Pause intensity:a no-reference quality assessment metric for video streaming in TCP networks

In this paper a full analytic model for pause intensity (PI), a no-reference metric for video quality assessment, is presented. The model is built upon the video play out buffer behavior at the client side and also encompasses the characteristics of a TCP network. Video streaming via TCP produces impairments in play continuity, which are not typically reflected in current objective metrics such as PSNR and SSIM. Recently the buffer under run frequency/probability has been used to characterize the buffer behavior and as a measurement for performance optimization. But we show, using subjective testing, that under run frequency cannot reflect the viewers' quality of experience for TCP based streaming. We also demonstrate that PI is a comprehensive metric made up of a combination of phenomena observed in the play out buffer. The analytical model in this work is verified with simulations carried out on ns-2, showing that the two results are closely matched. The effectiveness of the PI metric has also been proved by subjective testing on a range of video clips, where PI values exhibit a good correlation with the viewers' opinion scores. © 2012 IEEE.

An objective approach to measuring video playback quality in lossy networks using TCP

In this work, we investigate a new objective measurement for assessing the video playback quality for services delivered in networks that use TCP as a transport layer protocol. We define the new metric as pause intensity to characterize the quality of playback in terms of its continuity since, in the case of TCP, data packets are protected from losses but not from delays. Using packet traces generated from real TCP connections in a lossy environment, we are able to simulate the playback of a video and monitor buffer behaviors in order to calculate pause intensity values. We also run subjective tests to verify the effectiveness of the metric introduced and show that the results of pause intensity and the subjective scores made over the same real video clips are closely correlated.

HYBRID TCP/UDP video transport for H.264/AVC content delivery in burst loss networks

In this paper we propose a hybrid TCP/UDP transport, specifically for H.264/AVC encoded video, as a compromise between the delay-prone TCP and the loss-prone UDP. When implementing the hybrid approach, we argue that the playback at the receiver often need not be 100% perfect, provided that a certain level of quality is assured. Reliable TCP is used to transmit and guarantee delivery of the most important packets. This allows use of additional features in the H.264/AVC standard which simultaneously provide an enhanced playback quality, in addition to a reduction in throughput. These benefits are demonstrated through experimental results using a test-bed to emulate the hybrid proposal. We compare the proposed system with other protection methods, such as FEC, and in one case show that for the same bandwidth overhead, FEC is unable to match the performance of the hybrid system in terms of playback quality. Furthermore, we measure the delay associated with our approach, and examine its potential for use as an alternative to the conventional methods of transporting video by either TCP or UDP alone. © 2011 IEEE.

A közvetlen külföldi befektetések és a korrupció közötti kapcsolat (The connection of Foreign Direct Investment and corruption)

A szerzők tanulmányának középpontjában a közvetlen külföldi befektetések és a korrupció kapcsolata áll. Feltételezésük az, hogy a közvetlen külföldi befektetők a kevésbé korrupt országokat kedvelik, mivel a korrupció egy további kockázati tényezőt jelent a befektetők számára, amely növelheti a befektetések költségeit. Megítélésük szerint ezt kvantitatív módszerekkel érdemes vizsgálni, így elemzésük során 79 országot vizsgálnak meg tíz évre vonatkozó átlagokkal a Gretl-program és az OLS becslőfüggvény segítségével. Több modell lefuttatása után azt az eredményt kapták, hogy a közvetlen külföldi befektetők döntéseiben a korrupció szignifikáns tényező, a két változó között negatív korrelációt figyeltek meg. / === / The study focuses on the connection of Foreign Direct Investment and corruption. The authors assume that investors prefer countries where corruption level is lower, as corruption an additional risk factor that might increase the cost of investment. They believe that the best way to prove the previous statement if they use quantitative methods, so they set up a model where 79 countries are tested for 10 years averages, with the help of the Gretl and OLS estimator. After running several models their finding was that corruption is a significant factor in the decisions of foreign investors, and there is a negative correlation between corruption and FDI.

A tudásmenedzsment és az IT audit kapcsolódási pontjai - a tudásmenedzsment-rendszerek auditja (Connection points of knowledge management and IT audit – audit of knowledge management systems)

