1,019 research outputs found
Massive Dualities in Six Dimensions
We study compactifications of string theory and M-theory to six dimensions
with background fluxes. The nonzero fluxes lead to additional mass parameters.
We derive the S- and T-duality rules for the corresponding (massive)
supergravity theories. Specifically, we investigate the massive T-duality
between Type IIA superstring theory compactified on K3 with background fluxes
and Type IIB superstring theory compactified on K3. Furthermore, we generalise
to the massive case the 6D 'string-string' S-duality between M-theory on K3 x
S^1 and the Heterotic String on T^4. Whereas in the case of massive T--duality
the mass parameters are in the fundamental representation of the U-duality
group O(4,20) we find that in the case of massive S-duality they are in the
3-index antisymmetric representation. In the latter case the mass parameters
involved extend those of Kaloper and Myers. We apply our duality rules to
massive brane solutions, like the domain wall solutions corresponding to the
mass parameters and find new massive brane solutions. Finally, we discuss the
higher-dimensional interpretation of the dualities and brane solutions.Comment: 28 page
N=31 is not IIB
We adapt the spinorial geometry method to investigate supergravity
backgrounds with near maximal number of supersymmetries. We then apply the
formalism to show that the IIB supergravity backgrounds with 31 supersymmetries
preserve an additional supersymmetry and so they are maximally supersymmetric.
This rules out the existence of IIB supergravity preons.Comment: 7 page
Geometry of all supersymmetric type I backgrounds
We find the geometry of all supersymmetric type I backgrounds by solving the
gravitino and dilatino Killing spinor equations, using the spinorial geometry
technique, in all cases. The solutions of the gravitino Killing spinor equation
are characterized by their isotropy group in Spin(9,1), while the solutions of
the dilatino Killing spinor equation are characterized by their isotropy group
in the subgroup Sigma(P) of Spin(9,1) which preserves the space of parallel
spinors P. Given a solution of the gravitino Killing spinor equation with L
parallel spinors, L = 1,2,3,4,5,6,8, the dilatino Killing spinor equation
allows for solutions with N supersymmetries for any 0 < N =< L. Moreover for L
= 16, we confirm that N = 8,10,12,14,16. We find that in most cases the Bianchi
identities and the field equations of type I backgrounds imply a further
reduction of the holonomy of the supercovariant connection. In addition, we
show that in some cases if the holonomy group of the supercovariant connection
is precisely the isotropy group of the parallel spinors, then all parallel
spinors are Killing and so there are no backgrounds with N < L supersymmetries.Comment: 73 pages. v2: minor changes, references adde
Strengthening of Parenthood; Developing a Life Skills Questionnaire for Dutch Parents (LSQ-P)
AbstractLife skills of parents have a positive effect on the wellbeing of parents and development of children. Currently, no reliable instrument is available to measure these skills. This study was set up to develop a questionnaire for assessing parentsâ life skills. The questionnaire was developed for professionals who are working with parents and for building behavioral interventions enhancing the wellbeing of parents. A pilot research using a translation of the Life Skills Scale (Erawan, 2010) was conducted. Construct validity and reliability by means of confirmatory factor analysis of nine scales were examined in a sample of 133 Dutch parents and reliability of the scales in terms of Cronbach's alpha was examined. Evidence for construct validity of the scales was found. Reliability coefficients were satisfactory for the scales Critical thinking, Social responsibility, Interpersonal relationships, Decision making, Self-awareness, and Creative thinking. Reliability coefficients were good for Empathy and Self-esteem. The LSQ-P can be used in social work practice as an assessment tool to measure strengths and weaknesses regarding life skills of parents. More attention for developing life skills of parents is necessary in order to increase their wellbeing. Implications for health promotion among parents are discussed. Suggestions for further research and development of the scales are outlined
Reduction of Coxiella burnetii prevalence by vaccination of goats and sheep, the Netherlands
Recently, the number of human Q fever cases in the Netherlands increased dramatically. In response to this increase, dairy goats and dairy sheep were vaccinated against Coxiella burnetii. All pregnant dairy goats and dairy sheep in herds positive for Q fever were culled. We identified the effect of vaccination on bacterial shedding by small ruminants. On the day of culling, samples of uterine fluid, vaginal mucus, and milk were obtained from 957 pregnant animals in 13 herds. Prevalence and bacterial load were reduced in vaccinated animals compared with unvaccinated animals. These effects were most pronounced in animals during their first pregnancy. Results indicate that vaccination may reduce bacterial load in the environment and human exposure to C. burnetii
Maximally supersymmetric G-backgrounds of IIB supergravity
We classify the geometry of all supersymmetric IIB backgrounds which admit
the maximal number of -invariant Killing spinors. For compact stability
subgroups and SU(2), the spacetime is locally isometric to a
product with , where is a maximally
supersymmetric solution of a -dimensional supergravity theory and
is a Riemannian manifold with holonomy . For non-compact stability
subgroups, G=K\ltimes\bR^8, , SU(4), ,
and , the spacetime is a pp-wave propagating in an eight-dimensional
manifold with holonomy . We find new supersymmetric pp-wave solutions of IIB
supergravity.Comment: 22 page
The Classification of Highly Supersymmetric Supergravity Solutions
The spinorial geometry method is an effective method for constructing
systematic classifications of supersymmetric supergravity solutions. Recent
work on analysing highly supersymmetric solutions in type IIB supergravity
using this method is reviewed [arXiv:hep-th/0606049, arXiv:0710.1829]. It is
shown that all supersymmetric solutions of IIB supergravity with more than 28
Killing spinors are locally maximally supersymmetric.Comment: 23 pages, latex. To appear in the proceedings of the Special Metrics
and Supersymmetry conference at Universidad del Pais Vasco, May 2008.
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