1. |
- Niemi, MEK, et al.
(author)
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- 2021
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swepub:Mat__t
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2. |
- Kanai, M, et al.
(author)
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- 2023
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swepub:Mat__t
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3. |
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4. |
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5. |
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6. |
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- 2017
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In: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
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Journal article (peer-reviewed)
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7. |
- Adrian-Martinez, S., et al.
(author)
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A first search for coincident gravitational waves and high energy neutrinos using LIGO, Virgo and ANTARES data from 2007
- 2013
-
In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :6
-
Journal article (peer-reviewed)abstract
- We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.
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8. |
- Evans, P. A., et al.
(author)
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Swift Follow-up Observations of Candidate Gravitational-wave Transient Events
- 2012
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In: The Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 203:2
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Journal article (peer-reviewed)abstract
- We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.
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9. |
- Aasi, J., et al.
(author)
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Parameter estimation for compact binary coalescence signals with the first generation gravitational-wave detector network
- 2013
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 88:6
-
Journal article (peer-reviewed)abstract
- Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and in the calibration of the detectors. Here we report such measurements on a selection of simulated signals added either in hardware or software to the data collected by the two LIGO instruments and the Virgo detector during their most recent joint science run, including a "blind injection'' where the signal was not initially revealed to the collaboration. We exemplify the ability to extract information about the source physics on signals that cover the neutron-star and black-hole binary parameter space over the component mass range 1M(circle dot)-25M(circle dot) and the full range of spin parameters. The cases reported in this study provide a snapshot of the status of parameter estimation in preparation for the operation of advanced detectors.
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10. |
- Aasi, J., et al.
(author)
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Search for gravitational waves from binary black hole inspiral, merger, and ringdown in LIGO-Virgo data from 2009-2010
- 2013
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 87:2
-
Journal article (peer-reviewed)abstract
- We report a search for gravitational waves from the inspiral, merger and ringdown of binary black holes (BBH) with total mass between 25 and 100 solar masses, in data taken at the LIGO and Virgo observatories between July 7, 2009 and October 20, 2010. The maximum sensitive distance of the detectors over this period for a (20, 20)M-circle dot coalescence was 300 Mpc. No gravitational wave signals were found. We thus report upper limits on the astrophysical coalescence rates of BBH as a function of the component masses for nonspinning components, and also evaluate the dependence of the search sensitivity on component spins aligned with the orbital angular momentum. We find an upper limit at 90% confidence on the coalescence rate of BBH with nonspinning components of mass between 19 and 28M(circle dot) of 3:3 x 10(-7) mergers Mpc(-3) yr(-1).
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11. |
- Aasi, J., et al.
(author)
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The characterization of Virgo data and its impact on gravitational-wave searches
- 2012
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In: Classical and Quantum Gravity. - : IOP Publishing. - 1361-6382 .- 0264-9381. ; 29:15
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Journal article (peer-reviewed)abstract
- Between 2007 and 2010 Virgo collected data in coincidence with the LIGO and GEO gravitational-wave (GW) detectors. These data have been searched for GWs emitted by cataclysmic phenomena in the universe, by non-axisymmetric rotating neutron stars or from a stochastic background in the frequency band of the detectors. The sensitivity of GW searches is limited by noise produced by the detector or its environment. It is therefore crucial to characterize the various noise sources in a GW detector. This paper reviews the Virgo detector noise sources, noise propagation, and conversion mechanisms which were identified in the three first Virgo observing runs. In many cases, these investigations allowed us to mitigate noise sources in the detector, or to selectively flag noise events and discard them from the data. We present examples from the joint LIGO-GEO-Virgo GW searches to show how well noise transients and narrow spectral lines have been identified and excluded from the Virgo data. We also discuss how detector characterization can improve the astrophysical reach of GW searches.
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12. |
- Aasi, J., et al.
(author)
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Einstein@Home all-sky search for periodic gravitational waves in LIGO S5 data
- 2013
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 87:4
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Journal article (peer-reviewed)abstract
- This paper presents results of an all-sky search for periodic gravitational waves in the frequency range [50, 1190] Hz and with frequency derivative range of similar to[-20, 1.1] x 10(-10) Hz s(-1) for the fifth LIGO science run (S5). The search uses a noncoherent Hough-transform method to combine the information from coherent searches on time scales of about one day. Because these searches are very computationally intensive, they have been carried out with the Einstein@Home volunteer distributed computing project. Postprocessing identifies eight candidate signals; deeper follow-up studies rule them out. Hence, since no gravitational wave signals have been found, we report upper limits on the intrinsic gravitational wave strain amplitude h(0). For example, in the 0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with h(0) greater than 7.6 x 10(-25) at a 90% confidence level. This search is about a factor 3 more sensitive than the previous Einstein@Home search of early S5 LIGO data.
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13. |
- Abadie, J., et al.
(author)
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Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts
- 2012
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In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 539
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Journal article (peer-reviewed)abstract
- Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with similar to 50% or better probability with a few pointings of wide-field telescopes.
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14. |
- Abadie, J., et al.
(author)
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Search for Gravitational Waves Associated with Gamma-Ray Bursts during LIGO Science Run 6 and Virgo Science Runs 2 and 3
- 2012
-
In: Astrophysical Journal. - 0004-637X. ; 760:1
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Journal article (peer-reviewed)abstract
- We present the results of a search for gravitational waves associated with 154 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments in 2009-2010, during the sixth LIGO science run and the second and third Virgo science runs. We perform two distinct searches: a modeled search for coalescences of either two neutron stars or a neutron star and black hole, and a search for generic, unmodeled gravitational-wave bursts. We find no evidence for gravitational-wave counterparts, either with any individual GRB in this sample or with the population as a whole. For all GRBs we place lower bounds on the distance to the progenitor, under the optimistic assumption of a gravitational-wave emission energy of 10(-2) M-circle dot c(2) at 150 Hz, with a median limit of 17 Mpc. For short-hard GRBs we place exclusion distances on binary neutron star and neutron-star-black-hole progenitors, using astrophysically motivated priors on the source parameters, with median values of 16 Mpc and 28 Mpc, respectively. These distance limits, while significantly larger than for a search that is not aided by GRB satellite observations, are not large enough to expect a coincidence with a GRB. However, projecting these exclusions to the sensitivities of Advanced LIGO and Virgo, which should begin operation in 2015, we find that the detection of gravitational waves associated with GRBs will become quite possible.
