498 research outputs found
Overweight, obesity and underweight in nurses in Vhembe and Capricorn districts, Limpopo
Background: In South Africa, anecdotal evidence concerning the prevalence of overweight and obesity in nurses is alarming, but no scientific studies have confirmed this notion. This study aimed to determine the prevalence of underweight, overweight and obesity in black nurses practising in South Africa.Method: A cross-sectional study involving 153 nurses, aged 19-50 years and older, was undertaken in the Vhembe and Capricorn districts, Limpopo province. Height and weight were measured to determine body mass index (BMI) and physical activity was assessed by report. The World Health Organization criteria determined the BMI categories.Results: The mean BMI of the nurses was 31.7 ± 18.1 kg/m2. The prevalence of underweight, overweight, obesity and extreme obesity in the nurses was 2%, 27.5%, 44.4% and 7.2%, respectively. The prevalence of overweight and obesity increased with age, peaking at ages 30-39 for overweight, and over 50 years of age for obesity. Among the males nurses, the prevalence of underweight, overweight, obesity and extreme obesity were 2%, 30.6%, 36.7% and 6.1%, respectively. Corresponding figures for the female nurses were 1.9%, 26%, 48.1% and 7.7%, respectively.Conclusion: The study revealed a high prevalence of overweight and obesity in nurses in the Vhembe and Capricorn districts, a rate that is comparable with that of the general population in South Africa. Future studies are needed to identify risk factors for the prevalence of overweight and obesity in nurses.Keywords: nurses, body mass index, overweight, obesity, underweight, South Afric
DBI Galileon and Late time acceleration of the universe
We consider 1+3 dimensional maximally symmetric Minkowski brane embedded in a
1+4 dimensional maximally symmetric Minkowski background. The resulting 1+3
dimensional effective field theory is of DBI (Dirac-Born-Infeld) Galileon type.
We use this model to study the late time acceleration of the universe. We study
the deviation of the model from the concordance \Lambda CDM behaviour. Finally
we put constraints on the model parameters using various observational data.Comment: 16 pages, 7 eps figures, Latex Style, new references added, corrected
missing reference
Galileons as Wess-Zumino Terms
We show that the galileons can be thought of as Wess-Zumino terms for the
spontaneous breaking of space-time symmetries. Wess-Zumino terms are terms
which are not captured by the coset construction for phenomenological
Lagrangians with broken symmetries. Rather they are, in d space-time
dimensions, d-form potentials for (d+1)-forms which are non-trivial co-cycles
in Lie algebra cohomology of the full symmetry group relative to the unbroken
symmetry group. We introduce the galileon algebras and construct the
non-trivial (d+1)-form co-cycles, showing that the presence of galileons and
multi-galileons in all dimensions is counted by the dimensions of particular
Lie algebra cohomology groups. We also discuss the DBI and conformal galileons
from this point of view, showing that they are not Wess-Zumino terms, with one
exception in each case.Comment: 49 pages. v2 minor changes, version appearing in JHE
Effect of Nenas honey supplementation on the oxidative status of undergraduate students
Honey is a dietary antioxidant as it contains phenolic compounds, such as flavonoids and phenolic acids. Antioxidants are non-nutritive, biologically active ingredients in food that reduce oxidative stress. The antioxidant content in each type of honey varies depending on its source. This study was aimed to determine the effect of Nenas honey supplementation on the oxidative status of a group of healthy medical students. They were divided into two groups; control (n=10) and supplemented (n=13), where 1 tablespoon of Nenas honey was given each day. Blood sampling was done at baseline, 1st and 2nd month of the study for determination of DNA damage and antioxidant enzyme activities, such as superoxide dismutase (SOD), glutathione peroxidise (GPx), and catalase (CAT). Results showed that Nenas honey increased the level of DNA damage at the 1st month but reduced it significantly at the 2nd month as compared to control. GPx and CAT activities also decreased significantly with honey supplementation throughout the study, though no changes were observed in SOD activity. Fasting glucose levels remained within the normal range with honey supplementation. In conclusion, Nenas honey decreases oxidative stress which leads to a reduction of antioxidant enzyme activities in the body
Conditions for the cosmological viability of the most general scalar-tensor theories and their applications to extended Galileon dark energy models
In the Horndeski's most general scalar-tensor theories with second-order
field equations, we derive the conditions for the avoidance of ghosts and
Laplacian instabilities associated with scalar, tensor, and vector
perturbations in the presence of two perfect fluids on the flat
Friedmann-Lemaitre-Robertson-Walker (FLRW) background. Our general results are
useful for the construction of theoretically consistent models of dark energy.
