32 research outputs found
Deprojecting and constraining the vertical thickness of exoKuiper belts
Constraining the vertical and radial structure of debris discs is crucial to
understanding their formation, evolution and dynamics. To measure both the
radial and vertical structure, a disc must be sufficiently inclined. However,
if a disc is too close to edge-on, deprojecting its emission becomes
non-trivial. In this paper we show how Frankenstein, a non-parametric tool to
extract the radial brightness profile of circumstellar discs, can be used to
deproject their emission at any inclination as long as they are optically thin
and axisymmetric. Furthermore, we extend Frankenstein to account for the
vertical thickness of an optically thin disc () and show how it can be
constrained by sampling its posterior probability distribution and assuming a
functional form (e.g. constant ), while fitting the radial profile
non-parametrically. We use this new method to determine the radial and vertical
structure of 16 highly inclined debris discs observed by ALMA. We find a wide
range of vertical aspect ratios, , ranging from (AU Mic) to
(HD 110058), which are consistent with parametric models. We find
a tentative correlation between and the disc fractional width, as expected
if wide discs were more stirred. Assuming discs are self-stirred, the thinnest
discs would require the presence of at least 500 km-sized planetesimals. The
thickest discs would likely require the presence of planets. We also recover
previously inferred and new radial structures, including a potential gap in the
radial distribution of HD 61005. Finally, our new extension of Frankenstein
also allows constraining how varies as a function of radius, which we test
on 49 Ceti, finding that is consistent with being constant.Comment: Accepted for publication in MNRAS. 17 pages. 16 figure
YOLOv8-ACU: improved YOLOv8-pose for facial acupoint detection
IntroductionAcupoint localization is integral to Traditional Chinese Medicine (TCM) acupuncture diagnosis and treatment. Employing intelligent detection models for recognizing facial acupoints can substantially enhance localization accuracy.MethodsThis study introduces an advancement in the YOLOv8-pose keypoint detection algorithm, tailored for facial acupoints, and named YOLOv8-ACU. This model enhances acupoint feature extraction by integrating ECA attention, replaces the original neck module with a lighter Slim-neck module, and improves the loss function for GIoU.ResultsThe YOLOv8-ACU model achieves impressive accuracy, with an [email protected] of 97.5% and an [email protected]–0.95 of 76.9% on our self-constructed datasets. It also marks a reduction in model parameters by 0.44M, model size by 0.82 MB, and GFLOPs by 9.3%.DiscussionWith its enhanced recognition accuracy and efficiency, along with good generalization ability, YOLOv8-ACU provides significant reference value for facial acupoint localization and detection. This is particularly beneficial for Chinese medicine practitioners engaged in facial acupoint research and intelligent detection
Resolving Decades of Periodic Spirals from the Wolf-Rayet Dust Factory WR 112
WR 112 is a dust-forming carbon-rich Wolf-Rayet (WC) binary with a dusty
circumstellar nebula that exhibits a complex asymmetric morphology, which
traces the orbital motion and dust formation in the colliding winds of the
central binary. Unraveling the complicated circumstellar dust emission around
WR 112 therefore provides an opportunity to understand the dust formation
process in colliding-wind WC binaries. In this work, we present a multi-epoch
analysis of the circumstellar dust around WR 112 using seven high spatial
resolution (FWHM ) N-band ( m) imaging
observations spanning almost 20 years and includes newly obtained images from
Subaru/COMICS in Oct 2019. In contrast to previous interpretations of a face-on
spiral morphology, we observe clear evidence of proper motion of the
circumstellar dust around WR 112 consistent with a nearly edge-on spiral with a
half-opening angle and a -yr period. The revised
near edge-on geometry of WR 112 reconciles previous observations of highly
variable non-thermal radio emission that was inconsistent with a face-on
geometry. We estimate a revised distance to WR 112 of kpc based on the observed dust expansion rate and a
spectroscopically derived WC terminal wind velocity of
km s. With the newly derived WR 112 parameters we fit optically-thin
dust spectral energy distribution models and determine a dust production rate
of M yr, which
demonstrates that WR 112 is one of the most prolific dust-making WC systems
known.Comment: 17 pages, 9 figures, 1 animated gif, accepted for publication in Ap
Resolving Decades of Periodic Spirals from the Wolf–Rayet Dust Factory WR 112
WR 112 is a dust-forming carbon-rich Wolf–Rayet (WC) binary with a dusty circumstellar nebula that exhibits a complex asymmetric morphology, which traces the orbital motion and dust formation in the colliding winds of the central binary. Unraveling the complicated circumstellar dust emission around WR 112 therefore provides an opportunity to understand the dust formation process in colliding-wind WC binaries. In this work, we present a multi-epoch analysis of the circumstellar dust around WR 112 using seven high spatial resolution (FWHM ~ 0farcs3–0farcs4) N-band (λ ~ 12 μm) imaging observations spanning almost 20 yr and that includes images obtained from Subaru/COMICS in 2019 October. In contrast to previous interpretations of a face-on spiral morphology, we observe clear evidence of proper motion of the circumstellar dust around WR 112 consistent with a nearly edge-on spiral with a θ_s = 55° half-opening angle and a ~20 yr period. The revised near edge-on geometry of WR 112 reconciles previous observations of highly variable nonthermal radio emission that was inconsistent with a face-on geometry. We estimate a revised distance to WR 112 of d = 3.39_(-0.84)^(+0.89) kpc based on the observed dust expansion rate and a spectroscopically derived WC terminal wind velocity of v_∞ = 1230 ± 260 km s⁻¹. With the newly derived WR 112 parameters, we fit optically thin dust spectral energy distribution models and determine a dust production rate of Ṁ_d = 2.7_(-1.3)^(+1.0) x 10⁻⁶ M_⊙ yr⁻¹, which demonstrates that WR 112 is one of the most prolific dust-making WC systems known
