416 research outputs found
L’efecte de les intervencions escolars en la promoció d’activitat física
L’entorn escolar és considerat el més adequat per implementar-hi intervencions que contrarestin la inactivitat física, tot i que encara hi ha controvèrsia sobre quina és la millor estratègia. L’objectiu d’aquest article va ser revisar d’una manera sistemàtica les intervencions escolars actuals en la promoció de l’activitat física. Varen ser inclosos en la revisió estudis controlats i aleatoritzats duts a terme a les escoles, que haguessin inclòs alguna mesura d’activitat física o de condició física i en els quals haguessin participat nins de sis a dotze anys, i que foren publicats entre els anys 2007 i 2012. En aquesta revisió, entre el 70-80% dels estudis varen ser efectius. La intervenció basada en la combinació de diferents components va ser l’estratègia més consistent.School-based interventions are thought to be the most appropriate, effective way of counteracting low physical activity, although controversy surrounds what the best strategy is. This paper aims to make a systematic review of current interventions in schools. Random controlled trials in schools with some resulting measurement of physical activity or fitness were reviewed, using a population aged 6 to12 and studies published from 2007 to 2012. In the review, 70 to 80% of the trials were found to be effective. The most consistent intervention strategy was based on combination of different components
On the super edge-magicness of graphs with a specific degree sequence
A graph is said to be super edge-magic if there exists a bijective
function such that and is a constant for each . In this paper, we study the super edge-magicness of graphs of order
with degree sequence . We also investigate the super
edge-magic properties of certain families of graphs. This leads us to propose
some open problems
Non-isomorphic graphs with common degree sequences
For all positive even integers , graphs of order with degree sequence
\begin{equation*} S_{n}:1,2,\dots,n/2,n/2,n/2+1,n/2+2,\dots,n-1 \end{equation*}
naturally arose in the study of a labeling problem in \cite{IMO}. This fact
motivated the authors of the aforementioned paper to study these sequences and
as a result of this study they proved that there is a unique graph of order
realizing for every even integer . The main goal of this paper is to
generalize this result
Some results concerning the valences of (super) edge-magic graphs
A graph is called edge-magic if there exists a bijective function
such that is a constant (called the valence of ) for each . If , then is called a super
edge-magic graph. A stronger version of edge-magic and super edge-magic graphs
appeared when the concepts of perfect edge-magic and perfect super edge-magic
graphs were introduced. The super edge-magic deficiency of a graph is defined to be either the smallest
nonnegative integer with the property that is super
edge-magic or if there exists no such integer . On the other
hand, the edge-magic deficiency of a graph is the
smallest nonnegative integer for which is edge-magic, being
always finite. In this paper, the concepts of (super)
edge-magic deficiency are generalized using the concepts of perfect (super)
edge-magic graphs. This naturally leads to the study of the valences of
edge-magic and super edge-magic labelings. We present some general results in
this direction and study the perfect (super) edge-magic deficiency of the star
A method to compute the strength using bounds
A numbering of a graph of order is a labeling that assigns
distinct elements of the set to the vertices of . The
strength of is defined by , where . A few lower and upper bounds for the strength are known
and, although it is in general hard to compute the exact value for the
strength, a reasonable approach to this problem is to study for which graphs a
lower bound and an upper bound for the strength coincide. In this paper, we
study general conditions for graphs that allow us to determine which graphs
have the property that lower and upper bounds for the strength coincide and
other graphs for which this approach is useless
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