6,226 research outputs found
Quasinormal mode approach to modelling light-emission and propagation in nanoplasmonics
We describe a powerful and intuitive technique for modeling light-matter
interactions in classical and quantum nanoplasmonics. Our approach uses a
quasinormal mode expansion of the Green function within a metal nanoresonator
of arbitrary shape, together with a Dyson equation, to derive an expression for
the spontaneous decay rate and far field propagator from dipole oscillators
outside resonators. For a single quasinormal mode, at field positions outside
the quasi-static coupling regime, we give a closed form solution for the
Purcell factor and generalized effective mode volume. We augment this with an
analytic expression for the divergent LDOS very near the metal surface, which
allows us to derive a simple and highly accurate expression for the electric
field outside the metal resonator at distances from a few nanometers to
infinity. This intuitive formalism provides an enormous simplification over
full numerical calculations and fixes several pending problems in quasinormal
mode theory
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Functional and morphological analysis of the subretinal injection of human retinal progenitor cells under Cyclosporin A treatment
Purpose The purpose of this study is to evaluate the functional and morphological changes in subretinal xenografts of human retinal progenitor cells (hRPCs) in B6 mice treated with Cyclosporin A (CsA; 210 mg/l in drinking water). Methods: The hRPCs from human fetal eyes were isolated and expanded for transplantation. These cells, with green fluorescent protein (GFP) at 11 passages, were transplanted into the subretinal space in B6 mice. A combination of invasive and noninvasive approaches was used to analyze the structural and functional consequences of the subretinal injection of the hRPCs. The process of change was monitored using spectral domain optical coherence tomography (SDOCT), histology, and electroretinography (ERG) at 3 days, 1 week, and 3 weeks after transplantation. Cell counts were used to evaluate the survival rate with a confocal microscope. ERGs were performed to evaluate the physiologic changes, and the structural changes were evaluated using SDOCT and histological examination. Results: The results of the histological examination showed that the hRPCs gained a better survival rate in the mice treated with CsA. The SDOCT showed that the bleb size of the retinal detachment was significantly decreased, and the retinal reattachment was nearly complete by 3 weeks. The ERG response amplitudes in the CsA group were less decreased after the injection, when compared with the control group, in the dark-adapted and light-adapted conditions. However, the cone-mediated function in both groups was less affected by the transplantation after 3 weeks than the rod-mediated function. Conclusions: Although significant functional and structural recovery was observed after the subretinal injection of the hRPCs, the effectiveness of CsA in xenotransplantation may be a novel and potential approach for increasing retinal progenitor cell survival
Pole-skipping points in 2D gravity and SYK model
We represent the first investigation of pole-skipping on both the gravity and
field theory sides. In contrast to the higher dimensional models, there is no
momentum degree of freedom in dimensional bulk theory. Thus, we then
consider a scalar field mass as our degree of freedom for the pole-skipping
phenomenon instead of momentum. The pole-skipping frequencies of the scalar
field in 2D gravity are the same as higher dimensional cases: for positive integer . At each of these frequencies, there is a
corresponding pole-skipping mass, so the pole-skipping points exist in the
space. We also compute the pole-skipping points of the SYK model
in space where is the dimension of the bilinear primary
operator. We find that there is a one-to-one correspondence of the
pole-skipping points between the JT gravity and the SYK model. To obtain the
pole-skipping points, we need to consider the parameter related to
chemical potential on the horizon of charged JT gravity and the particle-hole
asymmetric parameter of the complex SYK model as shift
parameters. This highlights the correspondence in
relation to pole-skipping
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Identification of H3K4me1-associated proteins at mammalian enhancers.
Enhancers act to regulate cell-type-specific gene expression by facilitating the transcription of target genes. In mammalian cells, active or primed enhancers are commonly marked by monomethylation of histone H3 at lysine 4 (H3K4me1) in a cell-type-specific manner. Whether and how this histone modification regulates enhancer-dependent transcription programs in mammals is unclear. In this study, we conducted SILAC mass spectrometry experiments with mononucleosomes and identified multiple H3K4me1-associated proteins, including many involved in chromatin remodeling. We demonstrate that H3K4me1 augments association of the chromatin-remodeling complex BAF to enhancers in vivo and that, in vitro, H3K4me1-marked nucleosomes are more efficiently remodeled by the BAF complex. Crystal structures of the BAF component BAF45C indicate that monomethylation, but not trimethylation, is accommodated by BAF45C's H3K4-binding site. Our results suggest that H3K4me1 has an active role at enhancers by facilitating binding of the BAF complex and possibly other chromatin regulators
Properties of the Broad-Range Nematic Phase of a Laterally Linked H-Shaped Liquid Crystal Dimer
In search for novel nematic materials, a laterally linked H-shaped liquid
crystal dimer have been synthesized and characterized. The distinct feature of
the material is a very broad temperature range (about 50 oC) of the nematic
phase, which is in contrast with other reported H-dimers that show
predominantly smectic phases. The material exhibits interesting textural
features at the scale of nanometers (presence of smectic clusters) and at the
macroscopic scales. Namely, at a certain temperature, the flat samples of the
material show occurrence of domain walls. These domain walls are caused by the
surface anchoring transition and separate regions with differently tilted
director. Both above and below this transition temperature the material
represents a uniaxial nematic, as confirmed by the studies of defects in flat
samples and samples with colloidal inclusions, freely suspended drops, X-ray
diffraction and transmission electron microscopy.Comment: 30 pages (including Supplementary Information), 7 Figure
Internet and gaming addiction: a systematic literature review of neuroimaging studies
In the past decade, research has accumulated suggesting that excessive Internet use can lead to the development of a behavioral addiction. Internet addiction has been considered as a serious threat to mental health and the excessive use of the Internet has been linked to a variety of negative psychosocial consequences. The aim of this review is to identify all empirical studies to date that used neuroimaging techniques to shed light upon the emerging mental health problem of Internet and gaming addiction from a neuroscientific perspective. Neuroimaging studies offer an advantage over traditional survey and behavioral research because with this method, it is possible to distinguish particular brain areas that are involved in the development and maintenance of addiction. A systematic literature search was conducted, identifying 18 studies. These studies provide compelling evidence for the similarities between different types of addictions, notably substance-related addictions and Internet and gaming addiction, on a variety of levels. On the molecular level, Internet addiction is characterized by an overall reward deficiency that entails decreased dopaminergic activity. On the level of neural circuitry, Internet and gaming addiction led to neuroadaptation and structural changes that occur as a consequence of prolonged increased activity in brain areas associated with addiction. On a behavioral level, Internet and gaming addicts appear to be constricted with regards to their cognitive functioning in various domains. The paper shows that understanding the neuronal correlates associated with the development of Internet and gaming addiction will promote future research and will pave the way for the development of addiction treatment approaches
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