2,023 research outputs found
Endogenous Instability in Credit-Constrained Emerging Economies with Leontief Technology
This work provides a framework to analyze the role of financial development as a source of endogenous instability in emerging economies subject to moral hazard problems. We propose
and study a dynamic model describing a small open economy with a tradeable good produced by internationally mobile capital and a country specific input, using Leontief technology. We
demonstrate that emerging markets could be endogenously unstable since large capital inflows increase risk and exacerbate asymmetric information problems, according to empirical evidences.
Using bifurcation and stability analysis, we describe the properties of the system attractors, we assess the plausibility for complex dynamics and, we find out that border collision bifurcations
can emerge due to the fact that the state space is piecewise smooth. As a consequence, when a fixed or periodic point loses its stability, the final dynamics may become suddenly chaotic. This
fact may explain how financial crises occurred in emerging economies
Exciton-phonon scattering and photo-excitation dynamics in J-aggregate microcavities
We have developed a model accounting for the photo-excitation dynamics and
the photoluminescence of strongly coupled J-aggregate microcavities. Our model
is based on a description of the J-aggregate film as a disordered Frenkel
exciton system in which relaxation occurs due to the presence of a thermal bath
of molecular vibrations. In a strongly coupled microcavity exciton-polaritons
are formed, mixing superradiant excitons and cavity photons. The calculation of
the microcavity steady-state photoluminescence, following a CW non resonant
pumping, is carried out. The experimental photoluminescence intensity ratio
between upper and lower polariton branches is accurately reproduced. In
particular both thermal activation of the photoluminescence intensity ratio and
its Rabi splitting dependence are a consequence of the bottleneck in the
relaxation, occurring at the bottom of the excitonic reservoir. The effects due
to radiative channels of decay of excitons and to the presence of a
paritticular set of discrete optical molecular vibrations active in relaxation
processes are investigared.Comment: 8 pages, 6 figure
Is “Unconsummated Marriage” still an appropriate term? A snapshot of reality
The most shared definition of Unconsummated Marriage (UM) refers to “the failure to perform successful sexual intercourse at the beginning of
the marriage. UM usually occurs in the first few nights of marriage and so it is frequently referred to as “honeymoon impotence” or “wedding night
impotence”. In the Middle-Eastern (MES) and Western (WS) societies, sexuality follows different patterns in terms of meaning and rules. Moreover
the evolution of societies all around the world created new contexts and kinds of relationship. This could hamper a correct taxonomy of such sexual
dysfunction where a social variable seems crucial.
Aim: To analyze and review data on UM all around the world, to understand if in different societies it refers to the same situation.
Method: A review of published literature on UM from 1970 to date, was conducted.
Results: Substantial difference emerged from MES to WS. In MES, sexuality is allowable only in marriage, while in WS sexuality and relationship are
not strongly linked. This could suggest that the term “marriage” is unable to cover the phenomenon in such different countries. Moreover, the average
time before the consultation, causal attribution and prevalence are very different in Western and Middle Eastern countries.
Conclusion: We found that the term “first attempts dysfunction” could be better used to describe male, female or both difficulties related to
ignorance about sexuality or state/performance anxiety. On the other hand over the individual category of sexual dysfunctions, we suggest a new term
as “Unconsummated relationship”, where individual difficulties toward sexuality are involved creating a couple’s dysfunction.
Keywords: Unconsummated marriage; Honeymoon impotence; White marriage; Vaginismus; Infertilit
Non-linear Dynamics in a Business-Cycle Model with Logistic Population Growth
We consider a discrete-time growth model of the Solow type where workers and shareholders have different but constant
saving rates and the population growth dynamics is described by the logistic equation able to exhibit complicated
dynamics. We show conditions for the resulting system having a compact global attractor and we describe its structure.
We also perform a mainly numerical analysis using the critical lines method able to describe the strange attractor and
the absorbing area, in order to show how cyclical or complex fluctuations may be produced in a business-cycle model.
