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Molecular profiling of single cells has advanced our knowledge of the molecular basis of development. However, current approaches mostly rely on dissociating cells from tissues, thereby losing the crucial spatial context of regulatory processes. Here, we apply an image-based single-cell transcriptomics method, sequential fluorescence in situ hybridization (seqFISH), to detect mRNAs for 387 target genes in tissue sections of mouse embryos at the 8–12 somite stage. By integrating spatial context and multiplexed transcriptional measurements with two single-cell transcriptome atlases, we characterize cell types across the embryo and demonstrate that spatially resolved expression of genes not profiled by seqFISH can be imputed. We use this high-resolution spatial map to characterize fundamental steps in the patterning of the midbrain–hindbrain boundary (MHB) and the developing gut tube. We uncover axes of cell differentiation that are not apparent from single-cell RNA-sequencing (scRNA-seq) data, such as early dorsal–ventral separation of esophageal and tracheal progenitor populations in the gut tube. Our method provides an approach for studying cell fate decisions in complex tissues and development. Improved integration of spatial and single-cell transcriptomic data provides insights into mouse development.

Although not an intrinsic superconductor, graphite exhibits superconductivity when intercalated with certain dopants 1 . Perhaps the most studied of these graphite-based superconductors are the alkali metal–graphite intercalation compounds (GICs) (ref.  2 ), of which the easiest to fabricate is C 8 K (ref.  3 ), with a transition temperature (ref.  2 ). By increasing the alkali metal concentration (through high-pressure fabrication techniques), the transition temperature can be increased up to 5 K in C 2 Na (ref.  4 ). Superconductivity in C 6 Yb and C 6 Ca with and 11.5 K, respectively, and at ambient conditions has been observed 5 . Here we explore the architecture of the states near the Fermi level and identify characteristics of the electronic band structure generic to GICs. In addition to the expected charge transfer from the intercalant atoms to the graphene sheets, resulting from the occupation of the π bands, we find that in all of those—and only those—compounds that superconduct, an interlayer state, which is well-separated from the carbon sheets, also becomes occupied. We show that the energy of the interlayer band is controlled by a combination of its occupancy and the separation between the carbon layers.

The two-component Fermi gas is the simplest fermion system exhibiting superfluidity, and as such is relevant to topics ranging from superconductivity to quantum chromodynamics. Ultracold atomic gases provide an exceptionally clean realization of this system, where interatomic interactions and atom spin populations are both independently tuneable. Here we show that the finite-temperature phase diagram contains a region of phase separation between the superfluid and normal states that touches the boundary of second-order superfluid transitions at a tricritical point, reminiscent of the phase diagram of 3 He– 4 He mixtures. A variation of interaction strength then results in a line of tricritical points that terminates at zero temperature on the molecular Bose–Einstein condensate side. On this basis, we argue that tricritical points are fundamental to understanding experiments on polarized atomic Fermi gases.

Unlike mammals, Xenopus laevis tadpoles have a high regenerative potential. To characterize this regenerative response, we performed single-cell RNA sequencing after tail amputation. By comparing naturally occurring regeneration-competent and -incompetent tadpoles, we identified a previously unrecognized cell type, which we term the regeneration-organizing cell (ROC). ROCs are present in the epidermis during normal tail development and specifically relocalize to the amputation plane of regeneration-competent tadpoles, forming the wound epidermis. Genetic ablation or manual removal of ROCs blocks regeneration, whereas transplantation of ROC-containing grafts induces ectopic outgrowths in early embryos. Transcriptional profiling revealed that ROCs secrete ligands associated with key regenerative pathways, signaling to progenitors to reconstitute lost tissue. These findings reveal the cellular mechanism through which ROCs form the wound epidermis and ensure successful regeneration.

ABSTRACTPurpose: To evaluate retrospectively the surgical technique, visual outcome, and complications of pediatric cataract extraction (CE) and intraocular lens (IOL) implantation.Methods: Forty-three patients ages 2 to 12 underwent CE with IOL implantation with a minimum follow up of 1 month.Results: All IOLs were implanted in the posterior chamber with 17 (40%) in the bag, 25 (58%) sulcus fixated, and one (2%) partially in the bag (one haptic in the bag, one in the sulcus). Primary posterior capsulectomy was performed in 12 (28%) cases. A final visual acuity of at least 20/40 was achieved in 26 (60%) and at least 20/80 in 32 (74%). Posterior capsule opacification developed in 18 (42%) and pupillary capture in 7 (16%). Seventeen (40%) patients had postoperative visual acuity worse than 20/40. Of these, nine (53%) had this visual outcome as a result of presumed amblyopia.Conclusions: Posterior chamber IOL implantation affords a safe and effective method of visual rehabilitation for cataractous children 2 years of age and older. Amblyopia and antecedent posterior segment trauma, rather than IOL-related or surgical complications, are the limiting factors in final visual outcome.Journal of Pediatric Ophthalmology & Strabismus 1999; 36:118-124.

Following the experimental realization of Dicke superradiance in Bose gases coupled to cavity light fields, we investigate the behavior of ultra cold fermions in a transversely pumped cavity. We focus on the equilibrium phase diagram of spinless fermions coupled to a single cavity mode and establish a zero temperature transition to a superradiant state. In contrast to the bosonic case, Pauli blocking leads to lattice commensuration effects that influence self-organization in the cavity light field. This includes a sequence of discontinuous transitions with increasing atomic density and tricritical superradiance. We discuss the implications for experiment.

At low temperatures, indirect excitons formed at the in-plane electron-hole interface in a coupled quantum well structure undergo a spontaneous transition into a spatially modulated state. We report on the control of the instability wavelength, measurement of the dynamics of the exciton emission pattern, and observation of the fluctuation and commensurability effect of the exciton density wave. We found that fluctuations are strongly suppressed when the instability wavelength is commensurate with defect separation along the exciton density wave. The commensurability effect is also found in numerical simulations within the model describing the exciton density wave in terms of an instability due to stimulated processes.

Amblyopia is a condition that, if detected and treated early, can improve vision for most children. Thus, both pediatric and ophthalmologic groups have acknowledged the need for preschool vision screening. However, vision screening is the exception rather than the rule for preschoolers, since traditional methods of vision screening are often inappropriate for the preschool population and almost impossible for those children who are preverbal or nonverbal, developmentally delayed, and/or have chronic illnesses or disabilities. This study evaluated the use of a photoscreener to detect vision problems in a preschool population. Fifty-one children ages 3 to 5 years were evaluated using the MTI Photoscreener. Results were compared with a complete ophthalmologic examination, including cycloplegia. The sensitivity and specificity calculated for this study was 83% and 68%, respectively. Findings conclude that the MTI Photoscreener detected a broad range of vision problems, seemed to require less time, and seemed more acceptable to preschoolers when compared with the traditional vision screening methods performed by registered nurses. Although the sensitivity and specificity rates for this study were less than desired, it is likely that both could be improved with additional photo interpretation training.