2,214 research outputs found
Karhunen-Lo\`eve Data Imputation in High Contrast Imaging
Detection and characterization of extended structures is a crucial goal in
high contrast imaging. However, these structures face challenges in data
reduction, leading to over-subtraction from speckles and self-subtraction with
most existing methods. Iterative post-processing methods offer promising
results, but their integration into existing pipelines is hindered by selective
algorithms, high computational cost, and algorithmic regularization. To address
this for reference differential imaging (RDI), here we propose the data
imputation concept to Karhunen-Lo\`eve transform (DIKL) by modifying two steps
in the standard Karhunen-Lo\`eve image projection (KLIP) method. Specifically,
we partition an image to two matrices: an anchor matrix which focuses only on
the speckles to obtain the DIKL coefficients, and a boat matrix which focuses
on the regions of astrophysical interest for speckle removal using DIKL
components. As an analytical approach, DIKL achieves high-quality results with
significantly reduced computational cost (~3 orders of magnitude less than
iterative methods). Being a derivative method of KLIP, DIKL is seamlessly
integrable into high contrast imaging pipelines for RDI observations.Comment: 7 pages, 5 figures, A&A accepte
Loss of FKBP5 Affects Neuron Synaptic Plasticity: An Electrophysiology Insight
FKBP5 (FKBP51) is a glucocorticoid receptor (GR) binding protein, which acts as a co-chaperone of heat shock protein 90 (HSP90) and negatively regulates GR. Its association with mental disorders has been identified, but its function in disease development is largely unknown. Long-term potentiation (LTP) is a functional measurement of neuronal connection and communication, and is considered one of the major cellular mechanisms that underlies learning and memory, and is disrupted in many mental diseases. In this study, a reduction in LTP in Fkbp5 knockout (KO) mice was observed when compared to WT mice, which correlated with changes to the glutamatergic and GABAergic signaling pathways. The frequency of mEPSCs was decreased in KO hippocampus, indicating a decrease in excitatory synaptic activity. While no differences were found in levels of glutamate between KO and WT, a reduction was observed in the expression of excitatory glutamate receptors (NMDAR1, NMDAR2B and AMPAR), which initiate and maintain LTP. The expression of the inhibitory neurotransmitter GABA was found to be enhanced in Fkbp5 KO hippocampus. Further investigation suggested that increased expression of GAD65, but not GAD67, accounted for this increase. Additionally, a functional GABAergic alteration was observed in the form of increased mIPSC frequency in the KO hippocampus, indicating an increase in presynaptic GABA release. Our findings uncover a novel role for Fkbp5 in neuronal synaptic plasticity and highlight the value of Fkbp5 KO as a model for studying its role in neurological function and disease development
Osseous differentiation of human fat tissue grafts: From tissue engineering to tissue differentiation
Conventional bone tissue engineering approaches require isolation and in vitro propagation of autologous cells, followed by seeding on a variety of scaffolds. Those protracted procedures impede the clinical applications. Here we report the transdifferentiation of human fat tissue fragments retrieved from subcutaneous fat into tissue with bone characteristics in vitro without prior cell isolation and propagation. 3D collagen-I cultures of human fat tissue were cultivated either in growth medium or in osteogenic medium (OM) with or without addition of Bone Morphogenetic Proteins (BMPs) BMP-2, BMP-7 or BMP-9. Ca2+ depositions were observed after two weeks of osteogenic induction which visibly increased when either type of BMP was added. mRNA levels of alkaline phosphatase (ALP) and osteocalcin (OCN) increased when cultured in OM alone but addition of BMP-2, BMP-7 or BMP-9 caused significantly higher expression levels of ALP and OCN. Immunofluorescent staining for OCN, osteopontin and sclerostin supported the observed real-time-PCR data. BMP-9 was the most effective osteogenic inducer in this system. Our findings reveal that tissue regeneration can be remarkably simplified by omitting prior cell isolation and propagation, therefore removing significant obstacles on the way to clinical applications of much needed regeneration treatments
Stellar Flyby Analysis for Spiral Arm Hosts with Gaia DR3
Scattered light imaging studies have detected nearly two dozen spiral arm
systems in circumstellar disks, yet the formation mechanisms for most of them
are still under debate. Although existing studies can use motion measurements
to distinguish leading mechanisms such as planet-disk interaction and disk
self-gravity, close-in stellar flybys can induce short-lived spirals and even
excite arm-driving planets into highly eccentric orbits. With unprecedented
stellar location and proper motion measurements from Gaia DR3, here we study
for known spiral arm systems their flyby history with their stellar neighbours
by formulating an analytical on-sky flyby framework. For stellar neighbors
currently located within 10 pc from the spiral hosts, we restrict the flyby
time to be within the past yr and the flyby distance to be within
times the disk extent in scattered light. Among a total of neighbors
that are identified in Gaia DR3 for spiral systems, we do not identify
credible flyby candidates for isolated systems. Our analysis suggests that
close-in recent flyby is not the dominant formation mechanism for isolated
spiral systems in scattered light.Comment: 14 pages, 4 figures, 2 tables, ApJS accepted. Data files for Table 2
in the ancillary folder. Code framework available at
https://github.com/slinling/afm-spiral
Suppression of Black-body Radiation Induced Zeeman Shifts in the Optical Clocks due to the Fine-structure Intramanifold Resonances
The roles of the fine-structure intramanifold resonances to the Zeeman shifts
caused by the blackbody radiation (BBRz shifts) in the optical clock
transitions are analyzed. The clock frequency measurement in the
clock transition of the singly charged aluminium ion (Al) has already been
reached the level at which the BBRz effect can be significant in
determining the uncertainty. In view of this, we probe first the BBRz shift in
this transition rigorously and demonstrate the importance of the contributions
from the intramanifold resonances explicitly. To carry out the analysis, we
determine the dynamic magnetic dipole (M1) polarizabilities of the clock states
over a wide range of angular frequencies by employing two variants of
