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Background: Migraine is a prevalent and disabling condition with limited understanding in the developing brain. Adults with chronic migraine show structural alterations in pain and sensory processing regions. Similar data is lacking in children and required for early intervention. Methods: Case-control feasibility study assessing structural brain differences between adolescents with chronic migraine and healthy controls using 3T Siemens structural volumetric MRI analysis. Fifteen subjects with chronic migraine were compared to 25 age and sex matched healthy controls. Non-parametric statistics performed (Kruskal-Wallis). Results: Migraine subjects had reduced volumes in total brain (grey and white matter) (KW p <0.03), total thalamus (KW p <0.01) and hippocampal regions (KW p <0.03). Unilateral (right) cerebellar grey matter volumes were significantly reduced in migraine subjects versus controls (KW p<0.05). No significant differences were found in other regions, including basal ganglia, cortical grey matter and brainstem. Conclusions: Total brain, hippocampal and thalamic volumetric reductions are seen in adolescents with chronic migraine. The regions identified are involved in migraine pathogenesis. This volumetric imaging study should improve understanding of the causes and effects of pediatric migraine.
Cambodia supports populations of three Critically Endangered vulture species that are believed to have become isolated from the rest of the species’ global range. Until recently Cambodia’s vulture populations had remained stable. However a recent spike in the number of reports of the use of poisons in hunting practices suggests the need to re-evaluate the conservation situation in Cambodia. Population trend analysis showed that since 2010 populations of the White-rumped Vulture Gyps bengalensis and Red-headed Vulture Sarcogyps calvus have declined, while the Slender-billed Vulture Gyps tenuirostris may also have started to decline since 2013. These trends are supported by evidence of reduced nesting success. A survey of veterinary drug availability revealed that diclofenac, the non-steroid anti-inflammatory drug responsible for vulture declines in South Asia was not available for sale in any of the 74 pharmacies surveyed. However, a poisoned Slender-billed Vulture tested positive for carbofuran in toxicology tests. This provides the first evidence of a vulture mortality resulting from carbofuran in Cambodia. The findings suggest the urgent need to tackle use of carbamate pesticides in hunting. Proposed conservation actions are: a) prevention of poisoning through national bans on harmful carbamate pesticides and diclofenac and education campaigns to reduce demand and use; b) training of personnel in priority protected areas in detection and response to poisoning incidents; c) maintenance of a safe and reliable food source through vulture restaurants to ensure short-term survival, and d) protection and restoration of large areas of deciduous dipterocarp forests to enable long-term species recovery.
A new VLBI system has been developed and put into operation. The system has three distinctive characteristics as compared with current VLBI practice, namely, the use of a wavefront clock at each station, the capability of a burst mode operation with high speed sampling, and the use of multiple 12 Mb/s data recording channels on commercial VCR's. The main use of the system is to be in geophysical investigations where these new features may prove of value.
The Gaia-ESO Survey (GES, Gilmore et al. 2012) provides a unique opportunity to detect spectroscopically multiplicity among different populations of the Galaxy using the cross-correlation functions (CCFs). We present here the GES internal Data Release 4 (iDR4) results of the detection of double, triple and quadruple-line spectroscopic binary candidates (SBs) and discuss some peculiar systems.
The Gaia-ESO survey (GES; Gilmore et al. (2012), Randich et al. (2013)) is a spectroscopic survey complementing the Gaia mission to bring accurate radial velocities and chemical abundances for 105 stars. Merle et al. (submitted to A&A; see also this volume) developped a tool (DOE) to detect multiple peaks in the cross-correlation functions (CCFs) of GES spectra. Using the GIRAFFE HR10 and HR21 settings, we were able to compare the efficiency of our SB detection tool depending on the wavelength range and resolution. We show that a careful design of CCF masks can improve the detection rate in the HR21 settings. HR21 spectra are similar to the ones produced by the RVS spectrograph of the Gaia mission, though the lower resolution of RVS spectra may result in a lower detection efficiency than the case of HR21. Analysis of RVS spectra in the context of spectroscopic binaries can take advantage of the lessons learnt from the GES to maximize the detection rate.
The objective of the Apollon 10 PW project is the generation of 10 PW peak power pulses of 15 fs at
. In this paper a brief update on the current status of the Apollon project is presented, followed by a more detailed presentation of our experimental and theoretical investigations of the temporal characteristics of the laser. More specifically the design considerations as well as the technological and physical limitations to achieve the intended pulse duration and contrast are discussed.
