A time-based admission control mechanism for IEEE 802.11 ad Hoc networks

This paper presents a time-based admission control mechanism (TAC) for IEEE 802.11 ad hoc networks. The proposed mechanism was adapted to the QoS AODV routing protocol, which takes the quality of service requirements of the data flow into account in the route discovery process. TAC-AODV estimates the idle time of the physical medium based on the frames listened. The incoming traffic is admitted according to the offered load as well as the intra-flow interference, calculated based on the number of hops in the forwarding chain. TAC-AODV is compared to AAC-AODV, another admission control mechanism found in the literature, and the simulation results show that TAC-AODV is in average 12.5% better in terms of the packet delivery rate.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Impacts of species misidentification on species distribution modeling with presence-only data

Spatial records of species are commonly misidentified, which can change the predicted distribution of a species obtained from a species distribution model (SDM). Experiments were undertaken to predict the distribution of real and simulated species using MaxEnt and presence-only data “contaminated” with varying rates of misidentification error. Additionally, the difference between the niche of the target and contaminating species was varied. The results show that species misidentification errors may act to contract or expand the predicted distribution of a species while shifting the predicted distribution towards that of the contaminating species. Furthermore the magnitude of the effects was positively related to the ecological distance between the species’ niches and the size of the error rates. Critically, the magnitude of the effects was substantial even when using small error rates, smaller than common average rates reported in the literature, which may go unnoticed while using a standard evaluation method, such as the area under the receiver operating characteristic curve. Finally, the effects outlined were shown to impact negatively on practical applications that use SDMs to identify priority areas, commonly selected for various purposes such as management. The results highlight that species misidentification should not be neglected in species distribution modeling

Impacts of species misidentification on species distribution modeling with presence-only data

Spatial records of species are commonly misidentified, which can change the predicted distribution of a species obtained from a species distribution model (SDM). Experiments were undertaken to predict the distribution of real and simulated species using MaxEnt and presence-only data “contaminated” with varying rates of misidentification error. Additionally, the difference between the niche of the target and contaminating species was varied. The results show that species misidentification errors may act to contract or expand the predicted distribution of a species while shifting the predicted distribution towards that of the contaminating species. Furthermore the magnitude of the effects was positively related to the ecological distance between the species’ niches and the size of the error rates. Critically, the magnitude of the effects was substantial even when using small error rates, smaller than common average rates reported in the literature, which may go unnoticed while using a standard evaluation method, such as the area under the receiver operating characteristic curve. Finally, the effects outlined were shown to impact negatively on practical applications that use SDMs to identify priority areas, commonly selected for various purposes such as management. The results highlight that species misidentification should not be neglected in species distribution modeling

Cyclotron Production of Unconventional Radionuclides for PET Imaging: the Example of Titanium-45 and Its Applications

Positron emitting radionuclides are used to label different compounds, allowing the study of the major biological systems using PET (positron emission tomography) imaging. Although there are several radionuclides suited for PET imaging, routine clinical applications are still based on a restrict group constituted by 18F, 11C, and, more recently, 68Ga. However, with the enlarged availability of low-energy cyclotrons and technical improvements in radionuclide production, the use of unconventional radionuclides is progressively more common. Several examples of unconventional radionuclides for PET imaging are being suggested, and 45Ti could be suggested as a model, due to its interesting properties such as its abundant positron emission (85%), reduced positron energy (β+ endpoint energy = 1040 keV), physical half-life of 3.09 h, and interesting chemical properties. This review aims to introduce the role of cyclotrons in the production of unconventional radionuclides for PET imaging while using 45Ti as an example to explore the potential biomedical applications of those radionuclides in PET imaginginfo:eu-repo/semantics/publishedVersio

PET imaging using titanium-45: Could it be useful?

In the last decade a wider application of positron emission tomography (PET) as one of the most powerful medical imaging technologies was observed. This was largely due to the increased availability of equipment dedicated to production of radioisotopes, mainly due to the installation of low energy cyclotrons in hospitals, research institutes and pharmaceutical industries specialized in radiopharmaceutical production.info:eu-repo/semantics/publishedVersio

The use of radiolabeled nanoparticles for biomedical imaging

Introduction: In the last years, the practice of medicine is being changing with a special emphasis on the application of technological innovations where medical imaging modalities play an important role. Between several imaging modalities, Molecular Imaging (that is essentially based on Nuclear Medicine) is one of the most interesting solutions. On the other hand, assuming that nanoparticles are being studied as drug delivery systems, its application as vectors for radionuclide-based imaging is in a clear growing