3,793 research outputs found
Sparticle Spectrum of Large Volume Compactification
We examine the large volume compactification of Type IIB string theory or its
F theory limit and the associated supersymmetry breakdown and soft terms. It is
crucial to incorporate the loop-induced moduli mixing, originating from
radiative corrections to the Kahler potential. We show that in the presence of
moduli mixing, soft scalar masses generically receive a D-term contribution of
the order of the gravitino mass m_{3/2} when the visible sector cycle is
stabilized by the D-term potential of an anomalous U(1) gauge symmetry, while
the moduli-mediated gaugino masses and A-parameters tend to be of the order of
m_{3/2}/8pi^2. It is noticed also that a too large moduli mixing can
destabilize the large volume solution by making it a saddle point.Comment: 29 page
Universal criterion and phase diagram for switching a magnetic vortex core in soft magnetic nanodots
The universal criterion for ultrafast vortex-core switching between the up-
and down-core bistates in soft magnetic nanodots was investigated by
micromagnetic simulations along with analytical calculations. Vortex-core
switching occurs whenever the velocity of vortex-core motion reaches the
critical velocity that is expressed as (e.g. m/s for Permalloy), where Aex is
the exchange stiffness, and is the gyromagnetic ratio. On the basis of the
above results, phase diagrams for the vortex-core switching event and switching
times with respect to both the amplitude and frequency of applied circularly
rotating magnetic field were calculated, which offer practical guidance for
implementing nanodots in vortex states into future solid-state
information-storage devices.Comment: 25 pages, 5 figures. To whom all correspondence should be addressed:
[email protected]
Maximal surface group representations in isometry groups of classical Hermitian symmetric spaces
Higgs bundles and non-abelian Hodge theory provide holomorphic methods with
which to study the moduli spaces of surface group representations in a
reductive Lie group G. In this paper we survey the case in which G is the
isometry group of a classical Hermitian symmetric space of non-compact type.
Using Morse theory on the moduli spaces of Higgs bundles, we compute the number
of connected components of the moduli space of representations with maximal
Toledo invariant.Comment: v2: added due credits to the work of Burger, Iozzi and Wienhard. v3:
corrected count of connected components for G=SU(p,q) (p \neq q); added due
credits to the work of Xia and Markman-Xia; minor corrections and
clarifications. 31 page
Polarization-selective vortex-core switching by orthogonal Gaussian-pulse currents
We experimentally demonstrate low-power-consumption vortex-core switching in
magnetic nanodisks using tailored rotating magnetic fields that are produced
with orthogonal and unipolar Gaussian-pulse currents. Optimal width of the
orthogonal pulses and their time delay are found to be determined only by the
angular eigenfrequency {\omega}_D for a given vortex-state disk of its
polarization p, such that {\sigma} = 1/{\omega}_D and {\Delta}t =
{\pi}p/2{\omega}_D, as studied from analytical and micromagnetic numerical
calculations. The estimated optimal pulse parameters are in good agreements
with the experimentally found results. This work provides a foundation for
energy-efficient information recording in vortex-core cross-point architecture.Comment: 32 pages, 10 figure
Stimulation of Na<sup>+</sup>/H<sup>+</sup> Exchanger Isoform 1 Promotes Microglial Migration
Regulation of microglial migration is not well understood. In this study, we proposed that Na+/H+ exchanger isoform 1 (NHE-1) is important in microglial migration. NHE-1 protein was co-localized with cytoskeletal protein ezrin in lamellipodia of microglia and maintained its more alkaline intracellular pH (pHi). Chemoattractant bradykinin (BK) stimulated microglial migration by increasing lamellipodial area and protrusion rate, but reducing lamellipodial persistence time. Interestingly, blocking NHE-1 activity with its potent inhibitor HOE 642 not only acidified microglia, abolished the BK-triggered dynamic changes of lamellipodia, but also reduced microglial motility and microchemotaxis in response to BK. In addition, NHE-1 activation resulted in intracellular Na+ loading as well as intracellular Ca2+ elevation mediated by stimulating reverse mode operation of Na+/Ca2+ exchange (NCXrev). Taken together, our study shows that NHE-1 protein is abundantly expressed in microglial lamellipodia and maintains alkaline pHi in response to BK stimulation. In addition, NHE-1 and NCXrev play a concerted role in BK-induced microglial migration via Na+ and Ca2+ signaling. © 2013 Shi et al
Evidence of and search for double-charmonium production in and decays
Using data samples of and
events collected with the Belle detector, a first experimental
search has been made for double-charmonium production in the exclusive decays
, where , , , , and . No significant signal is
observed in the spectra of the mass recoiling against the reconstructed
or except for the evidence of production with a
significance of for . The
measured branching fraction \BR(\Upsilon(1S)\rightarrow J/\psi+\chi_{c1}) is
. The
confidence level upper limits on the branching fractions of the other modes
having a significance of less than are determined. These results are
consistent with theoretical calculations using the nonrelativistic QCD
factorization approach.Comment: 12 pages, 4 figures, 1 table. The fit range was extended to include
X(4160) signal according to referee's suggestions. Other results unchanged.