We study the dynamic behaviour of the model under different ranges of the main parameters, i.e. the elasticity of substitution
between the two production factors and the one in the logistic equation (namely m). We prove the existence of
complex dynamics when the elasticity of substitution between production factors drops below one (so that capital
income declines) or m increases (so that the amplitude of movements in the population growth rate increases)
Tunable quantum spin Hall effect in double quantum wells
The field of topological insulators (TIs) is rapidly growing. Concerning
possible applications, the search for materials with an easily controllable TI
phase is a key issue. The quantum spin Hall effect, characterized by a single
pair of helical edge modes protected by time-reversal symmetry, has been
demonstrated in HgTe-based quantum wells (QWs) with an inverted bandgap. We
analyze the topological properties of a generically coupled HgTe-based double
QW (DQW) and show how in such a system a TI phase can be driven by an
inter-layer bias voltage, even when the individual layers are non-inverted. We
argue, that this system allows for similar (layer-)pseudospin based physics as
in bilayer graphene but with the crucial absence of a valley degeneracy.Comment: 9 pages, 8 figures, extended version (accepted Phys. Rev. B
On the Effect of Labour Productivity on Growth: Endogenous Fluctuations and Complex Dynamics
This paper introduces a sigmoidal production function that considers production possible even when the only input is labour. The long-run behaviour of an economy described by the neoclassical Solow-type growth model with differential savings is investigated considering the technology presented. It is found that labour productivity influences the existence of boom and bust periods as well as the level of capital per capita in equilibrium
Helical edge states in multiple topological mass domains
The two-dimensional topological insulating phase has been experimentally
discovered in HgTe quantum wells (QWs). The low-energy physics of
two-dimensional topological insulators (TIs) is described by the
Bernevig-Hughes-Zhang (BHZ) model, where the realization of a topological or a
normal insulating phase depends on the Dirac mass being negative or positive,
respectively. We solve the BHZ model for a mass domain configuration, analyzing
the effects on the edge modes of a finite Dirac mass in the normal insulating
region (soft-wall boundary condition). We show that at a boundary between a TI
and a normal insulator (NI), the Dirac point of the edge states appearing at
the interface strongly depends on the ratio between the Dirac masses in the two
regions. We also consider the case of multiple boundaries such as NI/TI/NI,
TI/NI/TI and NI/TI/NI/TI.Comment: 11 pages, 15 figure
Helical edge states in multiple topological mass domains
The two-dimensional topological insulating phase has been experimentally
discovered in HgTe quantum wells (QWs). The low-energy physics of
two-dimensional topological insulators (TIs) is described by the
Bernevig-Hughes-Zhang (BHZ) model, where the realization of a topological or a
normal insulating phase depends on the Dirac mass being negative or positive,
respectively. We solve the BHZ model for a mass domain configuration, analyzing
the effects on the edge modes of a finite Dirac mass in the normal insulating
region (soft-wall boundary condition). We show that at a boundary between a TI
and a normal insulator (NI), the Dirac point of the edge states appearing at
the interface strongly depends on the ratio between the Dirac masses in the two
regions. We also consider the case of multiple boundaries such as NI/TI/NI,
TI/NI/TI and NI/TI/NI/TI.Comment: 11 pages, 15 figure
Variable fault tip propagation rates affected by near-surface lithology and implications for fault displacement hazard assessment
The fabric of reverse fault zones close to the surface is usually partitioned in between a narrow discrete rupture zone and a more distributed one, where folding is predominant. This makes quite challenging the adoption of proper setbacks in surface rupture hazard studies for critical facilities or microzoning. Some of the parameters controlling fault zone fabric are related to mechanics of near-surface geology (lithology, overburden thickness, cohesion and water content) whose interaction is complex and only partially understood. Nevertheless, these can be seldom measured or derived. Kinematic models, conversely, express such an interaction of complex variables as simple synthetic parameters, such as the amount of upward propagation of the fault tip for unit of slip, usually referred to as the P/S ratio (Propagation on Slip). Here, we discuss results on the trishear kinematic inverse modeling of a contractional fault propagation fold at Monte Netto Hill (Capriano del Colle, N. Italy), observing a two-stage fault and fold growth evolution, marked by a significant shift in the P/S parameter. At this site, exceptional sequence of exposures due to ca. 10 years of quarry excavations allowed to obtain a series of cross-sections across the fault zone. We use this detailed, high-resolution, example as a natural \u201canalogue\u201d for more general, large-scale surface ruptures involving a thick alluvial cover, a very common setting for the siting of critical facilities. During the early stage of displacement, the fault cut through clast-supported fluvial gravels with a high propagation rate (P/S\u202f=\u202f7) and a discrete rupture width. Then, during the latest movements of the thrust, fault tip propagation slowed down to P/S\u202f 48\u202f2.9, as the fault started cutting through several stacked bodies of clays and silty clays, pedogenized aeolian silts and overbank deposits, causing a pronounced folding of the layers over a wider deformation zone. These results strongly suggest that lithological changes in the underlying shallow stratigraphy, common in an alluvial plain depositional setting, would significantly affect the potential for surface faulting across the same tectonic structure, with relevant implications in the fault displacement hazard assessment
Ground effects of the 18 October 1992, Murindo earthquake (NW Colombia), using the Environmental Seismic Intensity Scale (ESI 2007) for the assessment of intensity
The macroseismic intensity of the 18 October 1992 Murindo-Atrato earthquake that affected the northwestern states of Colombia (Choco\ub4 and Antioquia) is reassessed using the
newly developed INQUA Environmental Seismic Intensity Scale (ESI 2007) which is based on the evaluation of earthquake environmental effects. To generate the ESI 2007 isoseismal map of northwestern Colombia, a geographical information system was used. Unifying the available information on the seismological and active tectonics framework including historical seismicity, hypocentral depths, foreshocks, aftershocks, focal mechanism, macroseismic data under the same GIS and the map of Quaternary faults allowed us to reinterpret the geological and environmental effects of the 1992 earthquakes sequence. A total of 24 sites from the areas of Quibdo\ub4, Bojaya\ub4, Rio Sucio, Murindo, Vig\u131\ub4a del Fuerte and Turbo were evaluated. A systematic comparison among evaluated intensities (Modified Mercalli and ESI scale) revealed differences from one to two degrees. According to the ESI 2007 scale, the epicentral intensity Io is XI. This represents one degree higher than the epicentral intensity obtained using MM and Medveded Sponhauer Karnik (MSK) intensity scales, probably due to the lack of suitable observations on building damage in this poorly populated and developed region. This information is also useful in order to shed some light on the persistent question of the exact location and dimension of the main rupture zone associated with the earthquake. The isoseismal map derived from the integration of the whole set of environmental effects with other macroseismic data strongly suggests that the causative tectonic structure is the Murindo fault. However, the rupture length derived from the distribution of ground effects is greater than the Murindo fault length, implying that other nearby fault segments were activated during the 1992 event. The new isoseismal map resulting from this work is relevant for the assessment of future seismic risk in the northwestern region of Colombia. Overall, the application of the ESI 2007 scale to the 18 October 1992 earthquake, and to similar strong events in the region, can be useful for disaster management and planning, estimation of damage, and post-earthquake recovery efforts
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