19,604 research outputs found
The implications of precise timekeeping of Doppler gravitational wave observations
Gravitational radiation from galactic and extragalactic astrophysical sources will induce spatial strains in the solar system, strains which can be measured directly by the Doppler radio link to distant spacecraft. Current noise sources in Pioneer and Voyager Doppler data are delineated and a comparison is made with expected signal levels from gravitational wave sources. The main conclusion is that it is possible to detect gravitational radiation with current DSN hydrogen maser systems stable in fractional frequency + or - 2 x 10 to the minus 14th power over 1000 sec. In the future, however, a serious Doppler observational program in gravitational wave astronomy will require frequency systems stable to at least 10 to the minus 16th power, but at the same time the current single frequency S-band uplink transmission will have to be replaced by a dual frequency capability
Conodont biostratigraphy of the Crawford Group, Southern Uplands, Scotland
Extensive new conodont collections from the Crawford Group, the oldest succession in the Southern Uplands of Scotland, support the previously documented biostratigraphical ages for the included formations. The Raven Gill Formation is lower Whitlandian, Arenig (comparable in age to the Dounans Limestone in the Highland Border Complex) and the Kirkton Formation is latest Llandeilian-Aurelucian, Llanvirn to Caradoc in age. It is concluded that there is a significant stratigraphical gap within the Crawford Group. The restricted and probably fault-bounded nature of the Raven Gill outcrops suggests that these may represent olistoliths within a mélange of Llandeilian-Aurelucian age. The chert-bearing succession of the Northern Belt of the Southern Uplands thus represents the juxtaposed sedimentary records of two entirely separate basins – the oldest pre-dates the Grampian assembly of the Laurentian margin, and the younger, the Northern Belt Basin sensu stricto, entirely post-dates this event
On the Abundance of Circumbinary Planets
We present here the first observationally based determination of the rate of
occurrence of circumbinary planets. This is derived from the publicly available
Kepler data, using an automated search algorithm and debiasing process to
produce occurrence rates implied by the seven systems already known. These
rates depend critically on the planetary inclination distribution: if
circumbinary planets are preferentially coplanar with their host binaries, as
has been suggested, then the rate of occurrence of planets with
orbiting with \ d is \% (95\% confidence limits),
higher than but consistent with single star rates. If on the other hand the
underlying planetary inclination distribution is isotropic, then this
occurrence rate rises dramatically, to give a lower limit of 47\%. This implies
that formation and subsequent dynamical evolution in circumbinary disks must
either lead to largely coplanar planets, or proceed with significantly greater
ease than in circumstellar disks. As a result of this investigation we also
show that giant planets () are significantly less common in
circumbinary orbits than their smaller siblings, and confirm that the proposed
shortfall of circumbinary planets orbiting the shorter period binaries in the
Kepler sample is a real effect.Comment: Accepted for publication in MNRAS (1st August 2014). 12 pages. Update
to match final version, including clarifications and new figures. Results are
unchange
Regulation of vascular endothelial growth factor bioactivity in patients with acute lung injury
Background: Reduced bioactive vascular endothelial growth factor (VEGF) has been demonstrated in
several inflammatory lung conditions including the acute respiratory distress syndrome (ARDS). sVEGFR-1,
a soluble form of VEGF-1 receptor, is a potent natural inhibitor of VEGF. We hypothesised that sVEGFR-1
plays an important role in the regulation of the bioactivity of VEGF within the lung in patients with ARDS.
Methods: Forty one patients with ARDS, 12 at risk of developing ARDS, and 16 normal controls were
studied. Bioactive VEGF, total VEGF, and sVEGFR-1 were measured by ELISA in plasma and
bronchoalveolar lavage (BAL) fluid. Reverse transcriptase polymerase chain reaction for sVEGFR-1 was
performed on BAL cells.
Results: sVEGFR-1 was detectable in the BAL fluid of 48% (20/41) of patients with early ARDS (1.4–
54.8 ng/ml epithelial lining fluid (ELF)) compared with 8% (1/12) at risk patients (p = 0.017) and none of
the normal controls (p = 0.002). By day 4 sVEGFR-1 was detectable in only 2/18 ARDS patients
(p = 0.008). Patients with detectable sVEGFR-1 had lower ELF median (IQR) levels of bioactive VEGF than
those without detectable sVEGFR-1 (1415.2 (474.9–3192) pg/ml v 4761 (1349–7596.6) pg/ml, median
difference 3346 pg/ml (95% CI 305.1 to 14711.9), p = 0.016), but there was no difference in total VEGF
levels. BAL cells expressed mRNA for sVEGFR-1 and produced sVEGFR-1 protein which increased
following incubation with tumour necrosis factor a.