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15. |
- Abadie, J., et al.
(author)
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All-sky search for gravitational-wave bursts in the second joint LIGO-Virgo run
- 2012
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 85:12
-
Journal article (peer-reviewed)abstract
- We present results from a search for gravitational-wave bursts in the data collected by the LIGO and Virgo detectors between July 7, 2009 and October 20, 2010: data are analyzed when at least two of the three LIGO-Virgo detectors are in coincident operation, with a total observation time of 207 days. The analysis searches for transients of duration less than or similar to 1 s over the frequency band 64-5000 Hz, without other assumptions on the signal waveform, polarization, direction or occurrence time. All identified events are consistent with the expected accidental background. We set frequentist upper limits on the rate of gravitational-wave bursts by combining this search with the previous LIGO-Virgo search on the data collected between November 2005 and October 2007. The upper limit on the rate of strong gravitational-wave bursts at the Earth is 1.3 events per year at 90% confidence. We also present upper limits on source rate density per year and Mpc(3) for sample populations of standard-candle sources. As in the previous joint run, typical sensitivities of the search in terms of the root-sum-squared strain amplitude for these waveforms lie in the range similar to 5 x 10(-22) Hz(-1/2) to similar to 1 x 10(-20) Hz(-1/2). The combination of the two joint runs entails the most sensitive all-sky search for generic gravitational-wave bursts and synthesizes the results achieved by the initial generation of interferometric detectors.
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16. |
- Abadie, J., et al.
(author)
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First low-latency LIGO plus Virgo search for binary inspirals and their electromagnetic counterparts
- 2012
-
In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 541
-
Journal article (peer-reviewed)abstract
- Aims. The detection and measurement of gravitational-waves from coalescing neutron-star binary systems is an important science goal for ground-based gravitational-wave detectors. In addition to emitting gravitational-waves at frequencies that span the most sensitive bands of the LIGO and Virgo detectors, these sources are also amongst the most likely to produce an electromagnetic counterpart to the gravitational-wave emission. A joint detection of the gravitational-wave and electromagnetic signals would provide a powerful new probe for astronomy. Methods. During the period between September 19 and October 20, 2010, the first low-latency search for gravitational-waves from binary inspirals in LIGO and Virgo data was conducted. The resulting triggers were sent to electromagnetic observatories for followup. We describe the generation and processing of the low-latency gravitational-wave triggers. The results of the electromagnetic image analysis will be described elsewhere. Results. Over the course of the science run, three gravitational-wave triggers passed all of the low-latency selection cuts. Of these, one was followed up by several of our observational partners. Analysis of the gravitational-wave data leads to an estimated false alarm rate of once every 6.4 days, falling far short of the requirement for a detection based solely on gravitational-wave data.
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17. |
- Abadie, J., et al.
(author)
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Upper limits on a stochastic gravitational-wave background using LIGO and Virgo interferometers at 600-1000 Hz
- 2012
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 85:12
-
Journal article (peer-reviewed)abstract
- A stochastic background of gravitational waves is expected to arise from a superposition of many incoherent sources of gravitational waves, of either cosmological or astrophysical origin. This background is a target for the current generation of ground-based detectors. In this article we present the first joint search for a stochastic background using data from the LIGO and Virgo interferometers. In a frequency band of 600-1000 Hz, we obtained a 95% upper limit on the amplitude of Omega(GW)(f) = Omega(3)(f/900 Hz)(3), of Omega(3) < 0.32, assuming a value of the Hubble parameter of h(100) = 0.71. These new limits are a factor of seven better than the previous best in this frequency band.
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18. |
- Abadie, J., et al.
(author)
-
Search for gravitational waves from intermediate mass binary black holes
- 2012
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 85:10
-
Journal article (peer-reviewed)abstract
- We present the results of a weakly modeled burst search for gravitational waves from mergers of nonspinning intermediate mass black holes in the total mass range 100-450 M-circle dot and with the component mass ratios between 1: and 4:1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the intermediate mass black holes mergers as a function of the component masses. In the most efficiently detected bin centered on 88 + 88 M-circle dot, for nonspinning sources, the rate density upper limit is 0.13 per Mpc(3) per Myr at the 90% confidence level.
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19. |
- Abadie, J., et al.
(author)
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Search for gravitational waves from low mass compact binary coalescence in LIGO's sixth science run and Virgo's science runs 2 and 3
- 2012
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 85:8
-
Journal article (peer-reviewed)abstract
- We report on a search for gravitational waves from coalescing compact binaries using LIGO and Virgo observations between July 7, 2009, and October 20, 2010. We searched for signals from binaries with total mass between 2 and 25M(circle dot); this includes binary neutron stars, binary black holes, and binaries consisting of a black hole and neutron star. The detectors were sensitive to systems up to 40 Mpc distant for binary neutron stars, and further for higher mass systems. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass, including the results from previous LIGO and Virgo observations. The cumulative 90% confidence rate upper limits of the binary coalescence of binary neutron star, neutron star-black hole, and binary black hole systems are 1.3 x 10(-4), 3.1 x 10(-5), and 6.4 x 10(-6) Mpc(-3) yr(-1), respectively. These upper limits are up to a factor 1.4 lower than previously derived limits. We also report on results from a blind injection challenge.
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20. |
- Abadie, J., et al.
