239 research outputs found
The Political Economy of Privatization
This paper provides an empirical analysis of the role of political institutions in privatization. The empirical testing relies on a new political database with continuous and time-varying measures of the political-institutional setting, and of the partisan orientation of the executive. Using panel data for 21 industrialized countries in the 1977-1999 period, first we show the likelihood and the extent of privatization to be strongly and positively associated with majoritarian political systems. On the contrary, in consensual democracies privatization seems delayed by a âwar of attritionâ among different political actors. Second, we identify a partisan determinant of the choice of the privatization method. As theory predicts, right wing executives with re-election concerns design privatization to spread share ownership among domestic voters.Political institutions, Partisan politics, Privatization
Resonant translational, breathing and twisting modes of pinned transverse magnetic domain walls
We study translational, breathing and twisting resonant modes of transverse
magnetic domain walls pinned at notches in ferromagnetic nanostrips. We
demonstrate that a mode's sensitivity to notches depends strongly on the
characteristics of that particular resonance. For example, the frequencies of
modes involving lateral motion of the wall are the ones which are most
sensitive to changes in the notch intrusion depth (especially at the narrower,
more strongly confined end of the domain wall). In contrast, the breathing
mode, whose dynamics are concentrated away from the notches is relatively
insensitive to changes in the notches' sizes. We also demonstrate a sharp drop
in the translational mode's frequency towards zero when approaching depinning
which is found, using a harmonic oscillator model, to be consistent with a
reduction in the local slope of the notch-induced confining potential at its
edge.Comment: 11 pages, 10 figures, additional data and analysi
TOUGH2Viewer tutorial
TOUGH2Viewer is a Java program capable of displaying unstructured (Voronoi complying) grids, locally refined and structured grids (complying with the MESHMAKER iTOUGH2 format).
In particular, TOUGH2Viewer allows to navigate through a 3D grid compatible with the iTOUGH2 data file format and see:
(1) the thermodynamic variables and the material (namely, petrophysical properties) of each block;
(2) maps of isovalues (2D) of all thermodynamic variables;
(3) isosurfaces (3D) of all thermodynamic variables;
(4) flows of mass and heat between blocks;
(5) spatial profiles of thermodynamic variables, of a selected set of blocks, long a Cartesian directions;
(6) time plot of thermodynamic variables of a selected block.
All commands to manage a 3D visualization (zooming, pan, rotations) are CAD complying
Reservoir computing with the frequency, phase and amplitude of spin-torque nano-oscillators
Spin-torque nano-oscillators can emulate neurons at the nanoscale. Recent
works show that the non-linearity of their oscillation amplitude can be
leveraged to achieve waveform classification for an input signal encoded in the
amplitude of the input voltage. Here we show that the frequency and the phase
of the oscillator can also be used to recognize waveforms. For this purpose, we
phase-lock the oscillator to the input waveform, which carries information in
its modulated frequency. In this way we considerably decrease amplitude, phase
and frequency noise. We show that this method allows classifying sine and
square waveforms with an accuracy above 99% when decoding the output from the
oscillator amplitude, phase or frequency. We find that recognition rates are
directly related to the noise and non-linearity of each variable. These results
prove that spin-torque nano-oscillators offer an interesting platform to
implement different computing schemes leveraging their rich dynamical features
Robust Algorithms for the Analysis of Fast-Field-Cycling Nuclear Magnetic Resonance Dispersion Curves
Fast-Field-Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometry is a powerful,
