3,495 research outputs found

    Moderate inflation and the deflation-depression link

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    In a recent paper, Atkeson and Kehoe (2004) demonstrated the lack of a robust empirical relationship between inflation and growth for a cross-section of countries with 19th and 20th century data, concluding that the historical evidence only provides weak support for the contention that deflation episodes are harmful to economic growth. In this paper, we revisit this relationship by allowing for inflation and growth to have a nonlinear specification dependent on inflation levels. In particular, we allow for the possibility that high inflation is negatively correlated with growth, while a positive relationship exists over the range of negative-to-moderate inflation. Our results confirm a positive relationship between inflation and growth at moderate inflation levels, and support the contention that the relationship between inflation and growth is non-linear over the entire sample range.Inflation (Finance)

    Nanoflare Activity in the Solar Chromosphere

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    We use ground-based images of high spatial and temporal resolution to search for evidence of nanoflare activity in the solar chromosphere. Through close examination of more than 10^9 pixels in the immediate vicinity of an active region, we show that the distributions of observed intensity fluctuations have subtle asymmetries. A negative excess in the intensity fluctuations indicates that more pixels have fainter-than-average intensities compared with those that appear brighter than average. By employing Monte Carlo simulations, we reveal how the negative excess can be explained by a series of impulsive events, coupled with exponential decays, that are fractionally below the current resolving limits of low-noise equipment on high-resolution ground-based observatories. Importantly, our Monte Carlo simulations provide clear evidence that the intensity asymmetries cannot be explained by photon-counting statistics alone. A comparison to the coronal work of Terzo et al. (2011) suggests that nanoflare activity in the chromosphere is more readily occurring, with an impulsive event occurring every ~360s in a 10,000 km^2 area of the chromosphere, some 50 times more events than a comparably sized region of the corona. As a result, nanoflare activity in the chromosphere is likely to play an important role in providing heat energy to this layer of the solar atmosphere.Comment: 7 pages, 3 figures, accepted into Ap

    Tracking magnetic bright point motions through the solar atmosphere

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    High-cadence, multiwavelength observations and simulations are employed for the analysis of solar photospheric magnetic bright points (MBPs) in the quiet Sun. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere (ROSA) imager and the Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope. Our analysis reveals that photospheric MBPs have an average transverse velocity of approximately 1 km s−1, whereas their chromospheric counterparts have a slightly higher average velocity of 1.4 km s−1. Additionally, chromospheric MBPs were found to be around 63 per cent larger than the equivalent photospheric MBPs. These velocity values were compared with the output of numerical simulations generated using the MURAM code. The simulated results were similar, but slightly elevated, when compared to the observed data. An average velocity of 1.3 km s−1 was found in the simulated G-band images and an average of 1.8 km s−1 seen in the velocity domain at a height of 500 km above the continuum formation layer. Delays in the change of velocities were also analysed. Average delays of ∼4 s between layers of the simulated data set were established and values of ∼29 s observed between G-band and Ca II K ROSA observations. The delays in the simulations are likely to be the result of oblique granular shock waves, whereas those found in the observations are possibly the result of a semi-rigid flux tube

    New Crop Testing Nutritional and Organoleptic Analysis

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    Final Poster for New Crop Testing Nutritional and Organoleptic Analysi

    THE DECLINE (AND REVIVAL?) OF BLACK FARMERS AND RURAL LANDOWNERS: A REVIEW OF THE RESEARCH LITERATURE

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    African-Americans as a group went from owning almost no land in the United States after the Civil War to peaking at 15 million acres by 1920. In that year, 14% of all US farmers were black. Of these 926,000 black farmers, all but 10,000 were in the South. By 1997, fewer than 20,000, or 1% of all farmers, were black, and they owned only about two million acres. The loss of landownership and farming operations has contributed to the poverty of many rural communities in the South. This paper consists of a review of 74 journal articles, reports, chapters, and books on African-Americans and farming, comprising most of the scholarly literature on the issue published since 1971. One of the commonalities in the literature is the sense of hopelessness in stemming the tide of black land loss. On the other hand, another commonality is the view that the black farmer and rural landowner must be sustained, even brought back. Among the studies are those claiming that landowners make up the backbone of civic and political life in rural black communities. Other advantages of landownership include increased personal pride, higher educational achievement of children, and an overall better sense of wellbeing. Most of the works offer similar perspectives of the decline of blacks in farming, and suggested solutions also are often repeated in these works. But there are differences in the works, and together they cover a wide range of issues that differentiate black farmers by sub-region, state, farm size, tenure, crops raised, and social and economic situation.Afro-American farmers -- Bibliography, Afro-American farmers -- Government policy -- United States -- Bibliography, Afro-American landowners -- Bibliography, Farm ownership -- United States -- Bibliography, Agrarian structure -- United States -- Bibliography, Labor and Human Capital, Land Economics/Use,

