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I exploit a reform that required Italian municipalities to disclose their balance sheets before elections to study whether having more informed voters affects the political budget cycle. Municipal investment in the year before elections is 28.5% higher than in electoral years, and the reform reduced this pre-electoral spending increase by one third. I then study the role of local newspapers in disseminating municipal financial information to voters and find that the effect of the reform is twice as large in areas with relatively many newspaper readers, suggesting that mayors react to more informed voters by reducing spending manipulation.

The continuous advances of Nanofluidics have been stimulating the development of novel nanostructures and strategies to accumulate very diluted analytes, for implementing a new class of high sensitivity miniaturized polymeric sensors. We take advantage of the electrokinetic properties of these structures, which allow accumulating analytes inside asymmetric microfluidic structures to implement miniaturized sensors able to detect diluted solutions down to nearly 1.2 pg/mL. In particular, exploiting polydimethylsiloxane devices, fabricated by using the junction gap breakdown technique, we concentrate antigens inside a thin microfunnel functionalized with specific antibodies to favor the interaction and, if it is the case, the recognition between antigens in solution and antibodies anchored to the surface. The transduction mechanism consists in detecting the fluorescence signal of labeled avidin when it binds to biotinylated antigens. Here, we demonstrate that exploiting these electrokinetic phenomena, typical of nanofluidic structures, we succeeded in concentrating biomolecules in correspondence of a 1 pL sensing region, a strategy that grants to the device performance comparable to standard immunoassays.

The purpose of this investigation is to fabricate PDMS membranes with reliable surface roughness in order to reduce the surface resistances and to study its impact on the permeation rate. The permeance of CO 2 through PDMS membranes with rough surfaces at nanoscale is studied and compared with the one of membranes with flat surfaces. At very low thickness, rough membranes have a permeance greater than that of membranes with flat surfaces. The enhancement occurs in a regime where the gas transport is sorption desorption surface rate limited, and cannot be explained by the increase in surface area due to the corrugation. The analysis, introducing a phenomenological model in analogy with electrical flow, indicates that nano-corrugation reduces the surface resistance. To test the model, the permeance of N 2 is also measured in the same experimental conditions and the influence of surface roughness on permeation rate of CO 2 , He, CH 4 and N 2 is studied. The comparison among the gases suggests that the Henry’s coefficient depends on the surface roughness and allows discussing the role of roughness on membrane selectivity.

Several strategies have been developed for the control of DNA translocation in nanopores and nanochannels. However, the possibility to reduce the molecule speed is still challenging for applications in the field of single molecule analysis, such as ultra-rapid sequencing. This paper demonstrates the possibility to alter the DNA translocation process through an elastomeric nanochannel device by dynamically changing its cross section. More in detail, nanochannel deformation is induced by a macroscopic mechanical compression of the polymeric device. This nanochannel squeezing allows slowing down the DNA molecule passage inside it. This simple and low cost method is based on the exploitation of the elastomeric nature of the device, can be coupled with different sensing techniques, is applicable in many research fields, such as DNA detection and manipulation and is promising for further development in sequencing technology.

Nanofluidic systems offer new functionalities for the development of high sensitivity biosensors, but many of the interesting electrokinetic phenomena taking place inside or in the proximity of nanostructures are still not fully characterized. Here, to better understand the accumulation phenomena observed in fluidic systems with asymmetric nanostructures, we study the distribution of the ion concentration inside a long (more than 90 µm) micrometric funnel terminating with a nanochannel. We show numerical simulations, based on the finite element method, and analyze how the ion distribution changes depending on the average concentration of the working solutions. We also report on the effect of surface charge on the ion distribution inside a long funnel and analyze how the phenomena of ion current rectification depend on the applied voltage and on the working solution concentration. Our results can be used in the design and implementation of high-performance concentrators, which, if combined with high sensitivity detectors, could drive the development of a new class of miniaturized biosensors characterized by an improved sensitivity.