We present new observations of projected rotational velocities of main sequence B stars in the galactic clusters NGC 2439, NGC 3293, NGC 3766, NGC 4755, NGC 7160 and h & χ Persei. 257 stars have been observed with three instruments, 207 of which are presented here. Projected rotational velocities have been determined by least-squares fit to synthetic spectra. Our v sin i scale is compared with that of Slettebak et al. (1975).
At the current epoch, the dynamics of galactic systems is largely controlled by the behaviour of the stellar component. There is probably also a large amount of non-stellar matter present, which probably dominates the dynamics on large scales. Nevertheless, the (centers of) galaxies are still, for better or worse, defined as those regions were there happens to be a lot of stellar light.
The nature of the binary population in clusters is of interest for numerous reasons. Through their study we gain insight into the star-formation process, dynamical interactions in the clusters, mass-luminosity-age relations, chromospheric activity and more. We have made a detailed analysis of the binary population of the Hyades, using radial-velocity, visual and proper-motion data in the literature and new multiple high-precision (σ = 0.85 km/sec) radial-velocity observations of over 100 Hyads with 6 < V < 14 (see Latham and Stefanik 1985 and this colloquium). Complete details are given in Mathieu 1983 and Mathieu, Stefanik and Latham 1985. In this report we focus our analysis on the 95 Hyads found by van Bueren (1952) with 6 < V < 9 (0.9 to 1.7 M⊙), thus providing a stellar sample analogous to that of the classic study of the field binary population by Abt and Levy (1976).
The objective of the Apollon project is the generation of 10 PW peak power pulses of 15 fs at 1 shot/minute. In this paper the Apollon facility design, the technological challenges and the current progress of the project will be presented.
Hurwitz numbers count branched covers of the Riemann sphere with specified ramification data, or equivalently, transitive permutation factorizations in the symmetric group with specified cycle types. Monotone Hurwitz numbers count a restricted subset of these branched covers related to the expansion of complete symmetric functions in the Jucys–Murphy elements, and have arisen in recent work on the the asymptotic expansion of the Harish-Chandra–Itzykson–Zuber integral. In this paper we begin a detailed study of monotone Hurwitz numbers. We prove two results that are reminiscent of those for classical Hurwitz numbers. The first is the monotone join-cut equation, a partial differential equation with initial conditions that characterizes the generating function for monotone Hurwitz numbers in arbitrary genus. The second is our main result, in which we give an explicit formula for monotone Hurwitz numbers in genus zero.
In 2011 the IRSN conducted several assessments of atmospheric
radioactive releases due to the Fukushima Daiichi NPP accident (March
11, 2011) and of their impact on Japan’s terrestrial environment.
They were based on the IRSN’s emergency management tools and on
the abundant information and technical data gradually published
in Japan. According to these assessments, the main release phase
lasted from March 12 to 25, 2011 and impacted Japanese land in two
events, the first on 15 and 16 March, in which the main radioactive
deposits were formed, and the second from March 20 to 23, which
was less significant. The highest amounts of radioactive deposits were
found in an area extending upwards of several tens of kilometers
northwest of the plant. Lower amounts were discontinuously scattered
in an area extending up to over 250 km away. Initially composed
mainly of short-lived radionuclides, the deposits’ activity sharply
decreased in the subsequent weeks. Since the summer of 2011, cesium-134
and cesium-137 have become the residual deposits’ main components.
According to IRSN estimates, in the absence of protection, the doses
due to exposure to the radioactive plume during the atmospheric
release phase may have been potentially higher for people who remained
in coastal areas up to several tens of kilometers north and south
of the damaged plant. Thereafter, people living up to 50 km northwest
of the plant, outside the 20-km emergency evacuation zone, were potentially
most vulnerable to residual radioactive deposits over time.
The dynamic model of plant growth GreenLab describes plant architecture and functional
growth at the level of individual organs. Structural development is controlled by formal
grammars and empirical equations compute the amount of biomass produced by the plant, and
its partitioning among the growing organs, such as leaves, stems and fruits. The number of
organs initiated at each time step depends on the trophic state of the plant, which is
evaluated by the ratio of biomass available in plant to the demand of all the organs. The
control of the plant organogenesis by this variable induces oscillations in the simulated
plant behaviour. The mathematical framework of the GreenLab model allows to compute the
conditions for the generation of oscillations and the value of the period according to the
set of parameters. Two case-studies are presented, corresponding to emergence of
oscillations associated to fructification and branching.
