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Bottleneck and selection in the germline and maternal age influence transmission of mitochondrial DNA in human pedigrees.
Heteroplasmy-the presence of multiple mitochondrial DNA (mtDNA) haplotypes in an individual-can lead to numerous mitochondrial diseases. The presentation of such diseases depends on the frequency of the heteroplasmic variant in tissues, which, in turn, depends on the dynamics of mtDNA transmissions during germline and somatic development. Thus, understanding and predicting these dynamics between generations and within individuals is medically relevant. Here, we study patterns of heteroplasmy in 2 tissues from each of 345 humans in 96 multigenerational families, each with, at least, 2 siblings (a total of 249 mother-child transmissions). This experimental design has allowed us to estimate the timing of mtDNA mutations, drift, and selection with unprecedented precision. Our results are remarkably concordant between 2 complementary population-genetic approaches. We find evidence for a severe germline bottleneck (7-10 mtDNA segregating units) that occurs independently in different oocyte lineages from the same mother, while somatic bottlenecks are less severe. We demonstrate that divergence between mother and offspring increases with the mother's age at childbirth, likely due to continued drift of heteroplasmy frequencies in oocytes under meiotic arrest. We show that this period is also accompanied by mutation accumulation leading to more de novo mutations in children born to older mothers. We show that heteroplasmic variants at intermediate frequencies can segregate for many generations in the human population, despite the strong germline bottleneck. We show that selection acts during germline development to keep the frequency of putatively deleterious variants from rising. Our findings have important applications for clinical genetics and genetic counseling
A Guideline for Humanoid Leg Design with Oblique Axes for Bipedal Locomotion
The kinematics of humanoid robots are strongly inspired by the human archetype. A close analysis of the kinematics of the human musculoskeletal system reveals that the human joint axes are oriented within certain inclinations. This is in contrast to the most popular humanoid design with a configuration based on perpendicular joint axes. This paper reviews the oblique joint axes of the mainly involved joints for locomotion of the human musculoskeletal system. We elaborate on how the oblique axes affect the performance of walking and running. The mechanisms are put into perspective for the locomotion types of walking and running. In particular, walking robots can highly benefit from using oblique joint axes. For running, the primary goal is to align the axis of motion to the mainly active sagittal plane. The results of this analysis can serve as a guideline for the kinematic design of a humanoid robot and a prior for optimization-based approaches
A Robotic Torso Joint With Adjustable Linear Spring Mechanism for Natural Dynamic Motions in a Differential-Elastic Arrangement
To be operated in unknown or complex environments, modern robots have to fulfill various challenging criteria. Among them, one finds requirements such as a high level of robustness to withstand impacts and the capabilities to physically interact in a safe manner. One way to achieve that is to integrate variable-stiffness actuators into the systems, enabling compliant behavior through the elastic components and providing the additional adaptability of the impedance. Here, we introduce a novel adjustable linear stiffness joint mounted in a differential-elastic arrangement. The mechanism is integrated into the anthropomorphic upper body of the DLR David robot and responsible for the spinal rotation. Consequently, the actuator is crucial for the overall workspace of the robot and the realization of energy-efficient natural motions such as in dynamic running. The proposed hardware setup is experimentally validated in terms of the linearity in the spring characteristics, intrinsic damping, the excitation of resonance frequencies, and the ability to alter these resonance frequencies through stiffness adaptation during dynamic motions
Streamlined Lensed Quasar Identification in Multiband Images via Ensemble Networks
Quasars experiencing strong lensing offer unique viewpoints on subjects
related to the cosmic expansion rate, the dark matter profile within the
foreground deflectors, and the quasar host galaxies. Unfortunately, identifying
them in astronomical images is challenging since they are overwhelmed by the
abundance of non-lenses. To address this, we have developed a novel approach by
ensembling cutting-edge convolutional networks (CNNs) -- for instance, ResNet,
Inception, NASNet, MobileNet, EfficientNet, and RegNet -- along with vision
transformers (ViTs) trained on realistic galaxy-quasar lens simulations based
on the Hyper Suprime-Cam (HSC) multiband images. While the individual model
exhibits remarkable performance when evaluated against the test dataset,
achieving an area under the receiver operating characteristic curve of 97.3%
and a median false positive rate of 3.6%, it struggles to generalize in real
data, indicated by numerous spurious sources picked by each classifier. A
significant improvement is achieved by averaging these CNNs and ViTs, resulting
in the impurities being downsized by factors up to 50. Subsequently, combining
the HSC images with the UKIRT, VISTA, and unWISE data, we retrieve
approximately 60 million sources as parent samples and reduce this to 892,609
after employing a photometry preselection to discover lensed quasars
with Einstein radii of arcsec. Afterward, the ensemble
classifier indicates 3080 sources with a high probability of being lenses, for
which we visually inspect, yielding 210 prevailing candidates awaiting
spectroscopic confirmation. These outcomes suggest that automated deep learning
pipelines hold great potential in effectively detecting strong lenses in vast
datasets with minimal manual visual inspection involved.Comment: Accepted for publication in the Astronomy & Astrophysics journal. 28
pages, 11 figures, and 3 tables. We welcome comments from the reade
CLASH: Extreme Emission Line Galaxies and Their Implication on Selection of High-Redshift Galaxies
We utilize the CLASH (Cluster Lensing And Supernova survey with Hubble)
observations of 25 clusters to search for extreme emission-line galaxies
(EELGs). The selections are carried out in two central bands: F105W (Y105) and
F125W (J125), as the flux of the central bands could be enhanced by the
presence of [O III] 4959, 5007 at redshift of about 0.93-1.14 and 1.57-1.79,
respectively. The multi-band observations help to constrain the equivalent
widths of emission lines. Thanks to cluster lensing, we are able to identify 52
candidates down to an intrinsic limiting magnitude of 28.5 and to a rest-frame
[O III] 4959,5007 equivalent width of about 3737 angstrom. Our samples include
a number of EELGs at lower luminosities that are missed in other surveys, and
the extremely high equivalent width can be only found in such faint galaxies.
