Bert Janssen

Kaluza-Klein Monopoles and Gauged Sigma Models

Abstract We propose an effective action for the eleven-dimensional (bosonic) Kaluza-Klein monopole solution. The construction of the action requires that the background fields admit an Abelian isometry group. The corresponding sigma-model is gauged with respect to this isometry. The gauged sigma-model is the source for the monopole solution. A direct (double) dimensional reduction of the action leads to the effective action of a 10-dimensional D-6-brane (IIA Kaluza-Klein monopole). We also show that the effective action of the 10-dimensional heterotic Kaluza-Klein monopole (which is a truncation of the IIA monopole action) is T-dual to the effective action of the solitonic 5-brane. We briefly discuss the kappa-symmetric extension of our proposal and the possible role of gauged sigma-models in connection with the conjectured M-theory 9-brane.

Five-branes, KK monopoles and T-duality

We construct the explicit world-volume effective actions of the type IIB NS5-brane and KK monopole. These objects are obtained through a T-duality transformation from the IIA KK monopole and the IIA NS5-brane respectively. We show that the world-volume field content of these actions is precisely that necessary to describe their world-volume solitons. The IIB NS5-brane effective action is shown to be related to the D5-branes by an S-duality transformation, suggesting the way to construct (p, q) 5-brane multiplets. The IIB KK monopole is described by a gauged sigma model, in agreement with the general picture for KK monopoles, and behaves as a singlet under S-duality. We derive the explicit T-duality rules NS5-brane KK, which we use for the construction of the previous actions, as well as NS5 NS5, and KK KK

An alternative route for multistep tumorigenesis in a novel case of hereditary renal cell cancer and a t(2;3)(q35;q21) chromosome translocation.

Through allele-segregation and loss-of-heterozygosity analyses, we demonstrated loss of the translocation-derivative chromosome 3 in five independent renal cell tumors of the clear-cell type, obtained from three members of a family in which a constitutional t(2;3)(q35;q21) was encountered. In addition, analysis of the von Hippel-Lindau gene, VHL, revealed distinct insertion, deletion, and substitution mutations in four of the five tumors tested. On the basis of these results, we conclude that, in this familial case, an alternative route for renal cell carcinoma development is implied. In contrast to the first hit in the generally accepted two-hit tumor-suppressor model proposed by Knudson, the familial translocation in this case may act as a primary oncogenic event leading to (nondisjunctional) loss of the der(3) chromosome harboring the VHL tumor-suppressor gene. The risk of developing renal cell cancer may be correlated directly with the extent of somatic (kidney) mosaicism resulting from this loss.

A Microscopical Description of Giant Gravitons

Abstract We construct a non-Abelian world volume effective action for a system of multiple M-theory gravitons. This action contains multipole moment couplings to the eleven-dimensional background potentials. We use these couplings to study, from the microscopical point of view, giant graviton configurations where the gravitons expand into an M2-brane, with the topology of a fuzzy 2-sphere, that lives in the spherical part of the AdS7×S4 background or in the AdS part of AdS4×S7. When the number of gravitons is large we find perfect agreement with the Abelian, macroscopical, description of giant gravitons given in the literature.

The super D9-brane and its truncations

Abstract We consider two inequivalent truncations of the super D9-brane: the “Heterotic” and the “Type I” truncation. Both of them lead to an N = 1 non-linear supersymmetrization of the D = 10 cosmological constant. The propagating degrees of freedom in the Heterotic and Type I truncation are given by the components of a D = 10 vector multiplet and a single Majorana-Weyl spinor, respectively. As a by-product we find that, after the Type I truncation, the Ramond-Ramond super ten-form provides an interesting reformulation of the Volkov-Akulov action. These results can be extended to all dimensions in which space-time filling D-branes exist, i.e. D = 3, 4, 6 and 10.

Multiple intersections of D-branes and M-branes

We give a classification of all multiple intersections of D-branes in ten dimensions and M-branes in eleven dimensions that correspond to threshold BPS bound states. The residual supersymmetry of these composite branes is determined. By dimensional reduction composite p-branes in lower dimensions can be constructed. We emphasize in dimensions D ⩾ 2 those solutions which involve a single scalar and depend on a single harmonic function. For these extremal branes we obtain the strength of the coupling between the scalar and the gauge field. In particular, we give a D-brane and M-brane interpretation of extreme p-branes in two, three and four dimensions.

Intersections involving monopoles and waves in eleven dimensions

We consider intersections in eleven dimensions involving Kaluza-Klein monopoles and Brinkmann waves. Besides these purely gravitational configurations, we also construct solutions to the equations of motion that involve additional M2- and M5-branes. The maximal number of independent objects in these intersections is nine, and such maximal configurations, when reduced to two dimensions, give rise to a 0-brane solution with dilaton coupling aD 4 .

Intersecting D-branes in ten and six dimensions

We show how, via T duality, intersecting D brane configurations in ten (six) dimensions can be obtained from the elementary D-brane configurations by embedding a type IIB D-brane into a type IIB nine-brane (five-brane) and give a classification of such configurations. We show that only a very specific subclass of these configurations can be realized as (supersymmetric) solutions to the equations of motion of IIA or IIB supergravity. Whereas the elementary D-brane solutions in d=10 are characterized by a single harmonic function, those in d=6 contain two independent harmonic functions and may be viewed as the intersection of two d=10 elementary D-branes. Using string-string-string triality in six dimensions we show that the heterotic version of the elementary d=6 D-brane solutions correspond in ten dimensions to intersecting Neveu-Schwarz{endash}Neveu-Schwarz (NS-NS) strings or five-branes and their T duals. We comment on the implications of our results in other than ten and six dimensions. {copyright} {ital 1997} {ital The American Physical Society}

Palatini versus metric formulation in higher-curvature gravity

We compare the metric and the Palatini formalism to obtain the Einstein equations in the presence of higher-order curvature corrections that consist of contractions of the Riemann tensor, but not of its derivatives. We find that there is a class of theories for which the two formalisms are equivalent. This class contains the Palatini version of Lovelock theory, but also more Lagrangians that are not Lovelock, but respect certain symmetries. For the general case, we find that imposing the Levi-Civita connection as an ansatz, the Palatini formalism is contained within the metric formalism, in the sense that any solution of the former also appears as a solution of the latter, but not necessarily the other way around. Finally we give the conditions the solutions of the metric equations should satisfy in order to solve the Palatini equations.

Fine mapping of the human renal oncocytoma-associated translocation (5;11)(q35;q13) breakpoint

Recent cytogenetic analysis of a series of human renal oncocytomas revealed the presence of a recurring chromosomal translocation (5;11)(q35;q13) as sole anomaly in a subset of the tumors. The molecular characterization of this translocation was initiated using two primary t(5;11)-positive renal oncocytomas and a panel of somatic cell hybrids derived from one of these tumors, in conjunction with fluorescence in situ hybridization (FISH) and Southern blot analysis. The breakpoint in chromosome band 11q13 could be located within a genomic interval of at maximum 400 Kb immediately centromeric to the BCL1 locus.