392 research outputs found
S-Duality at the Black Hole Threshold in Gravitational Collapse
We study gravitational collapse of the axion/dilaton field in classical low
energy string theory, at the threshold for black hole formation. A new critical
solution is derived that is spherically symmetric and continuously
self-similar. The universal scaling and echoing behavior discovered by Choptuik
in gravitational collapse appear in a somewhat different form. In particular,
echoing takes the form of SL(2,R) rotations (cf. S-duality). The collapse
leaves behind an outgoing pulse of axion/dilaton radiation, with nearly but not
exactly flat spacetime within it.Comment: 8 pages of LaTeX, uses style "revtex"; 1 figure, available in
archive, or at ftp://ftp.itp.ucsb.edu/figures/nsf-itp-95-15.ep
Charged Dilaton Black Holes with Unusual Asymptotics
We present a new class of black hole solutions in Einstein-Maxwell-dilaton
gravity in dimensions. These solutions have regular horizons and a
singularity only at the origin. Their asymptotic behavior is neither
asymptotically flat nor (anti-) de Sitter. Similar solutions exist for certain
Liouville-type potentials for the dilaton.Comment: 24 pages, harvmac.tex, no figure
Real-Time Measurement of Face Recognition in Rapid Serial Visual Presentation
Event-related potentials (ERPs) have been used extensively to study the processes involved in recognition memory. In particular, the early familiarity component of recognition has been linked to the FN400 (mid-frontal negative deflection between 300 and 500âms), whereas the recollection component has been linked to a later positive deflection over the parietal cortex (500â800âms). In this study, we measured the ERPs elicited by faces with varying degrees of familiarity. Participants viewed a continuous sequence of faces with either low (novel faces), medium (celebrity faces), or high (faces of friends and family) familiarity while performing a separate face-identification task. We found that the level of familiarity was significantly correlated with the magnitude of both the early and late recognition components. Additionally, by using a single-trial classification technique, applied to the entire evoked response, we were able to distinguish between familiar and unfamiliar faces with a high degree of accuracy. The classification of high versus low familiarly resulted in areas under the curve of up to 0.99 for some participants. Interestingly, our classifier model (a linear discriminant function) was developed using a completely separate object categorization task on a different population of participants
Exact Black String Solutions in Three Dimensions
A family of exact conformal field theories is constructed which describe
charged black strings in three dimensions. Unlike previous charged black hole
or extended black hole solutions in string theory, the low energy spacetime
metric has a regular inner horizon (in addition to the event horizon) and a
timelike singularity. As the charge to mass ratio approaches unity, the event
horizon remains but the singularity disappears.Comment: 17 page
Rotating Dilaton Black Holes
It is shown that an arbitrarily small amount of angular momentum can
qualitatively change the properties of extremal charged black holes coupled to
a dilaton. In addition, the gyromagnetic ratio of these black holes is computed
and an exact rotating black string solution is presented.Comment: 14 page
Continuous Self-Similarity and -Duality
We study the spherically symmetric collapse of the axion/dilaton system
coupled to gravity. We show numerically that the critical solution at the
threshold of black hole formation is continuously self-similar. Numerical and
analytical arguments both demonstrate that the mass scaling away from
criticality has a critical exponent of .Comment: 17 pages, harvmac, six figures uuencoded in separate fil
Constraints on Jupiters from Observations of Galactic bulge microlensing events during 2000
Peer reviewe
Effective suppression of Dengue virus using a novel group-I intron that induces apoptotic cell death upon infection through conditional expression of the Bax C-terminal domain
Introduction:
Approximately 100 million confirmed infections and 20,000 deaths are caused by Dengue virus (DENV) outbreaks annually. Global warming and rapid dispersal have resulted in DENV epidemics in formally non-endemic regions. Currently no consistently effective preventive measures for DENV exist, prompting development of transgenic and paratransgenic vector control approaches. Production of transgenic mosquitoes refractory for virus infection and/or transmission is contingent upon defining antiviral genes that have low probability for allowing escape mutations, and are equally effective against multiple serotypes. Previously we demonstrated the effectiveness of an anti-viral group I intron targeting U143 of the DENV genome in mediating trans-splicing and expression of a marker gene with the capsid coding domain. In this report we examine the effectiveness of coupling expression of ÎN Bax to trans-splicing U143 intron activity as a means of suppressing DENV infection of mosquito cells.
Results:
Targeting the conserved DENV circularization sequence (CS) by U143 intron trans-splicing activity appends a 3â exon RNA encoding ÎN Bax to the capsid coding region of the genomic RNA, resulting in a chimeric protein that induces premature cell death upon infection. TCID50-IFA analyses demonstrate an enhancement of DENV suppression for all DENV serotypes tested over the identical group I intron coupled with the non-apoptotic inducing firefly luciferase as the 3â exon. These cumulative results confirm the increased effectiveness of this αDENV-U143-ÎN Bax group I intron as a sequence specific antiviral that should be useful for suppression of DENV in transgenic mosquitoes. Annexin V staining, caspase 3 assays, and DNA ladder observations confirm DCA-ÎN Bax fusion protein expression induces apoptotic cell death.
Conclusion:
This report confirms the relative effectiveness of an anti-DENV group I intron coupled to an apoptosis-inducing ÎN Bax 3â exon that trans-splices conserved sequences of the 5â CS region of all DENV serotypes and induces apoptotic cell death upon infection. Our results confirm coupling the targeted ribozyme capabilities of the group I intron with the generation of an apoptosis-inducing transcript increases the effectiveness of infection suppression, improving the prospects of this unique approach as a means of inducing transgenic refractoriness in mosquitoes for all serotypes of this important disease
Toward Eclipse Mapping of Hot Jupiters
Recent Spitzer infrared measurements of hot Jupiter eclipses suggest that
eclipse mapping techniques could be used to spatially resolve the day-side
photospheric emission of these planets using partial occultations. As a first
step in this direction, we simulate ingress/egress lightcurves for the three
brightest known eclipsing hot Jupiters and evaluate the degree to which
parameterized photospheric emission models can be distinguished from each other
with repeated, noisy eclipse measurements. We find that the photometric
accuracy of Spitzer is insufficient to use this tool effectively. On the other
hand, the level of photospheric details that could be probed with a few JWST
eclipse measurements could greatly inform hot Jupiter atmospheric modeling
efforts. A JWST program focused on non-parametric eclipse map inversions for
hot Jupiters should be actively considered.Comment: 32 pages, 6 figures, 3 tables, accepted for publication in Ap
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