363 research outputs found
The role of climate in human mitochondrial DNA evolution: A reappraisal
AbstractPrevious studies have proposed that selection has been involved in the differentiation of human mitochondrial DNA (mtDNA) and climate was the main driving force. This viewpoint, however, gets no support from the subsequent studies and remains controversial thus far. To clarify this issue, a total of 237 complete mtDNA sequences belonging to autochthonous lineages from South Asia, Oceania, and East Asia were collected to seek for the imprint of selection. Based on nonsynonymous (N) and synonymous (S) substitutions analysis, our results confirmed that purifying selection was the predominant force during the evolution of human mtDNA. However, no significant and extensive difference was detected among these three regions, which did not support the climate adaptation hypothesis but preferred random genetic drift to be the main factor in shaping the current landscape of human mtDNA, at least those from Asian and Oceanian regions
PosterLayout: A New Benchmark and Approach for Content-aware Visual-Textual Presentation Layout
Content-aware visual-textual presentation layout aims at arranging spatial
space on the given canvas for pre-defined elements, including text, logo, and
underlay, which is a key to automatic template-free creative graphic design. In
practical applications, e.g., poster designs, the canvas is originally
non-empty, and both inter-element relationships as well as inter-layer
relationships should be concerned when generating a proper layout. A few recent
works deal with them simultaneously, but they still suffer from poor graphic
performance, such as a lack of layout variety or spatial non-alignment. Since
content-aware visual-textual presentation layout is a novel task, we first
construct a new dataset named PosterLayout, which consists of 9,974
poster-layout pairs and 905 images, i.e., non-empty canvases. It is more
challenging and useful for greater layout variety, domain diversity, and
content diversity. Then, we propose design sequence formation (DSF) that
reorganizes elements in layouts to imitate the design processes of human
designers, and a novel CNN-LSTM-based conditional generative adversarial
network (GAN) is presented to generate proper layouts. Specifically, the
discriminator is design-sequence-aware and will supervise the "design" process
of the generator. Experimental results verify the usefulness of the new
benchmark and the effectiveness of the proposed approach, which achieves the
best performance by generating suitable layouts for diverse canvases.Comment: Accepted to CVPR 2023. Dataset and code are available at
https://github.com/PKU-ICST-MIPL/PosterLayout-CVPR202
Dynamic DNA Methylation During Aging: A “Prophet” of Age-Related Outcomes
The biological markers of aging used to predict physical health status in older people are of great interest. Telomere shortening, which occurs during the process of cell replication, was initially considered a promising biomarker for the prediction of age and age-related outcomes (e.g., diseases, longevity). However, the high instability in detection and low correlation with age-related outcomes limit the extension of telomere length to the field of prediction. Currently, a growing number of studies have shown that dynamic DNA methylation throughout human lifetime exhibits strong correlation with age and age-related outcomes. Indeed, many researchers have built age prediction models with high accuracy based on age-dependent methylation changes in certain CpG loci. For now, DNA methylation based on epigenetic clocks, namely epigenetic or DNA methylation age, serves as a new standard to track chronological age and predict biological age. Measures of age acceleration (Δage, DNA methylation age – chronological age) have been developed to assess the health status of a person. In addition, there is evidence that an accelerated epigenetic age exists in patients with certain age-related diseases (e.g., Alzheimer’s disease, cardiovascular disease). In this review, we provide an overview of the dynamic signatures of DNA methylation during aging and emphasize its practical utility in the prediction of various age-related outcomes
Insights into long noncoding RNAs of naked mole rat (Heterocephalus glaber) and their potential association with cancer resistance
Additional file 4: Table S3. Differential expressed lncRNAs identified in naked mole rat (Heterocephalus glaber) genome
IPS Observation System for Miyun 50m Radio Telescope and Its Acceptance Observation
Ground-based observation of Interplanetary Scintillation(IPS) is an important
approach of monitoring solar wind. A ground-based IPS observation system is
newly implemented on 50m radio telescope, Miyun station, National Astronomical
Observatories, Chinese Academy of Sciences(NAOC). This observation system is
constructed for purpose of observing the solar wind speed and scintillation
index by using the normalized cross-spectrum of simultaneous dual-frequency IPS
measurement. The system consists of a universal dual-frequency front-end and a
dual-channel multi-function back-end specially designed for IPS. After careful
calibration and testing, IPS observations on source 3C273B and 3C279 are
successfully carried out. The preliminary observation results show that this
newly developed observation system is capable of doing IPS observation.The
system sensitivity for IPS observation can reach over 0.3Jy in terms of IPS
polarization correlator with 4MHz bandwidth and 2s integration time.Comment: 8 pages, 7 figure
Distilling Artificial Recombinants from Large Sets of Complete mtDNA Genomes
BACKGROUND: Large-scale genome sequencing poses enormous problems to the logistics of laboratory work and data handling. When numerous fragments of different genomes are PCR amplified and sequenced in a laboratory, there is a high imminent risk of sample confusion. For genetic markers, such as mitochondrial DNA (mtDNA), which are free of natural recombination, single instances of sample mix-up involving different branches of the mtDNA phylogeny would give rise to reticulate patterns and should therefore be detectable. METHODOLOGY/PRINCIPAL FINDINGS: We have developed a strategy for comparing new complete mtDNA genomes, one by one, to a current skeleton of the worldwide mtDNA phylogeny. The mutations distinguishing the reference sequence from a putative recombinant sequence can then be allocated to two or more different branches of this phylogenetic skeleton. Thus, one would search for two (or three) near-matches in the total mtDNA database that together best explain the variation seen in the recombinants. The evolutionary pathway from the mtDNA tree connecting this pair together with the recombinant then generate a grid-like median network, from which one can read off the exchanged segments. CONCLUSIONS: We have applied this procedure to a large collection of complete human mtDNA sequences, where several recombinants could be distilled by our method. All these recombinant sequences were subsequently corrected by de novo experiments--fully concordant with the predictions from our data-analytical approach
Trace the Accretion Geometry of H 1743--322 with Type C Quasi-periodic Oscillations in Multiple Outbursts
We present a systematic analysis of type C quasi-periodic oscillation (QPO)
observations of H 1743--322 throughout the Rossi X-ray Timing Explorer (RXTE)
era. We find that, while different outbursts have significant flux differences,
they show consistent positive correlations between the QPO fractional
root-mean-square (rms) amplitude and non-thermal fraction of the emission,
which indicate an independence of the intrinsic QPO rms on individual outburst
brightness in H 1743--322. However, the dependence of the QPO rms on frequency
is different between the outburst rise and decay phases, where QPO fractional
rms of the decay phase is significantly lower than that of the rise phase at
low frequencies. The spectral analysis also reveals different ranges of coronal
temperature between the two outburst stages. A semi-quantitative analysis shows
that the Lense-Thirring precession model could be responsible for the QPO rms
differences, requiring a variable coronal geometric shape. However, the
variable-Comptonization model could also account for the findings. The fact
that the rms differences and the hysteresis traces in the hardness-intensity
diagram (HID) accompany each other indicates a connection between the two
phenomena. By correlating the findings with QPO phase lags and the
quasi-simultaneous radio flux previously published, we propose there could be
corona-jet transitions in H 1743--322 similar to those that have been recently
reported in GRS 1915+105.Comment: 21 pages, 12 figure
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