3,777 research outputs found
Are Protective Labor Market Institutions Really at the Root of Unemployment? A Critical Perspective on the Statistical Evidence
This report debunks the myth that labor market protections, such as unions and unemployment benefits, are responsible for high European unemployment rates.
Triggers and maintenance of multiple shifts in the state of a natural community
Ecological communities can undergo sudden and dramatic shifts between alternative persistent community states. Both ecological prediction and natural resource management rely on understanding the mechanisms that trigger such shifts and maintain each state. Differentiating between potential mechanisms is difficult, however, because shifts are often recognized only in hindsight and many occur on such large spatial scales that manipulative experiments to test their causes are difficult or impossible. Here we use an approach that focuses first on identifying changes in environmental factors that could have triggered a given state change, and second on examining whether these changes were sustained (and thus potentially maintained the new state) or transitory (explaining the shift but not its persistence). We use this approach to evaluate a community shift in which a benthic marine species of filter feeding sea cucumber (Pachythyone rubra) suddenly came to dominate subtidal rocky reefs that had previously supported high abundances of macroalgae, persisted for more than a decade, then abruptly declined. We found that a sustained period without large wave events coincided with the shift to sea cucumber dominance, but that the sea cucumbers persisted even after the end of this low wave period, indicating that different mechanisms maintained the new community. Additionally, the period of sea cucumber dominance occurred when their predators were rare, and increases in the abundance of these predators coincided with the end of sea cucumber dominance. These results underscore the complex nature of regime shifts and illustrate that focusing separately on the causes and maintenance of state change can be a productive first step for analyzing these shifts in a range of systems
Student morningness-eveningness type and performance:does class timing matter?
Circadian rhythms have often been linked to people’s performance outcomes, although this link has not been examined within the context of University students. We therefore sought to test whether students’ perceptions of their morning-evening (ME) type had an influence on their performance on modules. We tested this hypothesis using students from a number of modules at two UK Universities. Results indicated that, contrary to our hypothesis, the further the discrepancy between a student’s ME type and the teaching time of the class, the better the student’s performance. These results have implications for teaching as student ME type could be taken into account for timetabling especially if modules need to be taught multiple times. We also provide implications for those seeking to measure ME, as our results are consistent with a 5-item ME scale, a 3-item ME scale, and a single-item ME scale
High-resolution soft x-ray spectrometry using the electron-multiplying charge-coupled device (EM-CCD)
The Electron-Multiplying Charge-Coupled Device (EM-CCD) shares a similar structure to the CCD except for the inclusion of a gain register that multiplies signal before the addition of read-noise, offering sub-electron effective readnoise at high frame-rates. EM-CCDs were proposed for the dispersive spectrometer on the International X-ray Observatory (IXO) to bring sub-300 eV X-rays above the noise, increasing the science yield. The high-speed, low-noise performance of the EMCCD brought added advantages of reduced dark current and stray-light per frame, reducing cooling and filtering requirements. To increase grating efficiency, several diffracted spectral orders were co-located so the inherent energy resolution of the detector was required for order separation. Although the spectral resolution of the EM-CCD is degraded by the gain process, it was shown that the EM-CCD could achieve the required separation. The RIXS spectrometer at the Advanced Resonant Spectroscopy beamline (ADRESS) of the Swiss Light Source (SLS) at the Paul Scherrer Institute currently uses a CCD, with charge spreading between pixels limiting the spatial resolution to 24 μm (FWHM). Through improving the spatial resolution below 5 μm alongside upgrading the grating, a factor of two energy resolution improvement could theoretically be made. With the high-speed, low-noise performance of the EM-CCD, photon-counting modes could allow the use of centroiding techniques to improve the resolution. Using various centroiding techniques, a spatial resolution of 2 μm (FWHM) has been achieved experimentally, demonstrating the benefits of this detector technology for soft X-ray spectrometry. This paper summarises the use of EM-CCDs from our first investigations for IXO through to our latest developments in ground-based testing for synchrotron-research and looks beyond to future possibilities
Maine\u27s climate future: an initial assessment
Earth’s atmosphere is experiencing unprecedented changes that are modifying global climate. Discussions continue around the world, the nation, and in Maine on how to reduce and eventually eliminate emissions of carbon dioxide (CO2), other greenhouse gases, and other pollutants to the atmosphere, land, and oceans. These efforts are vitally important and urgent. However, even if a coordinated response succeeds in eliminating excess greenhouse gas emissions by the end of the century, something that appears highly unlikely today, climate change will continue, because the elevated levels of CO2 can persist in the atmosphere for thousands of years to come.
