247 research outputs found
Kupeantha (Coffeeae, Rubiaceae), a new genus from Cameroon and Equatorial Guinea
Two new coffee relatives (tribe Coffeeae, Rubiaceae), discovered during botanical expeditions to Cameroon, are examined for generic placement, and the placement of three previously known species (Argocoffeopsis fosimondi, A. spathulata and Calycosiphonia pentamera) is reinvestigated using plastid sequence (accD-psa1, rpl16, trnL-F) and morphological data. Seed biochemistry of the new species and pollen micromorphology (only one of the two species) are also studied. Based on the plastid sequence data, the new taxa are nested in a wellsupported monophyletic group that includes Argocoffeopsis and Calycosiphonia. Within this clade, three well-supported subclades are recovered that are morphologically easy to diagnose: (1) Calycosiphonia (excluding C. pentamera), (2) Argocoffeopsis (excluding A. fosimondi and A. spathulata), and (3) a clade including the above excluded species, in addition to the new species. Based on the results, Kupeantha, a new genus of five species, is described, including two new Critically Endangered taxa from the Highlands of Cameroon: Kupeantha ebo and K. kupensis. Phytochemical analysis of Kupeantha seeds reveals compounds assigned as hydroxycinnamic acid derivatives, amino acids and ent-kaurane diterpenoids; caffeine was not detected. Kupeantha is the first new genus described in tribe Coffeeae in 40 years
Moho depth and crustal thinning in the Marmara Sea region from gravity data inversion
The freeâair gravity in the Marmara Sea reveals that the low density of sedimentary basins is partly compensated in the lower crust. We compiled geophysical upper crust studies to determine the sediment basin geometries in and around the Marmara Sea and corrected the gravity signal from this upper crust geology with the Parker method. Then, assuming long wavelength anomalies in the residual gravity signal is caused by variations in the Moho topography, we inverted the residual to build the Moho topography. The result shows that the Moho is uplifted on an area greater than the Marmara Sea with a maximum crust thinning beneath the basins where the Moho is at about 25âkm, 5âkm above the reference depth. We then evaluated the Neogene extension by comparing the surface covered by our 3âD thinned model with the surface covered by an unthinned model with same crustal volume. Comparing this surface with areal extension rate from GPS data, we found a good compatibility indicating that the extension rate averaged over the Sea of Marmara area probably remained close to its presentâday value during major changes of tectonic regime, as the incursion of the North Anatolian Fault system during the Pliocene leads to the establishment of the dominantly strikeâslip presentâday system. We also show that crustal extension is distributed over a wider domain in the lower crust than in the upper crust, and that this may be accounted for by a relatively minor component of lower crustal ductile flow
Coronal Diagnostics from Narrowband Images around 30.4 nm
Images taken in the band centered at 30.4 nm are routinely used to map the
radiance of the He II Ly alpha line on the solar disk. That line is one of the
strongest, if not the strongest, line in the EUV observed in the solar
spectrum, and one of the few lines in that wavelength range providing
information on the upper chromosphere or lower transition region. However, when
observing the off-limb corona the contribution from the nearby Si XI 30.3 nm
line can become significant. In this work we aim at estimating the relative
contribution of those two lines in the solar corona around the minimum of solar
activity. We combine measurements from CDS taken in August 2008 with
temperature and density profiles from semiempirical models of the corona to
compute the radiances of the two lines, and of other representative coronal
lines (e.g., Mg X 62.5 nm, Si XII 52.1 nm). Considering both diagnosed
quantities from line ratios (temperatures and densities) and line radiances in
absolute units, we obtain a good overall match between observations and models.
