| 1. |
- Cohen, Judah, et al.
(författare)
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ARCTIC CHANGE AND POSSIBLE INFLUENCE ON MID-LATITUDE CLIMATE AND WEATHER - A US CLIVAR White Paper
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Arctic has warmed more than twice as fast as the global average since the mid 20th century, a phenomenon known as Arctic amplification (AA). These profound changes to the Arctic system have coincided with a period of ostensibly more frequent events of extreme weather across the Northern Hemisphere (NH) mid-latitudes, including extreme heat and rainfall events and recent severe winters. Though winter temperatures have generally warmed since 1960 over mid-to-high latitudes, the acceleration in the rate of warming at high-latitudes, relative to the rest of the NH, started approximately in 1990. Trends since 1990 show cooling over the NH continents, especially in Northern Eurasia. The possible link between Arctic change and mid-latitude climate and weather has spurred a rush of new observational and modeling studies. A number of workshops held during 2013-2014 have helped frame the problem and have called for continuing and enhancing efforts for improving our understanding of Arctic-mid-latitude linkages and its attribution to the occurrence of extreme climate and weather events. Although these workshops have outlined some of the major challenges and provided broad recommendations, further efforts are needed to synthesize the diversified research results to identify where community consensus and gaps exist. Building upon findings and recommendations of the previous workshops, the US CLIVAR Working Group on Arctic Change and Possible Influence on Mid-latitude Climate and Weather convened an international workshop at Georgetown University in Washington, DC, on February 1-3, 2017. Experts in the fields of atmosphere, ocean, and cryosphere sciences assembled to assess the rapidly evolving state of understanding, identify consensus on knowledge and gaps in research, and develop specific actions to accelerate progress within the research community. With more than 100 participants, the workshop was the largest and most comprehensive gathering of climate scientists to address the topic to date. In this white paper, we synthesize and discuss outcomes from this workshop and activities involving many of the working group members.
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| 2. |
- de Jong, Roelof S., et al.
(författare)
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4MOST-4-metre Multi-Object Spectroscopic Telescope
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147
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Konferensbidrag (refereegranskat)abstract
- 4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with similar to 2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; similar to 1600 fibres go to two spectrographs with resolution R> 5000 (lambda similar to 390-930 nm) and similar to 800 fibres to a spectrograph with R> 18,000 (lambda similar to 392-437 nm & 515-572 nm & 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020. This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].
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| 3. |
- Ebner, Natalie C., et al.
(författare)
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Oxytocin modulates meta-mood as a function of age and sex
- 2015
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Ingår i: Frontiers in Aging Neuroscience. - : Frontiers Media SA. - 1663-4365 .- 1663-4365. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Attending to and understanding one's own feelings are components of meta mood and constitute important socio-affective skills across the entire lifespan. Growing evidence suggests a modulatory role of the neuropeptide oxytocin on various socio-affective processes. Going beyond previous work that almost exclusively examined young men and perceptions of emotions in others, the current study investigated effects of intranasal oxytocin on meta-mood in young and older men and women. In a double-blind between-group design, participants were randomly assigned to self-administer either intranasal oxytocin or a placebo before responding to items from the Trait Meta Mood Scale (TMMS) about attention to feelings and clarity of feelings. In contrast to older women, oxytocin relative to placebo increased attention to feelings in older men. Oxytocin relative to placebo enhanced meta-mood in young female participants but reduced it in older female participants. This pattern of findings supports an age- and sex-differential modulatory function of the neuropeptide oxytocin on meta-mood, possibly associated with neurobiological differences with age and sex.
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| 4. |
- Ebner, Natalie C., et al.
(författare)
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Oxytocin’s effect on resting-state functional connectivity varies by age and sex
- 2016
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Ingår i: Psychoneuroendocrinology. - : Elsevier BV. - 0306-4530 .- 1873-3360. ; 69, s. 50-59
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Tidskriftsartikel (refereegranskat)abstract
- The neuropeptide oxytocin plays a role in social cognition and affective processing. The neural processes underlying these effects are not well understood. Modulation of connectivity strength between subcortical and cortical regions has been suggested as one possible mechanism. The current study investigated effects of intranasal oxytocin administration on resting-state functional connectivity between amygdala and medial prefrontal cortex (mPFC), as two regions involved in social-cognitive and affective processing. Going beyond previous work that largely examined young male participants, our study comprised young and older men and women to identify age and sex variations in oxytocin’s central processes. This approach was based on known hormonal differences among these groups and emerging evidence of sex differences in oxytocin’s effects on amygdala reactivity and age-by-sex-modulated effects of oxytocin in affective processing. In a double-blind design, 79 participants were randomly assigned to self-administer either intranasal oxytocin or placebo before undergoing resting-state functional magnetic resonance imaging. Using a targeted region-to-region approach, resting-state functional connectivity strength between bilateral amygdala and mPFC was examined. Participants in the oxytocin compared to the placebo group and men compared to women had overall greater amygdala–mPFC connectivity strength at rest. These main effects were qualified by a significant three-way interaction: while oxytocin compared to placebo administration increased resting-state amygdala–mPFC connectivity for young women, oxytocin did not significantly influence connectivity in the other age-by-sex subgroups. This study provides novel evidence of age-by-sex differences in how oxytocin modulates resting-state brain connectivity, furthering our understanding of how oxytocin affects brain networks at rest.
