834 research outputs found
Solidification of liquid metal drops during impact
Hot liquid metal drops impacting onto a cold substrate solidify during their
subsequent spreading. Here we experimentally study the influence of
solidification on the outcome of an impact event. Liquid tin drops are impacted
onto sapphire substrates of varying temperature. The impact is visualised both
from the side and from below, which provides a unique view on the
solidification process. During spreading an intriguing pattern of radial
ligaments rapidly solidifies from the centre of the drop. This pattern
determines the late-time morphology of the splat. A quantitative analysis of
the drop spreading and ligament formation is supported by scaling arguments.
Finally, a phase diagram for drop bouncing, deposition and splashing as a
function of substrate temperature and impact velocity is provided
IRAS 19135+3937: An SRd variable as interacting binary surrounded by a circumbinary disc
Semi-regular (SR) variables are not a homogeneous class and their variability
is often explained due to pulsations and/or binarity. This study focuses on
IRAS 19135+3937, an SRd variable with an infra-red excess indicative of a dusty
disc. A time-series of high-resolution spectra, UBV photometry as well as a
very accurate light curve obtained by the Kepler satellite, allowed us to study
the object in unprecedented detail. We discovered it to be a binary with a
period of 127 days. The primary has a low surface gravity and an atmosphere
depleted in refractory elements. This combination of properties unambiguously
places IRAS 19135+3937 in the subclass of post-Asymptotic Giant Branch stars
with dusty discs.
We show that the light variations in this object can not be due to
pulsations, but are likely caused by the obscuration of the primary by the
circumbinary disc during orbital motion. Furthermore, we argue that the
double-peaked Fe emission lines provide evidence for the existence of a gaseous
circumbinary Keplerian disc inside the dusty disc. A secondary set of
absorption lines has been detected near light minimum, which we attribute to
the reflected spectrum of the primary on the disc wall, which segregates due to
the different Doppler shift. This corroborates the recent finding that
reflection in the optical by this type of discs is very efficient. The system
also shows a variable Halpha profile indicating a collimated outflow
originating around the companion. IRAS 19135+3937 thus encompasses all the
major emergent trends about evolved disc systems, that will eventually help to
place these objects in the evolutionary context.Comment: Accepted to MNRA
Multi‐object detector YOLOv4‐tiny enables high‐throughput combinatorial and spatially‐resolved sorting of cells in microdroplets
This is the final version. Available from Wiley via the DOI in this record. Data Availability Statement:
The data that support the findings of this study are available from the corresponding author upon reasonable request.The encapsulation of cells together with micro-objects in monodispersed water-in-oil microdroplets offers a powerful means to perform quantitative biological studies within large cell populations. In such applications, accurate object detection is crucial to ensure control over the content for every compartment. In particular, the ability to rapidly count and localize objects is key to future applications in single-cell -omics, cellular aggregation, and cell-to-cell interactions. In this paper, the authors combine the Deep Learning object detector YOLOv4-tiny with microfluidic Image-Activated Droplet Sorting (DL-IADS), to perform flexible, label-free classification, counting, and localization of multiple micro-objects simultaneously and at high-throughput. They trained YOLOv4-tiny to detect SH-SY5Y cells, polyacrylamide beads, and cellular aggregates in a single model, with a precision of 92% for cells, 98% for beads, and 81% for aggregates. They exploit this accuracy and counting ability to implement a closed-loop feedback that enables controlled loading of microbeads via the automated adjustment of flow rates. They subsequently demonstrate the combinatorial sorting of co-encapsulated single cells and single beads based on real-time classification at up to 111 Hz, with enrichment factors of up to 145. Finally, they demonstrate spatially-resolved sorts by evaluating cell-to-cell distances in real-time to isolate cell doublets with high purity.Biotechnology and Biological Sciences Research CouncilEuropean Union’s Horizon 202
