42 resultados para Madde-Julian Oscillation
Resumo:
Recent research on the dynamics of moral behavior has documented two contrastingphenomena - moral consistency and moral balancing. Moral balancing refers to thephenomenon whereby behaving (un)ethically decreases the likelihood of doing so againat a later time. Moral consistency describes the opposite pattern - engaging in(un)ethical behavior increases the likelihood of doing so later on. Three studies supportthe hypothesis that individuals' ethical mindset (i.e., outcome-based versus rule-based)moderates the impact of an initial (un)ethical act on the likelihood of behaving ethicallyin a subsequent occasion. More specifically, an outcome-based mindset facilitates moralbalancing and a rule-based mindset facilitates moral consistency.
Resumo:
Does ethical differentiation of products affect market behavior? We examined this issue in triopolistic experimental markets where producers set prices. One producer s costs were higher than the others. In two treatments, the additional costs were attributed tocompliance with ethical guidelines. In the third, no justification was provided. Manyparticipants playing the role of consumers reduced their experimental gains by purchasing the ethically differentiated product at a higher price whether or not they knew the amount of extra cost. Individual differences were important (students of business/economics paid smaller premia than others). Finally, we speculate about the observed demand function for ethics and emphasize the use of experimental methodology to complement empirical studies designed to assess the potential market for ethically differentiated products.
Resumo:
This paper presents a new respiratory impedance estimator to minimize the error due to breathing. Its practical reliability was evaluated in a simulation using realistic signals. These signals were generated by superposing pressure and flow records obtained in two conditions: 1) when applying forced oscillation to a resistance- inertance- elastance (RIE) mechanical model; 2) when healthy subjects breathed through the unexcited forced oscillation generator. Impedances computed (4-32 Hz) from the simulated signals with the new estimator resulted in a mean value which was scarcely biased by the added breathing (errors less than 1 percent in the mean R, I , and E ) and had a small variability (coefficients of variation of R, I, and E of 1.3, 3.5, and 9.6 percent, respectively). Our results suggest that the proposed estimator reduces the error in measurement of respiratory impedance without appreciable extracomputational cost.
Resumo:
A general asymptotic analysis of the Gunn effect in n-type GaAs under general boundary conditions for metal-semiconductor contacts is presented. Depending on the parameter values in the boundary condition of the injecting contact, different types of waves mediate the Gunn effect. The periodic current oscillation typical of the Gunn effect may be caused by moving charge-monopole accumulation or depletion layers, or by low- or high-field charge-dipole solitary waves. A new instability caused by multiple shedding of (low-field) dipole waves is found. In all cases the shape of the current oscillation is described in detail: we show the direct relationship between its major features (maxima, minima, plateaus, etc.) and several critical currents (which depend on the values of the contact parameters). Our results open the possibility of measuring contact parameters from the analysis of the shape of the current oscillation.
Resumo:
The longitudinal dipole response of a quantum dot has been calculated in the far-infrared regime using local-spin-density-functional theory. We have studied the coupling between the collective spin and density modes as a function of the magnetic field. We have found that the spin dipole mode and single-particle excitations have a sizable overlap, and that the magnetoplasmon modes can be excited by the dipole spin operator if the dot is spin polarized. The frequency of the dipole spin edge mode presents an oscillation which is clearly filling factor (v) related. We have found that the spin dipole mode is especially soft for even-n values. Results for selected numbers of electrons and confining potentials are discussed.
Resumo:
Mikheyev-Smirnov-Wolfenstein (MSW) solutions of the solar neutrino problem predict a seasonal dependence of the zenith angle distribution of the event rates, due to the nonzero latitude at the Super-Kamiokande site. We calculate this seasonal dependence and compare it with the expectations in the no-oscillation case as well as just-so scenario, in the light of the latest Super-Kamiokande 708-day data. The seasonal dependence can be sizable in the large mixing angle MSW solution and would be correlated with the day-night effect. This may be used to discriminate between MSW and just-so scenarios and should be taken into account in refined fits of the data.
