385 research outputs found
Periodic Solutions of Differential Equations
In this paper, we study the existence of periodic solutions of neutral differential equations with infinite delay and delay equations of nth order. Some necessary and sufficient conditions for existence of periodic solutions are obtained
Pregnancy loss is related to body mass index and prediabetes in early adulthood: Findings from Add Health
Pregnancy loss, including miscarriage and stillbirth, affects 15–20% of pregnancies in the United States (US) annually. Accumulating evidence suggests that pregnancy loss is associated with a greater cardiovascular disease (CVD) burden later in life. However, few studies have evaluated the impact of pregnancy loss on CVD risk factors in early adulthood (age <35 years). The aim of this study was to examine associations between pregnancy loss and CVD risk factors (body mass index, blood pressure, hyperlipidemia, diabetes status) in early adulthood. We conducted a cross-sectional analysis using the public-use dataset for Wave IV (2007–2009) of the National Longitudinal Study of Adolescent to Adult Health (Add Health). Our sample consisted of women, ages 24–32 years, with a previous pregnancy who completed biological data collection (n = 2,968). Pregnancy loss was assessed as any history of miscarriage or stillbirth; and quantified as none, one, or recurrent (≥2) pregnancy loss. Associations between pregnancy loss and each CVD risk factor were tested using linear and logistic regression adjusting for sociodemographic factors, parity, health behaviors during pregnancy, and depression. We tested for interactions with race/ethnicity. A total of 670 women reported a pregnancy loss, of which 28% reported recurrent pregnancy loss. A prior pregnancy loss was related to a 3.79 (kg/mm2) higher BMI in non-Hispanic Black women, but not white women. Women with recurrent pregnancy loss were more likely to have prediabetes (AOR, 1.93; 95% CI, 1.10–3.37, p<0.05) than women with all live births. Findings suggest that pregnancy loss may be associated with a more adverse CVD risk profile in early adulthood, particularly for women who experience recurrent pregnancy loss. This highlights the need for CVD risk assessment in young women with a prior pregnancy loss. Further research is necessary to identify underlying risk factors of pregnancy loss that may predispose women to CVD
Phase diagram of a superconductor / ferromagnet bilayer
The magnetic field (H) - temperature (T) phase diagram of a superconductor is
significantly altered when domains are present in an underlying ferromagnet
with perpendicular magnetic anisotropy. When the domains have a band-like
shape, the critical temperature Tc of the superconductor in zero field is
strongly reduced, and the slope of the upper critical field as a function of T
is increased by a factor of 2.4 due to the inhomogeneous stray fields of the
domains. Field compensation effects can cause an asymmetric phase boundary with
respect to H when the ferromagnet contains bubble domains. For a very
inhomogeneous domain structure, Tc~H^2 for low H and Tc~H for higher fields,
indicating a dimensional crossover from a one-dimensional network-like to a
two-dimensional behavior in the nucleation of superconductivity.Comment: 6 pages, 7 figure
Analysis of long-term depression in the Purkinje cell circuit (a model study)
In the cerebellum, long-term depression (LTD) plays a key function in sculpting neuronal
circuits to store information, since motor learning and memory are thought to be associated
with such long-term changes in synaptic efficacy. To better understand the principles of
transmission of information in the cerebellum, we, in our model, distinguished different types
of neurons (type 1- and type 2-like) to examine the neuronal excitability and analyze the
interspike interval (ISI) bifurcation phenomenon in these units, and then built a Purkinje cell
circuit to study the impact of external stimulation on LTD in this circuit. According to the
results of computational analysis, both climbing fiber-Purkinje cell and granule cell-Purkinje
cell circuits were found to manifest LTD; the external stimuli would influence LTD by
changing both depression time and depression intensity. All of the simulated results showed
that LTD is a very significant factor in the Purkinje circuit networks. Finally, to deliver the
learning regularities, we simulated spike timing-dependent plasticity (STDP) by increasing
the CaP conductance.У мозочку довготривала депресія (ДД) відіграє ключову роль у пристосуванні нейронних мереж до накопичення інформації, оскільки моторне навчання та пам’ять, як
вважають, асоційовані з подібними тривалими змінами синаптичної ефективності. Намагаючись краще зрозуміти
принципи передачі інформації в мозочку, в перебігу дослідження збудливості нервових клітин та аналізу феномена
біфуркації міжімпульсних інтервалів у цих нейронах ми диференціювали в нашій моделі різні види нейронів (першого і другого типів). Потім була сформована модель нервової
мережі клітини Пуркін̕ є для дослідження впливів зовнішньої стимуляції на ДД у такій мережі. Відповідно до результатів комп’ютерного аналізу, ДД проявляється і в мережі «ліаноподібне волокно–клітина Пуркін̕ є», і в мережі
«гранулярна клітина–клітина Пуркін̕ є». Зовнішня стимуляція може впливати на ДД, змінюючи як час, так і інтенсивність депресії. Згідно з результатами моделювання, ДД
є дуже істотним фактором при функціонуванні мереж, котрі
містять у собі клітини Пуркін̕ є. Нарешті, ми, щоб виявити
закономірності процесу навчання, за допомогою збільшення
CaP-провідності моделювали пластичність, залежну від
часу генерації піка (STDP)
A Detailed Monte-Carlo Simulation for the Belle TOF System
We have developed a detailed Monte Carlo simulation program for the Belle TOF
system. Based on GEANT simulation, it takes account of all physics processes in
the TOF scintillation counters and readout electronics. The simulation
