The low viscosity and the ability to control solidification rate make colloidal nanosilica grout an excellent ground-improvement solution which is functional for different engineering purposes. A comprehensive experimental programme was performed to test the effectiveness and applicability of low-pressure injection of aqueous nanosilica suspensions against seismic liquefaction and to provide the experimental basis for the design, execution, and control of treatments. Scanning electron microscope and X-ray diffraction tests carried out on samples prepared with variable dosages enabled analysis of the microstructure of the original material and grouted sand. The influence of the grout composition on the solidification rate, viscosity, and shear strength of the treated sand was evaluated with preliminary tests to optimize the use of material. The efficacy of treatment in terms of stress-strain response and liquefaction resistance was investigated with a series of drained monotonic and undrained cyclic triaxial tests. A quality control procedure based on sonic wave transmission was established by performing bender element tests on samples cured for different times. The intent was to find the trade-off between a cost-effective use of materials and the mechanical performance of the treated sand.

This paper analyses the effect of polyurethane injections on the seismic surficial response of cohesionless soils. For this purpose, dynamic finite element numerical analyses were performed through GiD + OpenSees. Both the soil and the composite material, resulted after the expansion of the injected polyurethane, are modelled with a nonlinear hysteretic constitutive model. Based on the polyurethane percentage, a homogenisation of the characteristics was considered for the composite material: linear for density and damping, and exponential (experimentally calibrated) for the stiffness. An expansion coefficient quantifies how much the injected polyurethane expands: three expansion coefficients were considered, each of them related to a different polyurethane density. For the evaluation of the foam stiffness, a linear stiffness–density correlation was used, derived after impact tests. Results showed that polyurethane reduces the surficial accelerations proportionally to the ratio of its seismic impedance and volumetric percentage with respect to the soil seismic impedance and total volume. This is a preliminary indication for the design of polyurethane injections in cohesionless soils for seismic acceleration reduction.

In this article, we argue that þÿ b o t h d e m o c r a c y a n d g o v e r n m e n t s partisanship have had a bearing on state capacity in Latin America.We also maintain that state capacity is a condition rooted in history and society: it can be built or purposefully undermined. In particular, Dear Editors, Please find enclosed our manuscript, "Political Determinants of State Capacity in Latin America )", which we would like to submit for publication in World Development.In this article, we argue that both democracy and governments' partisanship have had a bearing on state capacity in Latin America. We also maintain that state capacity is a condition rooted in history and society: it can be built or purposefully undermined. In particular, in Latin America parties of the left have frequently operated to reallocate social and political clout in favor of underprivileged groups: the inclusion of the latter in the political process helped states to thwart pressures from dominant elites opposing redistribution and tax increases. These mobilized groups have also pushed for universal public services, as high-quality education, health care or public housing, which required well-functioning administrations and an adequate institutional capacity, thus contributing to consolidate stateness in the area. Whereas previous qualitative studies analyzed the mechanisms that relate democracy and political partisanship to state capacity, we test this hypothesis quantitatively. To this end, we estimate the effect over time of democracy, political parties and other socio-demographic factors on a composite measure of stateness, obtaining supportive evidence: in particular, we find that higher democracy levels and left-leaning governments favored the growth of state strength in the area between 1975 and 2009 and discuss these findings with reference to the political experience of Latin America. We believe our findings would appeal to the readership of WD for both methodological and substantive reasons. We look forward to hearing from you at your earliest convenience. Davide Grassi and Vincenzo Memoli Short Bio State CapacityState capacity is a thorny concept, arduous to define and operationalize: in fact, there is greater scholarly agreement on key features of the state than on how to operationalize such features or the concept of the state itself (Carbone 2013, p. 6).In the last few years, however, political scientists and sociologists have engaged in an extensive and critical debate:7 while failing to yield a common position, the ongoing discussion Other indicators, finally, show the link between actual revenue collection and the expected tax yield, given GDP per capita, mineral production, exports and additional relevant factors. Independent and control variablesWe decided to use a minimalist notion of democracy to avoid merging attributes of political authority and state qualities 14 We begin with a descriptive analysis of the trend of stateness (Fig. 1). This impression is strengthened by a graphic assessment of the wa...

The return of democracy in Latin America has been associated with a decline in political violence, but also with a failure to redress welfare troubles or restore social justice. This essay provides an exploration of these problematic relationships. It argues that the impact of democracy on social welfare and internal civil violence is complex, develops unevenly and is mediated by a host of contributing factors. The bearing of democracy on political violence has been especially weak. In some countries democratic elites played a role in reducing or eliminating armed conflicts by offering a series of political concessions to the opposition, in particular communication channels with the government and social and political rewards. However, political violence survived or intensified under democracy elsewhere, while it was eradicated by force and (less frequently) by concessions in a number of authoritarian settings. Democracy has also affected welfare policies, through the appearance and progressive strengthening of social organisations and political parties that favoured channelling benefits towards the less advantaged. Yet, welfare protection also took place under populist and authoritarian governments, and it was influenced by a series of additional economic, political and social factors.

This article aims to assess how democracy affects social welfare by analyzing Uruguay and Paraguay, one country with a vibrant democratic history and a progressive political landscape, the other with a generally authoritarian past and a conservative dominant party. The article maintains that welfare systems in these countries have been critically shaped by the impact of democracy, or by its absence, and by the strategies adopted by major social and political actors, especially parties; these strategies have been determined, in turn, by parties' ideologies and by the workings of electoral competition. The article also emphasizes that the impact of democracy on social welfare is critically mediated by the role of previous welfare legacies, the presence of welfare constituencies defending acquired rights and privileges, and social and economic variables, such as overall wealth levels, the formal or informal nature of labor markets, and the political organization of domestic economies.