12,282 research outputs found
Anglo-American corporate governance and the employment relationship: a case to answer
The corporate governance environment in the UK and US is generally thought to be hostile to the emergence of cooperative employment relations of the kind exemplified by labour-management partnerships. We discuss case study
evidence from the UK which suggests that, contrary to this widespread perception, enduring and proactive partnerships may develop, in conditions where management can convince shareholders of the long-term gains from this approach, and where other regulatory factors operate to extend the time-horizon for financial returns. We conclude that there is more scope than is commonly allowed for measures which could reconcile liquidity in capital markets with cooperation in labour relations
High N, dry: Experimental nitrogen deposition exacerbates native shrub loss and nonnative plant invasion during extreme drought.
Hotter, longer, and more frequent global change-type drought events may profoundly impact terrestrial ecosystems by triggering widespread vegetation mortality. However, severe drought is only one component of global change, and ecological effects of drought may be compounded by other drivers, such as anthropogenic nitrogen (N) deposition and nonnative plant invasion. Elevated N deposition, for example, may reduce drought tolerance through increased plant productivity, thereby contributing to drought-induced mortality. High N availability also often favors invasive, nonnative plant species, and the loss of woody vegetation due to drought may create a window of opportunity for these invaders. We investigated the effects of multiple levels of simulated N deposition on a Mediterranean-type shrubland plant community in southern California from 2011 to 2016, a period coinciding with an extreme, multiyear drought in the region. We hypothesized that N addition would increase native shrub productivity, but that this would increase susceptibility to drought and result in increased shrub loss over time. We also predicted that N addition would favor nonnatives, especially annual grasses, leading to higher biomass and cover of these species. Consistent with these hypotheses, we found that high N availability increased native shrub canopy loss and mortality, likely due to the higher productivity and leaf area and reduced water-use efficiency we observed in shrubs subject to N addition. As native shrub cover declined, we also observed a concomitant increase in cover and biomass of nonnative annuals, particularly under high levels of experimental N deposition. Together, these results suggest that the impacts of extended drought on shrubland ecosystems may be more severe under elevated N deposition, potentially contributing to the widespread loss of native woody species and vegetation-type conversion
Discovery of 28 pulsars using new techniques for sorting pulsar candidates
Modern pulsar surveys produce many millions of candidate pulsars, far more
than can be individually inspected. Traditional methods for filtering these
candidates, based upon the signal-to-noise ratio of the detection, cannot
easily distinguish between interference signals and pulsars. We have developed
a new method of scoring candidates using a series of heuristics which test for
pulsar-like properties of the signal. This significantly increases the
sensitivity to weak pulsars and pulsars with periods close to interference
signals. By applying this and other techniques for ranking candidates from a
previous processing of the Parkes Multi-beam Pulsar Survey, 28 previously
unknown pulsars have been discovered. These include an eccentric binary system
and a young pulsar which is spatially coincident with a known supernova
remnant.Comment: To be published in Monthly Notices of the Royal Astronomical Society.
11 pages, 9 figure
Millimeter wave radiometry as a means of determining cometary surface and subsurface temperature
Thermal emission spectra for a variety of cometary nucleus models were evaluated by a radiative transfer technique adapted from modeling of terrestrial ice and snow fields. It appears that millimeter wave sensing from an interplanetary spacecraft is the most effective available means for distinguishing between alternate models of the nucleus and for evaluating the thermal state of the layer which is below the instantaneous surface where modern theories of the nucleus indicate that sublimation of the cometary volatiles actually occurs
Pulsar timing analysis in the presence of correlated noise
Pulsar timing observations are usually analysed with least-square-fitting
procedures under the assumption that the timing residuals are uncorrelated
(statistically "white"). Pulsar observers are well aware that this assumption
often breaks down and causes severe errors in estimating the parameters of the
timing model and their uncertainties. Ad hoc methods for minimizing these
errors have been developed, but we show that they are far from optimal.
Compensation for temporal correlation can be done optimally if the covariance
matrix of the residuals is known using a linear transformation that whitens
both the residuals and the timing model. We adopt a transformation based on the
Cholesky decomposition of the covariance matrix, but the transformation is not
unique. We show how to estimate the covariance matrix with sufficient accuracy
to optimize the pulsar timing analysis. We also show how to apply this
procedure to estimate the spectrum of any time series with a steep red
power-law spectrum, including those with irregular sampling and variable error
bars, which are otherwise very difficult to analyse.Comment: Accepted by MNRA
Li I and K I Scatter in Cool Pleiades Dwarfs
We utilize high-resolution (R~60,000), high S/N (~100) spectroscopy of 17
cool Pleiades dwarfs to examine the confounding star-to-star scatter in the
6707 Li I line strengths in this young cluster. Our Pleiads, selected for their
small projected rotational velocity and modest chromospheric emission, evince
substantial scatter in the linestrengths of 6707 Li I feature that is absent in
the 7699 K I resonance line. The Li I scatter is not correlated with that in
the high-excitation 7774 O I feature, and the magnitude of the former is
greater than the latter despite the larger temperature sensitivity of the O I
feature. These results suggest that systematic errors in linestrength
measurements due to blending, color (or color-based T_eff) errors, or line
formation effects related to an overlying chromosphere are not the principal
source of Li I scatter in our stars. There do exist analytic spot models that
can produce the observed Li scatter without introducing scatter in the K I line
strengths or the color-magnitude diagram. However, these models predict factor
of >3 differences in abundances derived from the subordinate 6104 and resonance
6707 Li I features; we find no difference in the abundances determined from
these two features. These analytic spot models also predict CN line strengths
significantly larger than we observe in our spectra. The simplest explanation
of the Li, K, CN, and photometric data is that there must be a real abundance
component to the Pleiades Li dispersion. We suggest that this real abundance
component is the manifestation of relic differences in erstwhile
pre-main-sequence Li burning caused by effects of surface activity on stellar
structure. We discuss observational predictions of these effects.Comment: 35 pages, 7 figures; accepted by Ap
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