University of Luxembourg

About: University of Luxembourg is a education organization based out in Luxembourg, Luxembourg. It is known for research contribution in the topics: Population & European union. The organization has 4744 authors who have published 22175 publications receiving 381824 citations.

Invariance Principles for Homogeneous Sums: Universality of Gaussian Wiener Chaos

Abstract: We compute explicit bounds in the normal and chi-square approximations of multilinear homogenous sums (of arbitrary order) of general centered independent random variables with unit variance. In particular, we show that chaotic random variables enjoy the following form of universality: (a) the normal and chi-square approximations of any homogenous sum can be completely characterized and assessed by first switching to its Wiener chaos counterpart, and (b) the simple upper bounds and convergence criteria available on the Wiener chaos extend almost verbatim to the class of homogeneous sums.

Assessing cellular and circulating miRNA recovery: the impact of the RNA isolation method and the quantity of input material

Abstract: MicroRNAs (miRNAs) have emerged as promising cancer biomarkers. However, exploiting their informative potential requires careful optimization of their detection. Here, we compared the efficiency of commonly used RNA extraction kits in miRNA recovery from cells, plasma and urine/plasma-derived exosomes, using single-gene RT-qPCR and miRNA profiling. We used increasing amounts of starting material to investigate the impact of the input material size on miRNA extraction. We showed that miRNA recovery was largely influenced by the isolation method and by the amount of input material. In particular, the miRCURY™ kit provided highly pure RNA. However, its columns poorly recovered miRNAs from limiting amounts of cells and plasma, and rapidly saturated by large RNA species and plasma components, thus impeding miRNA recovery from high input amounts. Overall, the miRNeasy® kit permitted a better miRNA detection despite a less pure extracted RNA. Nevertheless, some miRNAs were preferentially or exclusively isolated by either of the methods. Trizol® LS resulted in very low purity RNA which affected RT-qPCR efficiency. In general, miRCURY™ biofluids kit efficiently extracted miRNAs from plasma. A careful selection of the RNA isolation method and the consideration of the type and size of input material are highly recommended to avoid biased results.

Content and Popularity Analysis of Tor Hidden Services

Abstract: Tor hidden services allow running Internet services while protecting the location of the servers. Their main purpose is to enable freedom of speech even in situations in which powerful adversaries try to suppress it. However, providing location privacy and client anonymity also makes Tor hidden services an attractive platform for every kind of imaginable shady service. The ease with which Tor hidden services can be set up has spurred a huge growth of anonymously provided Internet services of both types. In this paper we analyse the landscape of Tor hidden services. We have studied 39824 hidden service descriptors collected on 4th of Feb 2013: we scanned them for open ports, in the case of 3050 HTTP services, we analysed and classified their content. We also estimated the popularity of hidden services by looking at the request rate for hidden service descriptors by clients. We found that while the content of Tor hidden services is rather varied, the most popular hidden services are related to botnets. We also propose a method for opportunistic deanonymisation of Tor Hidden Service clients. In addtiton, we identify past attempts to track "Silk road" by consensus history analysis.

Methodology of mental stress testing in cardiovascular research.

Abstract: Many issues related to the selection, reliability, and validity of mental stress testing in cardiovascular research are discussed. Five categories of mental stress testing are distinguished: problem-solving tasks, information-processing tasks, psychomotor tasks, affective conditions, and aversive or painful conditions. A series of practical and theoretical criteria are outlined for the selection of appropriate tests, and the measurement of a range of dependent variables is emphasized. The temporal stability of cardiovascular responses to mental stress tests is examined through an analysis of test-retest correlations (weighted for sample size) in 28 comparisons with intervals between sessions varying from 1 day to more than 1 year. Heart rate reactions to tasks show an average-weighted Z of 0.732 +/- 0.031 (r = 0.62), with Z = 0.575 +/- 0.034 (r = 0.52) for systolic blood pressure and Z = 0.313 +/- 0.035 (r = 0.30) for diastolic blood pressure. It is argued that the validity of mental stress tests can be judged in relation to several different aspects, specifically, methodological, ecological, diagnostic, prognostic, and therapeutic validities. The nature of these standards is described, and pertinent literature is presented.

The Process of Solving Complex Problems

Abstract: This article is about Complex Problem Solving (CPS), its history in a variety of research domains (e.g., human problem solving, expertise, decision making, and intelligence), a formal definition and a process theory of CPS applicable to the interdisciplinary field. CPS is portrayed as (a) knowledge acquisition and (b) knowledge application concerning the goal-oriented control of systems that contain many highly interrelated elements (i.e., complex systems). The impact of implicit and explicit knowledge as well as systematic strategy selection on the solution process are discussed, emphasizing the importance of (1) information generation (due to the initial intransparency of the situation), (2) informa- tion reduction (due to the overcharging complexity of the problem's structure), (3) model building (due to the interconnectedness of the variables), (4) dynamic decision making (due to the eigendynamics of the system), and (5) evaluation (due to many, interfering and/or ill-defined goals).