TLR3, TLR4 and TLRs7-9 Induced Interferons Are Not Impaired in Airway and Blood Cells in Well Controlled Asthma
Defective Rhinovirus induced interferon-β and interferon-λ production has been reported in bronchial epithelial cells from asthmatics but the mechanisms of defective interferon induction in asthma are unknown. Virus infection can induce interferon through Toll like Receptors (TLR)3, TLR7 and TLR8. The role of these TLRs in interferon induction in asthma is unclear. This objective of this study was to measure the type I and III interferon response to TLR in bronchial epithelial cells and peripheral blood cells from atopic asthmatics and non-atopic non-asthmatics. Bronchial epithelial cells and peripheral blood mononuclear cells from atopic asthmatic and non-atopic non-asthmatic subjects were stimulated with agonists to TLR3, TLR4 & TLRs7-9 and type I and III interferon and pro-inflammatory cytokine, interleukin(IL)-6 and IL-8, responses assessed. mRNA expression was analysed by qPCR. Interferon proteins were analysed by ELISA. Pro-inflammatory cytokines were induced by each TLR ligand in both cell types. Ligands to TLR3 and TLR7/8, but not other TLRs, induced interferon-β and interferon-λ in bronchial epithelial cells. The ligand to TLR7/8, but not those to other TLRs, induced only type I interferons in peripheral blood mononuclear cells. No difference was observed in TLR induced interferon or pro-inflammatory cytokine production between asthmatic and non-asthmatic subjects from either cell type. TLR3 and TLR7/8,, stimulation induced interferon in bronchial epithelial cells and peripheral blood mononuclear cells. Interferon induction to TLR agonists was not observed to be different in asthmatics and non-asthmatics
Topological defects and shape of aromatic self-assembled vesicles
We show that the stacking of flat aromatic molecules on a curved surface
results in topological defects. We consider, as an example, spherical vesicles,
self-assembled from molecules with 5- and 6-thiophene cores. We predict that
the symmetry of the molecules influences the number of topological defects and
the resulting equilibrium shape.Comment: accepted as a Letter in the J. Phys. Chem.
X-Ray Structure and In Vitro Anti-Tumoural Activity of the Dimeric Bis[(2-Phenyl-1,2-Dicarba-Closo-Dodecaborane-1-Carboxylato)-Di-n-Butyltin] Oxide
X-ray diffraction studies reveal the structure of {[(2-C6H5-1,2-C2B10H10-1-COO)Bu2Sn]2O}2, 1, to conform to the common motif found for {[(R′COO)R2Sn]2O}2 compounds. The dimer features a central Bu2Sn2O2 unit (two-fold symmetry) with the two Bu2Sn groups being linked via bridging oxygen atoms, each of which also carries an exocyclic Bu2Sn moiety. The two pairs of exo- and endo-cyclic tin atoms are each linked via an almost symmetrically bridging carboxylate ligand and the two remaining ligands coordinate an exocyclic tin atom only, in the monodentate mode. The in vitro anti-tumour activity of 1, determined against a variety of cell lines, is compared with those of the corresponding 2-methylcarboranylacetate, derivative 2, and with clinically used compounds
Quantum simplicial geometry in the group field theory formalism: reconsidering the Barrett-Crane model
A dual formulation of group field theories, obtained by a Fourier transform
mapping functions on a group to functions on its Lie algebra, has been proposed
recently. In the case of the Ooguri model for SO(4) BF theory, the variables of
the dual field variables are thus so(4) bivectors, which have a direct
interpretation as the discrete B variables. Here we study a modification of the
model by means of a constraint operator implementing the simplicity of the
bivectors, in such a way that projected fields describe metric tetrahedra. This
involves a extension of the usual GFT framework, where boundary operators are
labelled by projected spin network states. By construction, the Feynman
amplitudes are simplicial path integrals for constrained BF theory. We show
that the spin foam formulation of these amplitudes corresponds to a variant of
the Barrett-Crane model for quantum gravity. We then re-examin the arguments
against the Barrett-Crane model(s), in light of our construction.Comment: revtex, 24 page
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