Reaction hijacking inhibition of Plasmodium falciparum asparagine tRNA synthetase
Malaria poses an enormous threat to human health. With ever increasing resistance to currently deployed drugs, breakthrough compounds with novel mechanisms of action are urgently needed. Here, we explore pyrimidine-based sulfonamides as a new low molecular weight inhibitor class with drug-like physical parameters and a synthetically accessible scaffold. We show that the exemplar, OSM-S-106, has potent activity against parasite cultures, low mammalian cell toxicity and low propensity for resistance development. In vitro evolution of resistance using a slow ramp-up approach pointed to the Plasmodium falciparum cytoplasmic asparaginyl-tRNA synthetase (PfAsnRS) as the target, consistent with our finding that OSM-S-106 inhibits protein translation and activates the amino acid starvation response. Targeted mass spectrometry confirms that OSM-S-106 is a pro-inhibitor and that inhibition of PfAsnRS occurs via enzyme-mediated production of an Asn-OSM-S-106 adduct. Human AsnRS is much less susceptible to this reaction hijacking mechanism. X-ray crystallographic studies of human AsnRS in complex with inhibitor adducts and docking of pro-inhibitors into a model of Asn-tRNA-bound PfAsnRS provide insights into the structure-activity relationship and the selectivity mechanism.</p
Reaction hijacking inhibition of Plasmodium falciparum asparagine tRNA synthetase
Malaria poses an enormous threat to human health. With ever increasing resistance to currently deployed drugs, breakthrough compounds with novel mechanisms of action are urgently needed. Here, we explore pyrimidine-based sulfonamides as a new low molecular weight inhibitor class with drug-like physical parameters and a synthetically accessible scaffold. We show that the exemplar, OSM-S-106, has potent activity against parasite cultures, low mammalian cell toxicity and low propensity for resistance development. In vitro evolution of resistance using a slow ramp-up approach pointed to the Plasmodium falciparum cytoplasmic asparaginyl-tRNA synthetase (PfAsnRS) as the target, consistent with our finding that OSM-S-106 inhibits protein translation and activates the amino acid starvation response. Targeted mass spectrometry confirms that OSM-S-106 is a pro-inhibitor and that inhibition of PfAsnRS occurs via enzyme-mediated production of an Asn-OSM-S-106 adduct. Human AsnRS is much less susceptible to this reaction hijacking mechanism. X-ray crystallographic studies of human AsnRS in complex with inhibitor adducts and docking of pro-inhibitors into a model of Asn-tRNA-bound PfAsnRS provide insights into the structure-activity relationship and the selectivity mechanism
Reaction hijacking inhibition of Plasmodium falciparum asparagine tRNA synthetase
Malaria poses an enormous threat to human health. With ever increasing resistance to currently deployed drugs, breakthrough compounds with novel mechanisms of action are urgently needed. Here, we explore pyrimidine-based sulfonamides as a new low molecular weight inhibitor class with drug-like physical parameters and a synthetically accessible scaffold. We show that the exemplar, OSM-S-106, has potent activity against parasite cultures, low mammalian cell toxicity and low propensity for resistance development. In vitro evolution of resistance using a slow ramp-up approach pointed to the Plasmodium falciparum cytoplasmic asparaginyl-tRNA synthetase (PfAsnRS) as the target, consistent with our finding that OSM-S-106 inhibits protein translation and activates the amino acid starvation response. Targeted mass spectrometry confirms that OSM-S-106 is a pro-inhibitor and that inhibition of PfAsnRS occurs via enzyme-mediated production of an Asn-OSM-S-106 adduct. Human AsnRS is much less susceptible to this reaction hijacking mechanism. X-ray crystallographic studies of human AsnRS in complex with inhibitor adducts and docking of pro-inhibitors into a model of Asn-tRNA-bound PfAsnRS provide insights into the structure-activity relationship and the selectivity mechanism
From 1/4° to 1/8°: Influence of Spatial Resolution on Eddy Detection Using Altimeter Data
A substantial portion of ocean eddies, especially small ones, may be missed due to insufficient spatial or temporal sampling by satellite altimetry. In order to illustrate the influence of spatial resolution on eddy detection, this study provides a comparison of eddy identification, tracking, and analysis between two sets of merged altimeter data with spatial resolutions of 1/4° and 1/8°. One main study area (the Mediterranean Sea), and three confirmatory areas (the South-China Sea, the North-West Pacific, and the South-East Pacific) are chosen. The results show that the number and density of eddies captured by the 1/8° data are about twice as much as those captured by the 1/4° data, while the ratios of corresponding eddy parameters, i.e., radius, amplitude, (eddy kinetic energy (EKE)) are about 0.6–0.8 (1.3) for the two datasets (1/8° ÷ 1/4°). Long-term eddy tracking (1993–2018) is conducted in the Mediterranean Sea, indicating that the improvement in spatial resolution will increase the observed values of both the lifetime and the propagation distance of robust eddies. The number of eddies identified using the 1/4° data only accounts for ~30% to 60% of those identified using the 1/8° data. However, for eddies that can be detected using the two datasets, ~5% to 10% present errors (i.e., confusion). In comparison between the four regions, we find that for the enclosed seas with complex conditions, the increase in spatial resolution may lead to more significant improvements in the efficiency and accuracy of eddy detection