1,673 research outputs found
Volume Stabilization and the Origin of the Inflaton Shift Symmetry in String Theory
The main problem of inflation in string theory is finding the models with a
flat potential, consistent with stabilization of the volume of the compactified
space. This can be achieved in the theories where the potential has (an
approximate) shift symmetry in the inflaton direction. We will identify a class
of models where the shift symmetry uniquely follows from the underlying
mathematical structure of the theory. It is related to the symmetry properties
of the corresponding coset space and the period matrix of special geometry,
which shows how the gauge coupling depends on the volume and the position of
the branes. In particular, for type IIB string theory on K3xT^2/Z with D3 or D7
moduli belonging to vector multiplets, the shift symmetry is a part of
SO(2,2+n) symmetry of the coset space [SU(1,1)/ U(1)]x[SO(2,2+n)/(SO(2)x
SO(2+n)]. The absence of a prepotential, specific for the stringy version of
supergravity, plays a prominent role in this construction, which may provide a
viable mechanism for the accelerated expansion and inflation in the early
universe.Comment: 12 page
English as an Asian Language
This paper outlines the dimensions of Asia's English, which constitutes a world of its own in linguistic, cultural, interactional, ideological, and political terms. The questions this paper raises are: What conditions must a transplanted colonial language satisfy to be accepted as part of the colonized's linguistic repertoire? Why not consider Asian Englishes as part of a local pluralistic linguistic heritage? Answers to these questions demand redefining the concept of «nativeness» and types of nativeness; this paper advances that proposal by describing the distinction between «genetic nativeness» and «functional nativeness». The remainder of the paper comprises the sections: Asian presence of English; domains of functions; the albatross of mythology; mythology and the Asian context; decolonizing context and text; canonicity, diversity and Asian English; English on Asian terms; and institutionalization of Asian Englishes. In concluding, the paper briefly considers the often repeated question: Where do we go with Asian Englishes?
Modeling M-Theory Vacua via Gauged S-Duality
We construct a model of M-theory vacua using gauged S-duality and the
Chan-Paton symmetries by introducing an infinite number of open string charges.
In the Bechi-Rouet-Stora-Tyutin formalism, the local description of the gauged
S-duality on its moduli space of vacua is fully determined by one physical
state condition on the vacua. We introduce the string probe of the spatial
degrees of freedom and define the increment of the cosmic time. The
dimensionality of space-time and the gauge group of the low energy effective
theory originate in the symmetries (with or without their breakdown) in our
model. This modeling leads to the derived category formulation of the quantum
mechanical world including gravity and to the concept of a non-linear potential
of gauged and affinized S-duality which specifies the morphism structure of
this derived category.Comment: 31 pages, version reflecting the erratum. arXiv admin note:
substantial text overlap with arXiv:1102.460
Euclidean N=2 Supergravity
Euclidean special geometry has recently been investigated in the context of
Euclidean supersymmetric theories with vector multiplets. In the rigid case,
the scalar manifold is described by affine special para-Kahler geometry while
the target geometries of Euclidean vector multiplets coupled to supergravity
are given by projective special para-Kahler manifolds. In this letter, we
derive the Killing spinor equations of Euclidean N=2 supergravity theories
coupled to vector multiplets. These equations provide the starting point for
finding general supersymmetric instanton solutions.Comment: 12 pages, latex. Minor sign corrections in section
Anthropic reasoning in multiverse cosmology and string theory
Anthropic arguments in multiverse cosmology and string theory rely on the
weak anthropic principle (WAP). We show that the principle, though ultimately a
tautology, is nevertheless ambiguous. It can be reformulated in one of two
unambiguous ways, which we refer to as WAP_1 and WAP_2. We show that WAP_2, the
version most commonly used in anthropic reasoning, makes no physical
predictions unless supplemented by a further assumption of "typicality", and we
argue that this assumption is both misguided and unjustified. WAP_1, however,
requires no such supplementation; it directly implies that any theory that
assigns a non-zero probability to our universe predicts that we will observe
our universe with probability one. We argue, therefore, that WAP_1 is
preferable, and note that it has the benefit of avoiding the inductive
overreach characteristic of much anthropic reasoning.Comment: 7 pages. Expanded discussion of selection effects and some minor
clarifications, as publishe
Physiological studies on dormancy in grape seeds (Vitis vinifera) 1. On the naturally occurring growth substances in grape seeds and their changes during low temperature after ripening