Modern photonics demands for high-resolution (HR) and deterministic lithography on transparent substrates. Thermal scanning-probe lithography (t-SPL) is a mask-less approach that couples a nanoscopic patterning resolution with the possibility to perform morphological characterizations without damaging delicate substrates unlike it happens for other techniques of similar resolution. In order to operate at its maximum performances, an electric bias between the scanning micromachined cantilever and the sample is needed thereby preventing, in principle, the patterning of transparent materials (that are usually insulators). In this work we demonstrate that by intercalating an ultrathin layer of a transparent conductive oxide (TCO) between an insulating and transparent substrate and the polymeric thin layer it is possible to exploit all the benefits of t-SPL also on challenging optically transparent substrates. Taking advantage of this particular lithographic configuration, we were effectively able to obtain a family of different gold plasmonic nanostructures resonating in the spectral range from the Visible to the Near-Infrared. The ensemble of the different resonators shows optical properties that encourage their exploitation in fields like sensing and thermoplasmonics.

This paper studies how political fragmentation affects government stability. Using a regression discontinuity design, we show that each additional party with representation in the local parliament increases the probability that the incumbent government is unseated by 5 percentage points. The entry of an additional party affects stability by reducing the probability of a single-party majority and increasing the instability of governments when such a majority is not available. We interpret our results in light of a bargaining model of coalition formation featuring government instability.

During the characterization of the demonstration model of the Cryogenic AntiCoincidence (CryoAC) Detector (ACS-10), a current-dependent parasitic resistance was found in series with the TES network on board the detector. Analysis was possible because the resistance rises for currents above 11 μ A, and is therefore not observed at low bias excitation. A comparison of measurements of the TES across its Nb wiring at different temperatures suggested that the source of resistance was in the wiring and not in the TES network. After several analysis of the wiring fabrication steps, FIB-FE-SEM studies of film sections and tests of niobium film quality, we understood that the parasitic resistance was due to point contact in the Nb step coverage caused by film cracks. The fracture was due to the wall steepness and thickness of the films, since rapid step coverage is less mechanically stable and the stress on the films is proportional to the fourth power of the thickness. Therefore, all thicknesses in the wiring were reduced to the minimum optimum step coverage values and the first negative lithography parameters were optimized to reduce the wall film angle. The samples after this optimization showed no current-dependent series resistance to TES.

This paper describes a procedure to measure the permeability P, diffusivity D, and rate of adsorption k1, thus determining the solubility S and rate of desorption k2 of He, N2, O2, CH4, and CO2 on a polydimethylsiloxane (PDMS) membrane. The described procedure is able to determine experimentally all the physical quantities that characterize the gas transport process through a thin rubber polymer membrane. The experiments were carried out at room temperature and at a transmembrane pressure of 1 atm. The results are in good agreement with the available data in the literature and offer an evaluation of k1 and k2.

The joint use of hourly resolution sampling and analyses with accelerated ion beams such as with the particle-induced X-ray emission (PIXE) technique has allowed the measurement of hourly temporal patterns of particulate matter (PM) composition at many sites in different parts of the world. The demand within the scientific community for this type of analysis has been continuously increasing in recent years, but hourly resolution samplers suitable for PIXE analysis have been discontinued and/or suffer from some technical limitations. In this framework, a new hourly sampler, STRAS (Size- and Time-Resolved Aerosol Sampler), was developed for the collection of PM10, PM2.5 or PM1. It allows automatic sequential sampling of up to 168 hourly samples (1 week), and it is mechanically robust, compact and easily transportable. To increase PIXE sensitivity, each sample is concentrated on a small surface area on a polycarbonate membrane. Comparison between the elemental concentrations retrieved by STRAS samples and samples collected using a standard sequential sampler operated in parallel shows very good agreement; indeed, if both the samplers use the same kind of membrane, the concentrations of all detected elements are in agreement within 10 %.