non-destructive magnetic resonance technique that enables, among other things, the investigation of slow molecular dynamics at low magnetic field intensities. FFC-NMR relaxometry measurements provide insight into molecular motion across various timescales within a single experiment. This study focuses on a model-free approach, representing the NMRD profile R1 as a linear combination of Lorentzian functions, thereby addressing the challenges of fitting data within an ill-conditioned linear least-squares framework. Tackling this problem, we present a comprehensive review and experimental validation of three regularization approaches to implement the model-free approach to analyzing NMRD profiles. These include (1) MF-UPen, utilizing locally adapted L2 regularization; (2) MF-L1, based on L1 penalties; and (3) a hybrid approach combining locally adapted L2 and global L1 penalties. Each methodâs regularization parameters are determined automatically according to the Balancing and Uniform Penalty principles. Our contributions include the implementation and experimental validation of the MF-UPen and MF-MUPen algorithms, and the development of a âdispersion analysisâ technique to assess the existence range of the estimated parameters. The objective of this work is to delineate the variance in fit quality and correlation time distribution yielded by each algorithm, thus broadening the set of software tools for the analysis of sample structures in FFC-NMR studies. The findings underline the efficacy and applicability of these algorithms in the analysis of NMRD profiles from samples representing different potential scenarios
Halyomorpha halys in Emilia, prime risposte dal monitoraggio
OSSERVAZIONI IN CAMPO CONDOTTE NEL 2013-2014. Dopo la sua comparsa in Italia, accertata nel 2012, Ăš stato attivato nella zona di ritrovamento un programma di monitoraggio teso a studiare lâinsetto e il suo comportamento nellâambiente. La specie desta maggiori preoccupazioni nel settore frutticolo, dove il danno rappresentato dalle tipiche deformazioni puĂČ giungere al 100
Non-hermiticity in spintronics: oscillation death in coupled spintronic nano-oscillators through emerging exceptional points
The emergence of exceptional points (EPs) in the parameter space of a
non-hermitian (2D) eigenvalue problem is studied in a general sense in
mathematical physics, and has in the last decade successively reached the scope
of experiments. In coupled systems, it gives rise to unique physical phenomena,
which enable novel approaches for the development of seminal types of highly
sensitive sensors. Here, we demonstrate at room temperature the emergence of
EPs in coupled spintronic nanoscale oscillators and hence exploit the system's
non-hermiticity. We describe the observation of amplitude death of
self-oscillations and other complex dynamics, and develop a linearized
non-hermitian model of the coupled spintronic system, which properly describes
the main experimental features. Interestingly, these spintronic nanoscale
oscillators are deployment-ready in different applicational technologies, such
as field, current or rotation sensors, radiofrequeny and wireless devices and,
more recently, novel neuromorphic hardware solutions. Their unique and
versatile properties, notably their large nonlinear behavior, open up
unprecedented perspectives in experiments as well as in theory on the physics
of exceptional points. Furthermore, the exploitation of EPs in spintronics
devises a new paradigm for ultrasensitive nanoscale sensors and the
implementation of complex dynamics in the framework of non-conventional
computing
Generation of coherent spin-wave modes in Yttrium Iron Garnet microdiscs by spin-orbit torque
Spin-orbit effects [1-4] have the potential of radically changing the field
of spintronics by allowing transfer of spin angular momentum to a whole new
class of materials. In a seminal letter to Nature [5], Kajiwara et al. showed
that by depositing Platinum (Pt, a normal metal) on top of a 1.3 m thick
Yttrium Iron Garnet (YIG, a magnetic insulator), one could effectively transfer
spin angular momentum through the interface between these two different
materials. The outstanding feature was the detection of auto-oscillation of the
YIG when enough dc current was passed in the Pt. This finding has created a
great excitement in the community for two reasons: first, one could control
electronically the damping of insulators, which can offer improved properties
compared to metals, and here YIG has the lowest damping known in nature;
second, the damping compensation could be achieved on very large objects, a
particularly relevant point for the field of magnonics [6,7] whose aim is to
use spin-waves as carriers of information. However, the degree of coherence of
the observed auto-oscillations has not been addressed in ref. [5]. In this
work, we emphasize the key role of quasi-degenerate spin-wave modes, which
increase the threshold current. This requires to reduce both the thickness and
lateral size in order to reach full damping compensation [8] , and we show
clear evidence of coherent spin-orbit torque induced auto-oscillation in
micron-sized YIG discs of thickness 20 nm
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