In Vitro Re-Hardening of Bleached Enamel Using Mineralizing Pastes: Toward Preventing Bacterial Colonization

The search for materials able to remineralize human hard tissues is a modern medical challenge. In this study, the protective effect on the enamel microhardness by a paste based on hydroxyapatite and sodium fluoride (Remin Pro) was evaluated after two different enamel bleaching procedures. Forty sound human incisors were randomly assigned to different treatments: bleaching with an in-office agent (Perfect Bleach Office+); bleaching with an at-home agent (Perfect Bleach); bleaching with the in-office agent followed by the prophylaxis paste; bleaching with the at-home agent followed by the prophylaxis paste; no treatment (control). Bleaching was performed at 0, 8, 24 and 32 h, followed by a 3-min re-mineralizing treatment in the subgroups designed to receive it. Specimens underwent a micro-hardness tester and a mean Vickers Hardness number was considered for each specimen. ANOVA exhibited significant differences among groups. Post-hoc Tukey testing showed significant micro-hardness decrease after the application of both the two bleaching agents. The treatment with prophylaxis paste significantly increased the micro-hardness values of bleached enamel.

Improved Direct Routing Approach for Mobile IP Systems

<p class="0abstract">The mobile IP communication protocol is a flexible system for mobile connection that is designed to allow the device to be moved between networks while maintaining a permanent IP address. IP datagrams using mobile IP can be routed to a specific mobile station (MS) regardless of its current internet location. However, to facilitate such routable characteristics, the communication with an MS that is visiting a foreign network is intermediate with communication between the home agent (HA) and the foreign agent (FA) which increase the total delay and harms the communication performance, especially when the MS continuously moves from a network to another. Accordingly, to handle the delay issue, this paper proposes a new approach for mobile IP direct routing, based on the “follow-me” principle. The proposed approach depends on sending a new temporary care-of-address (CoA) for the previously visited network as the MS moves to another to keep a reliable tracking–like process with the HA. Accordingly, the agents of all the visited networks play the same principles as the HA role whenever the MS moves from a network to another. The proposed approach influences the delay and the speed of the delivery of internet packets. The simulation showed that the proposed method decreases the delay by up to 50% compared to the direct routing approach. </p>

Analisis Kinerja Video Conference pada Jaringan Mobile IPv6 Dengan Triangle Tunneling Method

Mobile IP merupakan protocol yang mendukung mobilitas dari user, dengan mobile IP sebuah node dapat terus berkomunikasi dengan node yang lain dimanapun dia berada. Mobile IPv6 memperbolehkan node yang telah mempunyai dukungan terhadap IPv6 untuk meninggalkan jaringan asalnya sementara node tersebut sedang memperbarui koneksinya ke internet. Hal ini berarti bahwa mobile IPv6 bisa mengidentifikasi tiap-tiap node dengan static address-nya, tanpa memperhatikan point of attachment nya ke internet.Mobile IPv6 yang digunakan pada makalah ini memakai metode triangle tunneling yaitu metode perutean pengiriman paket dimana ketika correspondent node (CN) mengirimkan paket menuju mobile node (MN), home agent (HA) mengambil alih paket tersebut dan mengirimkannya ke care of address dari MN dengan tunneling, sedangkan MN dapat mengirimkan langsung menuju CN. Pada makalah ini dilakukan pengujian video conference (multipont) pada jaringan Mobile IPv6 dengan metode triangle tunneling untuk diukur parameter-parameter QoS meliputi packet loss, delay, jitter, throughput dan MOS.Berdasarkan hasil uji coba dengan memperhatikan parameter-parameter QoS yang dianalisa terlihat bahwa kualitas MN yang berada di jaringan asalnya (homenet) lebih baik ketika berada di jaringan yang sedang dikunjungi (visitnet), hal ini disebabkan dengan metode triangle tunneling paket yang dikirim menuju MN dirutekan ke HA terlebih dahulu sehingga meningkatkan trafik jaringan, selain itu pada uji coba handover terdapat nilai rata-rata delay yang cukup besar yaitu 3.367 detik untuk paket video dan 3.269 detik untuk paket audio, karena pada saat handover, MN membutuhkan waktu untuk memperbaharui koneksi dan melakukan konfigurasi ulang jaringan yang ada.

Analytical Study of a Dual Pointer Based Strategy for Location Update Using Node B Sojourn Time in UMTS Networks

This article describes how Universal Mobile Telecommunications System (UMTS) is a 3G cellular network standard that uses location update (LU) and location search (LS) for mobility management. LU requires update in two location registers (LRs) - home LR (HLR) and visiting LR (VLR) - where one HLR controls multiple VLRs. HLR updates (HLRUs) are costlier, and hence should be less frequent. To achieve it, VLRs maintain a forward pointer chain among themselves, instead of updating HLR. But a lengthy chain increases LS cost considerably. So, we propose to restrict the chain length to unity by introducing an additional backward pointer, and using the concept of root-VLR similar to the home agent concept of mobile IP. We derive a closed form solution to approximate the average HLRUs per call, and substantiate it by simulation in cases of both random and diurnal mobilities. Results reveal substantial reduction in HLRUs per call, even when call-to-mobility ratio is high. UMTS operators will find the analysis worth considering, while managing their 3G networks.

APPLICATION AND SIMULATION OF ROUTE OPTIMIZATION IN MOBILE IP

Mobile Internet Protocol has been proposed by Internet Engineering Task Force (IETF) to support portable IP addresses for mobile devices that often change their network access points to the Internet. In the basic mobile IP protocol, datagrams sent from wired or wireless hosts and destined for the mobile host that is away from home, have to be routed through the home agent. Nevertheless, datagrams sent from mobile hosts to wired hosts can be routed directly. This asymmetric routing, called “triangle routing,” is often far from optimal and “route optimization” has been proposed to address this problem. In this paper, we present the deep description and implementation of “route optimization”, Authentication extension to mobile IP in the ns-2 simulator. We illustrate simulations of the mobile IP with route optimization with simulation scenarios, parameters, and simulations results.