Serotonergic brain signaling is considered critical for an appropriate and dynamic adaptation to stress, seemingly through modulating limbic system functions, such as the ...hypothalamic-pituitary-adrenal (HPA)-axis. This interplay is of great interest since it holds promise as a target for preventing stress-related brain disorders, e.g., major depression. Our group has previously observed that prefrontal serotonin transporter (5-HTT) binding, imaged with positron emission tomography (PET), is positively associated with the cortisol awakening response (CAR), an index of HPA axis stress hormone dynamics. The aim of this cross-sectional study was to replicate the previous finding in a larger independent group of healthy individuals. Molecular imaging and cortisol data were available for 90 healthy individuals. Prefrontal 5-HTT binding was imaged with .sup.11 CDASB brain PET. Non-displaceable 5-HTT binding potential (BP.sub.ND) was quantified using the Multilinear Reference Tissue Model 2 (MRTM2) with cerebellum as the reference region. CAR was based on five serial salivary cortisol samples within the first hour upon awakening. The association between CAR and prefrontal 5-HTT BP.sub.ND was evaluated using a multiple linear regression model adjusted for age and sex. Further, we tested for sex differences in the association. Finally, an exploratory analysis of the association, was performed in 8 additional brain regions. We observed no statistically significant association between 5-HTT binding and CAR corrected for age and sex in the prefrontal cortex (beta = -0.28, p = 0.26). We saw no interaction with sex on the association (p = 0.99). We could not confirm a positive association between CAR and prefrontal 5-HTT BP.sub.ND in this independent dataset. Also, sex differences in the association were not apparent. Our data do not exclude that the serotonin transporter system is involved in the regulation of stress responses in at-risk or manifest depressed states.
Fish manipulation has been used to restore lakes in the temperate zone. Often strong short-term cascading effects have been obtained, but the long term-perspectives are less clear. Fish manipulation ...methods are far less advanced for warm lakes, and it is debatable whether it is, in fact, possible to create a trophic cascade in warm lakes due to the dominance and high densities of fast-reproducing omnivorous fish. However, removal of benthic feeding fish also reduce disturbance of the sediment, which not only affects the nutrient level but also the concentration of suspended organic and inorganic matter with enhanced water clarity and potentially better growth conditions for submerged macrophytes. We conducted a biomanipulation experiment in one of the basins in Chinese Huizhou West Lake that have remained highly turbid after extensive nutrient loading reduction. Another basin was used as control (control-treatment pairing design). Removal of a substantial amount of plankti-benthivorous fish was followed by planting of submerged macrophytes and stocking of piscivorous fish. We found strong and relatively long-lasting effects of the restoration initiative in the form of substantial improvements in water clarity and major reductions in nutrient concentrations, particularly total phosphorus, phytoplankton and turbidity, while only minor effects were detected for crustacean zooplankton grazers occurring in low densities before as well as after the restoration. Our results add importantly to the existing knowledge of restoration of warm lakes and are strongly relevant, not least in Asia where natural lakes frequently are used extensively for fish production, often involving massive stocking of benthivorous fish. With a growing economy and development of more efficient fish production systems, the interest in restoring lakes is increasing world-wide. We found convincing evidence that fish removal and piscivores stocking combined with transplantation of submerged macrophytes may have significant effects on water clarity in warm shallow lakes even if the zooplankton grazing potential remains low, the latter most likely as a result of high predation on the zooplankton.
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•Biomanipulation was used to restore a eutrophic shallow lake in tropical China.•Substantial reduction in TP and Chl a concentrations, and turbidity were observed.•Low densities in crustacean zooplankton indicated minor grazing effects on phytoplankton.•The increased bottom-up effect is likely the mechanism for success in restoration in this warm lake.
