619 research outputs found
Dilatonic Inflation and SUSY Breaking in String-inspired Supergravity
The theory of inflation will be investigated as well as supersymmetry
breaking in the context of supergravity, incorporating the target-space duality
and the nonperturbative gaugino condensation in the hidden sector. We found an
inflationary trajectory of a dilaton field and a condensate field which breaks
supersymmetry at once. The model satisfies the slow-roll condition which solves
the eta-problem. When the particle rolls down along the minimized trajectory of
the potential V(S,Y) at a duality invariant point of T=1, we can obtain the
e-fold value \sim 57. And then the cosmological parameters obtained from our
model well match the recent WMAP data combined with other experiments. This
observation suggests one to consider the string-inspired supergravity as a
fundamental theory of the evolution of the universe as well as the particle
theory.Comment: 10 pages, 4 eps figures. Typos and references corrected. Final
version to appear in Mod. Phys. Lett.
Exotic criticality in the dimerized spin-1 chain with single-ion anisotropy
We consider the dimerized spin-1 chain with single-ion anisotropy .
In absence of an explicit dimerization there are three phases: a large-, an
antiferromagnetically ordered and a Haldane phase. This phase structure
persists up to a critical dimerization, above which the Haldane phase
disappears. We show that for weak dimerization the phases are separated by
Gaussian and Ising quantum phase transitions. One of the Ising transitions
terminates in a critical point in the universality class of the dilute Ising
model. We comment on the relevance of our results to experiments on
quasi-one-dimensional anisotropic spin-1 quantum magnets.Comment: Received the Select label. 20 pages, 7 figures, final versio
Symmetry Reduction of Optimal Control Systems and Principal Connections
This paper explores the role of symmetries and reduction in nonlinear control
and optimal control systems. The focus of the paper is to give a geometric
framework of symmetry reduction of optimal control systems as well as to show
how to obtain explicit expressions of the reduced system by exploiting the
geometry. In particular, we show how to obtain a principal connection to be
used in the reduction for various choices of symmetry groups, as opposed to
assuming such a principal connection is given or choosing a particular symmetry
group to simplify the setting. Our result synthesizes some previous works on
symmetry reduction of nonlinear control and optimal control systems. Affine and
kinematic optimal control systems are of particular interest: We explicitly
work out the details for such systems and also show a few examples of symmetry
reduction of kinematic optimal control problems.Comment: 23 pages, 2 figure
Supportive intervention using a mobile phone in behavior modification
The authors previously developed a mobile ecological momentary assessment (EMA) system as a real-time data collection device using a mobile phone. In this study, a real-time advice function and real-time reporting function were added to the previous system as a supportive intervention. The improved system was found to work effectively and was applied to several clinical cases, including patients with depressive disorder, dizziness, smoking habit, and bronchial asthma. The average patient compliance rate was high (89%) without the real-time advice and higher (93%) with the advice. The trends in clinical data for patients using a mobile EMA with/without the new function were analyzed for up to several months. In the case of dizziness, an improving trend in its clinical data was observed after applying the real-time advice, and in the case of depressive disorder, a stabilizing trend was observed. The mobile EMA system with the real-time advice function could be useful as a supportive intervention in behavior modification and for motivating patients in self-management of their disease.</p
2D and 3D Stem Cell Models of Primate Cortical Development Identify Species-Specific Differences in Progenitor Behavior Contributing to Brain Size.