In late 2007, Governor Baldacci asked the University of Maine and its ClimateChange Institute to lead a wide-ranging analysis of the state’s future in the context of changing climate during the 21st century. The assignment involved making use of existing knowledge and understanding of climate change; the terrestrial, freshwater, and marine ecosystems that characterize our environment; and the socioeconomic characteristics of the state. The project involved no financial support for new research or data collection, but participating scientists contributed their time and expertise to initiate a process that could lead to systematic planning and thoughtful decisions for the future. Based on considerable prior research, this report serves as a preliminary step designed to frame future detailed analyses focused on Maine by teams that will likely continue for years
Practical metrics for establishing the health benefits of research to support research prioritisation
Introduction : We present practical metrics for estimating the expected health benefits of specific research proposals. These can be used by research funders, researchers, and health-care decision makers within low- and middle-income countries (LMICs) to support evidence-based research prioritisation. Methods : The methods require three key assessments: (1) the current level of uncertainty around the endpoints the proposed study will measure; (2) how uncertainty impacts on the health benefits and costs of health-care programmes; and (3) the health opportunity costs imposed by programme costs. Research is valuable because it can improve health by informing the choice of which programmes should be implemented. We provide a Microsoft Excel tool to allow readers to generate estimates of the health benefits of research studies based on these three assessments. The tool can be populated using clinical studies, existing cost-effectiveness models and expert opinion. Where such evidence is not available, the tool can quantify the value of research under different assumptions. Estimates of the health benefits of research can be considered alongside research costs, and the consequences of delaying implementation until research reports, to determine whether research is worthwhile. We illustrate the method using a case study of research on HIV self-testing programmes in Malawi. This analysis combines data from the literature with outputs from the HIV synthesis model. Results : For this case study we found a costing study that could be completed and inform decision making within one year offered the highest health benefits (67,000 DALYs averted). Research on outcomes improved population health to a lesser extent (12,000 DALYs averted) and only if carried out alongside programme implementation. Conclusion : Our work provides a method for estimating the health benefits of research in a practical and timely fashion. This can be used to support accountable use of research funds
Man versus Machine versus Ribozyme
A microfluidic device has been constructed to carry out the automated, continuous evolution of ribozymes. A comparison with manual efforts reveals that both are capable of far flung forays into sequence space
Indicators of Intrinsic AGN Luminosity: a Multi-Wavelength Approach
We consider five indicators for intrinsic AGN luminosity: the luminosities of
the [OIII]5007 line, the [OIV]25.89m line, the mid-infrared (MIR)
continuum emission by the torus, and the radio and hard X-ray (E 10keV)
continuum emission. We compare these different proxies using two complete
samples of low-redshift type 2 AGN selected in a homogeneous way based on
different indicators: an optically selected [OIII] sample and a mid-infrared
selected 12m sample. We examine the correlations between all five
different proxies, and find better agreement for the [OIV], MIR, and [OIII]
luminosities than for the hard X-ray and radio luminosities. Next, we compare
the ratios of the fluxes of the different proxies to their values in unobscured
Type 1 AGN. The agreement is best for the ratio of the [OIV] and MIR fluxes,
while the ratios of the hard X-ray to [OIII], [OIV], and MIR fluxes are
systematically low by about an order-of-magnitude in the Type 2 AGN, indicating
that hard X-ray selected samples do not represent the full Type 2 AGN
population. In a similar spirit, we compare different optical and MIR
diagnostics of the relative energetic contributions of AGN and star formation
processes in our samples of Type 2 AGN. We find good agreement between the
various diagnostic parameters, such as the equivalent width of the MIR
polycyclic aromatic hydrocarbon features, the ratio of the MIR [OIV]/[NeII]
emission-lines, the spectral index of the MIR continuum, and the commonly used
optical emission-line ratios. Finally, we test whether the presence of cold gas
associated with star-formation leads to an enhanced conversion efficiency of
AGN ionizing radiation into [OIII] or [OIV] emission. We find that no
compelling evidence exists for this scenario for the luminosities represented
in this sample (L 10 - 8 10
L_{\sun}). (abridged)Comment: accepted for publication in ApJ; 58 page
An outflow in the Seyfert ESO 362-G18 revealed by Gemini-GMOS/IFU Observations
We present two-dimensional stellar and gaseous kinematics of the inner 0.7
1.2 kpc of the Seyfert galaxy ESO 362-G18, derived from optical
spectra obtained with the GMOS/IFU on the Gemini South telescope at a spatial
resolution of 170 pc and spectral resolution of 36 km s. ESO
362-G18 is a strongly perturbed galaxy of morphological type Sa or S0/a, with a
minor merger approaching along the NE direction. Previous studies have shown
that the [OIII] emission shows a fan-shaped extension of 10\arcsec\
to the SE. We detect the [OIII] doublet, [NII] and H emission lines
throughout our field of view. The stellar kinematics is dominated by circular
motions in the galaxy plane, with a kinematic position angle of
137. The gas kinematics is also dominated by rotation, with
kinematic position angles ranging from 122 to 139. A
double-Gaussian fit to the [OIII]5007 and H lines, which
have the highest signal to noise ratios of the emission lines, reveal two
kinematic components: (1) a component at lower radial velocities which we
interpret as gas rotating in the galactic disk; and (2) a component with line
of sight velocities 100-250 km s higher than the systemic velocity,
interpreted as originating in the outflowing gas within the AGN ionization
cone. We estimate a mass outflow rate of 7.4 10 M
yr in the SE ionization cone (this rate doubles if we assume a biconical
configuration), and a mass accretion rate on the supermassive black hole (SMBH)
of 2.2 10 M yr. The total ionized gas mass
within 84 pc of the nucleus is 3.3 10 M; infall
velocities of 34 km s in this gas would be required to feed both
the outflow and SMBH accretion.Comment: 18 pages, 14 figure
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