Conclusion: This study shows for the first time the presence of sVEGFR-1 in the BAL fluid of patients with
ARDS. This may explain the presence of reduced bioactive VEGF in patients early in the course of ARDS
CORRUPTION AND FORMS OF GOVERNMENT
This paper addresses the issue of corruption, and does in the context of different forms of government. Using democracies as a reference point they are compared, using corruption as a measure, with each of the other forms of government. In the case of small states it was not possible to do an analysis as the Transparency website did not record their corruption score. In each case of governmental style: absolute monarchies, theocracies, dynasties, the most populous states, and countries with lesser attention to human rights. The overall results are that is no instance does the correlation between corruption and population reach statistical significance. With respect to corruption each comparison, of the form of government compared to democracies. This is also conservative in that it uses a two-tailed test, and is thus open to the possibility that the reverse could be true. It is concluded that when compared to democracies each of the other forms of government has a lesser corruption score, taking the mean difference and taking variance into account. This approach may commend itself to other researchers
The Immanent Contingency of Physical Laws in Leibniz’s Dynamics
This paper focuses on Leibniz’s conception of modality and its application to the issue of natural laws. The core of Leibniz’s investigation of the modality of natural laws lays in the distinction between necessary, geometrical laws on the one hand, and contingent, physical laws of nature on the other. For Leibniz, the contingency of physical laws entailed the assumption of the existence of an additional form of causality beyond mechanical or efficient ones. While geometrical truths, being necessary, do not require the use of the principle of sufficient reason, physical laws are not strictly determined by geometry and therefore are logically distinct from geometrical laws. As a consequence, the set of laws that regulate the physical laws could have been created otherwise by God. However, in addition to this, the contingency of natural laws does not consist only in the fact that God has chosen them over other possible ones. On the contrary, Leibniz understood the status of natural laws as arising from the action internal to physical substances. Hence the actuality of physical laws results from a causal power that is inherent to substances rather than being the mere consequence of the way God arranged the relations between physical objects. Focusing on three instances of Leibniz’s treatment of contingency in physics, this paper argues that, in order to account for the contingency of physical laws, Leibniz maintained that final causes, in addition to efficient and mechanical ones, must operate in physical processes and operations
Patient safety in acute care: are we going around in circles?
This article provides a critical discussion examining why adult patients continue to unnecessarily deteriorate and die despite repeated healthcare policy initiatives. After considering the policy background and reviewing current trends in the data, it proposes some solutions that, if enacted, would, the authors believe, have a direct impact on survival rates. Health professionals working in hospitals are failing to recognise signs of physiological deterioration. As a result, adult patients are dying unnecessarily, estimated to be in the region of 1000 a month. This is despite international healthcare policy requiring practitioners to be appropriately trained to recognise the deteriorating adult patient and to intervene. A literature review centred on health policy for England from 1999 to 2015 was undertaken, with reference to international policy and practice. This article also draws on the authors' combined clinical experience, which is underpinned by relevant research and theory. The implications for nursing could be significant. Change is urgently required otherwise people will continue to die unnecessarily. Health professionals, healthcare organisations and international governments working together can prevent unnecessary deaths from happening within acute hospitals
K2 Variable Catalogue: Variable Stars and Eclipsing Binaries in K2 Campaigns 1 and 0
We have created a catalogue of variable stars found from a search of the
publicly available K2 mission data from Campaigns 1 and 0. This catalogue
provides the identifiers of 8395 variable stars, including 199 candidate
eclipsing binaries with periods up to 60d and 3871 periodic or quasi-periodic
objects, with periods up to 20d for Campaign 1 and 15d for Campaign 0.
Lightcurves are extracted and detrended from the available data. These are
searched using a combination of algorithmic and human classification, leading
to a classifier for each object as an eclipsing binary, sinusoidal periodic,
quasi periodic, or aperiodic variable. The source of the variability is not
identified, but could arise in the non-eclipsing binary cases from pulsation or
stellar activity. Each object is cross-matched against variable star related
guest observer proposals to the K2 mission, which specifies the variable type
in some cases. The detrended lightcurves are also compared to lightcurves
currently publicly available. The resulting catalogue is made available online
via the MAST archive at https://archive.stsci.edu/prepds/k2varcat/, and gives
the ID, type, period, semi-amplitude and range of the variation seen. We also
make available the detrended lightcurves for each object.Comment: Accepted by A&A. 6 pages, 6 figures. Catalogue and lightcurves are
available online via MAST at https://archive.stsci.edu/prepds/k2varcat
Corporate Governance, Compensation Consultants, and CEO Pay Levels
This study investigates the relation between corporate governance and CEO pay levels and the extent to which the higher pay found in firms using compensation consultants is related to governance differences. Using proxy statement disclosures from 2,110 companies, we find that CEO pay is higher in firms with weaker governance and that firms with weaker governance are more likely to use compensation consultants. CEO pay remains higher in clients of consulting firms even after controlling for economic determinants of compensation. However, when consultant users and non-users are matched on both economic and governance characteristics, differences in pay levels are not statistically significant, indicating that governance differences explain much of the higher pay in clients of compensation consultants. We find no support for claims that CEO pay is higher in potentially “conflicted” consultants that also offer additional non-compensation-related services
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