Resumo:
Measurements of CP-violating observables in neutrino oscillation experiments have been studied in the literature as a way to determine the CP-violating phase in the mixing matrix for leptons. Here we show that such observables also probe new neutrino interactions in the production or detection processes. Genuine CP violation and fake CP violation due to matter effects are sensitive to the imaginary and real parts of new couplings. The dependence of the CP asymmetry on the source-detector distance is different from the standard one and, in particular, enhanced at short distances. We estimate that future neutrino factories will be able to probe in this way new interactions that are up to four orders of magnitude weaker than the weak interactions. We discuss the possible implications for models of new physics.
Resumo:
A general asymptotic analysis of the Gunn effect in n-type GaAs under general boundary conditions for metal-semiconductor contacts is presented. Depending on the parameter values in the boundary condition of the injecting contact, different types of waves mediate the Gunn effect. The periodic current oscillation typical of the Gunn effect may be caused by moving charge-monopole accumulation or depletion layers, or by low- or high-field charge-dipole solitary waves. A new instability caused by multiple shedding of (low-field) dipole waves is found. In all cases the shape of the current oscillation is described in detail: we show the direct relationship between its major features (maxima, minima, plateaus, etc.) and several critical currents (which depend on the values of the contact parameters). Our results open the possibility of measuring contact parameters from the analysis of the shape of the current oscillation.
Resumo:
This paper uses a database covering the universe of French firms for the period 1990-2007 to provide a forensic account of the role of individual firms in generating aggregatefluctuations. We set up a simple multi-sector model of heterogeneous firms selling tomultiple markets to motivate a theoretically-founded decomposition of firms' annualsales growth rate into different components. We find that the firm-specific componentcontributes substantially to aggregate sales volatility, mattering about as much as thecomponents capturing shocks that are common across firms within a sector or country.We then decompose the firm-specific component to provide evidence on two mechanismsthat generate aggregate fluctuations from microeconomic shocks highlighted in the recentliterature: (i) when the firm size distribution is fat-tailed, idiosyncratic shocks tolarge firms directly contribute to aggregate fluctuations; and (ii) aggregate fluctuationscan arise from idiosyncratic shocks due to input-output linkages across the economy.Firm linkages are approximately three times as important as the direct effect of firmshocks in driving aggregate fluctuations.
Resumo:
This paper evaluates the global welfare impact of China's trade integration and technological change in a multi-country quantitative Ricardian-Heckscher-Ohlin model.We simulate two alternative growth scenarios: a "balanced" one in which China's productivity grows at the same rate in each sector, and an "unbalanced" one in whichChina's comparative disadvantage sectors catch up disproportionately faster to theworld productivity frontier. Contrary to a well-known conjecture (Samuelson 2004),the large majority of countries experience significantly larger welfare gains whenChina's productivity growth is biased towards its comparative disadvantage sectors.This finding is driven by the inherently multilateral nature of world trade.
Resumo:
Recent experiments have established that information can be encoded in the spike times of neurons relative to the phase of a background oscillation in the local field potential—a phenomenon referred to as “phase-of-firing coding” (PoFC). These firing phase preferences could result from combining an oscillation in the input current with a stimulus-dependent static component that would produce the variations in preferred phase, but it remains unclear whether these phases are an epiphenomenon or really affect neuronal interactions—only then could they have a functional role. Here we show that PoFC has a major impact on downstream learning and decoding with the now well established spike timing-dependent plasticity (STDP). To be precise, we demonstrate with simulations how a single neuron equipped with STDP robustly detects a pattern of input currents automatically encoded in the phases of a subset of its afferents, and repeating at random intervals. Remarkably, learning is possible even when only a small fraction of the afferents (~10%) exhibits PoFC. The ability of STDP to detect repeating patterns had been noted before in continuous activity, but it turns out that oscillations greatly facilitate learning. A benchmark with more conventional rate-based codes demonstrates the superiority of oscillations and PoFC for both STDP-based learning and the speed of decoding: the oscillation partially formats the input spike times, so that they mainly depend on the current input currents, and can be efficiently learned by STDP and then recognized in just one oscillation cycle. This suggests a major functional role for oscillatory brain activity that has been widely reported experimentally.
