25,377 research outputs found
Foreign ownership, firm performance, and the geography of civic capital
It is well established in the literature that foreign affiliates are subject to a series of governance and assimilation costs that deteriorate their performance. This is particularly relevant for firms which have been recently acquired by foreign investors. We employ the variation in civic capital across Italian provinces as an exogenous determinant of these governance costs. We derive the testable implication that there should be a clean evidence of a negative effect of foreign ownership on performance in areas where civic capital is low. As the level of local civic capital increases, this reduces the scope for internal transaction costs, and makes the governance of foreign affiliates easier, and their performance better. We take this prediction to the data and find confirmation of our conceptual framework. Our analysis underlines the importance of the geographic heterogeneity of informal institutions when analyzing the effect of foreign ownership on firm performance.
Electrical resistivity of the Ti4O7 Magneli phase under high pressure
We have measured resistivity as a function of temperature and pressure of
Ti4O7 twinned crystals using different contact configurations. Pressures over
4kbar depress the localization of bipolarons and allow the study of the
electrical conduction of the bipolaronic phase down to low temperatures. For
pressures P > 40 kbar the bipolaron formation transition is suppressed and a
nearly pressure independent behavior is obtained for the resistivity. We
observed an anisotropic conduction. When current is injected parallel to the
principal axis, a metallic conduction with interacting carrier effects is
predominant. A superconducting state was not obtained down to 1.2 K, although
evidences of the proximity of a quantum critical point were noticed. While when
current is injected non-parallel to the crystal's principal axis, we obtained a
logarithmic divergence of the resistivity at low temperatures. For this case,
our results for the high pressure regime can be interpreted in the framework of
interacting carriers (polarons or bipolarons) scattered by Two Level Systems.Comment: 9 Revtex pages, 12 EPS figures included, submitted to The European
Physical Journal B. Contact author: C. Acha (e-mail address: [email protected]
On the heating of source of the Orion KL hot core
We present images of the J=10-9 rotational lines of HC3N in the vibrationally
excited levels 1v7, 1v6 and 1v5 of the hot core (HC) in Orion KL. The images
show that the spatial distribution and the size emission from the 1v7 and 1v5
levels are different. While the J=10-9 1v7 line has a size of 4''x 6'' and
peaks 1.1'' NE of the 3 mm continuum peak, the J=10--9 1v5 line emission is
unresolved (<3'') and peaks 1.3'' south of the 3 mm peak. This is a clear
indication that the HC is composed of condensations with very different
temperatures (170 K for the 1v7 peak and K for the 1v5 peak). The
temperature derived from the 1v7 and 1v5 lines increases with the projected
distance to the suspected main heating source I. Projection effects along the
line of sight could explain the temperature gradient as produced by source I.
However, the large luminosity required for source I, >5 10^5 Lsolar, to explain
the 1v5 line suggests that external heating by this source may not dominate the
heating of the HC. Simple model calculations of the vibrationally excited
emission indicate that the HC can be internally heated by a source with a
luminosity of 10^5 Lsolar, located 1.2'' SW of the 1v5 line peak (1.8'' south
of source I). We also report the first detection of high-velocity gas from
vibrationally excited HC3N emission. Based on excitation arguments we conclude
that the main heating source is also driving the molecular outflow. We
speculate that all the data presented in this letter and the IR images are
consistent with a young massive protostar embedded in an edge-on disk.Comment: 13 pages, 3 figures, To be published in Ap.J. Letter
Information-flux approach to multiple-spin dynamics
We introduce and formalize the concept of information flux in a many-body
register as the influence that the dynamics of a specific element receive from
any other element of the register. By quantifying the information flux in a
protocol, we can design the most appropriate initial state of the system and,
noticeably, the distribution of coupling strengths among the parts of the
register itself. The intuitive nature of this tool and its flexibility, which
allow for easily manageable numerical approaches when analytic expressions are
not straightforward, are greatly useful in interacting many-body systems such
as quantum spin chains. We illustrate the use of this concept in quantum
cloning and quantum state transfer and we also sketch its extension to
non-unitary dynamics.Comment: 7 pages, 4 figures, RevTeX
Spin-dependent beating patterns in thermoelectric properties: Filtering the carriers of the heat flux in a Kondo adatom system
We theoretically investigate the thermoelectric properties of a
spin-polarized two-dimensional electron gas hosting a Kondo adatom hybridized
with an STM tip. Such a setup is treated within the single-impurity Anderson
model in combination with the atomic approach for the Green's functions. Due to
the spin dependence of the Fermi wavenumbers the electrical and thermal
conductances, together with thermopower and Lorenz number reveal beating
patterns as function of the STM tip position in the Kondo regime. In
particular, by tuning the lateral displacement of the tip with respect to the
adatom vicinity, the temperature and the position of the adatom level, one can
change the sign of the Seebeck coefficient through charge and spin. This opens
a possibility of the microscopic control of the heat flux analogously to that
established for the electrical current
Measurement of ortho-Positronium Properties in Liquid Scintillators
Pulse shape discrimination in liquid scintillator detectors is a
well-established technique for the discrimination of heavy particles from light
particles. Nonetheless, it is not efficient in the separation of electrons and
positrons, as they give rise to indistinguishable scintillator responses. This
inefficiency can be overtaken through the exploitation of the formation of
ortho-Positronium (o-Ps), which alters the time profile of light pulses induced
by positrons.