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| 5. |
- Gérard, Violaine, et al.
(författare)
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Anionic, Cationic, and Nonionic Surfactants in Atmospheric Aerosols from the Baltic Coast at Asko, Sweden : Implications for Cloud Droplet Activation
- 2016
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 50:6, s. 2974-2982
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Tidskriftsartikel (refereegranskat)abstract
- Recent analyses of atmospheric aerosols from different regions have demonstrated the ubiquitous presence of strong surfactants and evidenced surface tension values, sigma, below 40 mN m(-1), suspected to enhance the cloud-forming potential of these aerosols. In this work, this approach was further improved and combined with absolute concentration measurements of aerosol surfactants by colorimetric titration. This analysis was applied to PM2.5 aerosols collected at the Baltic station of Asko, Sweden, from July to October 2010. Strong surfactants were found in all the sampled aerosols, with sigma = (32-40) +/- 1 mN m(-1) and concentrations of at least 27 +/- 6 mM or 104 +/- 21 pmol m(-3). The absolute surface tension curves and critical micelle concentrations (CMC) determined for these aerosol surfactants show that (1) surfactants are concentrated enough in atmospheric particles to strongly depress the surface tension until activation, and (2) the surface tension does not follow the Szyszkowski equation during activation but is nearly constant and minimal, which provides new insights on cloud droplet activation. In addition, both the CMCs determined and the correlation (R-2 similar to 0.7) between aerosol surfactant concentrations and chlorophyll-a seawater concentrations suggest a marine and biological origin for these compounds.
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| 6. |
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| 7. |
- Gulliford, Desiree, et al.
(författare)
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Gender-differential effects of intranasal oxytocin on resting-state anterior cingulate activity
- 2017
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Konferensbidrag (refereegranskat)abstract
- Introduction: As individuals age, there is an increased focus on social relationships (Carstensen, 2006). However, age-related changes in the brain can interfere with social functioning (Ebner, et al, 2012; Mather, et al, 2005; Ruffman, et al, 2008). While age-related changes in cognition are well studied, social-cognitive changes in aging are still underinvestigated, especially the brain mechanisms underlying this phenomenon. The administration of intranasal oxytocin (OT) has the potential to modulate social cognition (De Dreu, 2014) by altering BOLD signal in regions of the social brain (eg. amygdala and vmPFC) (Ebner, et al, 2016). Currently, there is very little known about the role of OT in human development in aging (Campbell, et al, 2014; Huffmeijer, et al, 2012). Methods: 40 young (18–31 years, 50% female) and 39 older (63–81 years, 59% female) were randomly assigned (in a double-blind design) to self-administer either 24 UIs of intranasal OT or placebo (P) 70-90 minutes prior to resting-state fMRI. T1-weighted anatomical reference images, using an MP-RAGE sequence (sagittal plane, FOV = 240 mm × 240 mm × 170; 1 × 1 × 1 mm isotropic voxels), and functional gradient-echo-planar imaging (EPI) data, during an open-eye, white cross-hair on black background, 8 minute resting-state scan (38 interleaved slices, TR 2 sec, TE 30 msec, FOV 252 × 252 × 133 mm, 80 × 80 × 38 mm matrix, flip angle 90°, in plane resolution of 3.15 × 3.15 mm, slice thickness 3.5 mm, 0 mm skip), were acquired with a 3T Philips Achieva MR Scanner using a 32-channel head coil. Preprocessing, including slice time correction, motion correction with artifact rejection, spatial normalization, and smoothing with an 8 mm Gaussian kernel, were implemented with Functional Connectivity Toolbox (Whitfield-Gabrieli, et al, 2012; http://www.nitrc.org/projects/conn/). Results: Younger individuals showed significantly greater overall anterior cingulate (AC) activity in P condition (p=.044). Intranasal OT administration significantly increased activity in the AC in both younger and older women (p=.024), but not men, when compared to P. The effect was slightly greater in older women than younger, but this effect was not significant potentially due to sample size.There were no significant gender effects in AC activity during rest between males and females in either younger or older P control groups. Conclusions: Intranasal OT has differential gender effects on AC activity during resting-state, increasing activity in women but not men. Additionally, there is evidence for age differences in overall AC activity at rest.