A cikkben a szerzők megvizsgálják a tudásmenedzsment komplex rendszerfejlesztési projektekben és az informatikai auditban játszott szerepét. Fő céljuk, hogy a tudásmenedzsment-rendszerek fejlesztéséhez kapcsolódó audit támogatására értékelési modellt készítsenek. Cikkükben megvizsgálják a tudásmenedzsmentnek az IT-auditban játszott általános szerepét, az auditban érintett tudásvagyon védelmének kérdését, a tudásmenedzsment-folyamatok szerepét a rendszerfejlesztésben (auditszempontból), a kontrollok implementálását, valamint a tudásmenedzsment és az IT-audittal kapcsolatos szabványok, módszertanok kapcsolatát. Az eredmények illusztrálására egy az Európai Unió 7. keretprogramjából finanszírozott nemzetközi projekt (GUIDE, IST–2003–507498) szolgál. ________________ Authors investigate the role of knowledge management in complex system development projects and IT audit. The primary goal is to provide an evaluation framework for an assessment of the development of special knowledge management solutions. On the other hand IT audit itself is a knowledge-dependent activity. The paper analyses the role of knowledge management in IT audit in general, the protection of knowledge assets during an audit, the role of knowledge management processes during system development (from audit point of view) and in the implementation of controls, the relationship of knowledge management with audit standards. Authors investigate the specialities of KM developments from audit point of view (particularly important aspects of audit, specific control objectives) A case study, based on experiences gained from GUIDE project (IST-2003-507498 funded by the European Commission’s 6th Framework Programme) illustrates the findings.

Korrupció: mérhetőség és modellezés = In the core of our study we focus on the connection of Foreign Direct Investment and corruption.

Tanulmányunk középpontjában a közvetlen külföldi befektetések és a korrupció kapcsolata áll. Feltételezésünk az, hogy a közvetlen külföldi befektetők a kevésbé korrupt országokat kedvelik, mivel a korrupció egy további kockázati tényezőt jelent a befektetők számára, amely növelheti a befektetések költségeit. Megítélésünk szerint ezt kvantitatív módszerekkel lehet a leginkább vizsgálni, így elemzésünk során 79 országot vizsgálunk meg 10 évre vonatkozó átlagokkal a GRETL program és az OLS becslőfüggvény segítségével. Több modell lefuttatása után azt az eredményt kaptuk, hogy a közvetlen külföldi befektetők döntéseiben a korrupció szignifikáns tényező, a két változó között negatív korrelációt figyelhetünk meg. ____ We assume that investors prefer countries where corruption level is lower, as corruption an additional risk factor that might increase the cost of investment. We believe that the best way to prove the previous statement if we use quantitative methods, so we set up a model where 79 countries are tested for 10 years averages, with the help of the GRETL and OLS estimator. After running several models our finding was that corruption is a significant factor in the decisions of foreign investors, and there is a negative correlation between corruption and FDI.

A „kivonulás, tiltakozás, hűség” koncepció és a „kapitalizmus változatai” elmélet közti kapcsolat (The connection between the ‘Exit, Voice, and Loyalty’ conception and the ‘Varieties of Capitalism’ theory)

Tanulmányunkban az Albert 0. Hirschman által kialakított „kivonulás, tiltakozás, hűség” koncepció metaelméleti felhasználásával a „kapitalizmus változatai” elméletet vesszük bírálat alá. Egyrészt arra mutatunk rá, hogy már a különböző piacgazdasági modellek tipologizálásához használt vállalatelméleti dimenziójú elemzések is építkeznek a Hirschman-trilemmából, másrészt arra hívjuk fel a figyelmet, hogy olyan sajátos eszközről van szó, amely a tőke- és munkaerő-piaci folyamatok elemzésére támaszkodva új perspektívát is kínál a kapitalista gazdaságok komparatív vizsgálatához. A dolgozat terjedelmi okokból az empirikus kutatásokat megalapozó elméleti alapozásra szorítkozik. ____ In our study we deal with the critical analysis of the “varieties of capitalism” theory by using the “exit, voice, and loyalty” meta-theory invented by Albert O. Hirschman. The paper emphasizes that on the one hand the analyses of the theory of the firm and business used for the classification of distinct market models are also building upon the “Hirschman trilemma”, and on the other hand, it draws attention to the fact that the Hirschmanian method based on labor market and capital market offers a new perspective for the comparative analysis of capitalist economies. The focus of the article is only the theoretical foundation of empirical studies as a result of limitation of scope.

Adding concurrent data transfer to transport layer

In recent years, the internet has grown exponentially, and become more complex. This increased complexity potentially introduces more network-level instability. But for any end-to-end internet connection, maintaining the connection's throughput and reliability at a certain level is very important. This is because it can directly affect the connection's normal operation. Therefore, a challenging research task is to improve a network's connection performance by optimizing its throughput and reliability. This dissertation proposed an efficient and reliable transport layer protocol (called concurrent TCP (cTCP)), an extension of the current TCP protocol, to optimize end-to-end connection throughput and enhance end-to-end connection fault tolerance. The proposed cTCP protocol could aggregate multiple paths' bandwidth by supporting concurrent data transfer (CDT) on a single connection. Here concurrent data transfer was defined as the concurrent transfer of data from local hosts to foreign hosts via two or more end-to-end paths. An RTT-Based CDT mechanism, which was based on a path's RTT (Round Trip Time) to optimize CDT performance, was developed for the proposed cTCP protocol. This mechanism primarily included an RTT-Based load distribution and path management scheme, which was used to optimize connections' throughput and reliability. A congestion control and retransmission policy based on RTT was also provided. According to experiment results, under different network conditions, our RTT-Based CDT mechanism could acquire good CDT performance. Finally a CWND-Based CDT mechanism, which was based on a path's CWND (Congestion Window), to optimize CDT performance was introduced. This mechanism primarily included: a CWND-Based load allocation scheme, which assigned corresponding data to paths based on their CWND to achieve aggregate bandwidth; a CWND-Based path management, which was used to optimize connections' fault tolerance; and a congestion control and retransmission management policy, which was similar to regular TCP in its separate path handling. According to corresponding experiment results, this mechanism could acquire near-optimal CDT performance under different network conditions.

