Physically consistent simulation of transport of inertial particles in porous media

A new numerical approach is presented for simulating the movement of test particles suspended in an incompressible fluid flowing through a porous matrix. This two-phase particle-laden flow is based on the Navier-Stokes equations for incompressible fluid flow and equations of motion for the individual particles in which Stokes drag is dominant. The Immersed Boundary method is applied to incorporate the geometric complexity of the porous medium. A symmetry-preserving finite volume discretization method in combination with a volume penalization method resolves the flow within the porous material. The new Lagrangian particle tracking is such that for mass-less test particles no (numerical) collision with the coarsely represented porous medium occurs at any spatial resolution

High coherence hybrid superconducting qubit

We measure the coherence of a new superconducting qubit, the {\em low-impedance flux qubit}, finding $T_2^* \sim T_1 \sim 1.5\mu$s. It is a three-junction flux qubit, but the ratio of junction critical currents is chosen to make the qubit's potential have a single well form. The low impedance of its large shunting capacitance protects it from decoherence. This qubit has a moderate anharmonicity, whose sign is reversed compared with all other popular qubit designs. The qubit is capacitively coupled to a high-Q resonator in a $\lambda/2$ configuration, which permits the qubit's state to be read out dispersively

White coat color of a Black Angus calf attributed to an occurrence of the delR217 variant of \u3ci\u3eMITF\u3c/i\u3e

A white calf, with minimal pigmented markings, was born to two registered Black Angus parents. Given the possibility of an unknown recessive or de novo dominant mutation, whole-genome sequencing was conducted on the trio of individuals. A 3-bp in-frame deletion in MITF was identified; this mutation was unique to the calf but identical to the delR217 variant reported in both humans and murine models of Waardenburg syndrome type 2A and Tietz syndrome. Given the coat color phenotype and identity of the mutation, our data support that this calf represents the first instance of this recurring MITF mutation in cattle

Pathology in Practice

A 1.5-year-old second-parity Large Black X Tamworth cross sow from a well-managed 20-sow, unvaccinated, pasture-raised herd of pigs in upstate New York aborted a litter of 7 variably mummified near-term fetuses and stillborn piglets. This sow had no signs of ill health other than abortion; it was housed in a group with 4 other sows and a 2-year-old Gloucestershire Old Spot boar. One of the stillborn piglets from this litter was submitted to the New York State Animal Health Diagnostic Center for necropsy; no placental tissue was submitted with the piglet. A second sow from this group had aborted a litter at the same late stage of gestation within the preceding 2 weeks; however, none of the fetuses were submitted for diagnostic investigation. No signs of ill health were reported for the rest of the herd. The referring veterinarian indicated that these pigs had access to corn standing in the field and that, because of recent wet weather, there was concern that mycotoxin contamination might be the cause of the abortions

Simulation of impaction filtration of aerosol droplets in porous media

We report on the development of a method to simulate from first principles the particle filtration efficiency of filters that are composed of structured porous media. We assume that the ratio of particle density to the fluid density is high. We concentrate on the motion of the particles in a laminar flow and quantify the role of inertial effects on the filtration of an ensemble of particles. We adopt the Euler-Lagrange approach, distinguishing a flow field in which the motion of a large number of discrete particles is simulated. We associate filtration with the deterministic collision of inertial particles with solid elements of the structured porous medium. To underpin the physical `consistency' of deterministic particle filtration, we investigate to what extent the particle tracking algorithm ensures that mass-less test-particles will not be captured by the structured porous filter at all. This element of the algorithm is essential in order to distinguish physical filtration by inertial effects from unwanted numerical filtration, due to the finite spatial resolution of the gas flow. We consider filtration of particles whose motion is governed by Stokes drag and determine the filtration efficiency in a range of Stokes relaxation times. An exponential decay of the number of particles with time is observed