Similar alternating patterns are
commonly reported by botanists. In this article, two examples were selected: alternate
patterns of fruits in cucumber plants and alternate appearances of branches in
Cecropia trees. The model was calibrated from experimental data
collected on these plants. It shows that a simple feedback hypothesis of trophic control
on plant structure allows the emergence of cyclic patterns corresponding to the observed
Despite electrification, over 90% of rural households in certain areas of South Africa continue to depend on fuelwood, and this affects woody vegetation structure, with associated cascading effects on biodiversity within adjacent lands. To promote sustainable use, the interactions between anthropogenic and environmental factors affecting vegetation structure in savannahs need to be understood. Airborne light detection and ranging (LiDAR) data collected over 4758 ha were used to examine woody vegetation structure in five communal rangelands around 12 settlements in Bushbuckridge, a municipality in the Kruger to Canyons Biosphere Reserve (South Africa). The importance of underlying abiotic factors was evaluated by measuring size class distributions across catenas and using canonical correspondence analysis. Landscape position was significant in determining structure, indicating the importance of underlying biophysical factors. Differences in structure were settlement-specific, related to mean annual precipitation at one site, and human population density and intensity of use at the other four sites. Size class distributions of woody vegetation revealed human disturbance gradients around settlements. Intensity of use affected the amplitude, not the shape, of the size class distribution, suggesting the same height classes were being harvested across settlements, but amount harvested varied between settlements. Highly used rangelands result in a disappearance of disturbance gradients, leading to homogeneous patches of low woody cover around settlements with limited rehabilitation options. Reductions in disturbance gradients can serve as early warning indicators of woodland degradation, a useful tool in planning for conservation and sustainable development.
Time-resolved photoluminescence experiments at varying temperature are performed on a series of InxGa1−xN/GaN quantum well and quantum box samples of similar compositions (0.15 < x < 0.20). The results are analyzed by using envelope-function calculations of transition energies and oscillator strengths, accounting for internal electric fields. The respective influences of localization and electric fields on radiative and nonradiative lifetimes and on the Stokes shift are deduced. The results indicate that the spatial extension of localization centers is much smaller than the size of the quantum boxes (∼10 × 3 nm, typically). The room-temperature radiative efficiency of both quantum well and quantum box samples is enhanced by replacing the topmost GaN barrier by an AlGaN one.
Apexes of commercial pyramidal silicon scanning microscopy tips were magnetically functionalized by means of local focused electron beam induced deposition. High aspect ratio supertips and local tip coatings with varying apex diameters can be produced by varying exposure time, beam current, and scan mode. The carbonyl precursor Co2(CO)8 was used as source of magnetic metal. Tip performance was tested with magnetic force microscopy (tapping / lift-retrace mode) and magnetically actuated cantilever atomic force microscopy. The deposit contains 34±2 at.% Co, dispersed as 2-5 nm metal nanocrystals in a carbonaceous matrix. Specific surface reactions and Boudouard reactions are proposed to explain the resulting deposit composition measured by Auger spectroscopy. The electrical resistivity is 104 higher than bulk Co resistivity.
Coppicing is an important regeneration mechanism in tropical dry forest after disturbance, but little is known about the long-term dynamics and the rate of recovery of the coppice shoots following clearance. This study reports on the growth and dynamics of coppice shoots following experimental cutting in a tropical dry forest in Jamaica. The fate of coppice shoots was tracked on a total of 481 stumps, representing 51 species over 10 y. The number of coppice shoots and the height and dbh of the leading shoots were measured on the tree stumps 14 mo and 10 y after cutting. Coppicing was vigorous for most tree species, but the average number of shoots per stump decreased significantly over the 9 y period, from 25 to 8 shoots per stump. The average height and diameter of the leading shoots after 10 y were 4.5 m and 3.8 cm, respectively, and the average percentage diameter recovered by the shoots varied between 36% and 95% among the species. Coppicing facilitates the long-term persistence of this dry forest, and the rapid growth of coppice shoots contributed to the resilience of most species after cutting.