Dilution effects in Ho2−x_{2-x}Yx_xSn2_2O7_7: from the Spin Ice to the single-ion magnet

A study of the modifications of the magnetic properties of Ho$_{2-x}$Y$_x$Sn$_2$O$_7$ upon varying the concentration of diamagnetic Y$^{3+}$ ions is presented. Magnetization and specific heat measurements show that the Spin Ice ground-state is only weakly affected by doping for $x\leq 0.3$, even if non-negligible changes in the crystal field at Ho$^{3+}$ occur. In this low doping range $\mu$SR relaxation measurements evidence a modification in the low-temperature dynamics with respect to the one observed in the pure Spin Ice. For $x\to 2$, or at high temperature, the dynamics involve fluctuations among Ho$^{3+}$ crystal field levels which give rise to a characteristic peak in $^{119}$Sn nuclear spin-lattice relaxation rate. In this doping limit also the changes in Ho$^{3+}$ magnetic moment suggest a variation of the crystal field parameters.Comment: 4 pages, 5 figures, proceedings of HFM2008 Conferenc

The Role of Consumer's Risk Aversion on Price Rigidity

This paper aims to contribute to the research agenda on the sources of price rigidity. Based on broadly accepted assumptions on the behavior of economic agents, we show that firms’ competition can lead to the adoption of sticky prices as a sub-game perfect equilibrium strategy to optimally deal with consumers’ risk aversion, even if firms have no adjustment costs. To this end, we build a model economy based on consumption centers with several complete markets and relax some traditional assumptions used in standard monetary policy models by assuming that households have imperfect information about the inefficient time-varying cost shocks faced by the .rms. Furthermore, we assume that the timing of events is such that, at every period, consumers have access to the actual prices prevailing in the market only after choosing a particular consumption center. Since such choices under uncertainty may decrease the expected utilities of risk-averse consumers, competitive firms adopt some degree of price stickiness in order to minimize the price uncertainty and "attract more customers".

Doping-induced quantum cross-over in Er2_2Ti2−x_{2-x}Snx_xO7_7

We present the results of the investigation of magnetic properties of the Er$_2$Ti$_{2-x}$Sn$_x$O$_7$ series. For small doping values the ordering temperature decreases linearly with $x$ while the moment configuration remains the same as in the $x = 0$ parent compound. Around $x = 1.7$ doping level we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time we present evidence of a long-range order (LRO) in Er$_2$Sn$_2$O$_7$ ($x = 2.0$) below $T_N = 130$ mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to $x = 0$. We discuss our results in the framework of a possible quantum phase transition occurring close to $x = 1.7$.Comment: accepted in PRB Rapi

Contribuição de poleiros naturais e artificiais para a recuperação de ecossistemas florestais.

Resumo

Energy Efficiency in Cloud Software Architectures

Cloud-based software is often considered as providing a greener, more energy-efficient solution. At the same time, it introduces more complexity and demands for new investments in cloud services, technologies, and competencies for migration, maintenance, and evolution of the underlying software architectures. To understand better the implications of cloud software architectures on energy efficiency, in this paper we present the preliminary results of a systematic literature review that investigates what kind of software architectures for cloud service provisioning allow to achieve energy-efficient solution

A systematic literature review on Energy Efficiency in Cloud Software Architectures

Cloud-based software architectures introduce more complexity and require new competences for migration, maintenance, and evolution. Although cloud computing is often considered as an energy-efficient technology, the implications of cloud-based software on energy efficiency lack scientific evidence. At the same time, energy efficiency is becoming a crucial requirement for cloud service provisioning, as energy costs significantly contribute to the Total Cost of Ownership (TCO) of a data center. In this paper, we present the results of a systematic literature review that investigates cloud software architectures addressing energy efficiency as a primary concern. The aim is to provide an analysis of the state-of-the-art in the field of energy-efficient software architectures

Calculation of the absolute hydration enthalpy and free energy of H+ and OH-

An ab initio density functional theory and a polarizable continuum model were used to calculate the hydration enthalpy and Gibbs free energy of proton and hydroxide. The proton hydration enthalpy data is found to be in agreement with the results from cluster-ion solvation data. It was found that the effect of adding explicit hydration molecules is more significant for the hydration free energies than for the enthalpies.Dirección General de Enseñanza Superior PB98-0326Junta de Andalucía FQ20

A new energy consumption technique for mobile ad hoc networks

A dynamic temporary network is created through wireless mobile nodes without the need for considerable infrastructure as well as a central manager. In a mobile ad hoc network, routing protocols allow a mobile for transmission and receiving packets. In the last decade, many variants have come up for the AODV. A minimum number of hop counts are chosen for enhancing routing protocols to include additional factors that can have an impact on path selections. As the distance between each node grows, the transmission power also rises accordingly. Hence, this impacts the network’s entire performance and the most important feature is the quality of service. Most of the traditional routing protocols include energy consumption levels of the nodes and various parameters, like residual battery power, consumption of energy per packet and energy needed per transmission. A new technique is proposed in this paper to enhance the routing efficiency by making use of lion optimization algorithm after identifying all possible paths in the network. This technique not only enhances the energy efficiency of each node but also the performance metrics