909 research outputs found
On dilaton dependence of type II superstring action
The supersymmetric action of type IIA D=10 superstring in N=2a, D=10
supergravity background can be derived by double dimensional reduction of the
action of supermembrane coupled to D=11 supergravity. We demonstrate that the
background Ramond-Ramond fields appear in the resulting superstring action with
an extra factor of exponential of the dilaton.Comment: 6 pages, harvmac (references added
Dualisation of the D=7 Heterotic String
The dualisation and the first-order formulation of the D=7 abelian Yang-Mills
supergravity which is the low energy effective limit of the D=7 fully Higssed
heterotic string is discussed. The non-linear coset formulation of the scalars
is enlarged to include the entire bosonic sector by introducing dual fields and
by constructing the Lie superalgebra which generates the dualized coset
element.Comment: 20 page
Kaluza-Klein electrically charged black branes in M-theory
We present a class of Kaluza-Klein electrically charged black p-brane
solutions of ten-dimensional, type IIA superstring theory. Uplifting to eleven
dimensions these solutions are studied in the context of M-theory. They can be
interpreted either as a p+1 extended object trapped around the eleventh
dimension along which momentum is flowing or as a boost of the following
backgrounds: the Schwarzschild black (p+1)-brane or the product of the
(10-p)-dimensional Euclidean Schwarzschild manifold with the (p+1)-dimensional
Minkowski spacetime.Comment: 16 pages, uses latex and epsf macro, figures include
On the sigma-model structure of type IIA supergravity action in doubled field approach
In this letter we describe how to string together the doubled field approach
by Cremmer, Julia, Lu and Pope with Pasti-Sorokin-Tonin technique to construct
the sigma-model-like action for type IIA supergravity. The relation of the
results with that of obtained in the context of searching for
Superstring/M-theory hidden symmetry group is discussed.Comment: 9 pp, LATEX; published in JETP Let
Livelihoods dependence on mangrove ecosystems: Empirical evidence from the Sundarbans
Comprehensive studies that employ larger data sets to explore the degree and conditions under which households depend on mangrove ecosystems account for only a negligible number in Asia\u27s context. We contribute to these lacunae by analysing households\u27 livelihood dependence on the Sundarbans of Asia. Specifically, we seek to: (i) appraise the livelihood strategies around the Sundarbans, (ii) analyse the conditions and determinants of household dependence on the Sundarbans, and (iii) explore perceptions surrounding livelihood dependence. An extensive survey of 1188 directly and indirectly dependent households drawn from 35 villages was conducted using structured interviews to address these topics. Twenty focus group discussions complemented this data. Using logistic regression, we analysed household dependence as a function of socioeconomic attributes. We suggest that socioeconomic factors have a substantial relationship with resource extraction and, therefore, policy prescriptions should focus on coordinating less-extractive diversification activities such as ecotourism to reduce the impact on the Sundarbans
Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet
We present inelastic neutron scattering and thermodynamic measurements
characterizing the magnetic excitations in a disordered non-magnetic
substituted spin-liquid antiferromagnet. The parent compound Ba3Mn2O8 is a
dimerized, quasi-two-dimensional geometrically frustrated quantum disordered
antiferromagnet. We substitute this compound with non-magnetic vanadium for the
S = 1 manganese atoms, Ba3(Mn1-xVx)2O8, and find that the singlet-triplet
excitations which dominate the spectrum of the parent compound persist for the
full range of substitution examined, x = 0.02 to 0.3. We also observe
additional low-energy magnetic fluctuations which are enhanced at the greatest
substitution values. These excitations may be a precursor to a low-temperature
random singlet phase which may exist in Ba3(Mn1-xVx)2O8Comment: 30 pages, 9 figure
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