133 research outputs found
Multiple D-branes as a D-brane
From BFSS matrix theory considerations, it is expected that a single
D-brane action can be obtained from N D-brane action in large N
limit. We examine and confirm this expectation by working out the details of
DBI and Chern-Simons terms of D-brane action from D-brane action.
We show that the same relation works for non-BPS, as well as BPS branesComment: 14 page
The interrelation between the generation of large-scale electric fields and that of large-scale magnetic fields during inflation
The interrelation between the generation of large-scale electric fields and
that of large-scale magnetic fields due to the breaking of the conformal
invariance of the electromagnetic field in inflationary cosmology is studied.
It is shown that if large-scale magnetic fields with a sufficiently large
amplitude are generated during inflation, the generation of large-scale
electric fields is suppressed, and vice versa. Furthermore, a physical
interpretation of the result and its cosmological significance are considered.Comment: 12 pages, no figure, title changed, typos correcte
1/4-BPS M-theory bubbles with SO(3) x SO(4) symmetry
In this paper we generalize the work of Lin, Lunin and Maldacena on the
classification of 1/2-BPS M-theory solutions to a specific class of 1/4-BPS
configurations. We are interested in the solutions of 11 dimensional
supergravity with symmetry, and it is shown that such
solutions are constructed over a one-parameter familiy of 4 dimensional almost
Calabi-Yau spaces. Through analytic continuations we can obtain M-theory
solutions having or factors. It is shown
that our result is equivalent to the solutions which have been recently
reported as the near-horizon geometry of M2 or M5-branes wrapped on 2 or
4-cycles in Calabi-Yau threefolds. We also discuss the hierarchy of M-theory
bubbles with different number of supersymmetries.Comment: 22 pages, JHEP3.cls; v2. revised version. showed that our results
agree with previous works hep-th/0605146 and hep-th/061219
Electrochemical determination of the antipsychotic medication clozapine by a carbon paste electrode modified with a nanostructure prepared from titania nanoparticles and copper oxide
A nanostructure was prepared from titania nanoparticles and copper oxide (TiO2NP@CuO) and used to modify a carbon paste electrode (CPE). The modified CPE is shown to enable sensitive voltammetric determination of the drug clozapine (CLZ). The sensor was characterized by various techniques and some key parameters were optimized. Under the optimum conditions and at a working potential of 0.6 V (vs. Ag/AgCl), the modified CPE has two linear response ranges, one from 30 pmol L�1 to 4 nmol L�1 of CLZ, the other from 4 nmol L�1 to 10 μmol L�1. The detection limit is as low as 9 pM. The transfer coefficient (α) and catalytic rate constant (kcat) were calculated and the reliability of the sensor was estimated for CLZ sensing in real samples where it gave satisfactory results. Figure not available: see fulltext.. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature
Interaction between M2-branes and Bulk Form Fields
We construct the interaction terms between the world-volume fields of
multiple M2-branes and the 3- and 6-form fields in the context of ABJM theory
with U()U() gauge symmetry. A consistency check is made in the
simplest case of a single M2-brane, i.e, our construction matches the known
effective action of M2-brane coupled to antisymmetric 3-form field. We show
that when dimensionally reduced, our couplings coincide with the effective
action of D2-branes coupled to R-R 3- and 5-form fields in type IIA string
theory. We also comment on the relation between a coupling with a specific
6-form field configuration and the supersymmetry preserving mass deformation in
ABJM theory.Comment: 30 pages, version to appear in JHE
Large-scale magnetic fields from inflation due to Chern-Simons-like effective interaction
We discuss the generation of large-scale magnetic fields due to the breaking
of the conformal invariance in the electromagnetic field through the -even
dimension-six Chern-Simons-like effective interaction with a fermion current in
inflationary cosmology. It is shown that the magnetic fields on 1Mpc scale with
the field strength of G at the present time can be generated even
for the scale of the effective interaction being the Planck scale.Comment: 13 pages, 2 figures, additional explanations include
A Quintessentially Geometric Model
We consider string inspired cosmology on a solitary -brane moving in the
background of a ring of branes located on a circle of radius . The motion of
the -brane transverse to the plane of the ring gives rise to a radion field
which can be mapped to a massive non-BPS Born-Infeld type field with a cosh
potential. For certain bounds of the brane tension we find an inflationary
phase is possible, with the string scale relatively close to the Planck scale.
The relevant perturbations and spectral indices are all well within the
expected observational bounds. The evolution of the universe eventually comes
to be dominated by dark energy, which we show is a late time attractor of the
model. However we also find that the equation of state is time dependent, and
will lead to late time Quintessence.Comment: 11 pages, 3 figures. References and comments adde
Potentiometric Electronic Tongue to Resolve Mixtures of Sulfide and Perchlorate Anions
This work describes the use of an array of potentiometric sensors and an artificial neural network response model to determine perchlorate and sulfide ions in polluted waters, by what is known as an electronic tongue. Sensors used have been all-solid-state PVC membrane selective electrodes, where their ionophores were different metal-phtalocyanine complexes with specific and anion generic responses. The study case illustrates the potential use of electronic tongues in the quantification of mixtures when interfering effects need to be counterbalanced: relative errors in determination of individual ions can be decreased typically from 25% to less than 5%, if compared to the use of a single proposed ion-selective electrode
Mass-Deformed Super Yang-Mills Theories from M2-Branes with Flux
We consider -dimensional mass-deformed SYM theories and their M-theory
origin. These are obtained from MP Higgsing of ABJM theory with constant flux
and fixing the mass terms via supersymmetry completion. Depending on the choice
of the flux, we obtain , , and
mass-deformed SYM theories. For each of these cases we solve the vacuum
equation and obtain the fuzzy two sphere solution for the first two cases. We
also discuss the D-brane interpretation of the obtained mass-deformed SYM
theories.Comment: 22 pages, no figure, vacuum solutions are more generalized, published
version in JHE
TAPCHA: An Invisible CAPTCHA Scheme
TAPCHA is a universal CAPTCHA scheme designed for touch-enabled smart devices such as
smartphones, tablets and smartwatches. The main difference between TAPCHA and other
CAPTCHA schemes is that TAPCHA retains its security by making the CAPTCHA test ‘invisible’ for
the bot. It then utilises context effects to maintain the readability of the instruction for human users
which eventually guarantees the usability of the scheme. Two reference designs, namely TAPCHA
SHAPE & SHADE and TAPCHA MULTI are developed to demonstrate the use of this scheme
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