Watching the IPv6 Takeoff from an IXP's Viewpoint

The different level of interest in deploying the new Internet address space across network operators has kept IPv6 tardy in its deployment. However, since the last block of IPv4 addresses has been assigned, Internet communities took the concern of the address space scarcity seriously and started to move forward actively. After the successful IPv6 test on 8 June, 2011 (World IPv6 Day [1]), network operators and service/content providers were brought together for preparing the next step of the IPv6 global deployment (World IPv6 Launch on 6 June, 2012 [2]). The main purpose of the event was to permanently enable their IPv6 connectivity. In this paper, based on the Internet traffic collected from a large European Internet Exchange Point (IXP), we present the status of IPv6 traffic mainly focusing on the periods of the two global IPv6 events. Our results show that IPv6 traffic is responsible for a small fraction such as 0.5% of the total traffic in the peak period. Nevertheless, we are positively impressed by the facts that the increase of IPv6 traffic/prefixes shows a steep increase and that the application mix of IPv6 traffic starts to imitate the one of IPv4-dominated Internet

Tigers vs Lions: Towards Characterizing Solitary and Group User Behavior in MMORPG

The development of Internet technologies enables software developers to build virtual worlds such as Massively Multi-Player Online Role-Playing Games (MMORPGs). The population of such games shows super-linear growing tendency. It is estimated that the number of Internet users subscribed in MMORPGs is more than 22 million worldwide [1]. However, only little is known about the characteristics of traffic generated by such games as well as the behavior of their subscribers. In this paper, we characterize the traffic behavior of World of Warcraft, the most subscribed MMORPG in the world, by analyzing Internet traffic data sets collected from a European tier-1 ISP in two different time periods. We find that World of Warcraft is an influential application regarding the time spent by users (1.76 and 4.17 Hours/day on average in our measurement), while its traffic share is comparatively low (< 1%). In this respect, we look at the World of Warcraft subscriber’s gaming behavior by categorizing them into two different types of users (solitary users and group users) and compare these two groups in relation to the playing behavior (duration as the metric) and the in-game behavior (distance as the metric)

A Local Approach to Fast Failure Recovery of LISP Ingress Tunnel Routers

Part 8: LISP and Multi-domain RoutingInternational audienceLISP (Locator/ID Separation Protocol) has been proposed as a future Internet architecture in order to solve the scalability issues the current architecture is facing. LISP tunnels packets between border routers, which are the locators of the non-globally routable identifiers associated to end-hosts. In this context, the encapsulating routers, which are called Ingress Tunnel Routers (ITR) and learn dynamically identifier-to-locators mappings needed for the encapsulation, can cause severe and long lasting traffic disruption upon failure. In this paper, thanks to real traffic traces, we first explore the impact of ITR failures on ongoing traffic. Our measurements confirm that the failure of an ITR can have severe impact on traffic. We then propose and evaluate an ITR synchronization mechanism to locally protect ITRs, achieving disruptionless traffic redirection. We finally explore how to minimize the number of ITRs to synchronize in large networks

MENINGKATKAN HASIL BELAJAR GERAK DASAR LOMPAT JAUH MELALUI PENDEKATAN BERMAIN PADA SISWA KELAS IV SD NEGERI 2 PADURESO KECAMATAN PADURESO KABUPATEN KEBUMEN TAHUN 2013

