Stabilization of Polar Nano Regions in Pb-free ferroelectrics

Formation of polar nano regions through solid-solution additions are known to enhance significantly the functional properties of ferroelectric materials. Despite considerable progress in characterizing the microscopic behavior of polar nano regions, understanding their real-space atomic structure and dynamics of formation remains a considerable challenge. Here, using the method of dynamic pair distribution function, we provide direct insights into the role of solid-solution additions towards the stabilization of polar nano regions in the Pb-free ferroelectric of Ba(Zr,Ti)O3. It is shown that for an optimum level of substitution of Ti by larger Zr ions, the dynamics of atomic displacements for ferroelectric polarization are slowed sufficiently, which leads to increased local correlation among dipoles below THz frequencies. The dynamic pair distribution function technique demonstrates unique capability to obtain insights into locally correlated atomic dynamics in disordered materials, including new Pb-free ferroelectrics, which is necessary to understand and control their functional properties

International Coercion, Emulation and Policy Diffusion: Market-Oriented Infrastructure Reforms, 1977-1999

Why do some countries adopt market-oriented reforms such as deregulation, privatization and liberalization of competition in their infrastructure industries while others do not? Why did the pace of adoption accelerate in the 1990s? Building on neo-institutional theory in sociology, we argue that the domestic adoption of market-oriented reforms is strongly influenced by international pressures of coercion and emulation. We find robust support for these arguments with an event-history analysis of the determinants of reform in the telecommunications and electricity sectors of as many as 205 countries and territories between 1977 and 1999. Our results also suggest that the coercive effect of multilateral lending from the IMF, the World Bank or Regional Development Banks is increasing over time, a finding that is consistent with anecdotal evidence that multilateral organizations have broadened the scope of the “conditionality” terms specifying market-oriented reforms imposed on borrowing countries. We discuss the possibility that, by pressuring countries into policy reform, cross-national coercion and emulation may not produce ideal outcomes.http://deepblue.lib.umich.edu/bitstream/2027.42/40099/3/wp713.pd

Evolution of Linear Absorption and Nonlinear Optical Properties in V-Shaped Ruthenium(II)-Based Chromophores

In this article, we describe a series of complexes with electron-rich cis-{Ru^(II)(NH_3)_4}^(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845−4859). They have been isolated as their PF_6− salts and characterized by using various techniques including ^1H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru^(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities β have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d → π^* metal-to-ligand charge-transfer (MLCT) and π → π^* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant β_0 responses as high as ca. 600 × 10^(−30) esu. These pseudo-C_(2v) chromophores show two substantial components of the β tensor, β_(zzz) and β_(zyy), although the relative significance of these varies with the physical method applied. According to HRS, β_(zzz) dominates in all cases, whereas the Stark analyses indicate that β_(zyy) is dominant in the shorter chromophores, but β_(zzz) and β_(zyy) are similar for the extended species. In contrast, finite field calculations predict that β_(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand π-systems are extended. Such unusual behavior has also been observed with related 1D complexes (Coe, B. J. et al. J. Am. Chem. Soc. 2004, 126, 3880−3891)

Diquat Derivatives: Highly Active, Two-Dimensional Nonlinear Optical Chromophores with Potential Redox Switchability

In this article, we present a detailed study of structure−activity relationships in diquaternized 2,2′-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, π-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF_6^− salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense π → π^* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities β have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities β_0. The directly and indirectly derived β values are large and increase with the extent of π-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E_(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based β_0 responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by ‘off-diagonal’ β_(zyy) components. The most significant findings of these studies are: (i) β_0 values as much as 6 times that of the chromophore in the technologically important material (E)-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior

Individual Liberty and the Importance of the Concept of the People

UID/FIL/00183/2013Through publically agreed laws that correspond to a common set of public restrictions, the ‘people as a sovereign body’ serves to protect against violations of individual liberty and despotic power. Where no such common body exists, individuals are deprived of this protection. In such cases, individuals must obey without liberty, while those in power command under a state of license. Neoliberal theorists maintain that any common personality, with its corresponding set of public and arbitrary positive and negative restrictions on liberty, undermines individual liberty. Neoliberal theory only allows for private restrictions on liberty. Against these neoliberal assumptions, we argue that rejecting public restrictions on liberty does not promote individual liberty. To the 1᢫ ᢬ ᢭ ᢮ 1 contrary, it creates conditions in which free individuals become servile and political inequality becomes entrenched, where citizens are divided into those who obey and those who command. Tracing the consequences of neoliberalism, we argue that unless we take seriously both the people as a political category and the right to equal and reciprocal coercion, individual liberty will be at risk. We also argue that neoliberalism ultimately leads to the total exclusion of certain citizens under the veil of full liberty. With the vanishing of the people’s will comes the utter disappearance of certain citizens, who live in the spontaneous society as if they were stateless or lawless persons. To better understand the connections between the rejection of the concept of the people, private restrictions on liberty and the fostering of the servile citizen, this paper considers the political philosophy of Hayek and Nozick. It also considers key ideas from Locke and Kant—theorists who, despite the differences between their philosophical perspectives, and despite the fact that they both provided crucial inspiration for Hayek’s political economy and Nozick’s libertarianism, stressed the protective role of the people with regard to individual liberty.publishersversionpublishe

Systematizing Policy Learning: From Monolith to Dimensions

notes: The authors wish to express their gratitude to the Norwegian Political Science Association Annual Conference, 6 January 2010, University of Agder, Kristiansand, participants of the ‘Establishing Causality in Policy Learning’ panel at the American Political Science Association (APSA) annual meeting,2–5 September 2010,Washington DC, and the European Consortium of Political Research (ECPR) Joint Sessions, St Gallen, 12–17 April 2011, workshop 2. Dunlop and Radaelli gratefully acknowledge the support of the European Research Council, grant on Analysis of Learning in Regulatory Governance, ALREG, http://centres.exeter.ac.uk/ceg/research/ALREG/index.php.publication-status: AcceptedThe definitive version is available at www.blackwell-synergy.com and also from DOI: 10.1111/j.1467-9248.2012.00982.xThe field of policy learning is characterised by concept stretching and lack of systematic findings. To systematize them, we combine the classic Sartorian approach to classification with the more recent insights on explanatory typologies. At the outset, we classify per genus et differentiam – distinguishing between the genus and the different species within it. By drawing on the technique of explanatory typologies to introduce a basic model of policy learning, we identify four major genera in the literature. We then generate variation within each cell by using rigorous concepts drawn from adult education research. Specifically, we conceptualize learning as control over the contents and goals of knowledge. By looking at learning through the lenses of knowledge utilization, we show that the basic model can be expanded to reveal sixteen different species. These types are all conceptually possible, but are not all empirically established in the literature. Up until now the scope conditions and connections among types have not been clarified. Our reconstruction of the field sheds light on mechanisms and relations associated with alternatives operationalizations of learning and the role of actors in the process of knowledge construction and utilization. By providing a comprehensive typology, we mitigate concept stretching problems and aim to lay the foundations for the systematic comparison across and within cases of policy learning.European Research Council, grant no 230267 on Analysis of Learning in Regulatory Governance, ALREG

The Presidency and the Executive Branch in Latin America: What We Know and What We Need to Know

The presidential politics literature depicts presidents either as all- powerful actors or figureheads and seeks to explain outcomes accordingly. Th e president and the executive branch are nonetheless usually treated as black boxes, particularly i n developing countries, even though the presidency has evolved into an extremely complex branch of government. While these developments have been studied in the U nited States, far less i s known in other countries, particularly in Latin America, where presi dential systems have been considered the source of all goods and evils. To help close the knowledge gap and explore differences in policymaking characteristics not only between Latin America and the US but also across Latin American countries, this paper s ummarizes the vast literature on the organization and resources of the Executive Branch in the Americas and sets a research agenda for the study of Latin American presidencies.Fil: Bonvecchi, Alejandro. Universidad Torcuato Di Tella. Departamento de Ciencia Política y Estudios Internacionales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Scartascini, Juan Carlos. Banco Interamericano de Desarrollo; Estados Unido