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| 8. |
- Haynes, Roger, et al.
(författare)
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The 4MOST instrument concept overview
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147, s. 91476-91476
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Konferensbidrag (refereegranskat)abstract
- The 4MOST([1]) instrument is a concept for a wide-field, fibre-fed high multiplex spectroscopic instrument facility on the ESO VISTA telescope designed to perform a massive (initially >25x10(6) spectra in 5 years) combined all-sky public survey. The main science drivers are: Gaia follow up of chemo-dynamical structure of the Milky Way, stellar radial velocities, parameters and abundances, chemical tagging; eROSITA follow up of cosmology with x-ray clusters of galaxies, X-ray AGN/galaxy evolution to z similar to 5, Galactic X-ray sources and resolving the Galactic edge; Euclid/LSST/SKA and other survey follow up of Dark Energy, Galaxy evolution and transients. The surveys will be undertaken simultaneously requiring: highly advanced targeting and scheduling software, also comprehensive data reduction and analysis tools to produce high-level data products. The instrument will allow simultaneous observations of similar to 1600 targets at R similar to 5,000 from 390-900nm and similar to 800 targets at R>18,000 in three channels between similar to 395-675nm (channel bandwidth: 45nm blue, 57nm green and 69nm red) over a hexagonal field of view of similar to 4.1 degrees2. The initial 5-year 4MOST survey is currently expect to start in 2020. We provide and overview of the 4MOST systems: opto-mechanical, control, data management and operations concepts; and initial performance estimates.
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| 9. |
- Lee, Ben H, et al.
(författare)
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Highly functionalized organic nitrates in the southeast United States: Contribution to secondary organic aerosol and reactive nitrogen budgets.
- 2016
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 113:6, s. 1516-21
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Tidskriftsartikel (refereegranskat)abstract
- Speciated particle-phase organic nitrates (pONs) were quantified using online chemical ionization MS during June and July of 2013 in rural Alabama as part of the Southern Oxidant and Aerosol Study. A large fraction of pONs is highly functionalized, possessing between six and eight oxygen atoms within each carbon number group, and is not the common first generation alkyl nitrates previously reported. Using calibrations for isoprene hydroxynitrates and the measured molecular compositions, we estimate that pONs account for 3% and 8% of total submicrometer organic aerosol mass, on average, during the day and night, respectively. Each of the isoprene- and monoterpenes-derived groups exhibited a strong diel trend consistent with the emission patterns of likely biogenic hydrocarbon precursors. An observationally constrained diel box model can replicate the observed pON assuming that pONs (i) are produced in the gas phase and rapidly establish gas-particle equilibrium and (ii) have a short particle-phase lifetime (∼2-4 h). Such dynamic behavior has significant implications for the production and phase partitioning of pONs, organic aerosol mass, and reactive nitrogen speciation in a forested environment.
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| 10. |
- Lessios, Nicolas, et al.
(författare)
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Multiple spectral channels in branchiopods. I. Vision in dim light and neural correlates
- 2018
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 221:10
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Tidskriftsartikel (refereegranskat)abstract
- Animals that have true color vision possess several spectral classes of photoreceptors. Pancrustaceans (Hexapoda+Crustacea) that integrate spectral information about their reconstructed visual world do so from photoreceptor terminals supplying their second optic neuropils, with subsequent participation of the third (lobula) and deeper centers (optic foci). Here, we describe experiments and correlative neural arrangements underlying convergent visual pathways in two species of branchiopod crustaceans that have to cope with a broad range of spectral ambience and illuminance in ephemeral pools, yet possess just two optic neuropils, the lamina and the optic tectum. Electroretinographic recordings and multimodel inference based on modeled spectral absorptance were used to identify the most likely number of spectral photoreceptor classes in their compound eyes. Recordings from the retina provide support for four color channels. Neuroanatomical observations resolve arrangements in their laminas that suggest signal summation at low light intensities, incorporating chromatic channels. Neuroanatomical observations demonstrate that spatial summation in the lamina of the two species are mediated by quite different mechanisms, both of which allow signals from several ommatidia to be pooled at single lamina monopolar cells. We propose that such summation provides sufficient signal for vision at intensities equivalent to those experienced by insects in terrestrial habitats under dim starlight. Our findings suggest that despite the absence of optic lobe neuropils necessary for spectral discrimination utilized by true color vision, four spectral photoreceptor classes have been maintained in Branchiopoda for vision at very low light intensities at variable ambient wavelengths that typify conditions in ephemeral freshwater habitats.
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