relativistic many-body methods. This showed the BBRz shift is highly suppressed
due to blue-detuning of the BBR spectrum to the fine-structure
intramanifold resonance in Al and it fails to follow the usually assumed
static M1 polarizability limit in the estimation of the BBRz shift. The
resonance also leads to a reversal behavior of the temperature dependence and a
cancellation in the shift. After learning this behavior, we extended our
analyses to other optical clocks and found that these shifts are of the order
of micro-hertz leading to fractional shifts in the clock transitions at the
level or below
NMF-based GPU accelerated coronagraphy pipeline
We present a generalized Non-negative factorization (NMF)-based data
reduction pipeline for circumstellar disk and exoplanet detection. By using an
adaptable pre-processing routine that applies algorithmic masks and corrections
to improper data, we are able to easily offload the computationally-intensive
NMF algorithm to a graphics processing unit (GPU), significantly increasing
computational efficiency. NMF has been shown to better preserve disk structural
features compared to other post-processing approaches and has demonstrated
improvements in the analysis of archival data. The adaptive pre-processing
routine of this pipeline, which automatically aligns and applies image
corrections to the raw data, is shown to significantly improve chromatic halo
suppression. Utilizing HST-STIS and JWST-MIRI coronagraphic datasets, we
demonstrate a factor of five increase in real-time computational efficiency by
using GPUs to perform NMF compared to using CPUs. Additionally, we demonstrate
the usefulness of higher numbers of NMF components with SNR and contrast
improvements, which necessitates the use of a more computationally efficient
approach for data reduction
A functional variant in the serotonin receptor 7 gene (HTR7), rs7905446, is associated with good response to SSRIs in bipolar and unipolar depression.
Predicting antidepressant response has been a clinical challenge for mood disorder. Although several genome-wide association studies have suggested a number of genetic variants to be associated with antidepressant response, the sample sizes are small and the results are difficult to replicate. Previous animal studies have shown that knockout of the serotonin receptor 7 gene (HTR7) resulted in an antidepressant-like phenotype, suggesting it was important to antidepressant action. In this report, in the first stage, we used a cost-effective pooled-sequencing strategy to sequence the entire HTR7 gene and its regulatory regions to investigate the association of common variants in HTR7 and clinical response to four selective serotonin reuptake inhibitors (SSRIs: citalopram, paroxetine, fluoxetine and sertraline) in a retrospective cohort mainly consisting of subjects with bipolar disorder (n = 359). We found 80 single-nucleotide polymorphisms (SNPs) with false discovery rate < 0.05 associated with response to paroxetine. Among the significant SNPs, rs7905446 (T/G), which is located at the promoter region, also showed nominal significance (P < 0.05) in fluoxetine group. GG/TG genotypes for rs7905446 and female gender were associated with better response to two SSRIs (paroxetine and fluoxetine). In the second stage, we replicated this association in two independent prospective samples of SSRI-treated patients with major depressive disorder: the MARS (n = 253, P = 0.0169) and GENDEP studies (n = 432, P = 0.008). The GG/TG genotypes were consistently associated with response in all three samples. Functional study of rs7905446 showed greater activity of the G allele in regulating expression of HTR7. The G allele displayed higher luciferase activity in two neuronal-related cell lines, and estrogen treatment decreased the activity of only the G allele. Electrophoretic mobility shift assay suggested that the G allele interacted with CCAAT/enhancer-binding protein beta transcription factor (TF), while the T allele did not show any interaction with any TFs. Our results provided novel pharmacogenomic evidence to support the role of HTR7 in association with antidepressant response
Dynamical detection of a companion driving a spiral arm in a protoplanetary disk
Radio and near-infrared observations have observed dozens of protoplanetary
disks that host spiral arm features. Numerical simulations have shown that
companions may excite spiral density waves in protoplanetary disks via
companion-disk interaction. However, the lack of direct observational evidence
for spiral-driving companions poses challenges to current theories of
companion-disk interaction. Here we report multi-epoch observations of the
binary system HD 100453 with the Spectro-Polarimetric High-contrast Exoplanet
REsearch (SPHERE) facility at the Very Large Telescope. By recovering the
spiral features via robustly removing starlight contamination, we measure
spiral motion across 4 yr to perform dynamical motion analyses. The spiral
pattern motion is consistent with the orbital motion of the eccentric
companion. With this first observational evidence of a companion driving a
spiral arm among protoplanetary disks, we directly and dynamically confirm the
long-standing theory on the origin of spiral features in protoplanetary disks.
With the pattern motion of companion-driven spirals being independent of
companion mass, here we establish a feasible way of searching for hidden
spiral-arm-driving planets that are beyond the detection of existing
ground-based high-contrast imagers.Comment: Accepted for publication in Astronomy and Astrophysics; 12 pages, 9
figure
Triangular clustering in document networks
Document networks are characteristic in that a document node, e.g. a webpage
or an article, carries meaningful content. Properties of document networks are
not only affected by topological connectivity between nodes, but also strongly
influenced by the semantic relation between content of the nodes. We observe
that document networks have a large number of triangles and a high value of
clustering coefficient. And there is a strong correlation between the
probability of formation of a triangle and the content similarity among the
three nodes involved. We propose the degree-similarity product (DSP) model
which well reproduces these properties. The model achieves this by using a
preferential attachment mechanism which favours the linkage between nodes that
are both popular and similar. This work is a step forward towards a better
understanding of the structure and evolution of document networks.Comment: 10 pages, 3 figures, 2 table
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