Paper was accepted for publication as a regular article in Physical Review
How are falls and fear of falling associated with objectively measured physical activity in a cohort of community-dwelling older men?
BACKGROUND: Falls affect approximately one third of community-dwelling older adults each year and have serious health and social consequences. Fear of falling (FOF) (lack of confidence in maintaining balance during normal activities) affects many older adults, irrespective of whether they have actually experienced falls. Both falls and fear of falls may result in restrictions of physical activity, which in turn have health consequences. To date the relation between (i) falls and (ii) fear of falling with physical activity have not been investigated using objectively measured activity data which permits examination of different intensities of activity and sedentary behaviour.
METHODS: Cross-sectional study of 1680 men aged 71-92 years recruited from primary care practices who were part of an on-going population-based cohort. Men reported falls history in previous 12 months, FOF, health status and demographic characteristics. Men wore a GT3x accelerometer over the hip for 7 days.
RESULTS: Among the 12% of men who had recurrent falls, daily activity levels were lower than among non-fallers; 942 (95% CI 503, 1381) fewer steps/day, 12(95% CI 2, 22) minutes less in light activity, 10(95% CI 5, 15) minutes less in moderate to vigorous PA [MVPA] and 22(95% CI 9, 35) minutes more in sedentary behaviour. 16% (n = 254) of men reported FOF, of whom 52% (n = 133) had fallen in the past year. Physical activity deficits were even greater in the men who reported that they were fearful of falling than in men who had fallen. Men who were fearful of falling took 1766(95% CI 1391, 2142) fewer steps/day than men who were not fearful, and spent 27(95% CI 18, 36) minutes less in light PA, 18(95% CI 13, 22) minutes less in MVPA, and 45(95% CI 34, 56) minutes more in sedentary behaviour. The significant differences in activity levels between (i) fallers and non-fallers and (ii) men who were fearful of falling or not fearful, were mediated by similar variables; lower exercise self-efficacy, fewer excursions from home and more mobility difficulties.
CONCLUSIONS: Falls and in particular fear of falling are important barriers to older people gaining health benefits of walking and MVPA. Future studies should assess the longitudinal associations between falls and physical activity
Cosmological Constant and Soft Terms in Supergravity
Some of the soft SUSY breaking parameters in hidden sector supergravity model
depend on the expectation value of the hidden sector scalar potential, ,
whose tree level value is equal to the tree level cosmological constant. The
current practice of calculating soft parameters assumes that $=0$. Quantum
correction to the cosmological constant can differ from the correction to
by an amount of order . This implies that, for
the vanishing cosmological constant, the --dependent parts of soft terms
can be sizable, and hence the supergravity phenomenology should be accordingly
modified.Comment: Latex file, 11 pages plus 1 figure (the figure not included), SNUTP
94--1
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