ABSTRAK Siti Rokhaniyah. MENINGKATKAN HASIL BELAJAR GERAK DASAR LOMPAT JAUH MELALUI PENDEKATAN BERMAIN PADA SISWA KELAS IV SD NEGERI 2 PADURESO KECAMATAN PADURESO KABUPATEN KEBUMEN TAHUN PELAJARAN 2012/2013. Skripsi, Fakultas Keguruan dan Ilmu Pendidikan Universitas Sebelas Maret Surakarta Juli 2013. Tujuan penelitian ini adalah untuk meningkatkan hasil belajar gerak dasar lompat jauh melalui pendekatan bermain pada siswa kelas IV SD Negeri 2 Padureso Kecamatan Padureso Kabupaten Kebumen tahun pelajaran 2012/2013. Penelitian ini dilakukan dengan menggunakan metode Penelitian Tindakan Kelas (PTK). Penelitian ini dilakukan dalam 2 siklus, tiap siklus terdiri dari perencanaan, pelaksanaan tindakan, observasi dan refleksi. Subyek penelitian adalah siswa kelas IV SD Negeri 2 Padureso yang berjumlah 20 siswa yang terdiri dari 11anak laki-laki dan 9 anak perempuan, .sumber data dalam tindakan kelas adalah data primer meliputi data hasil belajar lompat jauh, data dari guru dan Siswa Teknik pengumpulan data adalahdengan tes. Hasil penelitian menunjukkan bahwa melalui pendekatan bermain dapat meningkatkan hasil belajar gerak dasar lompat jauh pada siswa kelas IV SD Negeri 2 Padureso tahun pelajaran 2012/2013. hasil belajar dapat dibuktikan dengan hasil analisis pratindakan, siklus I dan siklus II di mana hasil belajar sebelum diadakan tindakan adalah 25% tuntas belajar dan 75% belum tuntas belajar. Pada siklus I ketuntasan belajar mencapai 70% siswa telah tuntas belajar dan 30% belum tuntas belajar. Pada siklus II ketuntasan belajar mencapai 90% dari jumlah siswa. Hasil penelitian menunjukkan bahwa hasil belajar gerak dasar lompat jauh melalui pendekatan bermain dapat meningkat hingga batas minimal KKM yang telah ditentukan sehingga 90% dari jumlah siswa dapat mencapai Kriteria Ketuntasan Minimal(KKM) yaitu7,5. Kesimpulan penelitian ini adalah penggunaan pendekatan bermain dapat meningkatkan hasil belajar gerak dasar lompat jauh pada siswa kelas IV SD Negeri 2 Padureso Kecamatan Padureso Kabupaten Tahun Pelajaran 2012/2013. Kata Kunci : Hasil belajar, Gerak dasar, Lompat jauh, Pendekatan Bermain

Attenuating the EGFR-ERK-SOX9 axis promotes liver progenitor cell‐mediated liver regeneration in zebrafish

The liver is a highly regenerative organ, but its regenerative capacity is compromised in severe liver injury settings. In chronic liver diseases, the number of liver progenitor cells (LPCs) correlates proportionally to disease severity, implying that their inefficient differentiation into hepatocytes exacerbates the disease. Moreover, LPCs secrete pro‐inflammatory cytokines; thus, their prolonged presence worsens inflammation and induces fibrosis. Promoting LPC‐to‐hepatocyte differentiation in patients with advanced liver disease, for whom liver transplantation is currently the only therapeutic option, may be a feasible clinical approach since such promotion generates more functional hepatocytes and concomitantly reduces inflammation and fibrosis. Here, using zebrafish models of LPC‐mediated liver regeneration, we present a proof‐of‐principle of such therapeutics by demonstrating a role for the EGFR signaling pathway in differentiation of LPCs into hepatocytes. We found that suppression of EGFR signaling promoted LPC‐to‐hepatocyte differentiation via the MEK‐ERK‐SOX9 cascade. Pharmacological inhibition of EGFR or MEK/ERK promoted LPC‐to‐hepatocyte differentiation as well as genetic suppression of the EGFR‐ERK‐SOX9 axis. Moreover, Sox9b overexpression in LPCs blocked their differentiation into hepatocytes. In the zebrafish liver injury model, both hepatocytes and biliary epithelial cells contributed to LPCs. EGFR inhibition promoted the differentiation of LPCs regardless of their origin. Notably, short‐term treatment with EGFR inhibitors resulted in better liver recovery over the long term. Conclusion: The EGFR‐ERK‐SOX9 axis suppresses LPC‐to‐hepatocyte differentiation during LPC‐mediated liver regeneration. We suggest EGFR inhibitors as a pro‐regenerative therapeutic drug for patients with advanced liver disease