    The Source of Three-minute Magneto-acoustic Oscillations in Coronal Fans

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    We use images of high spatial, spectral and temporal resolution, obtained using both ground- and space-based instrumentation, to investigate the coupling between wave phenomena observed at numerous heights in the solar atmosphere. Intensity oscillations of 3 minutes are observed to encompass photospheric umbral dot structures, with power at least three orders-of-magnitude higher than the surrounding umbra. Simultaneous chromospheric velocity and intensity time series reveal an 87 \pm 8 degree out-of-phase behavior, implying the presence of standing modes created as a result of partial wave reflection at the transition region boundary. An average blue-shifted Doppler velocity of ~1.5 km/s, in addition to a time lag between photospheric and chromospheric oscillatory phenomena, confirms the presence of upwardly-propagating slow-mode waves in the lower solar atmosphere. Propagating oscillations in EUV intensity are detected in simultaneous coronal fan structures, with a periodicity of 172 \pm 17 s and a propagation velocity of 45 \pm 7 km/s. Numerical simulations reveal that the damping of the magneto-acoustic wave trains is dominated by thermal conduction. The coronal fans are seen to anchor into the photosphere in locations where large-amplitude umbral dot oscillations manifest. Derived kinetic temperature and emission measure time-series display prominent out-of-phase characteristics, and when combined with the previously established sub-sonic wave speeds, we conclude that the observed EUV waves are the coronal counterparts of the upwardly-propagating magneto-acoustic slow-modes detected in the lower solar atmosphere. Thus, for the first time, we reveal how the propagation of 3 minute magneto-acoustic waves in solar coronal structures is a direct result of amplitude enhancements occurring in photospheric umbral dots.Comment: Accepted into ApJ (13 pages and 10 figures

    Reestablishing the income-democracy nexus

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    A number of recent empirical studies have cast doubt on the "modernization theory" of democratization, which posits that increases in income are conducive to increases in democracy levels. This doubt stems mainly from the fact that while a strong positive correlation exists between income and democracy levels, the relationship disappears when one controls for country fixed effects. This raises the possibility that the correlation in the data reflects a third causal characteristic, such as institutional quality. In this paper, we reexamine the robustness of the income-democracy relationship. We extend the research on this topic in two dimensions: first, we make use of newer income data, which allows for the construction of larger samples with more within-country observations. Second, we concentrate on panel estimation methods that explicitly allow for the fact that the primary measures of democracy are censored with substantial mass at the boundaries, or binary censored variables. Our results show that when one uses both the new income data available and a properly non linear estimator, a statistically significant positive income-democracy relationship is robust to the inclusion of country fixed effects.Income

    Propagating Wave Phenomena Detected in Observations and Simulations of the Lower Solar Atmosphere

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    We present high-cadence observations and simulations of the solar photosphere, obtained using the Rapid Oscillations in the Solar Atmosphere imaging system and the MuRAM magneto-hydrodynamic code, respectively. Each dataset demonstrates a wealth of magneto-acoustic oscillatory behaviour, visible as periodic intensity fluctuations with periods in the range 110-600 s. Almost no propagating waves with periods less than 140s and 110s are detected in the observational and simulated datasets, respectively. High concentrations of power are found in highly magnetised regions, such as magnetic bright points and intergranular lanes. Radiative diagnostics of the photospheric simulations replicate our observational results, confirming that the current breed of magneto-hydrodynamic simulations are able to accurately represent the lower solar atmosphere. All observed oscillations are generated as a result of naturally occurring magnetoconvective processes, with no specific input driver present. Using contribution functions extracted from our numerical simulations, we estimate minimum G-band and 4170 Angstrom continuum formation heights of 100 km and 25 km, respectively. Detected magneto-acoustic oscillations exhibit a dominant phase delay of -8 degrees between the G-band and 4170 Angstrom continuum observations, suggesting the presence of upwardly propagating waves. More than 73% of MBPs (73% from observations, 96% from simulations) display upwardly propagating wave phenomena, suggesting the abundant nature of oscillatory behaviour detected higher in the solar atmosphere may be traced back to magnetoconvective processes occurring in the upper layers of the Sun's convection zone.Comment: 13 pages, 9 figures, accepted into Ap

    The Area Distribution of Solar Magnetic Bright Points

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    Magnetic Bright Points (MBPs) are among the smallest observable objects on the solar photosphere. A combination of G-band observations and numerical simulations is used to determine their area distribution. An automatic detection algorithm, employing 1-dimensional intensity profiling, is utilized to identify these structures in the observed and simulated datasets. Both distributions peak at an area of \approx45000 km2^2, with a sharp decrease towards smaller areas. The distributions conform with log-normal statistics, which suggests that flux fragmentation dominates over flux convergence. Radiative magneto-convection simulations indicate an independence in the MBP area distribution for differing magnetic flux densities. The most commonly occurring bright point size corresponds to the typical width of intergranular lanes.Comment: Astrophysical Journal, accepte
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