In order to understand the hormonal factors affecting dormancy in grape seeds, studies were conducted on the endogenous auxins, inhibitcrs and gibberellin-like substances in the seeds stored moist at 5° C and at room temperature .The results show that moist after-ripening at 5° C resulted in an increase in the amount of growth promoting substances similar to auxins, in the extracts of chilled seeds. No correlation was observed between the content of inhibitor and dormancy in grape seeds. The extracts of neither chilled nor non-chilled seeds showed the presence of gibberellin-like substances when tested on D5 dwarf maize mutant plants.In the light of these findings, it is proposed that an increased synthesis of growth promoting substances during stratification may be one of the factors responsible for the termination of dormancy and resumption of germination of grape seeds
Non-supersymmetric Tachyon-free Type-II and Type-I Closed Strings from RCFT
We consider non-supersymmetric four-dimensional closed string theories
constructed out of tensor products of N=2 minimal models. Generically such
theories have closed string tachyons, but these may be removed either by
choosing a non-trivial partition function or a suitable Klein bottle
projection. We find large numbers of examples of both types.Comment: 9 pages, 1 tabl
Orientifolds, RG Flows, and Closed String Tachyons
We discuss the fate of certain tachyonic closed string theories from two
perspectives. In both cases our approach involves studying directly
configurations with finite negative tree-level cosmological constant. Closed
string analogues of orientifolds, which carry negative tension, are argued to
represent the minima of the tachyon potential in some cases. In other cases, we
make use of the fact, noted in the early string theory literature, that strings
can propagate on spaces of subcritical dimension at the expense of introducing
a tree-level cosmological constant. The form of the tachyon vertex operator in
these cases makes it clear that a subcritical-dimension theory results from
tachyon condensation. Using results of Kutasov, we argue that in some
Scherk-Schwarz models, for finely-tuned tachyon condensates, a minimal model
CFT times a subcritical dimension theory results. In some instances, these two
sets of ideas may be related by duality.Comment: 15 pages, 2 figures, uses harvmac; v2: references adde
Physiological studies on dormancy in grape seeds (Vitis vinifera var. Black Muscat) II. On the effect of exogenous application of growth substances, low chilling temperature and subjection of the seeds to running water
In order to break the dormancy of grape seeds in the minimum possible time, a number of treatments, including stratification, growth substances and subjecting the seeds to running water, were used. It was observed that grape seeds kept in running water for 8 days germinated in the muslin cloth itself (34.00%). The maximum percentage of germination obtained was 73.00% when the seeds were kept in running water for 16 days. However, the seedling stand was best under the 12 day treatment (72.11 %). This was followed by GA3 treatment (2000 ppm) before stratification, whereby grape seeds germinated within 8 days of stratification and maximum germination percentage was 81.05 after one month. Third best result was obtained under stratification for one month and then a treatment with GA3. Further, grape seeds, when soaked in water for 96 hours, leached some water soluble inhibitor. This could antagonize the germination of GA3 treated grape seeds. When this leached water was bioassayed by the cress seed germination test, it showed the presence of inhibitor at R1 0.7 to 0.85. It appears that the water soluble inhibitor might be responsible for masking the effect of growth substances present in the seeds and thereby disturbing the metabolism of germination.Physiologische Untersuchungen zur Dormanz von Rebensamen (Vitis vinifera var. Black Muscat). II. Über den Einfluß äußerlich angewandter Wuchsstoffe, niedriger Temperaturen und des Auswaschens der Samen in fließendem WasserUm die Dormanz von Rebensamen in der kürzestmöglichen Zeit zu brechen, wurden sie stratifiziert, mit Wuchsstoffen behandelt und in fließendem Wasser ausgewaschen. Es wurde beobachtet, daß Rebensamen, die in einem Musselinsäckchen 8 Tage lang ausgewaschen wurden, schon in dem Säckchen keimten (34,00°/o). Der h öchste Keimungsprozentsatz (73,000/o) wurde erzielt, wenn die Samen 16 Tage lang mit fließendem Wasser behandelt wurden. Bei einer 12tägigen Behandlung (72, 11% gekeimter Samen) war die Standfestigkeit der Sämlinge jedoch am besten. Das zweitbeste Resultat wurde mit GS3-Behandlung (2000 ppm) vor der Stratifikation erzielt, wobei die Rebensamen nach 8tägiger Stratifikation keimten; der höchste Anteil gekeimter Samen betrug - nach 30tägiger Stratifikation - 81,05%. 1monatige Stratifikation mit an schließender GS3-Behandlung lieferte das drittbeste Ergebnis. Ferner gaben Rebensamen, die 96 Std. lang in Wasser gequollen waren , einen wasserlöslichen Inhibitor ab. Dieser konnte die Keimung GS3-behandelter Samen hemmen. Mit Hilfe des Kressewurzeltests ließ sich im Einweichwasser ein Hemmstoff mit ein em Rr von 0,70-0,85 nachweisen. Möglicherweise stört der wasserlösliche Inhibitor den Stoffwechsel der Keimung, so daß die Wirkung der Wuchsstoffe in den Samen verdeckt wird
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