Zu Anwendungsbereichen der Netzwerkdiversität für zukünftige Internetprotokolle

In den vergangenen Jahrzehnten hat sich das Internet von einem Forschungsnetzwerk hin zu einer wichtigen, von der Allgemeinheit genutzten Infrastruktur entwickelt. Dabei hat es sich in nahezu allen Bereichen einschließlich seiner Größe, Topologie und Nutzungsweise entscheidend verändert. Die permanent steigende Anzahl von Nutzern und Endgeräten eröffnet Räume für unterschiedliche Aspekte von Netzwerkdiversität. So können sich Endnutzer über verschiedene Netzwerkprovider mit unterschiedlichen Geschwindigkeiten, über diverse Geräte, die mit multiplen Netzwerkschnittstellen ausgestattet sind und in zwei verschiedenen Adressräumen (IPv4 und IPv6) mit dem Internet verbinden. Diversität findet sich überall im Internet, jedoch inwieweit sie sich nutzen lässt, um das Internet zu verbessern, ist noch weitgehend unklar. In letzter Zeit traten im Internet Skalierungsprobleme auf, die mit der großen Anzahl von Endgeräten, mit der Erschöpfung des Internet-Adressraums und der Fülle von Routinginformationen im Kern des Internets zusammenhängen. Gleichzeitig erzeugt die konstant steigende Menge an digitalen Inhalten eine signifikante Diskrepanz zwischen der Nachfrage nach hoher End-to-End-Leistung und den gegenwärtigen Fähigkeiten der Internet-Infrastruktur. Da diese Probleme die zukünftige Entwicklung des Internets hemmen, sollen sie Thema dieser Dissertation sein. Zunächst führen wir eine Studie zur Annahme von IPv6 im heutigen Internet durch. Hierzu analysieren wir einen großen Datensatz, welcher an einem großen Internet-Knoten (IXP) aufgezeichnet wurde. Obwohl das Ergebnis einen starken Anstieg von IPv6-Datenverkehr in den letzten Jahren aufzeigt, ist das Gesamtniveau der IPv6-Nutzung weiterhin marginal. Demnach werden die beiden Internetprotokolle eine Zeitlang weiterhin nebeneinander bestehen. Um das Skalierungsproblem anzugehen, das durch die enorme Anzahl von Routing-Einträgen im Kern des Internets verursacht wird, untersuchen wir danach mit dem Locator/ID Separation Protocol (LISP) die vielversprechendste Lösung. Dabei steht die Bewertung der Leistung, der Sicherheitsaspekte und der Ausfallsicherheit von LISP im Mittelpunkt. Vorhergehende Studien haben durch die Analyse aktuellen Datenverkehrs gezeigt, dass der Großteil der Daten im Internet HTTP-basiert ist (> 60 % [67]) und dass Inhaltsanbieter ihre Inhalte auf verteilte Server replizieren [91]. Um die End-to-End-Leistung zu erhöhen, schlagen wir mit Multi-Source Multipath HTTP (mHTTP) eine leicht anwendbare Lösung vor, die den Datentransfer verbessert, indem unterschiedliche Aspekte von Netzwerkdiversität verwendet werden.In the past few decades, the Internet has evolved from a research network to an important infrastructure used by everyone. This means it has changed in almost all aspects including size, topology, and usage. Indeed, due to the ever-increasing number of users and capabilities of end-devices, various types of network diversity have been created in the Internet. For example, users can connect to the Internet through different service providers in various access speeds using miscellaneous devices equipped with multiple network interfaces via two different address spaces (IPv4 and IPv6). Such diversity can be found almost everywhere in the Internet. However, to what extent this diversity can be used to improve the Internet is largely uncharted. Recently, several scalability issues emerged in the Internet, i. e., those related to the large number of network-enabled devices. The exhaustion of the Internet address space is one, the plethora of the routing information within the core Internet is another one. Moreover, the constantly increasing volume of digital content causes significant mismatch between the demand for the high end-to-end performance and the actual capabilities of the Internet infrastructure. These problems hinder the future evolution of the Internet; hence, they are the topics of this thesis. First, we conduct an assessment study of IPv6 adoption in today’s Internet by analyzing a rich set of Internet traffic data collected from a large Internet eXchange Point (IXP). Although the result shows a sharp increase of IPv6 traffic in recent years, the level of IPv6 deployment is still marginal. Thus, the two Internet protocols have to coexist for a while. Next, to cope with scalability issue caused by the enormous number of routing entries in the core of the Internet, we closely examine the most promising solution for this problem, the Locator/ID Separation Protocol (LISP). In particular, our work focuses on evaluating the performance, security overhead, and resilience of LISP. By analyzing recent Internet traffic, previous studies found that a major portion of Internet traffic is delivered by HTTP (> 60 % [67]) and most of the content providers replicate their content on multiple servers [91]. To this end, we confront the challenge of end-to-end performance by suggesting an easily deployable solution, the Multi-source Multipath HTTP (mHTTP), for improving the HTTP performance based on utilizing various types of network diversity