These EELGs can mimic the dropout feature similar to that of high redshift
galaxies and contaminate the color-color selection of high redshift galaxies
when the S/N ratio is limited or the band coverage is incomplete. We predict
that the fraction of EELGs in the future high redshift galaxy selections cannot
be neglected.Comment: 17 pages, 9 figures, 2 tables, Accepted for publication in AP
The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
We present an analysis of the deepest Herschel images in four major extragalactic fields GOODS-North, GOODS-South, UDS and COSMOS obtained within the GOODS-Herschel and CANDELS-Herschel key programs. The picture provided by 10497 individual far-infrared detections is supplemented by the stacking analysis of a mass-complete sample of 62361 star-forming galaxies from the CANDELS-HST H band-selected catalogs and from two deep ground-based Ks band-selected catalogs in the GOODS-North and the COSMOS-wide fields, in order to obtain one of the most accurate and unbiased understanding to date of the stellar mass growth over the cosmic history. We show, for the first time, that stacking also provides a powerful tool to determine the dispersion of a physical correlation and describe our method called "scatter stacking" that may be easily generalized to other experiments. We demonstrate that galaxies of all masses from z=4 to 0 follow a universal scaling law, the so-called main sequence of star-forming galaxies. We find a universal close-to-linear slope of the logSFR-logM* relation with evidence for a flattening of the main sequence at high masses (log(M*/Msun) > 10.5) that becomes less prominent with increasing redshift and almost vanishes by z~2. This flattening may be due to the parallel stellar growth of quiescent bulges in star-forming galaxies. Within the main sequence, we measure a non varying SFR dispersion of 0.3 dex. The specific SFR (sSFR=SFR/M*) of star-forming galaxies is found to continuously increase from z=0 to 4. Finally we discuss the implications of our findings on the cosmic SFR history and show that more than 2/3 of present-day stars must have formed in a regime dominated by the main sequence mode. As a consequence we conclude that, although omnipresent in the distant Universe, galaxy mergers had little impact in shaping the global star formation history over the last 12.5 Gyr
Single-exposure elemental differentiation and texture-sensitive phase-retrieval imaging with a neutron-counting microchannel-plate detector
Microchannel-plate (MCP) detectors, when used at pulsed-neutron-source instruments, offer the possibility of high spatial resolution and high contrast imaging with pixel-level spectroscopic information. Here we demonstrate the possibility of multimodal analysis including total neutron cross-section spectra measurements, quantitative material differentiation imaging, and texture-sensitive in-line phase imaging, from a single exposure using an MCP detector. This multimodal approach operates in full-field imaging mode, with the neutron transmission spectra acquired at each individual detector pixel. Due to the polychromatic nature of the beam and spectroscopic resolving capability of the detector, no energy scanning is required. Good agreement with the library reference data is demonstrated for neutron cross-section spectra measurements. Two different images corresponding to two selected energy bandwidths are used for elemental differentiation imaging. Moreover, the presence of changes in texture, i.e., preferred grain orientation, in the sample is identified from our phase-retrieval imaging results
Relativistic MHD and black hole excision: Formulation and initial tests
A new algorithm for solving the general relativistic MHD equations is
described in this paper. We design our scheme to incorporate black hole
excision with smooth boundaries, and to simplify solving the combined Einstein
and MHD equations with AMR. The fluid equations are solved using a finite
difference Convex ENO method. Excision is implemented using overlapping grids.
Elliptic and hyperbolic divergence cleaning techniques allow for maximum
flexibility in choosing coordinate systems, and we compare both methods for a
standard problem. Numerical results of standard test problems are presented in
two-dimensional flat space using excision, overlapping grids, and elliptic and
hyperbolic divergence cleaning.Comment: 22 pages, 8 figure
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