices. LoRa technology achieves wide coverage areas, low power consumption and robustness to interference thanks to a chirp spread-spectrum modulation, in which chirps modulated with different spreading factors (SFs) are quasi-orthogonal. We focus on the performance analysis of a single receiver in presence of collisions. First, we analyze LoRa modulation numerically and show that collisions between packets modulated with different SFs can indeed cause packet loss if the interference power received is strong enough…