Resumo:
This paper evaluates the global welfare impact of observed levels of migration using a quantitativemulti-sector model of the world economy calibrated to aggregate and firm-level data.Our framework features cross-country labor productivity differences, international trade, remittances,and a heterogeneous workforce. We compare welfare under the observed levels ofmigration to a no-migration counterfactual. In the long run, natives in countries that receiveda lot of migration -such as Canada or Australia- are better o due to greater product varietyavailable in consumption and as intermediate inputs. In the short run the impact of migrationon average welfare in these countries is close to zero, while the skilled and unskilled nativestend to experience welfare changes of opposite signs. The remaining natives in countries withlarge emigration flows -such as Jamaica or El Salvador- are also better off due to migration,but for a different reason: remittances. The welfare impact of observed levels of migration issubstantial, at about 5 to 10% for the main receiving countries and about 10% in countries withlarge incoming remittances. Our results are robust to accounting for imperfect transferabilityof skills, selection into migration, and imperfect substitution between natives and immigrants.
Resumo:
En 2011, se aplicó la metodología del aprendizaje basado en problemas (ABP) en los seminarios prácticos de Pediatría a los estudiantes de 6º de Medicina. La ABP invierte la organización tradicional de los procesos de aprendizaje: primero se presenta el problema, ya partir de la delimitación de lo que ya se conoce, se establecen los objetivos, se identifican las necesidades de aprendizaje, y se diseña y se sigue un plan de actuación, para que el aprendizaje se acompañe de la reso-lución del problema. Previamente, los profesores realizaron un curso específico so-bre ABP organizado por el IES. Transcurrido el primer curso de aplicación del ABP, se pretende evaluar el grado de satisfacción y de aprendizaje obtenidos de los seminarios prácticos ba-sados en el ABP por parte de los estudiantes.
Resumo:
Many genes are regulated as an innate part of the eukaryotic cell cycle, and a complex transcriptional network helps enable the cyclic behavior of dividing cells. This transcriptional network has been studied in Saccharomyces cerevisiae (budding yeast) and elsewhere. To provide more perspective on these regulatory mechanisms, we have used microarrays to measure gene expression through the cell cycle of Schizosaccharomyces pombe (fission yeast). The 750 genes with the most significant oscillations were identified and analyzed. There were two broad waves of cell cycle transcription, one in early/mid G2 phase, and the other near the G2/M transition. The early/mid G2 wave included many genes involved in ribosome biogenesis, possibly explaining the cell cycle oscillation in protein synthesis in S.pombe. The G2/M wave included at least three distinctly regulated clusters of genes: one large cluster including mitosis, mitotic exit, and cell separation functions, one small cluster dedicated to DNA replication, and another small cluster dedicated to cytokinesis and division. S. pombe cell cycle genes have relatively long, complex promoters containing groups of multiple DNA sequence motifs, often of two, three, or more different kinds. Many of the genes, transcription factors, and regulatory mechanisms are conserved between S. pombe and S. cerevisiae. Finally, we found preliminary evidence for a nearly genome-wide oscillation in gene expression: 2,000 or more genes undergo slight oscillations in expression as a function of the cell cycle, although whether this is adaptive, or incidental to other events in the cell, such as chromatin condensation, we do not know.
Resumo:
We performed a spatiotemporal analysis of a network of 21 Scots pine (Pinus sylvestris) ring-width chronologies in northern Fennoscandia by means of chronology statistics and multivariate analyses. Chronologies are located on both sides (western and eastern) of the Scandes Mountains (67°N-70°N, 15°E-29°E). Growth relationships with temperature, precipitation, and North Atlantic Oscillation (NAO) indices were calculated for the period 1880-1991. We also assessed their temporal stability. Current July temperature and, to a lesser degree, May precipitation are the main growth limiting factors in the whole area of study. However, Principal Component Analysis (PCA) and mean interseries correlation revealed differences in radial growth between both sides of the Scandes Mountains, attributed to the Oceanic-Continental climatic gradient in the area. The gradient signal is temporally variable and has strengthened during the second half of the 20th century. Northern Fennoscandia Scots pine growth is positively related to early winter NAO indices previous to the growth season and to late spring NAO. NAO/growth relationships are unstable and have dropped in the second half of the 20th century. Moreover, they are noncontinuous through the range of NAO values: for early winter, only positive NAO indices enhance tree growth in the next growing season, while negative NAO does not. For spring, only negative NAO is correlated with radial growth.