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Observation of B + c → Dh + h− Decays
No full textSearches are presented for + →ℎ+ℎ− decays, where is a charmed meson and ℎ± is a charged pion or kaon, using collision data collected by the LHCb experiment corresponding to an integrated luminosity of 9 fb−1. The decays + →++−, + →*++−, and + →++− are observed for the first time. Their branching fractions, expressed as ratios relative to that of the + →0+ decay, are determined to be ℛ(+→++−)=(1.96±0.23±0.08±0.10)×10−3, ℛ(+→*++−)=(3.67±0.55±0.24±0.20)×10−3, ℛ(+→++−)=(1.61±0.35±0.13±0.07)×10−3, where the first uncertainty is statistical, the second is systematic, and the third is due to the limited precision on the -meson branching fractions. The decay channels proceed primarily through excited 0 or 0 resonances or mesons, and open a new avenue for studies of charge-parity violation in beauty mesons
De invloed van kiezers op de samenstelling van de Eerste Kamer in getallen
No full textDe verkiezing van de Eerste Kamer is aanhoudend onderwerp van discussie. In het debat blijft één cruciaal aspect echter onderbelicht: de wijze waarop de stemwaardeberekening sinds 1923 de verkiezing vormgeeft. Omdat een groot deel van deze berekening is gebaseerd op het inwonertal, roepen zowel de integratie van Bonaire, Sint Eustatius en Saba in het Nederlandse staatsbestel als de verschuivingen in de bevolkingssamenstelling gedurende de afgelopen eeuw steeds nadrukkelijker de vraag op in hoeverre deze berekeningsmethode nog toekomstbestendig is. In het licht van de grondwettelijk gegarandeerde evenredige vertegenwoordiging en het gelijkelijke kiesrecht van Nederlanders in de Eerste Kamer rijst de vraag of de berekeningsmethode blijvend op het aantal inwoners moet worden afgestemd, of dat het tijd is over te stappen op het aantal kiesgerechtigden als berekeningsmethode
Directionality range in Emlen funnels
No full textOur understanding of bird orientation guided by magnetic and visual cues is primarily based on Emlen funnel experiments. Migration-motivated birds jump in the direction they want to fly, and their feet leave marks on paper lining the funnel, which yields the preferred direction. Despite the low signal-to-noise ratio, this paradigm has proven instrumental for studying magnetoreception in birds. However, the high noise limits the questions that can be answered and there is no data-informed guideline for selecting sample sizes that have a high likelihood to be conclusive. Furthermore, differences in experimental design traditions limit comparison and reproducibility across studies, slowing down discovery. We performed a large meta-analysis across double-blind magnetic orientation studies with Emlen funnels performed at Oldenburg to statistically characterize Emlen funnel data and determine minimal sampling requirements for conclusive experimental design. The analysis confirms that pre-selecting migration-motivated animals before the real experiments start improves statistical power by reducing noise. We also highlight mathematical limitations of the widely used directionality measure 'r', due to lacking sample-size bias correction, and present realistic ranges for expected bird directedness in Emlen funnels. Combined, these results provide critical design and analysis guidelines for statistically informative magnetic orientation experiments.</p
MINDS:Strong oxygen depletion in the inner regions of a very low-mass star disk?
