Table 2.
Nomenclature of biophysical parameters.
| Symbol | Parameter |
|---|---|
| F s | Hydrodynamic shear force acting on rolling neutrophil along x-axis (pN) |
| T s | Hydrodynamic torque acting on rolling neutrophil (about the cell center) along y-axis (pN.μm) |
| F N | Normal reaction force acting on rolling neutrophil (pN) |
| r c | Cell radius (μm) |
| τ w | Wall shear stress (Pa) |
| νx(z) | x-component of fluid velocity as a function of z distance from the substrate |
| F te,i | Force on ith tether (pN) |
| F mv,j | Force on jth stressed tetherless microvillus (pN) |
| φ i | Tether angle with the P-selectin substrate (degrees) |
| θ j | Angle of stressed tetherless microvillus with P-selectin substrate (degrees) |
| T te,i | Torque (about the cell center) acting on rolling neutrophil along y-axis due to the tether force Fte,i (pN μm) |
| T mv,j | Torque (about the cell center) acting on rolling neutrophil along y-axis due to the microvillus force Fmv,j (pN μm) |
| L i | Distance (along x-axis) of the anchorage point of tether bonds from the center of the cell (μm) |
| l j | Distance (along x-axis) of the anchorage point of stressed (tetherless) microvillus bonds from the center of the cell (μm) |
| F b | Bond force (pN) |
| σ | Bound state spring constant of the bond (pN/μm) |
| L sep | Stressed length of the bond (nm) |
| λ | Unstressed length of the bond (nm) |
| R | Receptor |
| L | Ligand |
| RL | Receptor-ligand complex |
| Unstressed forward reaction rate at Fb = 0 (M-1s-1) | |
| Unstressed reverse reaction rate at Fb = 0 (s-1) | |
| kf | Forward reaction rate at Fb > 0 (M-1s-1) |
| kr | Reverse reaction rate at Fb > 0 (s-1) |
| γ | Reactive compliance (Å) |
| κ B | Boltzmann's constant (J/°K) |
| T | Absolute temperature (°K) |
| L new | Length of the possible new bond (nm) |
| σ ts | Transition state spring constant (pN/μm) |
| k1rup | Reverse reaction rate for pathway 1 (s-1) |
| k2rup | Reverse reaction rate for pathway 2 (s-1) |
| Unstressed reverse reaction rate for the pathway 2 at Fb = 0 (s-1) | |
| S1/S2 | Occupancy ratio of the two bound states |
| Φ o | Occupancy ratio of the two bound states at Fb = 0 |
| f 12 | Bond force at which occupancy ratio changes 2.7 fold (pN) |
| ΔE 21 | Energy barrier between two bound states (J) |
| Fmv(t) | Pulling force on the microvillus (pN) |
| Ḟmv(t) | Loading rate (pN/s) for microvillus |
| F th | Threshold force for dissociation of membrane from cytoskeleton (pN) |
| Lmv(t) | Microvillus extension (μm) |
| L̇mv(t) | Rate of microvillus extension (μm/s) |
| σ mv | Microvillus spring constant (pN/ μm) |
| κ mv | Spring constant of the second elastic unit in Fig. 8(c) (pN/ μm) |
| η eff_mv | Effective viscosity of microvilli (pN s/ μm) |
| Fte(t) | Pulling force on tether (pN) |
| Ḟte(t) | Loading rate (pN/s) for tether |
| Lte(t) | Tether extension (μm) |
| L̇te(t) | Rate of tether extension (μm/s) |
| η eff_te | Effective viscosity of tether (pN s/ μm) |
| k c | Cell membrane curvature modulus (pN μm) |
| d int | Interfacial drag coefficient (pN s/μm3) |
Symbols for different biophysical parameters are defined. Units are shown in parenthesis.