606 research outputs found
The effect of ram pressure on the star formation, mass distribution and morphology of galaxies
We investigate the dependence of star formation and the distribution of the
components of galaxies on the strength of ram pressure. Several mock
observations in X-ray, H and HI wavelength for different ram-pressure
scenarios are presented. By applying a combined N-body/hydrodynamic description
(GADGET-2) with radiative cooling and a recipe for star formation and stellar
feedback 12 different ram-pressure stripping scenarios for disc galaxies were
calculated. Special emphasis was put on the gas within the disc and in the
surroundings. All gas particles within the computational domain having the same
mass resolution. The relative velocity was varied from 100 km/s to 1000 km/s in
different surrounding gas densities in the range from to
g/cm. The temperature of the surrounding gas was
initially K. The star formation of a galaxy is enhanced by more
than a magnitude in the simulation with a high ram-pressure (
dyn/cm) in comparison to the same system evolving in isolation. The
enhancement of the star formation depends more on the surrounding gas density
than on the relative velocity. Up to 95% of all newly formed stars can be found
in the wake of the galaxy out to distances of more than 350 kpc behind the
stellar disc. Continuously stars fall back to the old stellar disc, building up
a bulge-like structure. Young stars can be found throughout the stripped wake
with surface densities locally comparable to values in the inner stellar disc.
Ram-pressure stripping can shift the location of star formation from the disc
into the wake on very short timescales. (Abridged)Comment: 19 pages, 25 figures, A&A accepted, high resolution version can be
found at http://astro.uibk.ac.at/~wolfgang/kapferer_rps_galaxies.pd
Chronic acceleration studies - Physiological responses to artificial alterations in weight Progress report
Influence of chronic acceleration on energy metabolism of chickens and animals, as indicated by maintenance feed requiremen
Quenched Slonczewski-Windmill in Spin-Torque Vortex-Oscillators
We present a combined analytical and numerical study on double-vortex
spin-torque nano-oscillators and describe a mechanism that suppresses the
windmill modes. The magnetization dynamics is dominated by the gyrotropic
precession of the vortex in one of the ferromagnetic layers. In the other layer
the vortex gyration is strongly damped. The dominating layer for the
magnetization dynamics is determined by the current polarity. Measurements on
Fe/Ag/Fe nano-pillars support these findings. The results open up a new
perspective for building high quality-factor spin-torque oscillators operating
at selectable, well-separated frequency bands
4-(Dimethylamino)pyridinium 4-toluenesulfonate
In the title compound, C7H11N2
+·C7H7O3S−, the cation is protonated at the N atom of the heterocyclic ring. The dimethylamino group lies close to the pyridinium ring plane with a dihedral angle between the pyridinium and the dimethylamine CNC planes of 3.82 (17)°. The N—C bond linking the dimethylamino substituent to the pyridinium ring is characteristically short [1.3360 (19) Å], suggesting some delocalization in the cation. In the crystal structure, N—H⋯O hydrogen bonds link individual pairs of cations and anions. The structure is further stabilized by an extensive series of C—H⋯O hydrogen bonds, augmented by π–π [centroid–centroid distance between adjacent pyridinium rings = 3.5807 (10) Å] and C—H⋯π interactions, giving a network structure
Core competencies for pain management: results of an interprofessional consensus summit.
ObjectiveThe objective of this project was to develop core competencies in pain assessment and management for prelicensure health professional education. Such core pain competencies common to all prelicensure health professionals have not been previously reported.MethodsAn interprofessional executive committee led a consensus-building process to develop the core competencies. An in-depth literature review was conducted followed by engagement of an interprofessional Competency Advisory Committee to critique competencies through an iterative process. A 2-day summit was held so that consensus could be reached.ResultsThe consensus-derived competencies were categorized within four domains: multidimensional nature of pain, pain assessment and measurement, management of pain, and context of pain management. These domains address the fundamental concepts and complexity of pain; how pain is observed and assessed; collaborative approaches to treatment options; and application of competencies across the life span in the context of various settings, populations, and care team models. A set of values and guiding principles are embedded within each domain.ConclusionsThese competencies can serve as a foundation for developing, defining, and revising curricula and as a resource for the creation of learning activities across health professions designed to advance care that effectively responds to pain
PWD/Ph-encoded genetic variants modulate the cellular Wnt/β-Catenin response to suppress ApcMin-triggered intestinal tumor formation
