Indefinite metacavities coupled to a mirror:bound states in the continuum with anomalous resonance scaling

Indefinite metacavities(IMCs)made of hyperbolic metamaterials show great advantages in terms of extremely small mode volume due to large wave vectors endowed by the unique hyperbolic dispersion.However,quality(Q)factors of IMCs are limited by Ohmic loss of metals and radiative loss of leaked waves.Despite the fact that Ohmic loss of metals is inevitable in IMCs,the radiative loss can be further suppressed by leakage engineering.Here we propose a mirror coupled IMC structure which is able to operate at Fabry–Pérot bound states in the continuum(BICs)while the hyperbolic nature of IMCs is retained.At the BIC point,the radiative loss of magnetic dipolar cavity modes in IMCs is completely absent,resulting in a considerably increased Q factor(>90).Deviating from the BIC point,perfect absorption bands(>0.99)along with a strong near-field intensity enhancement(>1.8×10^(4))appear when the condition of critical coupling is almost fulfilled.The proposed BICs are robust to the geometry and material composition of IMCs and anomalous scaling law of resonance is verified during the tuning of optical responses.We also demonstrate that the Purcell effect of the structure can be significantly improved under BIC and quasi-BIC regimes due to the further enhanced Q factor to mode volume ratio.Our results provide a new train of thought to design ultra-small optical nanocavities that may find many applications benefitting from strong light–matter interactions.

Temporal and spatial stability of the EM/PM molecular subtypes in adult diffuse glioma

Detailed characterizations of genomic alterations have not identified subtype-specific vulnerabilities in adult gliomas. Mapping gliomas into developmental programs may uncover new vulnerabilities that are not strictly related to genomic alterations. After identifying conserved gene modules co-expressed with EGFR or PDGFRA (EM or PM), we recently proposed an EM/PM classification scheme for adult gliomas in a histological subtype- and grade-independent manner. By using cohorts of bulk samples, paired primary and recurrent samples, multi-region samples from the same glioma, single-cell RNA-seq samples, and clinical samples, we here demonstrate the temporal and spatial stability of the EM and PM subtypes. The EM and PM subtypes, which progress in a subtype-specific mode, are robustly maintained in paired longitudinal samples. Elevated activities of cell proliferation, genomic instability and microenvironment, rather than subtype switching, mark recurrent gliomas. Within individual gliomas, the EM/PM subtype was preserved across regions and single cells. Malignant cells in the EM and PM gliomas were correlated to neural stem cell and oligodendrocyte progenitor cell compartment, respectively. Thus, while genetic makeup may change during progression and/or within different tumor areas, adult gliomas evolve within a neurodevelopmental framework of the EM and PM molecular subtypes. The dysregulated developmental pathways embedded in these molecular subtypes may contain subtype-specific vulnerabilities.