492 research outputs found
Insomnia symptoms and short sleep duration predict trajectory of mental health symptoms
Objectives: We evaluated whether insomnia symptoms and short or long sleep duration, alone or in combination, are robustly associated with subsequent trajectory of mental health symptoms. Methods: Participants were 2598 individuals (15 to 94 years of age) with elevated mental health symptoms at baseline (2013-14). Associations of baseline insomnia symptoms and sleep duration with two-year trajectory of mental health were estimated and adjusted for multiple potential confounders. Outcomes included recovery (well at both follow-up timepoints), intermittent symptoms (unwell at one follow-up timepoint), and chronic symptoms (unwell at each follow-up timepoint). Results: Adjusted for age and sex, baseline insomnia symptoms predicted intermittent (OR 1.43, 95% CI 1.15-1.80) and chronic (OR 2.16, 95% CI 1.77-2.68) trajectories of mental health symptoms. Short sleep duration (= 6 to Conclusion: A focus on just sleep duration or insomnia symptoms in those with elevated mental health symptoms will not be adequate to address chronicity. Both components of sleep disturbance, and in particular their co-occurrence, should be addressed. (c) 2018 Elsevier B.V. All rights reserved.Peer reviewe
Data on a new beta titanium alloy system reinforced with superlattice intermetallic precipitates
The data presented in this article are related to the research article entitled “a new beta titanium alloy system reinforced with superlattice intermetallic precipitates” (Knowles et al., 2018) [1]. This includes data from the as-cast alloy obtained using scanning electron microscopy (SEM) and x-ray diffraction (XRD) as well as SEM data in the solution heat treated condition. Transmission electron microscopy (TEM) selected area diffraction patterns (SADPs) are included from the alloy in the solution heat treated condition, as well as the aged condition that contained < 100 nm B2 TiFe precipitates [1], the latter of which was found to exhibit double diffraction owing to the precipitate and matrix channels being of a similar width to the foil thickness (Williams and Carter, 2009) [2]. Further details are provided on the macroscopic compression testing of small scale cylinders. Of the micropillar deformation experiment performed in [1], SEM micrographs of focused ion beam (FIB) prepared 2 µm micropillars are presented alongside those obtained at the end of the in-situ SEM deformation as well as videos of the in-situ deformation. Further, a table is included that lists the Schmidt factors of all the possible slip systems given the crystal orientations and loading axis of the deformed micropillars in the solution heat treated and aged conditions
Spitzer Space Telescope Infrared Imaging and Spectroscopy of the Crab Nebula
We present 3.6, 4.5, 5.8, 8.0, 24, and 70 micron images of the Crab Nebula
obtained with the Spitzer Space Telescope IRAC and MIPS cameras, Low- and
High-resolution Spitzer IRS spectra of selected positions within the nebula,
and a near-infrared ground-based image made in the light of [Fe II]1.644
micron. The 8.0 micron image, made with a bandpass that includes [Ar II]7.0
micron, resembles the general morphology of visible H-alpha and near-IR [Fe II]
line emission, while the 3.6 and 4.5 micron images are dominated by continuum
synchrotron emission. The 24 micron and 70 micron images show enhanced emission
that may be due to line emission or the presence of a small amount of warm dust
in the nebula on the order of less than 1% of a solar mass. The ratio of the
3.6 and 4.5 micron images reveals a spatial variation in the synchrotron power
law index ranging from approximately 0.3 to 0.8 across the nebula. Combining
this information with optical and X-ray synchrotron images, we derive a
broadband spectrum that reflects the superposition of the flatter spectrum jet
and torus with the steeper diffuse nebula, and suggestions of the expected
pileup of relativistic electrons just before the exponential cutoff in the
X-ray. The pulsar, and the associated equatorial toroid and polar jet
structures seen in Chandra and HST images (Hester et al. 2002) can be
identified in all of the IRAC images. We present the IR photometry of the
pulsar. The forbidden lines identified in the high resolution IR spectra are
all double due to Doppler shifts from the front and back of the expanding
nebula and give an expansion velocity of approximately 1264 km/s.Comment: 21 pages, 4 tables, 16 figure
Charge distributions of Ra recoil ions produced in 12C+Pb fusion-evaporation reactions
Charge state distributions of the Ra recoil ions produced in the 12C+Pb fusion-evaporation reactions have been obtained by measuring their yields as a function of the high voltage applied to an electrostatic deflector. Well-defined two-humped yield curves for evaporation residues (ERs) were observed. Such observations can be explained by the different sets of charge states inherent in Ra recoil ions. These charge sets correspond to the equilibrated and nonequilibrated components, as earlier observed for evaporation residues produced in different reactions. The main parameters of the distributions (mean charge values, widths, and relative intensities) for both components have been estimated using Monte Carlo simulations of the transmission of the Ra recoil ions through the deflector. For the equilibrated component the values of the mean charge and width are close to those given by different empirical systematics. For the nonequilibrated component these parameters have been obtained for the first time. The additional nonequilibrated ionization is presumably due to the formation of inner shell vacancies produced by the internal conversion of nuclear isomeric transitions of ERs. Nonequilibrated charge parameters obtained for Ra recoil ions are compared to similar available experimental data and some theoretical predictions