(author)
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All-sky search for periodic gravitational waves in the full S5 LIGO data
- 2012
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 85:2
-
Journal article (peer-reviewed)abstract
- We report on an all-sky search for periodic gravitational waves in the frequency band 50-800 Hz and with the frequency time derivative in the range of 0 through -6 x 10(-9) Hz/s. Such a signal could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our Galaxy. After recent improvements in the search program that yielded a 10x increase in computational efficiency, we have searched in two years of data collected during LIGO's fifth science run and have obtained the most sensitive all-sky upper limits on gravitational-wave strain to date. Near 150 Hz our upper limit on worst-case linearly polarized strain amplitude h(0) is 1 x 10(-24), while at the high end of our frequency range we achieve a worst-case upper limit of 3.8 x 10(-24) for all polarizations and sky locations. These results constitute a factor of 2 improvement upon previously published data. A new detection pipeline utilizing a loosely coherent algorithm was able to follow up weaker outliers, increasing the volume of space where signals can be detected by a factor of 10, but has not revealed any gravitational-wave signals. The pipeline has been tested for robustness with respect to deviations from the model of an isolated neutron star, such as caused by a low-mass or long-period binary companion.
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21. |
-
- 2019
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Journal article (peer-reviewed)
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22. |
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23. |
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24. |
- Rauer, H., et al.
(author)
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The PLATO 2.0 mission
- 2014
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In: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 38:1-2, s. 249-330
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Journal article (peer-reviewed)abstract
- PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s cadence) providing a wide field-of-view (2232 deg(2)) and a large photometric magnitude range (4-16 mag). It focuses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e. g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such a low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmospheres. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA's Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science.
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25. |
- Fresard, Laure, et al.
(author)
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Identification of rare-disease genes using blood transcriptome sequencing and large control cohorts
- 2019
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In: Nature Medicine. - : NATURE PUBLISHING GROUP. - 1078-8956 .- 1546-170X. ; 25:6, s. 911-919
-
Journal article (peer-reviewed)abstract
- It is estimated that 350 million individuals worldwide suffer from rare diseases, which are predominantly caused by mutation in a single gene(1). The current molecular diagnostic rate is estimated at 50%, with whole-exome sequencing (WES) among the most successful approaches(2-5). For patients in whom WES is uninformative, RNA sequencing (RNA-seq) has shown diagnostic utility in specific tissues and diseases(6-8). This includes muscle biopsies from patients with undiagnosed rare muscle disorders(6,9), and cultured fibroblasts from patients with mitochondrial disorders(7). However, for many individuals, biopsies are not performed for clinical care, and tissues are difficult to access. We sought to assess the utility of RNA-seq from blood as a diagnostic tool for rare diseases of different pathophysiologies. We generated whole-blood RNA-seq from 94 individuals with undiagnosed rare diseases spanning 16 diverse disease categories. We developed a robust approach to compare data from these individuals with large sets of RNA-seq data for controls (n = 1,594 unrelated controls and n = 49 family members) and demonstrated the impacts of expression, splicing, gene and variant filtering strategies on disease gene identification. Across our cohort, we observed that RNA-seq yields a 7.5% diagnostic rate, and an additional 16.7% with improved candidate gene resolution.
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26. |
- Zuntini, Alexandre R., et al.
(author)
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Phylogenomics and the rise of the angiosperms
- 2024
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In: NATURE. - 0028-0836 .- 1476-4687. ; 629, s. 843-850
-
Journal article (peer-reviewed)abstract
- Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods(1,2). A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome(3,4). Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins(5-7). However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes(8). This 15-fold increase in genus-level sampling relative to comparable nuclear studies(9) provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade.
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27. |
- Natali, S. M., et al.
(author)
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Large loss of CO2 in winter observed across the northern permafrost region
- 2019
-
In: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 9:11, s. 852-857
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Journal article (peer-reviewed)abstract
- Recent warming in the Arctic, which has been amplified during the winter(1-3), greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO2)(4). However, the amount of CO2 released in winter is not known and has not been well represented by ecosystem models or empirically based estimates(5,6). Here we synthesize regional in situ observations of CO2 flux from Arctic and boreal soils to assess current and future winter carbon losses from the northern permafrost domain. We estimate a contemporary loss of 1,662 TgC per year from the permafrost region during the winter season (October-April). This loss is greater than the average growing season carbon uptake for this region estimated from process models (-1,032 TgC per year). Extending model predictions to warmer conditions up to 2100 indicates that winter CO2 emissions will increase 17% under a moderate mitigation scenario-Representative Concentration Pathway 4.5-and 41% under business-as-usual emissions scenario-Representative Concentration Pathway 8.5. Our results provide a baseline for winter CO2 emissions from northern terrestrial regions and indicate that enhanced soil CO2 loss due to winter warming may offset growing season carbon uptake under future climatic conditions.
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28. |
- Aalbers, J., et al.
(author)
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A next-generation liquid xenon observatory for dark matter and neutrino physics
- 2023
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In: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 50:1
-
Research review (peer-reviewed)abstract
- The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.
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29. |
- Tjernström, Michael, et al.
