1,123 research outputs found
Studies on the flight medical aspects of the German Lufthansa non-stop route from Frankfurt to Rio de Janeiro, part 1
The problem of crew size for regularly scheduled flights between Frankfurt and Rio de Janeiro is discussed. Factors affecting crew performance are examined, comparisons are drawn to regulations of other countries and crew questionnaires and tests are presented
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Problematic social networking site use and associations with anxiety, attention deficit hyperactivity disorder, and resilience
Background: Social networking sites (SNSs) such as Facebook, Snapchat, and Instagram are now used frequently by millions of people worldwide. However, there are concerns of problematic social networking site use (PSNSU) and psychopathological symptoms that may be co-morbid with this behaviour. The present study investigated the interactions between PSNSU severity, time spent on SNSs, anxiety severity, attention deficit hyperactivity disorder (ADHD) severity, and resilience levels.
Method: A total of 458 SNS users (mean age = 32.35 years, SD = 10.44) completed an online survey consisting of measures assessing PSNSU severity, anxiety severity, ADHD severity, and resilience levels.
Results: Bivariate correlations identified moderate positive correlations between PSNSU severity, time spent on SNSs, anxiety severity, and ADHD severity, and a negative correlation between PSNSU severity and resilience levels. The moderated regression analyses revealed that anxiety severity as well as the interaction of anxiety severity and resilience levels significantly explained 28.6% of the variance in PSNSU severity. The simple slopes analysis was calculated indicating the main effect of anxiety severity. Furthermore, ADHD severity was also a significant predictor of PSNSU severity, but there was no significant interaction effect with resilience levels. Additional analysis illustrated that both variables investigating psychopathological symptoms significantly interact in predicting PSNSU severity. There was no significant effect of the three-way interaction between anxiety severity, ADHD severity, and resilience levels.
Conclusion: The study showed that anxiety severity and ADHD severity are risk factors in the development of PSNSU severity and resilience levels may have a preventive effect, which must be investigated in further studies
Combined SIMS-SPM Instrument For High Sensitivity And High Resolution Elemental 3D Analysis
Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 201
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The association between problematic social networking site use, dark triad traits, and emotion dysregulation
Background: Social networking sites (SNSs) allow people to socially connect with each other, collaborate, and share information. However, problematic SNS use (PSNSU) may be associated with negative personality traits. The present study investigated the associations between PSNSU, dark triad personality traits, and emotion dysregulation.
Method: In the present study, 555 SNS users (Mage = 33.32 years, SD = 10.88) completed an online survey comprising measures of PSNSU, dark triad personality traits, and emotion dysregulation.
Results: Bivariate correlations showed that PSNSU was significantly associated with dark triad traits as well as emotion dysregulation. Structural equation modelling (where the effect of the dark triad traits on PSNSU was mediated by emotion dysregulation) showed that 33.5% of the variance of PSNSU was explained by Machiavellianism, psychopathy, and narcissism.
Conclusion: The findings provide suggestive evidence of why PSNSU may occur as a function of the presence of dark triad traits and emotion dysregulation. The study also highlighted the important role that emotion regulation plays in the association between dark triad traits and PSNSU
The egiin davaa prehistoric rupture, central mongolia: A large magnitude normal faulting earthquake on a reactivated fault with little cumulative slip located in a slowly deforming intraplate setting
The prehistoric Egiin Davaa earthquake rupture is well-preserved in late Quaternary deposits within the Hangay Mountains of central Mongolia. The rupture is expressed by a semicontinuous 80 km-long topographic scarp. Geomorphological reconstructions reveal a relatively constant scarp height of 4-4.5 m and a NW-directed slip vector. Previous researchers have suggested that the scarp's exceptional geomorphological preservation indicates that it may correspond to an earthquake that occurred in the region c. 500 years ago. However, we constrain the last rupture to have been at least 4 ka ago from morphological dating and < 7.4 ka ago based on radiocarbon dating from one of two palaeoseismic trenches. Our study shows that discrete earthquake ruptures, along with details such as the locations of partially infilled fissures, can be preserved for periods well in excess of 1000 years in the interior of Asia, providing an archive of fault movements that can be directly read from the Earth's surface over a timescale appropriate for the study of slowly deforming continental interiors. The Egiin Davaa rupture involved c. 8 m of slip which, along with the observations that it is largely unsegmented along its length and that the ratio of cumulative slip (c. 250 m) to fault length (c. 80 km) is small, suggests relatively recent reactivation of a pre-existing geological structure
Many-body approach to proton emission and the role of spectroscopic factors
The process of proton emission from nuclei is studied by utilizing the
two-potential approach of Gurvitz and Kalbermann in the context of the full
many-body problem. A time-dependent approach is used for calculating the decay
width. Starting from an initial many-body quasi-stationary state, we employ the
Feshbach projection operator approach and reduce the formalism to an effective
one-body problem. We show that the decay width can be expressed in terms of a
one-body matrix element multiplied by a normalization factor. We demonstrate
that the traditional interpretation of this normalization as the square root of
a spectroscopic factor is only valid for one particular choice of projection
operator. This causes no problem for the calculation of the decay width in a
consistent microscopic approach, but it leads to ambiguities in the
interpretation of experimental results. In particular, spectroscopic factors
extracted from a comparison of the measured decay width with a calculated
single-particle width may be affected.Comment: 17 pages, Revte
Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine
The present study investigates flow dynamics in the hub region of a wind
turbine focusing on the influence of nacelle geometry on the root
aerodynamics by means of Reynolds averaged Navier–Stokes simulations with the
code FLOWer. The turbine considered is a generic version of the Enercon E44
converter incorporating blades with flat-back-profiled root sections. First, a
comparison is drawn between an isolated rotor assumption and a setup
including the baseline nacelle geometry in order to elaborate the basic flow
features of the blade root. It was found that the nacelle reduces the trailed
circulation of the root vortices and improves aerodynamic efficiency for
the inner portion of the rotor; on the other hand, it induces a complex
vortex system at the juncture to the blade that causes flow separation. The
origin of these effects is analyzed in detail. In a second step, the effects
of basic geometric parameters describing the nacelle have been analyzed with
the purpose of increasing the aerodynamic efficiency in the root region.