Elevation and plant species identity jointly shape a diverse arbuscular mycorrhizal fungal community in the High Arctic
Knowledge about the distribution and local diversity patterns of arbuscular mycorrhizal (AM) fungi are limited for extreme environments such as the Arctic, where most studies have focused on spore morphology or root colonization. We here studied the joint effects of plant species identity and elevation on AM fungal distribution and diversity. We sampled roots of 19 plant species in 18 locations in Northeast Greenland, using next generation sequencing to identify AM fungi. We studied the joint effect of plant species, elevation and selected abiotic conditions on AM fungal presence, richness and composition. We identified 29 AM fungal virtual taxa (VT), of which six represent putatively new VT. Arbuscular mycorrhizal fungal presence increased with elevation, and as vegetation cover and the active soil layer decreased. Arbuscular mycorrhizal fungal composition was shaped jointly by elevation and plant species identity. We demonstrate that the Arctic harbours a relatively species-rich and nonrandomly distributed diversity of AM fungi. Given the high diversity and general lack of knowledge exposed herein, we encourage further research into the diversity, drivers and functional role of AM fungi in the Arctic. Such insight is urgently needed for an area with some of the globally highest rates of climate change
Saldatura lineare per attrito (LFW) di compositi a matrice metallica
I compositi a matrice in lega d’alluminio rinforzati con carburo di silicio, combinando le proprietà dellamatrice e del rinforzo ceramico, offrono maggiore rigidezza e resistenza specifica, maggiore stabilità termica emigliore resistenza ad usura, rispetto alle corrispondenti leghe non rinforzate. Uno dei principali limitiall’utilizzo industriale di questi materiali è, tuttavia, rappresentato dalla difficoltà di realizzare giunti saldatiad elevata efficienza, mediante tecniche convenzionali di saldatura per fusione. Studi recenti hannoevidenziato come i compositi a matrice di alluminio e rinforzo particellare possano, invece, essere saldati consuccesso mediante Friction Stir Welding, pur con adeguato controllo dei parametri di processo. Obiettivo delpresente lavoro è stato quello di valutare la possibilità di utilizzare il processo di saldatura per attrito lineare(Linear Friction Welding, LFW) agli stessi materiali. La sperimentazione è stata condotta nel compositoAMC225xe (matrice in lega di alluminio AA2124, rinforzata con il 25% in vol. di particelle di SiC) prodottomediante metallurgia delle polveri, forgiato e trattato termicamente a T4. I giunti realizzati mediante LFWsono stati sottoposti a prove di durezza e trazione, analisi microstrutturali con microscopia ottica edelettronica in scansione, analisi con tecniche di diffrazione neutronica per la determinazione delle tensioniresidue. Il processo di saldatura ha permesso di ottenere giunti con efficienza superiore all’80%, valutatarispetto alla resistenza a trazione, con ridotte tensioni residue ed aventi una microstruttura estremamente fine
Elevation and plant species identity jointly shape a diverse arbuscular mycorrhizal fungal community in the High Arctic
Knowledge about the distribution and local diversity patterns of arbuscular mycorrhizal (AM) fungi are limited for extreme environments such as the Arctic, where most studies have focused on spore morphology or root colonization. We here studied the joint effects of plant species identity and elevation on AM fungal distribution and diversity. We sampled roots of 19 plant species in 18 locations in Northeast Greenland, using next generation sequencing to identify AM fungi. We studied the joint effect of plant species, elevation and selected abiotic conditions on AM fungal presence, richness and composition. We identified 29 AM fungal virtual taxa (VT), of which six represent putatively new VT. Arbuscular mycorrhizal fungal presence increased with elevation, and as vegetation cover and the active soil layer decreased. Arbuscular mycorrhizal fungal composition was shaped jointly by elevation and plant species identity. We demonstrate that the Arctic harbours a relatively species-rich and nonrandomly distributed diversity of AM fungi. Given the high diversity and general lack of knowledge exposed herein, we encourage further research into the diversity, drivers and functional role of AM fungi in the Arctic. Such insight is urgently needed for an area with some of the globally highest rates of climate change.Peer reviewe
RETRATO DE PRIMERA COMUNIÓN [Material gráfico]
Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201
Electron-phonon interaction in C70
The matrix elements of the deformation potential of C are calculated
by means of a simple, yet accurate solution of the electron-phonon coupling
problem in fullerenes, based on a parametrization of the ground state
electronic density of the system in terms of hybridized orbitals.
The value of the calculated dimensionless total electron-phonon coupling
constant is , an order of magnitude smaller than in
C, consistent with the lack of a superconducting phase transition in
CA fullerite, and in overall agreement with measurements of the
broadening of Raman peaks in CK. We also calculate the photoemission
cross section of C, which is found to display less structure than that
associated with C, in overall agreement with the experimental
findings.Comment: To be published in Phys. Rev.
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