(author)
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The Arctic Summer Cloud Ocean Study (ASCOS) : overview and experimental design
- 2014
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In: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:6, s. 2823-2869
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Journal article (peer-reviewed)abstract
- The climate in the Arctic is changing faster than anywhere else on earth. Poorly understood feedback processes relating to Arctic clouds and aerosol-cloud interactions contribute to a poor understanding of the present changes in the Arctic climate system, and also to a large spread in projections of future climate in the Arctic. The problem is exacerbated by the paucity of research-quality observations in the central Arctic. Improved formulations in climate models require such observations, which can only come from measurements in situ in this difficult-to-reach region with logistically demanding environmental conditions. The Arctic Summer Cloud Ocean Study (ASCOS) was the most extensive central Arctic Ocean expedition with an atmospheric focus during the International Polar Year (IPY) 2007-2008. ASCOS focused on the study of the formation and life cycle of low-level Arctic clouds. ASCOS departed from Longyearbyen on Svalbard on 2 August and returned on 9 September 2008. In transit into and out of the pack ice, four short research stations were undertaken in the Fram Strait: two in open water and two in the marginal ice zone. After traversing the pack ice northward, an ice camp was set up on 12 August at 87 degrees 21' N, 01 degrees 29' W and remained in operation through 1 September, drifting with the ice. During this time, extensive measurements were taken of atmospheric gas and particle chemistry and physics, mesoscale and boundary-layer meteorology, marine biology and chemistry, and upper ocean physics. ASCOS provides a unique interdisciplinary data set for development and testing of new hypotheses on cloud processes, their interactions with the sea ice and ocean and associated physical, chemical, and biological processes and interactions. For example, the first-ever quantitative observation of bubbles in Arctic leads, combined with the unique discovery of marine organic material, polymer gels with an origin in the ocean, inside cloud droplets suggests the possibility of primary marine organically derived cloud condensation nuclei in Arctic stratocumulus clouds. Direct observations of surface fluxes of aerosols could, however, not explain observed variability in aerosol concentrations, and the balance between local and remote aerosols sources remains open. Lack of cloud condensation nuclei (CCN) was at times a controlling factor in low-level cloud formation, and hence for the impact of clouds on the surface energy budget. ASCOS provided detailed measurements of the surface energy balance from late summer melt into the initial autumn freeze-up, and documented the effects of clouds and storms on the surface energy balance during this transition. In addition to such process-level studies, the unique, independent ASCOS data set can and is being used for validation of satellite retrievals, operational models, and reanalysis data sets.
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30. |
- Buunen, M, et al.
(author)
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COLOR II. A randomized clinical trial comparing laparoscopic and open surgery for rectal cancer.
- 2009
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In: Danish medical bulletin. - 1603-9629 .- 0907-8916. ; 56:2, s. 89-91
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Journal article (peer-reviewed)abstract
- INTRODUCTION: Laparoscopic resection of rectal cancer has been proven efficacious but morbidity and oncological outcome need to be investigated in a randomized clinical trial. Trial design: Non-inferiority randomized clinical trial. METHODS: The COLOR II trial is an ongoing international randomized clinical trial. Currently 27 hospitals from Europe, South Korea and Canada are including patients. The primary endpoint is loco-regional recurrence rate three years post-operatively. Secondary endpoints cover quality of life, overall and disease free survival, post-operative morbidity and health economy analysis. RESULTS: By July 2008, 27 hospitals from the Netherlands, Belgium, Germany, Sweden, Spain, Denmark, South Korea and Canada had included 739 patients. The intra-operative conversion rate in the laparoscopic group was 17%. Distribution of age, location of the tumor and radiotherapy were equal in both treatment groups. Most tumors are located in the mid-rectum (41%). CONCLUSION: Laparoscopic surgery in the treatment of rectal cancer is feasible. The results and safety of laparoscopic surgery in the treatment of rectal cancer remain unknown, but are subject of interim analysis within the COLOR II trial. Completion of inclusion is expected by the end of 2009. Trial registration: Clinicaltrials.gov, identifier: NCT00297791 (www.clinicaltrials.gov).
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31. |
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32. |
- Patterson, Brooke E., et al.
(author)
-
Evaluation of an injury prevention programme (Prep-to-Play) in women and girls playing Australian Football : design of a pragmatic, type III, hybrid implementation-effectiveness, stepped-wedge, cluster randomised controlled trial
- 2022
-
In: BMJ Open. - : BMJ Publishing Group. - 2044-6055. ; 12:9
-
Journal article (peer-reviewed)abstract
- Introduction Due to the increase in participation and risk of anterior cruciate ligament (ACL) injuries and concussion in womens Australian Football, an injury prevention programme (Prep-to-Play) was codesigned with consumers (eg, coaches, players) and stakeholders (eg, the Australian Football League). The impact of supported and unsupported interventions on the use of Prep-to-Play (primary aim) and injury rates (secondary aim) will be evaluated in women and girls playing community Australian Football. Methods and analysis This stepped-wedge, cluster randomised controlled trial will include >= 140 teams from U16, U18 or senior womens competitions. All 10 geographically separated clusters (each containing >= 14 teams) will start in the control (unsupported) phase and be randomised to one of five dates (or wedges) during the 2021 or 2022 season to sequentially transition to the intervention (supported Prep-to-Play), until all teams receive the intervention. Prep-to-Play includes four elements: a neuromuscular training warm-up, contact-focussed football skills (eg, tackling), strength exercises and education (eg, technique cues). When transitioning to supported interventions, study physiotherapists will deliver a workshop to coaches and player leaders on how to use Prep-to-Play, attend team training at least two times and provide ongoing support. In the unsupported phase, team will continue usual routines and may freely access available Prep-to-Play resources online (eg, posters and videos about the four elements), but without additional face-to-face support. Outcomes will be evaluated throughout the 2021 and 2022 seasons (similar to 14 weeks per season). Primary outcome: use of Prep-to-Play will be reported via a team designate (weekly) and an independent observer (five visits over the two seasons) and defined as the team completing 75% of the programme, two-thirds (67%) of the time. Secondary outcomes: injuries will be reported by the team sports trainer and/or players. Injury definition: any injury occurring during a football match or training that results in: (1) being unable to return to the field of play for that match or (2) missing >= one match. Outcomes in the supported and unsupported phases will be compared using a generalised linear mixed model adjusting for clustering and time. Due to the type III hybrid implementation-effectiveness design, the study is powered to detect a improvement in use of Prep-to-Play and a reduction in ACL injuries. Ethics and dissemination La Trobe University Ethics Committee (HREC 20488) approved. Coaches provided informed consent to receive the supported intervention and players provided consent to be contacted if they sustained a head or knee injury. Results will be disseminated through partner organisations, peer-reviewed publications and scientific conferences.
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33. |
- Solomonidou, A., et al.