We apply our formulas to extended Galileon models in which a tracker solution
with an equation of state smaller than -1 is present. We clarify the allowed
parameter space in which the ghosts and Laplacian instabilities are absent and
we numerically confirm that such models are indeed cosmologically viable.Comment: 18 pages, 6 figure
de Sitter Galileon
We generalize the Galileon symmetry and its relativistic extension to a de
Sitter background. This is made possible by studying a probe-brane in a flat
five-dimensional bulk using a de Sitter slicing. The generalized Lovelock
invariants induced on the probe brane enjoy the induced Poincar\'e symmetry
inherited from the bulk, while living on a de Sitter geometry. The
non-relativistic limit of these invariants naturally maintain a generalized
Galileon symmetry around de Sitter while being free of ghost-like pathologies.
We comment briefly on the cosmology of these models and the extension to the
AdS symmetry as well as generic FRW backgrounds
Cosmological constraints on extended Galileon models
The extended Galileon models possess tracker solutions with de Sitter
attractors along which the dark energy equation of state is constant during the
matter-dominated epoch, i.e. w_DE = -1-s, where s is a positive constant. Even
with this phantom equation of state there are viable parameter spaces in which
the ghosts and Laplacian instabilities are absent. Using the observational data
of the supernovae type Ia, the cosmic microwave background (CMB), and baryon
acoustic oscillations, we place constraints on the tracker solutions at the
background level and find that the parameter s is constrained to be s=0.034
(-0.034,+0.327) (95% CL) in the flat Universe. In order to break the degeneracy
between the models we also study the evolution of cosmological density
perturbations relevant to the large-scale structure (LSS) and the
Integrated-Sachs-Wolfe (ISW) effect in CMB. We show that, depending on the
model parameters, the LSS and the ISW effect is either positively or negatively
correlated. It is then possible to constrain viable parameter spaces further
from the observational data of the ISW-LSS cross-correlation as well as from
the matter power spectrum.Comment: 17 pages, 9 figures, uses RevTeX4-
Generalizing Galileons
The Galileons are a set of terms within four-dimensional effective field
theories, obeying symmetries that can be derived from the dynamics of a
3+1-dimensional flat brane embedded in a 5-dimensional Minkowski Bulk. These
theories have some intriguing properties, including freedom from ghosts and a
non-renormalization theorem that hints at possible applications in both
particle physics and cosmology. In this brief review article, we will summarize
our attempts over the last year to extend the Galileon idea in two important
ways. We will discuss the effective field theory construction arising from
co-dimension greater than one flat branes embedded in a flat background - the
multiGalileons - and we will then describe symmetric covariant versions of the
Galileons, more suitable for general cosmological applications. While all these
Galileons can be thought of as interesting four-dimensional field theories in
their own rights, the work described here may also make it easier to embed them
into string theory, with its multiple extra dimensions and more general
gravitational backgrounds.Comment: 16 pages; invited brief review article for a special issue of
Classical and Quantum Gravity. Submitted to CQ
Non-linear Representations of the Conformal Group and Mapping of Galileons
There are two common non-linear realizations of the 4D conformal group: in
the first, the dilaton is the conformal factor of the effective metric
\eta_{\mu\nu} e^{-2 \pi}; in the second it describes the fluctuations of a
brane in AdS_5. The two are related by a complicated field redefinition, found
by Bellucci, Ivanov and Krivonos (2002) to all orders in derivatives. We show
that this field redefinition can be understood geometrically as a change of
coordinates in AdS_5. In one gauge the brane is rigid at a fixed radial
coordinate with a conformal factor on the AdS_5 boundary, while in the other
one the brane bends in an unperturbed AdS_5. This geometrical picture
illuminates some aspects of the mapping between the two representations. We
show that the conformal Galileons in the two representations are mapped into
each other in a quite non-trivial way: the DBI action, for example, is mapped
into a complete linear combination of all the five Galileons in the other
representation. We also verify the equivalence of the dilaton S-matrix in the
two representations and point out that the aperture of the dilaton light-cone
around non-trivial backgrounds is not the same in the two representations.Comment: 16 pages. v2: typos corrected (notably eq 4.5), matches JHEP versio
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