Inexact Arnoldi residual estimates and decay properties for functions of non-Hermitian matrices

We derive a priori residual-type bounds for the Arnoldi approximation of a matrix function and a strategy for setting the iteration accuracies in the inexact Arnoldi approximation of matrix functions. Such results are based on the decay behavior of the entries of functions of banded matrices. Specifically, we will use a priori decay bounds for the entries of functions of banded non-Hermitian matrices by using Faber polynomial series. Numerical experiments illustrate the quality of the results

Power control and receiver design for energy efficiency in multipath CDMA channels with bandlimited waveforms

This paper is focused on the cross-layer design problem of joint multiuser detection and power control for energy-efficiency optimization in a wireless data network through a game-theoretic approach. Building on work of Meshkati, et al., wherein the tools of game-theory are used in order to achieve energy-efficiency in a simple synchronous code division multiple access system, system asynchronism, the use of bandlimited chip-pulses, and the multipath distortion induced by the wireless channel are explicitly incorporated into the analysis. Several non-cooperative games are proposed wherein users may vary their transmit power and their uplink receiver in order to maximize their utility, which is defined here as the ratio of data throughput to transmit power. In particular, the case in which a linear multiuser detector is adopted at the receiver is considered first, and then, the more challenging case in which non-linear decision feedback multiuser detectors are employed is considered. The proposed games are shown to admit a unique Nash equilibrium point, while simulation results show the effectiveness of the proposed solutions, as well as that the use of a decision-feedback multiuser receiver brings remarkable performance improvements.Comment: appeared in the Proceedings of the 41st Annual Conference on Information Sciences and Systems, John Hopkins University, March 200

Energy-Efficient Power Control in Multipath CDMA Channels via Large System Analysis

This paper is focused on the design and analysis of power control procedures for the uplink of multipath code-division-multiple-access (CDMA) channels based on the large system analysis (LSA). Using the tools of LSA, a new decentralized power control algorithm aimed at energy efficiency maximization and requiring very little prior information on the interference background is proposed; moreover, it is also shown that LSA can be used to predict with good accuracy the performance and operational conditions of a large network operating at the equilibrium over a multipath channel, i.e. the power, signal-to-interference-plus-noise ratio (SINR) and utility profiles across users, wherein the utility is defined as the number of bits reliably delivered to the receiver for each energy-unit used for transmission. Additionally, an LSA-based performance comparison among linear receivers is carried out in terms of achieved energy efficiency at the equilibrium. Finally, the problem of the choice of the utility-maximizing training length is also considered. Numerical results show a very satisfactory agreement of the theoretical analysis with simulation results obtained with reference to systems with finite (and not so large) numbers of users.Comment: Proceedings of the IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, Cannes, France, September 15-18, 200

Informality and social protection : preliminary results from pilot surveys in Bulgaria and Colombia.

There is a wide agreement on the fact that a large informal economy leaves many individuals without social protection and reduces government's tax revenue and social security contributions. However, it remains an open question what really drives informality, namely whether workers are simply trapped out of the formal sector or, at least some of them, choose it because it offers better alternatives than a formal job. The policy implications are clearly different in the two cases. In order to shed light on this important issue, the authors propose a household survey instrument to assess the links between informality and social protection. It can be implemented either through a stand-alone survey or by adding a specific module to an existing general survey such as the World Bank's Living Standards Measurement Study. After describing the main survey instrument, the study presents the results of two pilot surveys, carried out in Bulgaria and Colombia, to test the effectiveness of the questionnaire and improve its design. After the introduction is presented, the remainder of the paper is organized as follows. Section 2 discusses the design of the basic questionnaire on the informal sector. Since the instrument can be used also as a stand-alone survey, some questions are quite standard both in their content and format: in what follows, the study will focus on the parts that are not. Section 3 describes in detail the pilot surveys and the adaptation of the questionnaire to country-specific issues. Section 4 asks how representative is the sample of the two pilots. Section 5 presents some descriptive results emerging from the two pilots, and Section 6 examines how results differ according to informality status of respondents. Finally, Section 7 offers concluding remarks.,Access to Finance,Labor Markets,Population Policies,Labor Policies

Mapping the distribution of Well-Being in Europe beyond national borders

Well-being is a concept difficult to define and eventually harder to quantify. The idea of providing descriptions and metrics to evaluate well-being goes back to Aristotle (1095 bc) and from there an increasingly large number of studies attempted to quantify well-being of individuals and societies. Well-being is generally perceived as a description of the state of human life which always captured the attention of sociologists, economists, psychologist, politicians and citizens, making it a largely debated interdisciplinary topic. In particular in recent times, characterized by even increasing concerns related to the economic and the environmental situation, an increasing attention has been devoted to determining integrated descriptions to include all the aspects of human life. In addition, a large attention, demonstrated by the increasing literature on the topic, has also been devoted to the contribution of politics and societal organization in the progress toward well-being. The first part of this report tries to review the existing literature on well-being. Two main broad wellbeing approaches will be considered, the subjective and the objective approaches. For every one of them, the main definitions, the most important theoretical perspectives and the most relevant metrics and quantifications will be reported. The major contribution is to provide a synthesis of the vast literature that exists on the concept of well-being. In addition, by presenting the most recent well-being approach based on the integration between the objective and the subjective ones, an overview of the future directions of well-being investigations is also provided.JRC.H.2-Air and Climat

The role of microRNAs in thyroid carcinomas

Thyroid cancers (TCs) are the most common malignancies of endocrine organs. They originate from cells of different origin within the thyroid gland, which is located at the base of the neck. Several forms of TCs have been classified and great variability is observed in molecular, cellular and clinical features. The most common forms have favorable prognosis but a number of very aggressive TCs, which are characterized by a less differentiated cellular phenotype, have no effective treatment at the moment. While TC causes are not completely understood, many genetic factors involved in their onset have been discovered. In particular, activating mutations of BRAF, RET or RAS genes are known to be specifically associated with TC initiation, progression and outcome. The involvement of microRNAs in thyroid neoplasms has recently changed the paradigm for biomarker discovery in TC, suggesting that these small non-coding RNAs could be used to develop, refine or strengthen strategies for diagnosis and management of TCs. In this review, the importance of microRNA profiling in TC is explored suggesting that these molecules can be included in procedures that can perform better than any known clinical index in the identification of adverse outcomes