(author)
-
Spectral and emissivity analysis of the raised ramparts around Titan's northern lakes
- 2020
-
In: Icarus. - : Academic Press. - 0019-1035 .- 1090-2643. ; 344
-
Journal article (peer-reviewed)abstract
- Some of Titan's small northern hemisphere lakes show raised rampart features (which are distinct from raised rims), and appear as SAR-bright mound-like annuli extending away from the lake for up to tens of kilometers from the shoreline. We investigate the infrared and microwave characteristics of these features using Cassini Visual and Infrared Mapping Spectrometer (VIMS) and RADAR data. A spectral comparative analysis is performed among the lakes, their ramparts, and the surrounding regions. We overcome the profound difference in spatial resolution between VIMS and SAR data by using a method that provides overlays between the spectral images and SAR, thus enabling the correct selection of VIMS pixels. The surface properties of the selected areas are obtained using a radiative transfer analysis on the selected VIMS pixels, in addition to emissivity obtained from the RADAR in radiometry mode. Analysis of these combined and co-registered data provides constraints for the formation mechanism(s) of raised ramparts. The results show that the emissivity of the raised ramparts is close to that of Titan's labyrinthic terrains and to that of empty lake floors in the northern polar regions. This is confirmed by the VIMS analysis that also shows that the infrared spectral response of the raised ramparts is very similar to that of some empty lake floors. This suggests that both areas are made from or are covered by a similar material. In addition, two out of the eight lakes with raised ramparts show spectral differences at three specific wavelengths, 1.6, 2.0, and 5.0 mu m, between the ramparts and the surrounding terrain. We hypothesize that this could be due to some component, or mixture of components in the ramparts that is less absorbent at these specific wavelengths, or it could be an effect of different grain sizes. These observations provide first insights into the possible mechanisms leading to the formation of the raised ramparts that are discussed here.
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34. |
- Jacquet, Jennifer, et al.
(author)
-
Support US OCTOPUS Act to keep octopuses wild.
- 2024
-
In: Science (New York, N.Y.). - 1095-9203. ; 385:6710, s. 721-722
-
Journal article (peer-reviewed)abstract
- Commercial octopus farming is incapable of meeting welfare requirements, unsustainable, and unnecessary for sustenance. Although no commercial octopus farms currently exist, a Spanish seafood company plans to build one in the Canary Islands for Octopus vulgaris. In March, the US state of Washington banned octopus farming. Similar legislation has been introduced in California and Hawai‘i . Now, the federal government is proposing action. The US Congress should pass the OCTOPUS Act, a federal law that would prohibit commercial octopus aquaculture in the United States and the import of commercially farmed octopus or octopus products.
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35. |
- Keurhorst, M., et al.
(author)
-
Impact of primary healthcare providers' initial role security and therapeutic commitment on implementing brief interventions in managing risky alcohol consumption: a cluster randomised factorial trial
- 2016
-
In: Implementation Science. - : Springer Science and Business Media LLC. - 1748-5908. ; 11
-
Journal article (peer-reviewed)abstract
- Background: Brief interventions in primary healthcare are cost-effective in reducing drinking problems but poorly implemented in routine practice. Although evidence about implementing brief interventions is growing, knowledge is limited with regard to impact of initial role security and therapeutic commitment on brief intervention implementation. Methods: In a cluster randomised factorial trial, 120 primary healthcare units (PHCUs) were randomised to eight groups: care as usual, training and support, financial reimbursement, and the opportunity to refer patients to an internet-based brief intervention (e-BI); paired combinations of these three strategies, and all three strategies combined. To explore the impact of initial role security and therapeutic commitment on implementing brief interventions, we performed multilevel linear regression analyses adapted to the factorial design. Results: Data from 746 providers from 120 PHCUs were included in the analyses. Baseline role security and therapeutic commitment were found not to influence implementation of brief interventions. Furthermore, there were no significant interactions between these characteristics and allocated implementation groups. Conclusions: The extent to which providers changed their brief intervention delivery following experience of different implementation strategies was not determined by their initial attitudes towards alcohol problems. In future research, more attention is needed to unravel the causal relation between practitioners' attitudes, their actual behaviour and care improvement strategies to enhance implementation science.
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36. |
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37. |
- Anderson, P., et al.
(author)
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Improving the delivery of brief interventions for heavy drinking in primary health care: outcome results of the Optimizing Delivery of Health Care Intervention (ODHIN) five-country cluster randomized factorial trial
- 2016
-
In: Addiction. - : Wiley. - 1360-0443 .- 0965-2140. ; 111:11, s. 1935-1945
-
Journal article (peer-reviewed)abstract
- Aim: To test if training and support, financial reimbursement and option of referring screen-positive patients to an internet-based method of giving advice (eBI) can increase primary health-care providers' delivery of Alcohol Use Disorders Identification Test (AUDIT)-C-based screening and advice to heavy drinkers. Design: Cluster randomized factorial trial with 12-week implementation and measurement period. Setting: Primary health-care units (PHCU) in different locations throughout Catalonia, England, the Netherlands, Poland and Sweden. Participants: A total of 120 PHCU, 24 in each of Catalonia, England, the Netherlands, Poland and Sweden. Interventions: PHCUs were randomized to one of eight groups: care as usual, training and support (TS), financial reimbursement (FR) and eBI; paired combinations of TS, FR and eBI, and all of FR, TS and eBI. Measurements: The primary outcome measure was the proportion of eligible adult (age 18+ years) patients screened during a 12-week implementation period. Secondary outcome measures were proportion of screen-positive patients advised; and proportion of consulting adult patients given an intervention (screening and advice to screen-positives) during the same 12-week implementation period. Findings: During a 4-week baseline measurement period, the proportion of consulting adult patients who were screened for their alcohol consumption was 0.059 per PHCU (95% CI 0.034 to 0.084). Based on the factorial design, the ratio of the logged proportion screened during the 12-week implementation period was 1.48 (95% CI=1.13–1.95) in PHCU that received TS versus PHCU that did not receive TS; for FR, the ratio was 2.00 (95% CI=1.56–2.56). The option of referral to eBI did not lead to a higher proportion of patients screened. The ratio for TS plus FR was 2.34 (95% CI=1.77–3.10), and the ratio for TS plus FR plus eBI was1.68 (95% CI=1.11–2.53). Conclusions: Providing primary health-care units with training, support and financial reimbursement for delivering Alcohol Use Disorders Identification Test-C-based screening and advice to heavy drinkers increases screening for alcohol consumption. Providing primary health-care units with the option of referring screen-positive patients to an internet-based method of giving advice does not appear to increase screening for alcohol consumption. © 2016 Society for the Study of Addiction
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38. |
- Haas, Brian J., et al.