Variation in cerebral cortex size and complexity is thought to contribute to differences in cognitive ability between humans and other animals. Here we compare cortical progenitor cell output in humans and three nonhuman primates using directed differentiation of pluripotent stem cells (PSCs) in adherent two-dimensional (2D) and organoid three-dimensional (3D) culture systems. Clonal lineage analysis showed that primate cortical progenitors proliferate for a protracted period of time, during which they generate early-born neurons, in contrast to rodents, where this expansion phase largely ceases before neurogenesis begins. The extent of this additional cortical progenitor expansion differs among primates, leading to differences in the number of neurons generated by each progenitor cell. We found that this mechanism for controlling cortical size is regulated cell autonomously in culture, suggesting that primate cerebral cortex size is regulated at least in part at the level of individual cortical progenitor cell clonal output.T.O. was supported by the Wellcome Trust PhD Programme in Developmental Biology at the University of Cambridge. F.J.L. and B.D.S. are Wellcome Trust Investigators. This research was supported by core funding to the Gurdon Institute by the Wellcome Trust and Cancer Research UK. F.H.G. was supported by the Helmsley, Mathers, and JPB Foundations.This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.stem.2016.03.00
Lensed quasar search via time variability with the HSC transient survey
Gravitationally lensed quasars are useful for studying astrophysics and
cosmology, and enlarging the sample size of lensed quasars is important for
multiple studies. In this work, we develop a lens search algorithm for
four-image (quad) lensed quasars based on their time variability. In the
development of the lens search algorithm, we constructed a pipeline simulating
multi-epoch images of lensed quasars in cadenced surveys, accounting for quasar
variabilities, quasar hosts, lens galaxies, and the PSF variation. Applying the
simulation pipeline to the Hyper Suprime-Cam (HSC) transient survey, we
generated HSC-like difference images of the mock lensed quasars from Oguri &
Marshall's lens catalog. We further developed a lens search algorithm that
picks out variable objects as lensed quasar candidates based on their spatial
extent in the difference images. We tested our lens search algorithm with the
mock lensed quasars and variable objects from the HSC transient survey. Using
difference images from multiple epochs, our lens search algorithm achieves a
high true-positive rate (TPR) of 90.1% and a low false-positive rate (FPR) of
2.3% for the bright quads with wide separation. With a preselection of the
number of blobs in the difference image, we obtain a TPR of 97.6% and a FPR of
2.6% for the bright quads with wide separation. Even when difference images are
only available in one single epoch, our lens search algorithm can still detect
the bright quads with wide separation at high TPR of 97.6% and low FPR of 2.4%
in the optimal seeing scenario, and at TPR of and FPR of in
typical scenarios. Therefore, our lens search algorithm is promising and is
applicable to ongoing and upcoming cadenced surveys, particularly the HSC
transient survey and the Rubin Observatory Legacy Survey of Space and Time, for
finding new lensed quasar systems. [abridged]Comment: 15 pages, 11 figure
Prevalence of strong bottom currents in the greater Agulhas system
Deep current meter data and output from two high-resolution global ocean circulation models are used to determine the prevalence and location of strong bottom currents in the greater Agulhas Current system. The two models and current meter data are remarkably consistent, showing that benthic storms, with bottom currents greater than 0.2 m s(-1), occur throughout the Agulhas retroflection region south of Africa more than 20% of the time. Furthermore, beneath the mean Agulhas Current core and the retroflection front, bottom currents exceed 0.2 m s(-1) more than 50% of the time, while away from strong surface currents, bottom currents rarely exceed 0.2 m s(-1). Implications for sediment transport are discussed and the results are compared to atmospheric storms. Benthic storms of this strength (0.2 m s(-1)) are comparable to a 9 m s(-1) (Beaufort 5) windstorm, but scaling shows that benthic storms may be less effective at lifting and transporting sediment than dust storms
Auroral evidence of radial transport at Jupiter during January 2014
We present Jovian auroral observations from the 2014 January Hubble Space Telescope (HST) campaign and investigate the auroral signatures of radial transport in the magnetosphere alongside contemporaneous radio and Hisaki EUV data. HST FUV auroral observations on day 11 show, for the first time, a significantly superrotating polar spot poleward of the main emission on the dawnside. The spot transitions from the polar to main emission region in the presence of a locally broad, bright dawnside main emission feature and two large equatorward emission features. Such a configuration of the main emission region is also unreported to date. We interpret the signatures as part of a sequence of inward radial transport processes. Hot plasma inflows from tail reconnection are thought to flow planetward and could generate the superrotating spot. The main emission feature could be the result of flow shears from prior hot inflows. Equatorward emissions are observed. These are evidence of hot plasma injections in the inner magnetosphere. The images are thought to be part of a prolonged period of reconnection. Radio emissions measured by Wind suggest that hectometric (HOM) and non-Io decametric (DAM) signatures are associated with the sequence of auroral signatures, which implies a global magnetospheric disturbance. The reconnection and injection interval can continue for several hours
- …