Asia and Latin America: A Pacific Connection?

Co-edited by Cristina Eguizabal, Director, LACC, FIU and Ariel Armony, Director, Center for Latin American Studies, UM, this issue examines partnerships being established, negotiated and consolidated between Latin America and Asia. Articles remind us of long-standing existing relationships between the two regions, but also discuss evolving ties and new dynamics that will likely influence interactions for years to come. The issue provides readers with a glimpse of the complexities that are shaping an important connection that the world is watching.

Management of remote field instrumentation via the Internet

Supervisory Control & Data Acquisition (SCADA) systems are used by many industries because of their ability to manage sensors and control external hardware. The problem with commercially available systems is that they are restricted to a local network of users that use proprietary software. There was no Internet development guide to give remote users out of the network, control and access to SCADA data and external hardware through simple user interfaces. To solve this problem a server/client paradigm was implemented to make SCADAs available via the Internet. Two methods were applied and studied: polling of a text file as a low-end technology solution and implementing a Transmission Control Protocol (TCP/IP) socket connection. Users were allowed to login to a website and control remotely a network of pumps and valves interfaced to a SCADA. This enabled them to sample the water quality of different reservoir wells. The results were based on real time performance, stability and ease of use of the remote interface and its programming. These indicated that the most feasible server to implement is the TCP/IP connection. For the user interface, Java applets and Active X controls provide the same real time access.

Effective video content distribution by combining TCP with adaptive FEC coding

This paper will look at the benefits and limitations of content distribution using Forward Error Correction (FEC) in conjunction with the Transmission Control Protocol (TCP). FEC can be used to reduce the number of retransmissions which would usually result from a lost packet. The requirement for TCP to deal with any losses is then greatly reduced. There are however side-effects to using FEC as a countermeasure to packet loss: an additional requirement for bandwidth. When applications such as real-time video conferencing are needed, delay must be kept to a minimum, and retransmissions are certainly not desirable. A balance, therefore, between additional bandwidth and delay due to retransmissions must be struck. Our results show that the throughput of data can be significantly improved when packet loss occurs using a combination of FEC and TCP, compared to relying solely on TCP for retransmissions. Furthermore, a case study applies the result to demonstrate the achievable improvements in the quality of streaming video perceived by end users.

Vesicoureteral reflux and the extracellular matrix connection.

Primary vesicoureteral reflux (VUR) is a common pediatric condition due to a developmental defect in the ureterovesical junction. The prevalence of VUR among individuals with connective tissue disorders, as well as the importance of the ureter and bladder wall musculature for the anti-reflux mechanism, suggest that defects in the extracellular matrix (ECM) within the ureterovesical junction may result in VUR. This review will discuss the function of the smooth muscle and its supporting ECM microenvironment with respect to VUR, and explore the association of VUR with mutations in ECM-related genes.

A simple approach to the supernova progenitor–explosion connection

We present a new approach to understand the landscape of supernova explosion energies, ejected nickel masses, and neutron star birth masses. In contrast to other recent parametric approaches, our model predicts the properties of neutrino-driven explosions based on the pre-collapse stellar structure without the need for hydrodynamic simulations. The model is based on physically motivated scaling laws and simple differential equations describing the shock propagation, the contraction of the neutron star, the neutrino emission, the heating conditions, and the explosion energetics. Using model parameters compatible with multi-D simulations and a fine grid of thousands of supernova progenitors, we obtain a variegated landscape of neutron star and black hole formation similar to other parametrized approaches and find good agreement with semi-empirical measures for the ‘explodability’ of massive stars. Our predicted explosion properties largely conform to observed correlations between the nickel mass and explosion energy. Accounting for the coexistence of outflows and downflows during the explosion phase, we naturally obtain a positive correlation between explosion energy and ejecta mass. These correlations are relatively robust against parameter variations, but our results suggest that there is considerable leeway in parametric models to widen or narrow the mass ranges for black hole and neutron star formation and to scale explosion energies up or down. Our model is currently limited to an all-or-nothing treatment of fallback and there remain some minor discrepancies between model predictions and observational constraints.