(author)
-
Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans
- 2009
-
In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 461:7262, s. 393-398
-
Journal article (peer-reviewed)abstract
- Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, a distinct lineage of fungus-like eukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans has had a tremendous effect on human history, resulting in famine and population displacement(1). To this day, it affects world agriculture by causing the most destructive disease of potato, the fourth largest food crop and a critical alternative to the major cereal crops for feeding the world's population(1). Current annual worldwide potato crop losses due to late blight are conservatively estimated at $6.7 billion(2). Management of this devastating pathogen is challenged by its remarkable speed of adaptation to control strategies such as genetically resistant cultivars(3,4). Here we report the sequence of the P. infestans genome, which at similar to 240 megabases (Mb) is by far the largest and most complex genome sequenced so far in the chromalveolates. Its expansion results from a proliferation of repetitive DNA accounting for similar to 74% of the genome. Comparison with two other Phytophthora genomes showed rapid turnover and extensive expansion of specific families of secreted disease effector proteins, including many genes that are induced during infection or are predicted to have activities that alter host physiology. These fast-evolving effector genes are localized to highly dynamic and expanded regions of the P. infestans genome. This probably plays a crucial part in the rapid adaptability of the pathogen to host plants and underpins its evolutionary potential.
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39. |
- Backis, A., et al.
(author)
-
Time- and energy-resolved effects in the boron-10 based multi-grid and helium-3 based thermal neutron detectors
- 2021
-
In: Measurement science and technology. - : IOP PUBLISHING LTD. - 0957-0233 .- 1361-6501. ; 32:3
-
Journal article (peer-reviewed)abstract
- The boron-10 based multi-grid detector is being developed as an alternative to helium-3 based neutron detectors. At the European Spallation Source, the detector will be used for time-of-flight neutron spectroscopy at cold to thermal neutron energies. The objective of this work is to investigate fine time- and energy-resolved effects of the Multi-Grid detector, down to a few mu eV, while comparing it to the performance of a typical helium-3 tube. Furthermore, it is to characterize differences between the detector technologies in terms of internal scattering, as well as the time reconstruction of similar to mu s short neutron pulses. The data were taken at the Helmholtz Zentrum Berlin, where the Multi-Grid detector and a helium-3 tube were installed at the ESS test beamline, V20. Using a Fermi-chopper, the neutron beam of the reactor was chopped into a few tens of mu s wide pulses before reaching the detector, located a few tens of cm downstream. The data of the measurements show an agreement between the derived and calculated neutron detection efficiency curve. The data also provide fine details on the effect of internal scattering, and how it can be reduced. For the first time, the chopper resolution was comparable to the timing resolution of the Multi-Grid detector. This allowed a detailed study of time- and energy resolved effects, as well as a comparison with a typical helium-3 tube.
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40. |
- Bendtsen, Preben, et al.
(author)
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Professional's Attitudes Do Not Influence Screening and Brief Interventions Rates for Hazardous and Harmful Drinkers: Results from ODHIN Study
- 2015
-
In: Alcohol and Alcoholism. - : Oxford University Press (OUP). - 0735-0414 .- 1464-3502. ; 50:4, s. 430-437
-
Journal article (peer-reviewed)abstract
- To determine the relation between existing levels of alcohol screening and brief intervention rates in five European jurisdictions and role security and therapeutic commitment by the participating primary healthcare professionals. Health care professionals consisting of, 409 GPs, 282 nurses and 55 other staff including psychologists, social workers and nurse aids from 120 primary health care centres participated in a cross-sectional 4-week survey. The participants registered all screening and brief intervention activities as part of their normal routine. The participants also completed the Shortened Alcohol and Alcohol Problems Perception Questionnaire (SAAPPQ), which measure role security and therapeutic commitment. The only significant but small relationship was found between role security and screening rate in a multilevel logistic regression analysis adjusted for occupation of the provider, number of eligible patients and the random effects of jurisdictions and primary health care units (PHCU). No significant relationship was found between role security and brief intervention rate nor between therapeutic commitment and screening rate/brief intervention rate. The proportion of patients screened varied across jurisdictions between 2 and 10%. The findings show that the studied factors (role security and therapeutic commitment) are not of great importance for alcohol screening and BI rates. Given the fact that screening and brief intervention implementation rate has not changed much in the last decade in spite of increased policy emphasis, training initiatives and more research being published, this raises a question about what else is needed to enhance implementation.
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41. |
- Birch, Jens, et al.
(author)
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In-beam test of the Boron-10 Multi-Grid neutron detector at the IN6 time-of-flight spectrometer at the ILL
- 2014
-
In: INTERNATIONAL WORKSHOP ON NEUTRON OPTICS AND DETECTORS (NOPandD 2013). - : IOP Publishing: Conference Series / Institute of Physics (IoP).