We usemeasurements of nitrogen abundances in red giants to search formultiple stellar populations in the four most metal-poor globular clusters (GCs) in the Fornax dwarf spheroidal galaxy (Fornax 1, ...2, 3, and 5). New imaging in the F343N filter, obtained with the Wide Field Camera 3 on the Hubble Space Telescope, is combined with archival F555W and F814W observations to determine the strength of the NH band near 3370 A. After accounting for observational errors, the spread in the F343N-F555W colors of red giants in the Fornax GCs is similar to that in M15 and corresponds to an abundance range of Delta N/Fe ~ 2 dex, as observed also in several Galactic GCs. The spread in F555W-F814W is, instead, fully accounted for by observational errors. The stars with the reddest F343N-F555W colors (indicative of N-enhanced composition) have more centrally concentrated radial distributions in all four clusters, although the difference is not highly statistically significant within any individual cluster. From double-Gaussian fits to the color distributions, we find roughly equal numbers of "N-normal" and "N-enhanced" stars (formally ~40% N-normal stars in Fornax 1, 3, and 5 and ~60% in Fornax 2). We conclude that GC formation, in particular, regarding the processes responsible for the origin of multiple stellar populations, appears to have operated similarly in the Milky Way and in the Fornax dSph. Combined with the high ratio of metal-poor GCs to field stars in the Fornax dSph, this places an important constraint on scenarios for the origin of multiple stellar populations in GCs.
Full-Scale Spectrum of Boundary-Layer Winds Larsén, Xiaoli G.; Larsen, Søren E.; Petersen, Erik L.
Boundary-layer meteorology,
05/2016, Letnik:
159, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Extensive mean meteorological data and high frequency sonic anemometer data from two sites in Denmark, one coastal onshore and one offshore, have been used to study the full-scale spectrum of ...boundary-layer winds, over frequencies f from about Formula: see text to 10 Hz. 10-min cup anemometer data are used to estimate the spectrum from about Formula: see text to Formula: see text; in addition, using 20-Hz sonic anemometer data, an ensemble of 1-day spectra covering the range Formula: see text to 10 Hz has been calculated. The overlapping region in these two measured spectra is in good agreement. Classical topics regarding the various spectral ranges, including the spectral gap, are revisited. Following the seasonal peak at Formula: see text, the frequency spectrum fS(f) increases with Formula: see text and gradually reaches a peak at about Formula: see text. From this peak to about Formula: see text, the spectrum fS(f) decreases with frequency with a Formula: see text slope, followed by a Formula: see text slope, which can be described by Formula: see text, ending in the frequency range for which the debate on the spectral gap is ongoing. It is shown here that the spectral gap exists and can be modelled. The linear composition of the horizontal wind variation from the mesoscale and microscale gives the observed spectrum in the gap range, leading to a suggestion that mesoscale and microscale processes are uncorrelated. Depending on the relative strength of the two processes, the gap may be deep or shallow, visible or invisible. Generally, the depth of the gap decreases with height. In the low frequency region of the gap, the mesoscale spectrum shows a two-dimensional isotropic nature; in the high frequency region, the classical three-dimensional boundary-layer turbulence is evident. We also provide the cospectrum of the horizontal and vertical components, and the power spectra of the three velocity components over a wide range from Formula: see text to 10 Hz, which is useful in determining the necessary sample duration when measuring turbulence statistics in the boundary layer.
The legislative process before the adoption of the revised European Union renewable energy directive mobilised various actors around the forest biomass issue in Europe. Which storylines do actors use ...to discuss and define the sustainability of forest biomass, how are the differences between the existing storylines explained, and can distinct 'discourse coalitions' of actors be observed as following each storyline? These questions are addressed through a discourse analysis to critically evaluate the debate around the utilisation of forest biomass for European renewable energy to identify persistent storylines adopted by discourse coalitions as they communicate their understanding of the issue, and compete to influence the policymaking and public perception. The hypotheses are that there are more than the hypothetical binary arrangement of pro versus anti storylines, and that some actors follow multiple storylines. Locating the methodological approach on the two dimensions; text versus context and critical versus constructivist, this study pays closer attention to context rather than on individual linguistic elements of texts. Regarding the second dimension, this study builds upon constructivist epistemology, being concerned with understanding which truths these storylines produce for their speakers, and their external influences upon alternative storylines and actors. The three storylines presented here represent three competing discourses regarding forest biomass usage in European renewable energy: forestry prioritised, climate focussed and critical. Each of these are promoted by actors aiming to gain discursive hegemony on the issue, both in terms of the impact of their discourse upon EU policy making and in the eyes of the public. Despite the discursive differences created by these deeply held opposing views of what sustainability and nature are and what this means for forest biomass, there were several points where narrative elements overlapped. These can provide insight for developing a more constructive debate on the sustainability of forest biomass.
