7,914 research outputs found
How Fine Particulate Matter Modifies Preterm Birth Risks in Korea
Despite the increasing interest in preterm birth risk associated with maternal exposure to the current level of fine particulate matter (PM2.5) in Korea, there is little information on differences in PM2.5 exposure and its impact on preterm birth. This study was designed to examine the effects of Korea\u27s air quality on preterm birth, including the possibility of moderation and mediation. This work was also designed to investigate manipulable factors for PM2.5 exposure. The theoretical framework of this quantitative and observational study included the social ecological theory and systems theory. The conceptual framework of this partially ecologic and retrospective cohort study included the social ecological model and Rothman\u27s sufficient component cause model. Data of 19,371 Korean women who gave birth in 2015 were analyzed by logistic regression and multiple regression, including testing for moderation and mediation. An increase in PM2.5 exposure by 10 μg/m3 in the 3rd week before childbirth increased the likelihood of preterm birth by 6.52 times. Moderation and mediation by PM2.5 did not exist between sociodemographic factors and gestational age but existed between socioeconomic and energy policy factors and gestational age. The most influential factor for PM2.5 exposure was unemployment rate at the organizational level. These results show the need for socioeconomic interventions to reduce PM2.5 exposure more effectively. These �ndings indicate that prenatal care should be addressed with a socioeconomic- and energy-policy-sensitive approach to lower preterm birth due to severe air pollution in Korea. This study has the potential to change people\u27s perceptions of threats from PM2.5 exposure, which could lead to behavior changes
Forbidden Channels and SIMP Dark Matter
In this review, we focus on dark matter production from thermal freeze-out
with forbidden channels and SIMP processes. We show that forbidden channels can
be dominant to produce dark matter depending on the dark photon and / or dark
Higgs mass compared to SIMP.Comment: 5 pages, Prepared for the proceedings of the 13th International
Conference on Gravitation, 3-7 July 201
On thermal production of self-interacting dark matter
We consider thermal production mechanisms of self-interacting dark matter in
models with gauged symmetry. A complex scalar dark matter is stabilized
by the , that is the remnant of a local dark . Light dark matter
with large self-interaction can be produced from thermal freeze-out in the
presence of SM-annihilation, SIMP and/or forbidden channels. We show that dark
photon and/or dark Higgs should be relatively light for unitarity and then
assist the thermal freeze-out. We identify the constraints on the parameter
space of dark matter self-interaction and mass in cases that one or some of the
channels are important in determining the relic density.Comment: 26 pages, 11 figures, Version to appear in Journal of High Energy
Physic
Unitary inflaton as decaying dark matter
We consider the inflation model of a singlet scalar field (sigma field) with
both quadratic and linear non-minimal couplings where unitarity is ensured up
to the Planck scale. We assume that a symmetry for the sigma field is
respected by the scalar potential in Jordan frame but it is broken explicitly
by the linear non-minimal coupling due to quantum gravity. We discuss the
impacts of the linear non-minimal coupling on various dynamics from inflation
to low energy, such as a sizable tensor-to-scalar ratio, a novel reheating
process with quartic potential dominance, and suppressed physical parameters in
the low energy, etc. In particular, the linear non-minimal coupling leads to
the linear couplings of the sigma field to the Standard Model through the trace
of the energy-momentum tensor in Einstein frame. Thus, regarding the sigma
field as a decaying dark matter, we consider the non-thermal production
mechanisms for dark matter from the decays of Higgs and inflaton condensate and
show the parameter space that is compatible with the correct relic density and
cosmological constraints.Comment: 36 pages, 7 figures, v2: minor corrections made and references added,
v3: discussion on preheating added, accepted for Journal of High Energy
Physics, v4: Lyman-alpha bound included and inflationary predictions refined
for perturbative reheatin
A minimal flavored for -meson anomalies
We consider an anomaly-free model with favorable couplings to heavy
flavors in the Standard Model(SM), as motivated by -meson anomalies at LHCb.
Taking the charge to be , we can
explain the -meson anomalies without invoking extra charged fermions or
flavor violation beyond the SM. We show that there is a viable parameter space
with a small that is compatible with other meson decays, tau lepton and
neutrino experiments as well as the LHC dimuon searches. We briefly discuss the
prospects of discovering the gauge boson at the LHC in the proposed model.Comment: 20 pages, 4 figures, v2: references and discussion on electroweak
precision test added, v3: Version to appear in Physical Review
Labisia pumila extract protects skin cells from photoaging caused by UVB irradiation
Labisia pumila (Myrsinaceae), known as "Kacip Fatimah," has been used by many generations of Malay women to induce and facilitate child birth as well as a post partum medicine. However, its topical application on skin has not been reported yet. In this study, we have focused on the anti-photoaging effects of L. pumila. Extract of L. pumila was first analyzed for their antioxidant activities using DPPH (2,2-diphenyl-1-picrylhydrazyl) since UV irradiation is a primary cause of reactive oxygen species (ROS) generation in the skin. The 50% free radical scavenging activity (FSC(50)) of L. pumila extract was determined to be 0.006%, which was equal to that produced by 156 microM ascorbic acid. TNF-alpha and cyclooxygenase (COX-2) play a primary role in the inflammation process upon UV irradiation and are known to be stimulated by UVB. Treatment with L. pumila extract markedly inhibited the TNF-alpha production and the expression of COX-2. Decreased collagen synthesis of human fibroblasts by UVB was restored back to normal level after treatment with L. pumila extract. On the other hand, the enhanced MMP-1 expression upon UVB irradiation was down regulated by L. pumila extract in a dose-dependent manner. Furthermore, treatment of normal keratinocytes with L. pumila extract attenuated UVB-induced MMP-9 expression. These results collectively suggest L. pumila extract has tremendous potential as an anti-photoaging cosmetic ingredient
Optimal design of quadratic electromagnetic exciter
The vibration acceleration of collecting plates, which is the core indicator of rapping performance in an electrostatic precipitator’s vibration rapping process, is determined by magnetic force of a quadratic electromagnetic exciter. The larger exciter provides the larger magnetic force, but the installation space for the exciter is limited. Accordingly, this paper presents the optimal design of quadratic electromagnetic exciter to maximize the magnetic force with constraint that the size of exciter is constant. A design optimization problem was formulated in order to find the quadratic electromagnetic exciter shape parameters that maximized the magnetic force. The magnetic force of the quadratic electromagnetic exciter was evaluated using the commercial electromagnetic analysis software “MAXWELL”. For efficient design, we employed metamodel-based design optimization using design of experiments (DOE), metamodels, and an optimization algorithm equipped in PIAnO (Process Integration, Automation and Optimization), a commercial PIDO (Process Integration and Design Optimization) tool. Using the proposed design approach, the optimal magnetic force was increased by 1.68 % compared to the initial one. This result demonstrates the effectiveness of the established analysis and design procedure for the quadratic electromagnetic exciter
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