Therefore, three modification categories have been addressed: the first
alters the nacelle diameter, the second varies the blade position relative to
the nacelle and the third comprises modifications in the vicinity of the
blade–nacelle junction. The impact of the geometrical modifications on the
local flow physics are discussed and assessed with respect to aerodynamic
performance in the blade root region. It was found that increasing the
nacelle diameter deteriorates the root aerodynamics, since the flow
separation becomes more pronounced. Possible solutions identified to reduce the
flow separation are a shift of the blade in the direction of the rotation or the
installation of a fairing fillet in the junction between the blade and the
nacelle.</p
Evaluation of MPA designs that protect highly mobile megafauna now and under climate change scenarios
Marine protected area (MPA) designs, including large-scale MPAs (LSMPAs; \u3e150,000 km2), mobile MPAs (fluid spatiotemporal boundaries), and MPA networks, may offer different benefits to species and could enhance protection by encompassing spatiotemporal scales of animal movement. We sought to understand how well LSMPAs could benefit nine highly-mobile marine species in the tropics now and into the future by: 1) evaluating current range overlap within a LSMPA; 2) evaluating range overlap under climate change projections; and 3) evaluating how well theoretical MPA designs benefit these nine species. We focused on Palmyra Atoll and Kingman Reef, a 2000 km2 area within the 1.2 million km2 U.S. Pacific Remote Islands Marine National Monument (PRIMNM) that contains marine megafauna (reef and pelagic fishes; sea turtles; seabirds; cetaceans) reflecting different behaviors and habitat use. Our approach is useful for evaluating the effectiveness of the Palmyra-Kingman MPA and PRIMNM in protecting these species, and tropical LSMPAs in general, and for informing future MPA design. Stationary MPAs provided protection at varying scales. Reef manta rays (Mobula alfredi), grey reef sharks (Carcharhinus amblyrhynchos), green sea turtles (Chelonia mydas), and bottlenose dolphins (Tursiops truncatus) had overall small ranges (\u3c100 km from Palmyra-Kingman) and could benefit from stationary MPAs that contained heterogenous reef habitats. Yellowfin tuna (Thunnus albacares), sooty terns (Onychoprion fuscatus), red-footed boobies (Sula sula), great frigatebirds (Fregata minor), and melon-headed whales (Peponocephala electra) navigated complex oceanographic processes and may benefit most from mobile MPAs that shift with features including thermal fronts, cyclic regions of elevated productivity, and eddies, if relationships with these features are established and predictable. All species had capacity to travel to nearby reef systems, illustrating potential benefits of MPA networks and protected corridors. Suitable habitats will likely contract for all species as warm water expands under climate change scenarios (species habitats were predicted to decrease by 4–49% at Palmyra-Kingman) and MPAs may not protect suitable habitats into the future. Species habitat requirements and movement ecologies are critical aspects of marine spatial planning, especially with respect to dynamic ocean processes and a changing climate
Molecular crowding and RNA synergize to promote phase separation, microtubule interaction, and seeding of Tau condensates
Biomolecular condensation of the neuronal microtubule-associated protein Tau (MAPT) can be induced by coacervation with polyanions like RNA, or by molecular crowding. Tau condensates have been linked to both functional microtubule binding and pathological aggregation in neurodegenerative diseases. We find that molecular crowding and coacervation with RNA, two conditions likely coexisting in the cytosol, synergize to enable Tau condensation at physiological buffer conditions and to produce condensates with a strong affinity to charged surfaces. During condensate-mediated microtubule polymerization, their synergy enhances bundling and spatial arrangement of microtubules. We further show that different Tau condensates efficiently induce pathological Tau aggregates in cells, including accumulations at the nuclear envelope that correlate with nucleocytoplasmic transport deficits. Fluorescent lifetime imaging reveals different molecular packing densities of Tau in cellular accumulations and a condensate-like density for nuclear-envelope Tau. These findings suggest that a complex interplay between interaction partners, post-translational modifications, and molecular crowding regulates the formation and function of Tau condensates. Conditions leading to prolonged existence of Tau condensates may induce the formation of seeding-competent Tau and lead to distinct cellular Tau accumulations
The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets
This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics
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