Denmark and Sweden have an annual cultivation of straw-producing crops on about 16,000 and 11,000 km2 respectively. However, the actual use of straw for energy differs considerably: 1.35 Tg y−1 in ...Denmark and 0.11 Tg y−1 in Sweden. The main objective of this study was to investigate why the use of straw for energy is much larger in Denmark than in Sweden. Differences and commonalities in the conditions for the production and use of straw were reviewed. It was shown that both countries have used a large number of governmental support programmes, as well as monetary instruments (e.g. CO2-taxes), to promote the use of bioenergy in general. In contrast to Denmark, however, there have been no specific governmental incentives in Sweden directed at increasing the use of straw for energy. One reason may be the vast and relatively low-cost resources of forest biomass in relation to the available resources of straw. The price of competing fuels such as wood chips and wood pellets has generally been 5–15% higher in Denmark than in Sweden. More in depth regional analyses for eastern Denmark and Scania in south Sweden showed that straw production costs are somewhat lower in eastern Denmark as a result of shorter transport distances, earlier ripening of straw-producing crops and better weather conditions during harvest. At present, expert knowledge and the existence of a mature industry favour the large-scale production and use of straw in Denmark.
•Denmark uses 1.35 Tg of straw for energy annually compared to 0.11 Tg in Sweden.•The mandate on straw use result in a 1200% greater use of straw for energy in Denmark than in Sweden.•The price for fuels competing with straw is 5–15% higher in Denmark compared to Sweden.•The straw resource density in eastern Denmark is almost double that of Scania in southern Sweden.
We examine the radial distributions of stellar populations in the globular cluster (GC) M15, using Hubble Space Telescope/Wide Field Camera 3 (WFC3) photometry of red giants in the nitrogen-sensitive ...F343N-F555W color. Surprisingly, we find that giants with "primordial" composition (i.e., N abundances similar to those in field stars) are the most centrally concentrated within the WFC3 field. We then combine our WFC3 data with Sloan Digital Sky Survey u, g photometry and find that the trend reverses for radii > ~1' (3 pc) where the ratio of primordial to N-enhanced giants increases outward, as already found by Lardo et al. The ratio of primordial to enriched stars thus has a U-shaped dependency on radius with a minimum near the half-light radius. N-body simulations show that mass segregation might produce a trend resembling the observed one, but only if the N-enhanced giants are ~0.25 M sub(middot in circle) less massive than the primordial giants, which requires extreme He enhancement (Y > ~ 0.40). However, such a large difference in Y is incompatible with the negligible optical color differences between primordial and enriched giants, which suggest Delta Y <, ~ 0.03 and thus a difference in turn-off mass of Delta M <, ~ 0.04 M sub(middot in circle) between the different populations. The radial trends in M15 are thus unlikely to be of dynamical origin and presumably reflect initial conditions, a result that challenges all current GC formation scenarios. We note that population gradients in the central regions of GCs remain poorly investigated and may show a more diverse behavior than hitherto thought.
ABSTRACT We use the Panchromatic Hubble Andromeda Treasury survey data set to perform spatially resolved measurements of star cluster formation efficiency (Γ), the fraction of stellar mass formed in ...long-lived star clusters. We use robust star formation history and cluster parameter constraints, obtained through color-magnitude diagram analysis of resolved stellar populations, to study Andromeda's cluster and field populations over the last ∼300 Myr. We measure Γ of 4%-8% for young, 10-100 Myr-old populations in M31. We find that cluster formation efficiency varies systematically across the M31 disk, consistent with variations in mid-plane pressure. These Γ measurements expand the range of well-studied galactic environments, providing precise constraints in an H i-dominated, low-intensity star formation environment. Spatially resolved results from M31 are broadly consistent with previous trends observed on galaxy-integrated scales, where Γ increases with increasing star formation rate surface density ( SFR). However, we can explain observed scatter in the relation and attain better agreement between observations and theoretical models if we account for environmental variations in gas depletion time (τdep) when modeling Γ, accounting for the qualitative shift in star formation behavior when transitioning from a H2-dominated to a H i-dominated interstellar medium. We also demonstrate that Γ measurements in high SFR starburst systems are well-explained by τdep-dependent fiducial Γ models.