Genetic predisposition affects the penetrance of tumor-initiating mutations, such as APC mutations that stabilize β-catenin and cause intestinal tumors in mice and humans. However, the mechanisms involved in genetically predisposed penetrance are not well understood. Here, we analyzed tumor multiplicity and gene expression in tumor-prone ApcMin/+ mice on highly variant C57BL/6J (B6) and PWD/Ph (PWD) genetic backgrounds. (B6 × PWD) F1 APCMin offspring mice were largely free of intestinal adenoma, and several chromosome substitution (consomic) strains carrying single PWD chromosomes on the B6 genetic background displayed reduced adenoma numbers. Multiple dosage-dependent modifier loci on PWD chromosome 5 each contributed to tumor suppression. Activation of β-catenin–driven and stem cell–specific gene expression in the presence of ApcMin or following APC loss remained moderate in intestines carrying PWD chromosome 5, suggesting that PWD variants restrict adenoma initiation by controlling stem cell homeostasis. Gene expression of modifier candidates and DNA methylation on chromosome 5 were predominantly cis controlled and largely reflected parental patterns, providing a genetic basis for inheritance of tumor susceptibility. Human SNP variants of several modifier candidates were depleted in colorectal cancer genomes, suggesting that similar mechanisms may also affect the penetrance of cancer driver mutations in humans. Overall, our analysis highlights the strong impact that multiple genetic variants acting in networks can exert on tumor development
The Habitats and Biodiversity of Watamu Marine National Park: Evaluating Our Knowledge of One of East Africa's Oldest Marine Protected Areas
Watamu Marine National Park (WMNP) is one of the oldest no-take Marine Protected Areas (MPAs) in the world. Since its establishment in 1968, it has been the subject of a number of scientific studies as well as suffering from a range of modern threats to coastal marine habitats. The current state and conservation value of WMNP is documented in terms of habitat, biodiversity, and available scientific literature. There were 101 published references relating to WMNP found, which mostly focus on coral reef ecology, with less attention to other topics, such as biodiversity, socio-economics, or the ecology of non-coral reef habitats. The habitat map produced of WMNP is the first to show this level of detail and the only habitat map of a Kenyan MPA. Nine habitat categories were mapped; revealing that the most dominant habitat type is seagrass and the least is coral reef. Species lists were collected for fish, echinoderms, molluscs, crustaceans, corals, and seagrass, and species abundances were used to estimate total species richness, species diversity and sampling completeness. There were 18 species across all groups that fall into a category of conservation concern (other than Least Concern or Not Evaluated) on the IUCN Red List and 8 species found which are currently undescribed. The findings of this paper emphasise the importance of non-coral habitats in the WMNP, such as seagrass beds, and the need for more research into the ecology and conservation importance of these habitats. The information provided in this paper provides a comprehensive overview to any scientist or conservationist wanting to carry out further work in WMNP
Review article: Towards strongly coupled ensemble data assimilation with additional improvements from machine learning
We assessed different coupled data assimilation
strategies with a hierarchy of coupled models, ranging from a simple coupled
Lorenz model to the state-of-the-art coupled general circulation model
CFSv2 (Climate Forecast System version 2). With the coupled Lorenz model, we assessed the analysis accuracy by
strongly coupled ensemble Kalman filter (EnKF) and 4D-Variational (4D-Var)
methods with varying assimilation window lengths. The analysis accuracy of
the strongly coupled EnKF with a short assimilation window is comparable to
that of 4D-Var with a long assimilation window. For 4D-Var, the
strongly coupled approach with the coupled model produces more accurate
ocean analysis than the Estimating the Circulation and Climate of the
Ocean (ECCO)-like approach using the uncoupled ocean model.
Experiments with the coupled quasi-geostrophic model conclude that the
strongly coupled approach outperforms the weakly coupled and uncoupled
approaches for both the full-rank EnKF and 4D-Var, with the strongly coupled
EnKF and 4D-Var showing a similar level of accuracy higher than other
coupled data assimilation approaches such as outer-loop coupling. A
strongly coupled EnKF software framework is developed and applied to the
intermediate-complexity coupled model SPEEDY-NEMO and the state-of-the-art
operational coupled model CFSv2. Experiments assimilating synthetic or real
atmospheric observations into the ocean through strongly coupled EnKF show
that the strongly coupled approach improves the analysis of the atmosphere
and upper ocean but degrades observation fits in the deep ocean, probably
due to the unreliable error correlation estimated by a small ensemble. The
correlation-cutoff method is developed to reduce the unreliable error
correlations between physically irrelevant model states and observations.
Experiments with the coupled Lorenz model demonstrate that strongly coupled
EnKF informed by the correlation-cutoff method produces more accurate
coupled analyses than the weakly coupled and plain strongly coupled EnKF
regardless of the ensemble size. To extend the correlation-cutoff method to
operational coupled models, a neural network approach is proposed to
systematically acquire the observation localization functions for all pairs
between the model state and observation types. The following
strongly coupled EnKF experiments with an intermediate-complexity coupled
model show promising results with this method.</p
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