No full textContext. Thanks to JWST, a plethora of species in planet-forming disks around very low mass stars such as C2H2, C6H6, C4H2, CH3 etc. are being discovered. The column densities of these species retrieved from 0D slab models are very large (e.g. of the order of 1020 cm−2). This indicates a carbon-dominated chemistry in a gas with a high C/O ratio. The disk around 2MASS-J1605321-1993159 (M4.5) is one such source showing a molecular pseudo-continuum of C2H2. Notably, two oxygen-bearing molecules, CO and CO2, are also detected in this source. Aims. We aim to take the next step beyond 0D slab models to interpret the spectrum. We examine whether 2D thermo-chemical disk models can produce the large inferred column densities of C2H2 in the inner regions of the disk and produce a pseudo-continuum in the mid-IR spectrum. We also seek to constrain whether the depletion of oxygen or the enrichment of carbon causes the high C/O ratio triggering a carbon-dominated chemistry. Methods. We utilised the radiative thermo-chemical disk model PRODIMO to identify a disk structure that is capable of producing the observed molecular emission of species such as CO, CO2, C2H2, and H2O simultaneously. The spectrum was generated using the fast line tracer FLiTs. We derived the gas temperature ⟨T⟩, column density ⟨log10 N⟩, and the emitting area ⟨r 1 − r 2⟩ for these molecules from the 2D disk model and compared them to the parameters retrieved originally from 0D slab models. We used the different effect that changing the O or C abundance has on CO and C2H2, respectively to discriminate between O depletion and C enhancement. Results. We find that a disk structure characterised by the presence of a gap can best explain the observations. The inner disk is strongly depleted in dust, especially small grains (<5 µm), and elemental oxygen, leading to a large C/O ratio. This is required to produce a molecular pseudo-continuum of C2H2 and at the same time a relatively weak CO emission. The P- and R-branch of C2H2 probe deeper layers of the disk whereas the Q-branch probes mostly the surface layers. The combined emission of CO and CO2 puts strong constraints on the gap’s location (0.1–0.5 au) given a disk gas mass. We also report a new detection of the CO ν= 2→1 transition in the JWST spectrum. Conclusions. Two-dimensional thermo-chemical disk models are able to produce the observed molecular pseudo-continuum of C2H2. We find that the combination of different species emission in the JWST spectra can be used to discriminate between different scenarios such as O-depletion, C-enhancement or both, and offers the potential to extract spatial substructure at scales smaller than ∼1 au.</p
Path and bone-contour regularized unpaired MRI-to-CT translation
No full textAccurate MRI-to-CT translation promises the integration of complementary imaging information without the need for additional imaging sessions. Given the practical challenges associated with acquiring paired MRI and CT scans, the development of robust methods capable of leveraging unpaired datasets is essential for advancing the MRI-to-CT translation. Current unpaired MRI-to-CT translation methods, which predominantly rely on cycle consistency and contrastive learning frameworks, frequently encounter challenges in accurately translating anatomical features that are highly discernible on CT but less distinguishable on MRI, such as bone structures. This limitation renders these approaches less suitable for applications in radiation therapy, where precise bone representation is essential for accurate treatment planning. To address this challenge, we propose a path- and bone-contour regularized approach for unpaired MRI-to-CT translation. In our method, MRI and CT images are projected to a shared latent space, where the MRI-to-CT mapping is modeled as a continuous flow governed by neural ordinary differential equations. The optimal mapping is obtained by minimizing the transition path length of the flow. To enhance the accuracy of translated bone structures, we introduce a trainable neural network to generate bone contours from MRI and implement mechanisms to directly and indirectly encourage the model to focus on bone contours and their adjacent regions. Evaluations conducted on three datasets demonstrate that our method outperforms existing unpaired MRI-to-CT translation approaches, achieving lower overall error rates. Moreover, in a downstream bone segmentation task, our approach exhibits superior performance in preserving the fidelity of bone structures. Our code is available at: https://github.com/kennysyp/PaBoT.</p
Individualized Prediction of Platelet Transfusion Outcomes in Preterm Infants With Severe Thrombocytopenia
