1,667 research outputs found

    Endogenous Instability in Credit-Constrained Emerging Economies with Leontief Technology

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    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

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    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

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    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

    Tunable quantum spin Hall effect in double quantum wells

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    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

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    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

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    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

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    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

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    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

    Patient self-reported concerns in inflammatory bowel diseases: A gender-specific subjective quality-of-life indicator.

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    Patient-reported disease perceptions are important components to be considered within a holistic model of quality of care. Gender may have an influence on these perceptions. We aimed to explore gender-specific concerns of patients included in a national bilingual inflammatory bowel disease cohort. Following a qualitative study, we built a questionnaire comprising 37 items of concern. Answers were collected on a visual analog scale ranging from 0 to 100. Principal axis factor analysis was used to explore concern domains. Linear multiple regressions were conducted to assess associations with patient characteristics. Of 1102 patients who replied to the survey, 54% were female and 54% had Crohn's disease. We identified six domains of concern: socialization and stigmatization, disease-related constraints and uncertainty, symptoms and their impact on body and mind, loss of body control (including sexuality), disease transmission, and long-term impact of the disease. Cancer concerns were among the highest scored by all patients (median 61.8). Severity of symptoms was the only factor associated with concerns, unrelated to dimension and gender (p<0.015). In women, being >40 years decreased disease-related constraints and uncertainty concerns, and being at home or unemployed increased them. Treatments were associated with increased socialization and stigmatization and with increased disease-related constraints and uncertainty concerns in men. Overall, psychosomatic characteristics were highly associated with concerns for both men and women. Depending on the concern dimensions, increased levels of concern were associated with the highest signs of anxiety in women or depression in men, as well as lower health-related quality of life in men. Patients have numerous concerns related to their illness that need to be reassessed regularly. Concerns differ between men and women, suggesting that information and communication about the disease should take gender differences and subjective perceptions of quality of life into consideration

    Ground effects of the 18 October 1992, Murindo earthquake (NW Colombia), using the Environmental Seismic Intensity Scale (ESI 2007) for the assessment of intensity

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    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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