Zero-Dynamics Attack on Wind Turbines and Countermeasures Using Generalized Hold and Generalized Sampler

Most wind turbines are monitored and controlled by supervisory control and data acquisition systems that involve remote communication through networks. Despite the flexibility and efficiency that network-based monitoring and control systems bring, these systems are often threatened by cyberattacks. Among the various kinds of cyberattacks, some exploit the system dynamics so that the attack cannot be detected by monitoring system output, the zero-dynamics attack is one of them. This paper confirms that the zero-dynamics attack is fatal to wind turbines and the attack can cause system breakdown. In order to protect the system, we present two defense strategies using a generalized hold and a generalized sampler. These methods have the advantage that the zeros can be placed so that the zero dynamics of the system become stable; as a consequence, the zero-dynamics attack is neutralized. The effects of the countermeasures are validated through numerical simulations and the comparative discussion between two methods is provided

PPARα activation promotes liver progenitor cell-mediated liver regeneration by suppressing YAP signaling in zebrafish

Abstract Despite the robust regenerative capacity of the liver, prolonged and severe liver damage impairs liver regeneration, leading to liver failure. Since the liver co-opts the differentiation of liver progenitor cells (LPCs) into hepatocytes to restore functional hepatocytes, augmenting LPC-mediated liver regeneration may be beneficial to patients with chronic liver diseases. However, the molecular mechanisms underlying LPC-to-hepatocyte differentiation have remained largely unknown. Using the zebrafish model of LPC-mediated liver regeneration, Tg(fabp10a:pt-β-catenin), we present that peroxisome proliferator-activated receptor-alpha (PPARα) activation augments LPC-to-hepatocyte differentiation. We found that treating Tg(fabp10a:pt-β-catenin) larvae with GW7647, a potent PPARα agonist, enhanced the expression of hepatocyte markers and simultaneously reduced the expression of biliary epithelial cell (BEC)/LPC markers in the regenerating livers, indicating enhanced LPC-to-hepatocyte differentiation. Mechanistically, PPARα activation augments the differentiation by suppressing YAP signaling. The differentiation phenotypes resulting from GW7647 treatment were rescued by expressing a constitutively active form of Yap1. Moreover, we found that suppression of YAP signaling was sufficient to promote LPC-to-hepatocyte differentiation. Treating Tg(fabp10a:pt-β-catenin) larvae with the TEAD inhibitor K-975, which suppresses YAP signaling, phenocopied the effect of GW7647 on LPC differentiation. Altogether, our findings provide insights into augmenting LPC-mediated liver regeneration as a regenerative therapy for chronic liver diseases