-
Conference paper (peer-reviewed)abstract
- A neutron detector concept based on solid layers of boron carbide enriched in 1 B has been in development for the last few years as an alternative for He-3 by collaboration between the ILL, ESS and Linkoping University. This Multi-Grid detector uses layers of aluminum substrates coated with (B4C)-B-10 on both sides that are traversed by the incoming neutrons. Detection is achieved using a gas counter readout principle. By segmenting the substrate and using multiple anode wires, the detector is made inherently position sensitive. This development is aimed primarily at neutron scattering instruments with large detector areas, such as time-of-flight chopper spectrometers. The most recent prototype has been built to be interchangeable with the He-3 detectors of IN6 at ILL. The 1 B detector has an active area of 32 x 48 cm(2). It was installed at the IN6 instrument and operated for several weeks, collecting data in parallel with the regularly scheduled experiments, thus providing the first side-by-side comparison with the conventional He-3 detectors. Results include an efficiency comparison, assessment of the in-detector scattering contribution, sensitivity to gamma-rays and the signal-to-noise ratio in time-of-flight spectra. The good expected performance has been confirmed with the exception of an unexpected background count rate. This has been identified as natural alpha activity in aluminum. New convertor substrates are under study to eliminate this source of background.
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42. |
- Reed, Mark S., et al.
(author)
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The future of the uplands
- 2009
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In: Land use policy. - : Elsevier Limited. - 0264-8377 .- 1873-5754. ; 26:Supplement 1
-
Journal article (peer-reviewed)abstract
- Upland areas provide UK society with many important functions, goods and services, but have experienced a number of disturbing trends and face an uncertain future. This paper outlines historic, current and future drivers of environmental, economic, socio-cultural and policy change in UK uplands, and assesses how these have affected or are likely to affect ways in which land is used and the provision of ecosystem services. Information is synthesised into scenarios summarising a range of possible futures anticipated for UK uplands to 2060 and beyond. Finally, innovations in science, technology, governance and policy are evaluated that could enable uplands to continue providing key ecosystem services under a range of scenarios. The paper concludes that many upland areas will need to be prepared for significant reductions in grazing and prescribed burning. Conversely, other areas could experience agricultural intensification, for example significant increases in grazing or an expansion of arable or bioenergy crops into upland valleys, due to anticipated increases in global demand for food and energy. These scenarios will take place in the context of climate change. Many may take place together and may interact with each other, with complex and unpredictable implications for the upland environment, economy and society. In this context, a number of advances are needed in science, technology and policy to maintain viable uplandcommunities and the future provision of ecosystem services. These may include funding for ecological and hydrological restoration via carbon offsetting or other means. It may also involve advances in ecosystem service modelling, mapping and valuation, which through stakeholder participation could facilitate more integrated rural planning. New forms of environmental governance need to be explored that can empower those interested in developing upland economies to maintain thriving upland communities, while managing the ecosystem services they provide as efficiently as possible.
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43. |
- Schmitt, Deanna M., et al.
(author)
-
The role and mechanism of erythrocyte invasion by Francisella tularensis
- 2017
-
In: Frontiers in Cellular and Infection Microbiology. - : Frontiers Media S.A.. - 2235-2988. ; 7
-
Journal article (peer-reviewed)abstract
- Francisella tularensis is an extremely virulent bacterium that can be transmitted naturally by blood sucking arthropods. During mammalian infection, F. tularensis infects numerous types of host cells, including erythrocytes. As erythrocytes do not undergo phagocytosis or endocytosis, it remains unknown how F. tularensis invades these cells. Furthermore, the consequence of inhabiting the intracellular space of red blood cells (RBCs) has not been determined. Here, we provide evidence indicating that residing within an erythrocyte enhances the ability of F. tularensis to colonize ticks following a blood meal. Erythrocyte residence protected F. tularensis from a low pH environment similar to that of gut cells of a feeding tick. Mechanistic studies revealed that the F. tularensis type VI secretion system (T6SS) was required for erythrocyte invasion as mutation of mglA (a transcriptional regulator of T6SS genes), dotU, or iglC (two genes encoding T6SS machinery) severely diminished bacterial entry into RBCs. Invasion was also inhibited upon treatment of erythrocytes with venom from the Blue-bellied black snake (Pseudechis guttatus), which aggregates spectrin in the cytoskeleton, but not inhibitors of actin polymerization and depolymerization. These data suggest that erythrocyte invasion by F. tularensis is dependent on spectrin utilization which is likely mediated by effectors delivered through the T6SS. Our results begin to elucidate the mechanism of a unique biological process facilitated by F. tularensis to invade erythrocytes, allowing for enhanced colonization of ticks.
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44. |
- Sedlar, Joseph, et al.
(author)
-
A transitioning Arctic surface energy budget : the impacts of solar zenith angle, surface albedo and cloud radiative forcing
- 2011
-
In: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 37:7-8, s. 1643-1660
-
Journal article (peer-reviewed)abstract
- Snow surface and sea-ice energy budgets were measured near 87.5A degrees N during the Arctic Summer Cloud Ocean Study (ASCOS), from August to early September 2008. Surface temperature indicated four distinct temperature regimes, characterized by varying cloud, thermodynamic and solar properties. An initial warm, melt-season regime was interrupted by a 3-day cold regime where temperatures dropped from near zero to -7A degrees C. Subsequently mean energy budget residuals remained small and near zero for 1 week until once again temperatures dropped rapidly and the energy budget residuals became negative. Energy budget transitions were dominated by the net radiative fluxes, largely controlled by the cloudiness. Variable heat, moisture and cloud distributions were associated with changing air-masses. Surface cloud radiative forcing, the net radiative effect of clouds on the surface relative to clear skies, is estimated. Shortwave cloud forcing ranged between -50 W m(-2) and zero and varied significantly with surface albedo, solar zenith angle and cloud liquid water. Longwave cloud forcing was larger and generally ranged between 65 and 85 W m(-2), except when the cloud fraction was tenuous or contained little liquid water; thus the net effect of the clouds was to warm the surface. Both cold periods occurred under tenuous, or altogether absent, low-level clouds containing little liquid water, effectively reducing the cloud greenhouse effect. Freeze-up progression was enhanced by a combination of increasing solar zenith angles and surface albedo, while inhibited by a large, positive surface cloud forcing until a new air-mass with considerably less cloudiness advected over the experiment area.
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45. |
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46. |
- Solomonidou, A., et al.
