Mutual Information Optimization and Capacity Evaluation in MIMO Systems with Magnitude Knowledge and Phase Uncertainty

This paper discusses the design of a multiantenna transmitter in a multi-input, multi-output channel to maximize the mutual information and achieve capacity. The channel has been considered as an uncertain system where the magnitude of its gains is perfectly known and there is an incomplete knowledge of the phases. This describes several practical situations, such as time division duplex systems with uncalibrated phases of the radio frequency chains, or rapidly phase-varying mobile channels. This uncertainty is taken into account explicitly during the design from two different points of view. First, a statistical approach is taken to achieve ergodic capacity, i.e., to maximize the mutual information averaged over the phase statistics. Second, the objective is to achieve compound capacity, i.e., to maximize the worst-case mutual information for any possible phase realization. No closed-form solutions exist for these two problems; thus, alternative approximate techniques are proposed in each case, one of them based on random matrix theory. Finally, in the simulations section, the accuracies of the proposed algorithms and approximations are evaluated, jointly with the gains provided by the optimization of the transmitter.     

A bibliometric study of psychological research on tourism

The psychology of tourism is a new, multidisciplinary research field. However, no systematic analyses of the scientific production in this field have been carried out to date. This study presents a bibliometric analysis of the area of psychology of tourism between 1990 and 2005. The evolution of scientific production during this period, Price’s, Lotka’s and Bradford’s laws and citation patterns were studied. The results show a significant growth in the literature on the subject, as well as an increase in coauthorship and institutional collaboration. Bibliometric laws and empiric regularities observed in other disciplines are also present in this new research field.     

C3 Halogen and C8′′ Substituents on Stilbene Arotinoids Modulate Retinoic Acid Receptor Subtype Function

The synthesis and biological evaluation of the entire series of C3‐halogenated derivatives and bulkier substituents at the C8′′ position of the parent stilbene‐based RARβ‐selective agonist BMS641 4 c was undertaken. The synthesis uses an E‐selective Horner–Wadsworth–Emmons (HWE) condensation of C8‐substituted C5‐dimethyl dihydronaphthaldehyde and the benzylic phosphonates derived from the C3‐halogenated benzoates to construct the stilbene skeleton. Transactivation studies revealed the synergistic effect of small halogen atoms at C3 (F, Cl) and the moderately bulky phenyl group at C8′′ (in 4 b and 4 c ) to achieve RARβ selectivity. Our results, supported by computational studies, provide a structural rationale for the mixed agonist–antagonist activities of these arotinoids, which are potent agonists of the RARβ subtype and antagonists of the RARα paralogue. Moreover, transitions from partial agonists to inverse agonists and antagonists can be accomplished with the incorporation of the same halogen atoms into the structures of known modulators BMS701 ( 5 a ) and BMS493 ( 6 a ), which have bulkier substituents than phenyl (p‐tolyl and phenylethynyl, respectively) at C8′′. Conversely, incorporation of halogen atoms in 6 a converted the ligand from an RARβ inverse agonist ( 6 b ) to an antagonist ( 6 c ) or an agonist ( 6 d ). Amazingly, 6 a – c commonly acted as inverse agonists for RARα, while 6 d and 6 e acted as regular RARα antagonists, not affecting co‐repressor interaction. In the case of the mixed agonist/antagonist 5 a , C3‐halogenation yields inverse RARα and RARβ agonists ( 5 b – d ) with the exception of iodinated 5 e , which is a regular antagonist for both these receptors. Because RARβ gene expression is frequently deleted or epigenetically silenced in several tumor cells, the novel repertoire of receptor and function‐selective RAR agonists, mixed agonist/antagonists, regular antagonists, and inverse agonists will be useful in the elucidation of the mechanism of tumor suppression by retinoids.     

Recent advances in the analysis of behavioural organization and interpretation as indicators of animal welfare

While the incorporation of mathematical and engineering methods has greatly advanced in other areas of the life sciences, they have been under-utilized in the field of animal welfare. Exceptions are beginning to emerge and share a common motivation to quantify ‘hidden’ aspects in the structure of the behaviour of an individual, or group of animals. Such analyses have the potential to quantify behavioural markers of pain and stress and quantify abnormal behaviour objectively. This review seeks to explore the scope of such analytical methods as behavioural indicators of welfare. We outline four classes of analyses that can be used to quantify aspects of behavioural organization. The underlying principles, possible applications and limitations are described for: fractal analysis, temporal methods, social network analysis, and agent-based modelling and simulation. We hope to encourage further application of analyses of behavioural organization by highlighting potential applications in the assessment of animal welfare, and increasing awareness of the scope for the development of new mathematical methods in this area.     

Characteristics of hemocompatible TiO<Subscript>2</Subscript> nano-films produced by the sol-gel and anodic oxidation techniques

Hemocompatible films can be obtained by different techniques which must produce a smooth surface and a desired combination of crystal structure including rutile and anatase structures. Two of the simplest techniques include sol-gel and anodic oxidation. The characteristics of the films associated with the process variables are presented. The most important characteristics of the films are thickness, structure, roughness, and mechanical properties such as adhesion and wear resistance.     

Assessing the influence of manufacturing sectors on electricity demand. A cross-country input-output approach

The production and consumption of electricity is a major source of CO₂ emissions in Europe and elsewhere. In turn, the manufacturing sectors are significant end-users of electricity. In contrast to most papers in the literature, which focus on the supply-side, this study tackles the demand-side of electricity. An input–output approach combined with a sensitivity analysis has been developed to analyse the direct and indirect consumptions of electricity by eighteen manufacturing sectors in fifteen European countries, with indirect electricity demand related to the purchase of industrial products from other sectors which, in turn, require the consumption of electricity in their manufacturing processes. We identify the industrial transactions and sectors, which account for a greater share of electricity demand. In addition, the impact of an electricity price increase on the costs and prices of manufacturing products is simulated through a price model, allowing us to identify those sectors whose manufacturing costs are most sensitive to an increase in the electricity price.     

酵母抽提物行业标准及在原生态酱油发酵中的应用研究

酵母抽提物是一种优良的天然调味料,在食品行业中具有广泛的用途.本次发布会将介绍我国酵母抽提物行业标准及其相关注意事项,以及酵母抽提物在原生态酱油方面应用研究新进展.     

Characterization of non-alpha helical conformations in Ala peptides

The folded (alpha helical) and unfolded (non-alpha helical) ensembles of the 21 amino acid peptide Ace-A21-Nme are characterized structurally. The replica exchange molecular dynamics approach is used to generate these ensembles at 46 different temperatures ranging from 278 to 487 K. Each replica system is simulated in explicit solvent for a period of 10 ns/replica, for a total of 460 ns. In addition to alpha helices, poly proline II (PPII) structures were identified to occur significantly. At low T the alpha helical content is larger than the PPII content, but near 300 K the PPII population is larger. Below 300 K, the PPII population increases with T, but it decreases above 300 K. The alpha helical content decreases with temperature. At temperatures below 300 K, there is a PPII propagation free energy that enhances the formation of long segments of PPII structure. This propagation term is smaller than for alpha helices. PPII segments of length 8 or less are more likely to form than alpha helices of the same length. The obtained low propensity for the formation of PPII segments of length shorter than five suggest that the interactions are responsible for the formation of PPII structures require a PPII segment of at least four amino acids. Stretches of four consecutive amino acids in the PPII conformations are needed for the formation of a groove around the peptide backbone that is strongly hydrated. Water in this groove is delocalized along a channel formed by the peptide in the PPII conformation.