Abstract
Background
A prominent finding in major depressive disorder (MDD) is distorted stress hormone dynamics, which is regulated by serotonergic brain signaling. An interesting feature of the ...cerebral serotonin system is the serotonin 4 receptor (5-HT4R), which is lower in depressed relative to healthy individuals and also has been highlighted as a promising novel antidepressant target. Here, we test the novel hypothesis that brain 5-HT4R availability in untreated patients with MDD is correlated with cortisol dynamics, indexed by the cortisol awakening response (CAR). Further, we evaluate if CAR changes with antidepressant treatment, including a selective serotonin reuptake inhibitor, and if pretreatment CAR can predict treatment outcome.
Methods
Sixty-six patients (76% women) with a moderate to severe depressive episode underwent positron emission tomography imaging with 11CSB207145 for quantification of brain 5-HT4R binding using BPND as outcome. Serial home sampling of saliva in the first hour from awakening was performed to assess CAR before and after 8 weeks of antidepressant treatment. Treatment outcome was measured by change in Hamilton Depression Rating Scale 6 items.
Results
In the unmedicated depressed state, prefrontal and anterior cingulate cortices 5-HT4R binding was positively associated with CAR. CAR remained unaltered after 8 weeks of antidepressant treatment, and pretreatment CAR did not significantly predict treatment outcome.
Conclusions
Our findings highlight a link between serotonergic disturbances in MDD and cortisol dynamics, which likely is involved in disease and treatment mechanisms. Further, our data support 5-HT4R agonism as a promising precision target in patients with MDD and disturbed stress hormone dynamics.
1. Methods are needed to relate changing river flows to ecological response, particularly those which do not require collection of extensive new data for river segments that lack historical data. ...Using time-series of river biomonitoring data from wadeable lowland streams in Denmark and the East Midlands of the U.K., we describe how local-scale habitat features (indexed through River Habitat Survey or Danish Habitat Quality Survey) and changing river flow (discharge) influence the response of a macroinvertebrate community index. The approach has broad applicability in developing regional flow-ecological response models. 2. We analysed the data using multilevel linear regression, combining sample-level and site-level characteristics as predictors. We focused on the potential for common responses across sites; hence for each sample, the macroinvertebrate community was summarised into an index, Lotic Invertebrate index for Flow Evaluation (LIFE), an average of abundance-weighted flow groups which indicate the microhabitat preferences of each taxon for higher velocities and clean gravel/cobble substrata or slow/still velocities and finer substrata. 3. For the Danish fauna, the LIFE score responded to three predictors in an additive manner: high flows in the preceding 4 months (positive), substratum composition and whether the channel was meandering or straight. The East Midlands fauna responded to three predictors: high and low flows in the preceding 6 months (positive) and the degree of resectioning of the channel (negative). In both cases, LIFE responded negatively to features associated with historical channel modification. We suggest that there are several mechanisms for these relationships, including the narrower tolerances of taxa preferring high velocity habitat; these taxa are also continually recovering from extreme flow events over an inter-annual timescale. 4. At the East Midlands sites, there was an interaction between degree of resectioning and antecedent low flow. At sites with a greater extent of resectioning, the LIFE-discharge relationship was also steeper than at less modified sites. Consideration of the underlying data suggests that there are two mechanisms for this response. Firstly, in less modified sites, refugia are present during low flows for taxa preferring higher velocities such as riffle beetles, caseless caddis, mayflies and Gammarus pulex. Secondly, high flows are associated with decreasing abundances of taxa such as molluscs, flatworms and leeches at more resectioned sites, but with stable or increasing abundances at less modified sites. 5. The LIFE index responded to both antecedent flow and habitat modification in two separate data sets from lowland wadeable streams. This is the first time that the combined importance of these two factors has been demonstrated using routine invertebrate biomonitoring data. These results complement other site-specific studies that have shown how channel structure interacts with flow to create physical habitat, and should assist future work aiming to define flow-habitat-biota relationships. 6. The derived models may be used to help guide environmental flow allocations, for example by predicting the slope of response of LIFE score to flow for comparable new locations which lack biological data.
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