(author)
-
Detailed chemical composition analysis of the Soi crater region on Titan
- 2024
-
In: Icarus. - : Elsevier BV. - 0019-1035 .- 1090-2643. ; 421
-
Journal article (peer-reviewed)abstract
- The Soi crater region (0° to 60°N, 180°W to −110°W), which includes the well-preserved Soi crater in its center, spans a region from Titan's aeolian-dominated equatorial regions to fluvially-dominated high northern latitudes. This provides a rich diversity of landscapes, one that is also representative of the diversity encountered across Titan. Schoenfeld et al. (2023) mapped this region at 1:800,000 scale and produced a geomorphological map showing that the area consists of 22 types of geomorphological units. The Visual and Infrared Mapping Spectrometer (VIMS) coverage of the region enabled the detailed analysis of spectra of 261 different locations using a radiative transfer technique and a mixing model, yielding compositional constraints on Titan's optical surface layer. Additional constraints on composition on the near-surface substrate were obtained from microwave emissivity. We have derived combinations of top surface materials between dark materials, tholins, water-ice, and methane suggesting that dark mobile organic material at equatorial and high latitudes indicates “young” terrains and compositions, while tholin/water-ice mixtures that dominate areas around latitude 35°N show a material that is older plains deposits that we interpret to be the end stage of aeolian and fluvial transport and deposition. We found no spectral evidence of CO2, HC3N, and NH3 ice. We use the stratigraphic relations between the various mapping units and the relation between the geomorphology and the composition of the surface layers to build hypotheses on the origin and evolution of the regional geology. We suggest that sedimentary deposits, likely aeolian, are dominant in the region with fluvial activity and leaching changing the nature of the top surfaces of the midlatitude areas of the Soi crater region.
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47. |
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48. |
- Tjernström, Michael, et al.
(author)
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Meteorological conditions in the Central Arctic summer during the arctic summer cloud ocean study (ascos)
- 2012
-
In: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12:15, s. 6863-6889
-
Journal article (peer-reviewed)abstract
- Understanding the rapidly changing climate in the Arctic is limited by a lack of understanding of underlying strong feedback mechanisms that are specific to the Arctic. Progress in this field can only be obtained by process-level observations; this is the motivation for intensive ice-breaker-based campaigns such as the Arctic Summer Cloud-Ocean Study (ASCOS), described here. However, detailed field observations also have to be put in the context of the larger-scale meteorology, and short field campaigns have to be analysed within the context of the underlying climate state and temporal anomalies from this. To aid in the analysis of other parameters or processes observed during this campaign, this paper provides an overview of the synoptic-scale meteorology and its climatic anomaly during the ASCOS field deployment. It also provides a statistical analysis of key features during the campaign, such as key meteorological variables, the vertical structure of the lower troposphere and clouds, and energy fluxes at the surface. In order to assess the representativity of the ASCOS results, we also compare these features to similar observations obtained during three earlier summer experiments in the Arctic Ocean: the AOE-96, SHEBA and AOE-2001 expeditions. We find that these expeditions share many key features of the summertime lower troposphere. Taking ASCOS and the previous expeditions together, a common picture emerges with a large amount of low-level cloud in a well-mixed shallow boundary layer, capped by a weak to moderately strong inversion where moisture, and sometimes also cloud top, penetrate into the lower parts of the inversion. Much of the boundary-layer mixing is due to cloud-top cooling and subsequent buoyant overturning of the cloud. The cloud layer may, or may not, be connected with surface processes depending on the depths of the cloud and surface-based boundary layers and on the relative strengths of surface-shear and cloud-generated turbulence. The latter also implies a connection between the cloud layer and the free troposphere through entrainment at cloud top.
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49. |
- Barlind, Jonas G, et al.
(author)
-
Design and optimization of pyrazinecarboxamide-based inhibitors of diacylglycerol acyltransferase 1 (DGAT1) leading to a clinical candidate dimethylpyrazinecarboxamide phenylcyclohexylacetic acid (AZD7687)
- 2012
-
In: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 55:23, s. 10610-10629
-
Journal article (peer-reviewed)abstract
- A new series of pyrazinecarboxamide DGAT1 inhibitors was designed to address the need for a candidate drug with good potency, selectivity, and physical and DMPK properties combined with a low predicted dose in man. Rational design and optimization of this series led to the discovery of compound 30 (AZD7687), which met the project objectives for potency, selectivity, in particular over ACAT1, solubility, and preclinical PK profiles. This compound showed the anticipated excellent pharmacokinetic properties in human volunteers.
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50. |
- Beshkova, M., et al.
(author)
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Properties of AlN epitaxial layers on 6H-SiC substrate grown by sublimation in argon, nitrogen, and their mixtures
- 2006
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In: Materials Science & Engineering. - : Elsevier. - 0921-5107 .- 1873-4944. ; 129:1-3, s. 228-231
-
Journal article (peer-reviewed)abstract
- Epitaxial layers of aluminum nitride (AlN) have been grown at temperature 1900 °C on 10 mm × 10 mm 6H-SiC substrate via sublimation-recondensation in RF heated graphite furnace. The source material was polycrystalline sintered AlN. Growth of AlN layers in pure nitrogen, mixed nitrogen/argon and pure argon atmosphere of 50 mbar were compared. A maximum growth rate of about 30 µm/h was achieved in pure nitrogen atmosphere. The surface morphology reflects the hexagonal symmetry of the seed, which is characteristic of an epitaxial growth for samples grown in a pure nitrogen and mixed nitrogen/argon atmosphere. X-ray diffraction (XRD) measurements show very strong and well defined (0 0 0 2) reflection positioned at around 36° in symmetric ?-2? scans. Micro-Raman spectroscopy reveals that the films have a wurtzite structure. Secondary-ion mass spectroscopy (SIMS) results showed a low concentration of carbon incorporation in the AlN layers. This study demonstrates that nitrogen is necessary for the successful epitaxial growth of AlN on 6H-SiC by sublimation. © 2006 Elsevier B.V. All rights reserved.
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