No full textIMPORTANCE: Preterm infants with severe thrombocytopenia (platelet count <50 × 109/L) frequently receive platelet transfusions. However, it is unclear in what cases prophylactic transfusion truly reduces bleeding risk or whether it does more harm than good.OBJECTIVE: To develop and validate a dynamic prediction model for major bleeding or mortality if prophylactic platelet transfusion were or were not to be given to infants with severe thrombocytopenia.DESIGN, SETTING, AND PARTICIPANTS: The dynamic prediction model was developed in an international multicenter cohort (2017-2021) comprising 14 neonatal intensive care units in the Netherlands, Sweden, and Germany. Model evaluation was performed in a national multicenter cohort (2010-2014) including 7 Dutch neonatal intensive care units. The study population consisted of infants with severe thrombocytopenia less than 34 weeks' gestation.EXPOSURE: Two transfusion strategies were contrasted at each prediction point: receiving a platelet transfusion within 6 hours (prophylaxis) vs no platelet transfusion for 3 days (no prophylaxis).MAIN OUTCOMES AND MEASURES: The primary outcome was the 3-day risk of major bleeding or mortality, reestimated every 2 hours during the first week after severe thrombocytopenia onset. Predictors included gestational and postnatal age, small-for-gestational-age infant, necrotizing enterocolitis, sepsis, mechanical ventilation, vasoactive agents, platelet count, and prior platelet transfusion(s). Landmarking combined with the clone-censor-weight approach enabled dynamic prediction under the 2 transfusion strategies, accounting for time-varying confounding. Model performance was evaluated in the external validation cohort.RESULTS: In both the development (n = 1042) and validation (n = 637) cohorts, the median gestational age was 28 weeks and median birth weight was 900 g; there were 613 (59%) and 370 (58%) males, respectively. Major bleeding or death occurred in 235 infants (23%) in the development cohort and 135 (21%) in the validation cohort. In the validation cohort, the time-dependent area under the receiver operating characteristic curve was 0.69 (95% CI, 0.60-0.76) for the prophylaxis strategy and 0.85 (95% CI, 0.76-0.92) for the no prophylaxis strategy, with calibration plots showing good calibration. Estimated risks under both strategies varied considerably depending on the infant's clinical condition at the time of prediction.CONCLUSIONS AND RELEVANCE: Among preterm infants with severe thrombocytopenia, this modeling study found substantial variation among individuals in predicted benefits and harms of prophylactic platelet transfusion based on their current clinical characteristics. The dynamic prediction model performed well in a validation cohort, and its value to support individualized decisions warrants evaluation in future studies..</p
Diamagnetic microchip traps for levitated nanoparticle entanglement experiments
No full textThe quantum gravity mediated entanglement protocol offers a method to probe the quantumness of gravitational interactions at nonrelativistic scales. This protocol leverages the Stern-Gerlach effect to create O(µm) spatial superpositions of two nanodiamonds (mass ∼10−15 kg) with nitrogen-vacancy spins, which are then allowed to interact and become entangled solely through the gravitational interaction. Since electromagnetic interactions such as Casimir-Polder and dipole-dipole interactions dominate at this scale, screening them to ensure the masses interact exclusively via gravity is crucial. In this paper, we propose using magnetic traps based on microfabricated wires, which provide strong gradients with relatively modest magnetic fields to trap nanoparticles for interferometric entanglement experiments. The design consists of a small trap to cool the center-of-mass motion of the nanodiamonds and a long trap with a weak direction suitable for creating macroscopic superpositions. In contrast to permanent-magnet-based long traps, the microfabricated wire-based approach allows fast switching of the magnetic trapping and state manipulation potentials and permits integrated superconducting shielding, which can screen both electrostatic and magnetic interactions between nanodiamonds in a gravitational entanglement experiment. The setup also provides a possible platform for other tests of quantum coherence in macroscopic systems and searches for novel short-range forces.</p
Community Curation of Microbial Metabolites Enables Biological Insights of Metabolomics Data
No full textMicrobial metabolites play a critical role in regulating ecosystems, including the human body and its microbiota. However, understanding the physiologically relevant role of these molecules, especially through liquid chromatography tandem mass spectrometry (LC-MS/MS)-based untargeted metabolomics, poses significant challenges and often requires manual parsing of a large amount of literature, databases, and webpages. To address this gap, we established the Collaborative Microbial Metabolite Center knowledgebase (CMMC-KB), a platform that fosters collaborative efforts within the scientific community to curate knowledge about microbial metabolites. The CMMC-KB aims to collect comprehensive information about microbial molecules originating from microbial biosynthesis, drug metabolism, exposure-related molecules, food, host-derived molecules, and, whenever available, their known activities. Molecules from other sources, including host-produced, dietary, and pharmaceutical compounds, are also included. By enabling direct integration of this knowledgebase with downstream analytical tools, including molecular networking, we can deepen insights into microbiota and their metabolites, ultimately advancing our understanding of microbial ecosystems.</p