We find that the Si XI line dominates the He II line from just above the limb
up to ~2 R_Sun in streamers, while its contribution to narrowband imaging in
the 30.4 nm band is expected to become smaller, even negligible in the corona
beyond ~2 - 3 R_Sun, the precise value being strongly dependent on the coronal
temperature profile.Comment: 26 pages, 11 figures; to be published in: Solar Physic
Sediment Delivery to Sustain the Ganges-Brahmaputra Delta Under Climate Change and Anthropogenic Impacts
The principal nature-based solution for offsetting relative sea-level rise in the Ganges-Brahmaputra delta is the unabated delivery, dispersal, and deposition of the riversâ ~1 billion-tonne annual sediment load. Recent hydrological transport modeling suggests that strengthening monsoon precipitation in the 21st century could increase this sediment delivery 34-60%; yet other studies demonstrate that sediment could decline 15-80% if planned dams and river diversions are fully implemented. We validate these modeled ranges by developing a comprehensive field-based sediment budget that quantifies the supply of Ganges-Brahmaputra river sediment under varying Holocene climate conditions. Our data reveal natural responses in sediment supply comparable to previously modeled results and suggest that increased sediment delivery may be capable of offsetting accelerated sea-level rise. This prospect for a naturally sustained Ganges-Brahmaputra delta presents possibilities beyond the dystopian future often posed for this system, but the implementation of currently proposed dams and diversions would preclude such opportunities
Clinical, psychopathological, and personality characteristics associated with ADHD among individuals seeking treatment for gambling disorder
Objectives: (1) To assess the current presence of ADHD symptoms among patients seeking treatment for gambling disorder; (2) to explore clinical and sociodemographic differences between patients who score high and low on the measure of ADHD symptoms; (3) to analyze whether the presence of ADHD symptoms is associated with more severe psychopathology and with specific personality traits; (4) to analyze the mediating role of ADHD symptoms in the relationship between novelty seeking and gambling severity. Method: A total of 354 consecutive patients were administered an extensive battery assessing gambling behavior, psychopathology, and personality traits. Results: Male and female gamblers did not differ significantly in their mean scores on the ADHD measure. However, younger participants aged 18-35 scored higher. Higher ADHD scores were also associated with greater severity of gambling disorder and more general psychopathology. Regarding personality traits, high persistence and self-directedness were negatively related to ADHD scores, while in women alone a positive correlation was found between ADHD scores and scores on harm avoidance and self-transcendence. Conclusion: The presence of ADHD symptoms in both male and female gambling disorder patients may act as an indicator of the severity of gambling, general psychopathology, and dysfunctional personality traits
Maerl grounds : habitats of high biodiversity in European seas
The BIOMAERL programme is a 3-year collaborative programme between laboratories in UK, Spain, France and Malta which began in February 1996. Its main plans are described in the workplan. A full inventory of the biological composition (biodiversity) of maerl bed assemblages in these regions therefore has yet to be completed, but progress is outlined below.peer-reviewe
Gas and seismicity within the Istanbul seismic gap
Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the âIstanbul seismic gapâ) has been extensively studied in order to infer its mechanical behaviour (creeping vs locked). So far, the seismicity has been interpreted only in terms of being tectonic-driven, although the Main Marmara Fault (MMF) is known to strike across multiple hydrocarbon gas sources. Here, we show that a large number of the aftershocks that followed the M 5.1 earthquake of July, 25th 2011 in the western Sea of Marmara, occurred within a zone of gas overpressuring in the 1.5â5âkm depth range, from where pressurized gas is expected to migrate along the MMF, up to the surface sediment layers. Hence, gas-related processes should also be considered for a complete interpretation of the micro-seismicity (~Mâ<â3) within the Istanbul offshore domain
Origins of the Ambient Solar Wind: Implications for Space Weather
The Sun's outer atmosphere is heated to temperatures of millions of degrees,
and solar plasma flows out into interplanetary space at supersonic speeds. This
paper reviews our current understanding of these interrelated problems: coronal
heating and the acceleration of the ambient solar wind. We also discuss where
the community stands in its ability to forecast how variations in the solar
wind (i.e., fast and slow wind streams) impact the Earth. Although the last few
decades have seen significant progress in observations and modeling, we still
do not have a complete understanding of the relevant physical processes, nor do
we have a quantitatively precise census of which coronal structures contribute
to specific types of solar wind. Fast streams are known to be connected to the
central regions of large coronal holes. Slow streams, however, appear to come
from a wide range of sources, including streamers, pseudostreamers, coronal
loops, active regions, and coronal hole boundaries. Complicating our
understanding even more is the fact that processes such as turbulence,
stream-stream interactions, and Coulomb collisions can make it difficult to
unambiguously map a parcel measured at 1 AU back down to its coronal source. We
also review recent progress -- in theoretical modeling, observational data
analysis, and forecasting techniques that sit at the interface between data and
theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue
connected with a 2016 ISSI workshop on "The Scientific Foundations of Space
Weather." 44 pages, 9 figure
SIRTA, a ground-based atmospheric observatory for cloud and aerosol research
Ground-based remote sensing observatories have a crucial role to play in providing data to improve our understanding of atmospheric processes, to test the performance of atmospheric models, and to develop new methods for future space-borne observations. Institut Pierre Simon Laplace, a French research institute in environmental sciences, created the Site Instrumental de Recherche par T&#233;l&#233;d&#233;tection Atmosph&#233;rique (SIRTA), an atmospheric observatory with these goals in mind. Today SIRTA, located 20km south of Paris, operates a suite a state-of-the-art active and passive remote sensing instruments dedicated to routine monitoring of cloud and aerosol properties, and key atmospheric parameters. Detailed description of the state of the atmospheric column is progressively archived and made accessible to the scientific community. This paper describes the SIRTA infrastructure and database, and provides an overview of the scientific research associated with the observatory. Researchers using SIRTA data conduct research on atmospheric processes involving complex interactions between clouds, aerosols and radiative and dynamic processes in the atmospheric column. Atmospheric modellers working with SIRTA observations develop new methods to test their models and innovative analyses to improve parametric representations of sub-grid processes that must be accounted for in the model. SIRTA provides the means to develop data interpretation tools for future active remote sensing missions in space (e.g. CloudSat and CALIPSO). SIRTA observation and research activities take place in networks of atmospheric observatories that allow scientists to access consistent data sets from diverse regions on the globe
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