We characterized the o-Ps properties in the most commonly used liquid
scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the
effects of scintillator doping on the o-Ps properties for dopants currently
used in neutrino experiments, Gd and Nd. Further measurements for Li-loaded and
Tl-loaded liquid scintillators are foreseen. We found that the o-Ps properties
are suitable for enhancing the electron-positron discrimination.Comment: 4 pages, 1 figure. Contribution to proceedings of the Low
Radioactivity Techniques 2013 Workshop at LNGS, Assergi (AQ), Italy, April
10-12 201
A Web-Based Distributed Virtual Educational Laboratory
Evolution and cost of measurement equipment, continuous training, and distance learning make it difficult to provide a complete set of updated workbenches to every student. For a preliminary familiarization and experimentation with instrumentation and measurement procedures, the use of virtual equipment is often considered more than sufficient from the didactic point of view, while the hands-on approach with real instrumentation and measurement systems still remains necessary to complete and refine the student's practical expertise. Creation and distribution of workbenches in networked computer laboratories therefore becomes attractive and convenient. This paper describes specification and design of a geographically distributed system based on commercially standard components
Resposta aos movimentos jihadistas Somali e Mali: Que lições para Moçambique?
AbstractSince 2017, Mozambique’s Cabo Delgado province has witnessed an unprecedented level of violence attributed to jihadist movements. The security threat, instability and deteriorating humanitarian situation in the area has attracted the attention of regional and international actors. The aim of this article is twofold. On the one hand, it discusses the response to jihadist movements in Somalia and Mali in order to explain and contextualize external interventions in Mozambique. On the other hand, it explores the extent of lessons-learned based on the evidence from Somalia and Mali. Specifically, it considers how such interventions may help shade light towards a better understanding of the origin and evolution of Mozambican-based jihadist movement and the possible responses from external actors. The arguments are guided by a post-liberal approach. However, drawing from the relative deprivation theory, the article also focuses on the economic and social exclusion experienced in Cabo Delgado province and highlights the possible underlying root-causes of the current situation. As a main conclusion, lessons learned from stabilization and counterinsurgency interventions in Somalia and Mali must be an integral part of the responses to the Mozambique conflict.
Keywords: external interventions; jihadist movements; Mali; Mozambique; post-liberal; Somaliainfo:eu-repo/semantics/publishedVersio
Mimicking the probability distribution of a two-dimensional Grover walk with a single-qubit coin
Multi-dimensional quantum walks usually require large coin spaces. Here we
show that the non-localized case of the spatial density probability of the
two-dimensional Grover walk can be obtained using only a two-dimensional coin
space and a quantum walk in alternate directions. We present a formal proof of
this correspondence and analyze the behavior of the coin-position entanglement
as well as the x-y spatial entanglement in our scheme with respect to the
Grover one. We show that our experimentally simpler scheme allows to entangle
the two orthogonal directions of the walk more efficiently.Comment: 5 pages, 2 figures, RevTeX
- …