Reference values for placental growth factor (PlGF) concentration and uterine artery Doppler pulsatility index (PI) at 11–13+6 weeks of gestation in the Polish population

Objectives: The aim of the study was to determine placental growth factor (PlGF) concentration and uterine artery (UtA) Doppler pulsatility index (PI) at 11–13+6 weeks of gestation in the Polish population. Material and methods: A prospective study was performed in pregnant women who underwent routine ultrasound scan at 11–13+6 weeks of gestation. All participants completed a questionnaire about their medical history, demographicsand current pregnancy. Mean arterial pressure (MAP) was calculated. Gestational age was confirmed by CRL and mean UtA PI was calculated. Blood samples were taken to measure beta HCG, PAPP-A and PlGF concentrations. Results: Out of the 577 analyzed participants, 60 (10.4%) were found to have abnormal placentation disorders (20 – hypertensive disorders and 40 – IUGR). The patients were subdivided into two groups, depending on pregnancy utcome: unaffected (n=517) and affected (n=60). The study did not confirm the anticipated correlation between maternal BMI and PlGF, but the concentration of PlGF was significantly increased in smokers. UtA PI values were not statistically significantly different depending on maternal age, BMI, method of conception, smoking or parity. The study confirms that both, UtA PI and PlGF concentrations are CRL-dependent. Median MoM values for PlGF and UtA PI were obtained for each set of CRL measurements. Median PIGF MoM was decreased in pregnancies complicated by hypertensive disorders and IUGR as compared to the unaffected group. Conclusions: The established reference ranges for UtA PI and PlGF at 11–13+6 weeks of gestation may be of clinical value in predicting placenta-associated diseases in early stages of pregnancy in the Polish population

Adaptable peer-to-peer internet live media streaming

THESIS 8792Media streaming is an approach to delivering media, which may consist of video and audio, from a provider to viewers. Media streaming enables simultaneous delivery and playback of media and thus provides an alternative to media download, where the entire media content has to be delivered before the playback can begin. Media streaming can be on-demand for content archived at the provider or live for content produced at the time of delivery

Properties and Mechanisms of Self-Organising MANET and P2P Systems

Despite the recent appearance of self-organizing distributed systems for Mobile Ad Hoc Networks (MANETs) and Peer-to-Peer (P2P) networks, specific theoretical aspects of both their properties and the mechanisms used to establish those properties have been largely overlooked. This has left many researchers confused as to what constitutes a self-organizing distributed system and without a vocabulary with which to discuss aspects of these systems. This article introduces an agent-based model of self-organizing MANET and P2P systems and shows how it is realised in three existing network systems. The model is based on concepts such as partial views, evaluation functions, system utility, feedback and decay. We review the three network systems, AntHocNet, SAMPLE, and Freenet, and show how they can achieve high scalability, robustness and adaptability to unpredictable changes in their environment, by using self-organizing mechanisms similar to those found in nature. They are designed to improve their operation in a dynamic, heterogeneous environment, enabling them to often demonstrate superior performance to state of the art distributed systems. This article is also addressed at researchers interested in gaining a general understanding of different mechanisms and properties of self-organization in distributed systems

Tree-based Analysis of Mesh Overlays for Peer-to-Peer Streaming

Abstract. Mesh-based P2P streaming approaches have been recently proposed as an interesting alternative to tree-based approaches. However, many properties of mesh overlays remain little understood as they are difficult to study due to the lack of a predefined structure. In this paper we show that when data is streamed through mesh overlays, it follows tree-based diffusion patterns and thereby mesh-based streaming can be studied in a similar manner to tree-based approaches. We identify properties of the diffusion trees that emerge in mesh overlays and compare them to optimal diffusion trees. We show that the emerging diffusion trees exhibit suboptimal height and are unbalanced, which results in increased buffering delay of mesh-based P2P systems, particularly in heterogeneous environments. We present an algorithm that adapts the mesh overlay to shorten diffusion trees and to reduce the buffering delay