14,297 research outputs found
Dynamical mechanism for ultra-light scalar Dark Matter
Assuming a double-well bare potential for a self-interacting scalar field,
with the Higgs vacuum expectation value, it is shown that non-perturbative
quantum corrections naturally lead to ultra-light particles of mass
eV, if these non-perturbative effects occur at a time
consistent with the Electroweak phase transition. This mechanism could be
relevant in the context of Bose Einstein Condensate studies for the description
of cold Dark Matter. Given the numerical consistency with the Electroweak
transition, an interaction potential for Higgs and Dark Matter fields is
proposed, where spontaneous symmetry breaking for the Higgs field leads to the
generation of ultra-light particles, in addition to the usual Higgs mechanism.
This model also naturally leads to extremely weak interactions between the
Higgs and Dark Matter particles.Comment: 12 pages, includes the derivation of the effective potential
suppressed by the volum
Toroidal Carbon Nanotubes with Encapsulated Atomic Metal Loops
Toroidal carbon nanotubes can serve as hosts for encapsulated loops of atomic
metal wires. Such composite structures have been analyzed using density
functional theory for a semiconducting C torus encapsulating chains of
Fe, Au and Cu atoms. The sheathed metal necklaces form a zigzag structure and
drops the HOMO/LUMO bandgap to less than 0.1 eV. The iron composite is
ferromagnetic with a magnetic moment essentially the same as that of bcc iron.
The azimuthal symmetry of these toroidal composites suggests that they may
offer novel elecromagnetic properties not associated with straight,
metal-encapsulated carbon nanotubes.Comment: 6 pages, 9 figure
Bursty star formation feedback and cooling outflows
We study how outflows of gas launched from a central galaxy undergoing
repeated starbursts propagate through the circumgalactic medium (CGM), using
the simulation code RAMSES. We assume that the outflow from the disk can be
modelled as a rapidly moving bubble of hot gas at above
disk, then ask what happens as it moves out further into the halo around the
galaxy on scales. To do this we run 60 two-dimensional
simulations scanning over parameters of the outflow. Each of these is repeated
with and without radiative cooling, assuming a primordial gas composition to
give a lower bound on the importance of cooling. In a large fraction of
radiative-cooling cases we are able to form rapidly outflowing cool gas from in
situ cooling of the flow. We show that the amount of cool gas formed depends
strongly on the 'burstiness' of energy injection; sharper, stronger bursts
typically lead to a larger fraction of cool gas forming in the outflow. The
abundance ratio of ions in the CGM may therefore change in response to the
detailed historical pattern of star formation. For instance, outflows generated
by star formation with short, intense bursts contain up to 60 per cent of their
gas mass at temperatures ; for near-continuous star
formation the figure is 5 per cent. Further study of cosmological
simulations, and of idealised simulations with e.g., metal-cooling, magnetic
fields and/or thermal conduction, will help to understand the precise signature
of bursty outflows on observed ion abundances.Comment: 8 pages, 6 figures, accepted in MNRA
Donald McGavran’s Understanding of Conversion
This paper seeks to explore Donald McGavran’s understanding of conversion. First, we will look at the people and events that shaped his theology and methodology. Second, we will explore McGavran’s understanding of conversion. He clearly emphasized in his writings that Church Growth was conversion growth. He also was very clear that salvation is only through Jesus Christ. However, Donald McGavran’s understanding of conversion was clouded with the conflicting theological and sociological views that consequently influenced his methodology. Donald McGavran’s view of conversion lacked a clear theological explanation as to how man becomes a Christian. Most of McGavran’s explanation of conversion relied on methodology more than on theology
Ang Maganda sa Teolohiya by José de Mesa, Estela P. Padilla, Levy L. Lanaria, Rebecca G. Cacho, Yuri D. Cipriano, George N. Capaque, Timoteo D. Gener
Relationship Between Executive Function and Postural Control
While it has been established that postural control is affected by executive function, research is lacking in identifying if specific executive function components are most responsible or if certain aspects of postural control are more affected than others (e.g., proprioception, vestibular, visual). The current study examined the role of inhibition, processing speed, and visuospatial ability in postural control under conditions affecting visual, proprioceptive, and vestibular sensory input. Cognitive assessments consisted of the Flanker Inhibitory Control and Attention Test, Digit Symbol Substitution Test, Clock Drawing Test, Trail Making Test – Part B, and simple reaction time. Standing Balance was used to assess postural sway. Analyses revealed that average balance was significantly associated with simple reaction time (r(88) = -0.31, p \u3c .01) and the clock drawing test (r(88) = -0.25, p\u3c .05). Further analyses revealed a significantly stronger relationship between pose #1 (eyes opened, firm) and average balance (r(88) = -0.845, p\u3c 0.1) when compared to pose #2 (eyes closed, firm), and pose #3 (eyes opened, foam) and average balance r(88) = -0.8015, p\u3c 0.1) when compared to pose #4 (eyes closed, foam). The significantly stronger relationship between these two measures demonstrates that visual input in both conditions #1 and #3 was associated with better postural control. The findings of this study demonstrate that reaction time and visuospatial abilities are associated with overall postural control in healthy older adults. Results suggest that reaction time should be more thoroughly researched to determine the extent of its influence on EF and physical function
Donald McGavran’s Understanding of Conversion
This paper seeks to explore Donald McGavran’s understanding of conversion. First, we will look at the people and events that shaped his theology and methodology. Second, we will explore McGavran’s understanding of conversion. He clearly emphasized in his writings that Church Growth was conversion growth. He also was very clear that salvation is only through Jesus Christ. However, Donald McGavran’s understanding of conversion was clouded with the conflicting theological and sociological views that consequently influenced his methodology. Donald McGavran’s view of conversion lacked a clear theological explanation as to how man becomes a Christian. Most of McGavran’s explanation of conversion relied on methodology more than on theology
Evaluating River Water Quality Modelling Uncertainties at Multiple Time and Space Scales
Maintaining healthy river ecosystems is crucial for sustaining human needs and biodiversity. Therefore, accurately assessing the ecological status of river systems and their response to short and long-term pollution events is paramount. Water quality modelling is a useful tool for gaining a better understanding of the river system and for simulating conditions that may not be obtained by field monitoring. Environmental models can be highly unreliable due to our limited knowledge of environmental systems, the difficulty of mathematically and physically representing these systems, and limitations to the data used to develop, calibrate and run these models. The extensive range of physical, biochemical and ecological processes within river systems is represented by a wide variety of models: from simpler one-dimensional advection dispersion equation (1D ADE) models to complex eutrophication models. Gaining an understanding of uncertainties within catchment water quality models across different spatial and temporal scales for the evaluation and regulation of water compliance is still required. Thus, this thesis work 1) evaluates the impact of parameter uncertainty from the longitudinal dispersion coefficient on the one-dimensional advection-dispersion model and water quality compliance at the reach scale and sub-hourly scale, 2) evaluates the impact of input data uncertainty and the representation of ecological processes on an integrated catchment water quality model, and 3) evaluates the impact of one-dimensional model structures on water quality regulation. Findings from this thesis stress the importance of longitudinal mixing specifically in the sub daily time scales and in-between 10s of meters to 100s of meters. After the sub daily time scale, other biological and ecological processes become more important than longitudinal mixing for representing the seasonal dynamics of dissolved oxygen (DO). The thorough representation of the dominant ecological processes assists in obtaining accurate seasonal patterns even under input data variability. Furthermore, the use of incorrect model structures for water quality evaluation and regulation leads to considerable sources of uncertainty when applying duration over threshold regulation within the first 100s of meters and sub hourly time scale
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