reproduces very well the performance of the Belle TOF system, including the
dE/dx response, the time walk effect, the time resolution, and the hit
efficiency due to beam background. In this report, we will describe the Belle
TOF simulation program in detail.Comment: To be submitted to NI
Search for Small Trans-Neptunian Objects by the TAOS Project
The Taiwan-America Occultation Survey (TAOS) aims to determine the number of
small icy bodies in the outer reach of the Solar System by means of stellar
occultation. An array of 4 robotic small (D=0.5 m), wide-field (f/1.9)
telescopes have been installed at Lulin Observatory in Taiwan to simultaneously
monitor some thousand of stars for such rare occultation events. Because a
typical occultation event by a TNO a few km across will last for only a
fraction of a second, fast photometry is necessary. A special CCD readout
scheme has been devised to allow for stellar photometry taken a few times per
second. Effective analysis pipelines have been developed to process stellar
light curves and to correlate any possible flux changes among all telescopes. A
few billion photometric measurements have been collected since the routine
survey began in early 2005. Our preliminary result of a very low detection rate
suggests a deficit of small TNOs down to a few km size, consistent with the
extrapolation of some recent studies of larger (30--100 km) TNOs.Comment: 4 pages, 3 figures, IAU Symposium 23
Multiwavelength Study on Solar and Interplanetary Origins of the Strongest Geomagnetic Storm of Solar Cycle 23
We study the solar sources of an intense geomagnetic storm of solar cycle 23
that occurred on 20 November 2003, based on ground- and space-based
multiwavelength observations. The coronal mass ejections (CMEs) responsible for
the above geomagnetic storm originated from the super-active region NOAA 10501.
We investigate the H-alpha observations of the flare events made with a 15 cm
solar tower telescope at ARIES, Nainital, India. The propagation
characteristics of the CMEs have been derived from the three-dimensional images
of the solar wind (i.e., density and speed) obtained from the interplanetary
scintillation data, supplemented with other ground- and space-based
measurements. The TRACE, SXI and H-alpha observations revealed two successive
ejections (of speeds ~350 and ~100 km/s), originating from the same filament
channel, which were associated with two high speed CMEs (~1223 and ~1660 km/s,
respectively). These two ejections generated propagating fast shock waves
(i.e., fast drifting type II radio bursts) in the corona. The interaction of
these CMEs along the Sun-Earth line has led to the severity of the storm.
According to our investigation, the interplanetary medium consisted of two
merging magnetic clouds (MCs) that preserved their identity during their
propagation. These magnetic clouds made the interplanetary magnetic field (IMF)
southward for a long time, which reconnected with the geomagnetic field,
resulting the super-storm (Dst_peak=-472 nT) on the Earth.Comment: 24 pages, 16 figures, Accepted for publication in Solar Physic
Supercoherent States, Super K\"ahler Geometry and Geometric Quantization
Generalized coherent states provide a means of connecting square integrable
representations of a semi-simple Lie group with the symplectic geometry of some
of its homogeneous spaces. In the first part of the present work this point of
view is extended to the supersymmetric context, through the study of the
OSp(2/2) coherent states. These are explicitly constructed starting from the
known abstract typical and atypical representations of osp(2/2). Their
underlying geometries turn out to be those of supersymplectic OSp(2/2)
homogeneous spaces. Moment maps identifying the latter with coadjoint orbits of
OSp(2/2) are exhibited via Berezin's symbols. When considered within
Rothstein's general paradigm, these results lead to a natural general
definition of a super K\"ahler supermanifold, the supergeometry of which is
determined in terms of the usual geometry of holomorphic Hermitian vector
bundles over K\"ahler manifolds. In particular, the supergeometry of the above
orbits is interpreted in terms of the geometry of Einstein-Hermitian vector
bundles. In the second part, an extension of the full geometric quantization
procedure is applied to the same coadjoint orbits. Thanks to the super K\"ahler
character of the latter, this procedure leads to explicit super unitary
irreducible representations of OSp(2/2) in super Hilbert spaces of
superholomorphic sections of prequantum bundles of the Kostant type. This work
lays the foundations of a program aimed at classifying Lie supergroups'
coadjoint orbits and their associated irreducible representations, ultimately
leading to harmonic superanalysis. For this purpose a set of consistent
conventions is exhibited.Comment: 53 pages, AMS-LaTeX (or LaTeX+AMSfonts
Classification of K3-surfaces with involution and maximal symplectic symmetry
K3-surfaces with antisymplectic involution and compatible symplectic actions
of finite groups are considered. In this situation actions of large finite
groups of symplectic transformations are shown to arise via double covers of
Del Pezzo surfaces. A complete classification of K3-surfaces with maximal
symplectic symmetry is obtained.Comment: 26 pages; final publication available at http://www.springerlink.co
Observation of the and the Y(2175) in
The cross sections for and e^+ e^- \to \phi
\fzero are measured from threshold to using
initial state radiation. The analysis is based on a data sample of 673
fb collected on and below the resonance with the Belle
detector at the KEKB asymmetric-energy collider. First measurements
are reported for the resonance parameters of the in the
mode: MeV/ and MeV/. A structure at ,
corresponding to the so called Y(2175), is observed; its mass and width are
determined to be MeV/ and , respectively.Comment: 11 pages, 6 figures. Add one plot. Accepted by Phys.Rev.D(RC
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