We propose the first viable radiative seesaw model, in which the neutrino
masses are induced radiatively via the two-loop Feynman diagram involving
Strongly Interacting Massive Particles (SIMP). The stability of SIMP dark
matter (DM) is ensured by a ℤ5 discrete symmetry, through which the
DM annihilation rate is dominated by the 3→2 self-annihilating processes.
The right amount of thermal relic abundance can be obtained with perturbative
couplings in the resonant SIMP scenario, while the astrophysical bounds
inferred from the Bullet cluster and spherical halo shapes can be satisfied. We
show that SIMP DM is able to maintain kinetic equilibrium with thermal plasma
until the freeze-out temperature via the Yukawa interactions associated with
neutrino mass generation.
Recent research suggests that cancer stem-like cells (CSCs) are the key subpopulation for tumor relapse and metastasis. Due to cancer plasticity in surface antigen and enzymatic activity markers, functional tumorsphere assays are promising alternatives for CSC identification. To reliably quantify rare CSCs (1-5%), thousands of single-cell suspension cultures are required. While microfluidics is a powerful tool in handling single cells, previous works provide limited throughput and lack automatic data analysis capability required for high-throughput studies. In this study, we present the scaling and automation of high-throughput single-cell-derived tumor sphere assay chips, facilitating the tracking of up to ∼10 000 cells on a chip with ∼76.5% capture rate. The presented cell capture scheme guarantees sampling a representative population from the bulk cells. To analyze thousands of single-cells with a variety of fluorescent intensities, a highly adaptable analysis program was developed for cell/sphere counting and size measurement. Using a Pluronic® F108 (poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)) coating on polydimethylsiloxane (PDMS), a suspension culture environment was created to test a controversial hypothesis: whether larger or smaller cells are more stem-like defined by the capability to form single-cell-derived spheres. Different cell lines showed different correlations between sphere formation rate and initial cell size, suggesting heterogeneity in pathway regulation among breast cancer cell lines. More interestingly, by monitoring hundreds of spheres, we identified heterogeneity in sphere growth dynamics, indicating the cellular heterogeneity even within CSCs. These preliminary results highlight the power of unprecedented high-throughput and automation in CSC studies.
