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High speed shadowgraphy for the study of liquid drops
The book contains invited lectures and selected contributions presented at the Enzo Levi and XVII Annual Meeting of the Fluid Dynamic Division of the Mexican Physical Society in 2011.This was work was sponsored by EPSRC grant number RG5560
Approximate solutions for the single soliton in a Skyrmion-type model with a dilaton scalar field
We consider the analytical properties of the single-soliton solution in a
Skyrmion-type Lagrangian that incorporates the scaling properties of quantum
chromodynamics (QCD) through the coupling of the chiral field to a scalar field
interpreted as a bound state of gluons. The model was proposed in previous
works to describe the Goldstone pions in a dense medium, being also useful for
studying the properties of nuclear matter and the in-medium properties of
mesons and nucleons. Guided by an asymptotic analysis of the Euler-Lagrange
equations, we propose approximate analytical representations for the single
soliton solution in terms of rational approximants exponentially localized.
Following the Pad\'e method, we construct a sequence of approximants from the
exact power series solutions near the origin. We find that the convergence of
the approximate representations to the numerical solutions is considerably
improved by taking the expansion coefficients as free parameters and then
minimizing the mass of the Skyrmion using our ans\"atze for the fields. We also
perform an analysis of convergence by computation of physical quantities
showing that the proposed analytical representations are very useful useful for
phenomenological calculations.Comment: 13 pages, 3 eps figures, version to be published in Phys.Rev.
Distribution of skates and sharks in the North Sea: 112 years of change
How have North Sea skate and shark assemblages changed since the early 20th century when bottom trawling became widespread, whilst their environment became increasingly impacted by fishing, climate change, habitat degradation and other anthropogenic pressures? This article examines long-term changes in the distribution and occurrence of the elasmobranch assemblage of the southern North Sea, based on extensive historical time series (1902–2013) of fishery-independent survey data. In general, larger species (thornback ray, tope, spurdog) exhibited long-term declines, and the largest (common skate complex) became locally extirpated (as did angelshark). Smaller species increased (spotted and starry ray, lesser-spotted dogfish) as did smooth-hound, likely benefiting from greater resilience to fishing and/or climate change. This indicates a fundamental shift from historical dominance of larger, commercially valuable species to current prevalence of smaller, more productive species often of low commercial value. In recent years, however, some trends have reversed, with the (cold-water associated) starry ray now declining and thornback ray increasing. This shift may be attributed to (i) fishing, including mechanised beam trawling introduced in the 1960s–1970s, and historical target fisheries for elasmobranchs; (ii) climate change, currently favouring warm-water above cold-water species; and (iii) habitat loss, including potential degradation of coastal and outer estuarine nursery habitats. The same anthropogenic pressures, here documented to have impacted North Sea elasmobranchs over the past century, are likewise impacting shelf seas worldwide and may increase in the future; therefore, parallel changes in elasmobranch communities in other regions are to be expected
A New Radio Molecular Line Survey of Planetary Nebulae: HNC/HCN as a Diagnostic of Ultraviolet Irradiation
Certain planetary nebulae contain shells, filaments, or globules of cold gas
and dust whose heating and chemistry are likely driven by UV and X-ray emission
from their central stars and from wind-collision-generated shocks. We present
the results of a survey of molecular line emission in the 88-236 GHz range from
nine nearby (<1.5 kpc) planetary nebulae spanning a range of UV and X-ray
luminosities, using the 30 m telescope of the Institut de Radioastronomie
Millimetrique. Rotational transitions of thirteen molecules, including CO
isotopologues and chemically important trace species, were observed and the
results compared with and augmented by previous studies of molecular gas in
PNe. Lines of the molecules HCO+, HNC, HCN, and CN, which were detected in most
objects, represent new detections for five planetary nebulae in our study.
Specifically, we present the first detections of 13CO (1-0, 2-1), HCO+, CN,
HCN, and HNC in NGC 6445; HCO+ in BD+303639; 13CO (2-1), CN, HCN, and HNC in
NGC 6853; and 13CO (2-1) and CN in NGC 6772. Flux ratios were analyzed to
identify correlations between the central star and/or nebular UV and X-ray
luminosities and the molecular chemistries of the nebulae. This analysis
reveals a surprisingly robust dependence of the HNC/HCN line ratio on PN
central star UV luminosity. There exists no such clear correlation between PN
X-rays and various diagnostics of PN molecular chemistry. The correlation
between HNC/HCN ratio and central star UV luminosity demonstrates the potential
of molecular emission line studies of PNe for improving our understanding of
the role that high-energy radiation plays in the heating and chemistry of
photodissociation regions.Comment: 17 pages, 17 figures, 6 tables, accepted for publication in Astronomy
& Astrophysic
Synthesis of type A zeolites from natural kaolinite for their application in CO2 capture processes
Climate change is the greatest environmental threat of the 21st century, with major economic, social and environmental consequences. The level of carbon dioxide (CO2) emissions has increased by 31%, therefore, both governments and the scientific community are taking steps to mitigate emissions into the atmosphere. The most economically sustainable method is the use of low cost adsorbents that perform a selective adsorption of CO2 with respect to other inert gases such as N2. Clay minerals are highly available materials on the planet, are a low cost raw material and have great versatility for various processes in the field of adsorption and catalysis. The present work describes the synthesis of type A zeolite from a hydrothermal process in basic medium using metacaolinite as a starting material. Several parameters such as temperature and time were modified to evaluate the relationship between the formation conditions of the zeolite and its CO2 adsorption capacity.
Synthesized catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption at -196 ºC, nuclear magnetic resonance of solids (NMR) and infrared spectroscopy (IR).
In addition, the absorption capacity of CO2 with type A zeolites has been evaluated, and all the results were compared with the commercial zeolites.
With respect to the results obtained, it can be said that the bands obtained by IR for the synthesized Zeolites are similar to those of the commercial Zeolite. On the other hand, the NMR results show that the synthesized and commercial zeolite present the same chemical environment. Finally, the textural parameters corroborate that in all cases the surface area is low from 12 m2g-1 for kaolinite to 7 m2g-1 for commercial zeolite AUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Spectra of weighted algebras of holomorphic functions
We consider weighted algebras of holomorphic functions on a Banach space. We
determine conditions on a family of weights that assure that the corresponding
weighted space is an algebra or has polynomial Schauder decompositions. We
study the spectra of weighted algebras and endow them with an analytic
structure. We also deal with composition operators and algebra homomorphisms,
in particular to investigate how their induced mappings act on the analytic
structure of the spectrum. Moreover, a Banach-Stone type question is addressed.Comment: 25 pages Corrected typo
Improved models of upper-level wind for several astronomical observatories
An understanding of wind speed and direction as a function of height are
critical to the proper modeling of atmospheric turbulence. We have used
radiosonde data from launch sites near significant astronomical observatories
and created mean profiles of wind speed and direction and have also computed
Richardson number profiles. Using data from the last 30 years, we extend the
1977 Greenwood wind profile to include parameters that show seasonal variations
and differences in location. The added information from our models is useful
for the design of adaptive optics systems and other imaging systems. Our
analysis of the Richardson number suggests that persistent turbulent layers may
be inferred when low values are present in our long term averaged data.
Knowledge of the presence of these layers may help with planning for adaptive
optics and laser communications.Comment: 21 pages, 15 Figures, 8 table
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