Search results for "Head"
showing 10 items of 1640 documents
A performance analysis of block ACK scheme for IEEE 802.11e networks
2010
The demand for the IEEE 802.11 wireless local-area networks (WLANs) has been drastically increasing along with many emerging applications and services over WLAN. However, the IEEE 802.11 medium access control (MAC) is known to be limited in terms of its throughput performance due to the high MAC overhead, such as interframe spaces (IFS) or per-frame based acknowledgement (ACK) frame transmissions. The IEEE 802.11e MAC introduces the block ACK scheme for improving the system efficiency of the WLAN. Using the block ACK scheme can reduce the ACK transmission overhead by integrating multiple ACKs for a number of data frames into a bitmap that is contained in a block ACK frame, thus increasing t…
Increasing the VoIP Capacity through MAP Overhead Reduction in the IEEE 802.16 OFDMa Systems
2010
One of the main issues with supporting VoIP service over 802.16 networks is the signalling overhead caused by the downlink MAP messages due to frequent transmissions and small packets. To decrease the MAP overhead, the 802.16 standard proposes some mechanisms, such as the compressed MAP and sub-MAPs. In this paper, we show by means of extensive dynamic simulations that sub-MAPs can reduce dramatically the signalling overhead associated with VoIP traffic and significantly improve overall VoIP capacity. At the same time, since sub-MAPs are more sensitive to packet drops, they tend to increase the number of HARQ retransmissions in downlink and transmission delays in the uplink direction.
ARQ parameters for VoIP in IEEE 802.16 networks
2009
IEEE 802.16 standard defines two data retransmission mechanisms. HARQ provides fast retransmissions in cost of slightly increased overhead. On the contrary, ARQ has less overhead in cost of bit longer delays. It is therefore often used with BE connections. In addition to delay tolerant applications, BE can also be used for real-time services. Therefore, in this paper we analyze the ARQ mechanism and provide guidelines on how to set the ARQ parameters to achieve a good balance between the VoIP delay and packet loss.
Neighbor discovery and resource allocation for device-to-device communication
2014
Masteroppgave i Informasjons- og kommunikasjonsteknologi IKT590 Universitetet i Agder 2014 Device-to-Device (D2D) communication has attracted lots of attention as one of the most advanced wirelesscommunication technologies which allows access to services offered by nearby devices bypassing the BaseStation (BS). The potential advantages of this direct communication paradigm include high data rate, networkoffloading and range extension, as well as commercial proximity services and social networking. From the UserEquipments (UEs) and BS perspective, additional protocol overhead and discovery resource are required forD2D links. In such a context, neighbor discovery and resource allocation appro…
Extranodal extension of nodal metastasis is the main prognostic moderator in squamous cell carcinoma of the esophagus after neoadjuvant chemoradiothe…
2017
Several studies, including comprehensive systematic reviews with meta-analyses of our group of research, have demonstrated the negative prognostic impact of the extranodal extension of nodal metastasis (ENE) in different cancer types, including squamous cell carcinoma (SCC) of the vulva, of the penis and of head and neck, as well as in tumors of the digestive and genitourinary systems, in thyroid cancer and others (1-17).
Exemples de QSAR sur des coefficients de partage
2005
National audience
Squamous cell carcinoma related with dental implants. A clinical cases report
2020
One third of all cases of head and neck carcinoma (CA) concern the oral mucosa. The use of dental implants (DI) for dental rehabilitation is widely extended. However, a few studies have reported some cases with neoplasic alterations, among the tissue surrounding implants. Our aim was to analyze possible alterations at the bone-implant interface in patients with oral squamous cell carcinoma (SCC), providing new evidence that could relate or discard a possible link between these factors. We used, for the first time, different techniques, including electron microscopy and histology, to analyze the implant ´s surface and the surrounding tissue from four clinical cases with neoplasic alterations…
Using ultrasound transmission velocity to analyse the mechanical properties of teeth after in vitro, in situ, and in vivo irradiation.
2000
Ultrasound transmission velocity (UTV) in isotropic material as a measure for the modulus of elasticity was correlated to mechanical properties. Changes in micromechanical properties of radiated teeth and influence of the oral cavity were to be evaluated nondestructively. UTV was measured in extracted teeth after 36 Gy and 62 Gy of in situ (enorally, with no contact to the oral cavity) and in vitro irradiation. Relative to controls, teeth subjected to 62 Gy in vivo showed higher UTV values for dentine and enamel. Sound teeth irradiated with 60 Gy in situ also showed higher UTV values for enamel, whereas dentine values were not significantly different from those of control. The mechanical pr…
Molte Palermo. Temi
2019
Nel tema delle incompiute idee di città possibili si riconoscerà il paradigma connotativo dello stesso divenire di Palermo, lungo un percorso millenario di processi di trasformazione nessuno dei quali portato a compimento, in virtù di quel valore distintivo di exemplum che non necessita di ulteriori e conclusive dimostrazioni. Il corso della storia, del resto, ha imposto a Palermo il ciclico riproporsi di destini interrotti. Tale si rilevò l’invenzione della città capitale, quella della “quadratura geometrica e della croce di strade” sovrimpressa a quella archetipica e fondativa della Pan-ormos scambiatrice. E l’incompiutezza sarà il tratto distintivo della città dei rettifili stradali otto…
La responsabilità personale per il coinvolgimento di imprese in crimini internazionali. Il problema cruciale dei c.d. “atti neutrali”
2020
Il contributo considera l’intreccio fra livello individuale e livello collettivo dei crimini internazionali con specifico riferimento alla eventuale corresponsabilità di imprese e dei loro capi rispetto alla commissione di tali crimini da parte dei vertici militari o politici di un gruppo o di uno stato. Alla luce del principio di autoresponsabilità ricavabile dall’art. 25 dello Statuto di Roma, la relativa responsabilità può affermarsi per le attività di impresa direttamente strumentali a fatti violenti. Maggiormente problematica essa risulta invece per le ordinarie attività di impresa, che dunque appaiono neutrali ed estranee rispetto alle altrui condotte illecite. Per queste ultime la di…