Fluctuations and correlations in an individual-based model of biological coevolution

We extend our study of a simple model of biological coevolution to its statistical properties. Staring with a complete description in terms of a master equation, we provide its relation to the deterministic evolution equations used in previous investigations. The stationary states of the mutationless model are generally well approximated by Gaussian distributions, so that the fluctuations and correlations of the populations can be computed analytically. Several specific cases are studied by Monte Carlo simulations, and there is excellent agreement between the data and the theoretical predictions.Comment: 25 pages, 2 figure

Embedded Micro-Computer Base Force Plate as an Objective Tool to Measure Hoof Lameness Phases in Multiparous Sows

The objective of this study was to compare differences in weight placed on each hoof from sows in differing lameness phases. Twelve, clinically healthy, mixed-parity, crossbred sows (228.89±19.17 kg) were used. The sow was the experimental unit and a cross-over design with a 2 (hind left and hind right hoof) x 3 (days: D-1, D+1 and D+6) factorial arrangement of treatments were compared. On induction day, 10 mg of amphotericin B were injected in the distal interphalangeal joint space in both claws of one hind hoof. All sows served as their own control and treatment. After completion of the first round, sows were given a 7-day rest period and then the round procedures were repeated with the opposite hind hoof induced. Sows stood individually on an embedded force plate for 15 minutes, and weight on each hoof was measured independently. All data were statistically analyzed using the PROC MIXED procedure in SAS. On the D+1, sows exhibited less weight bearing on the induced lame hoof compared to D-1 (P \u3c 0.0001). Regardless of which hoof was injected, sow weight distribution did not vary between the injected left or right hind hooves (P = 0.99) or between rounds (P = 0.64). Findings from our study indicate that the embedded force plate exhibited differences between sound and most lame phases indicating the potential as an objective tool for detecting differences in weight distribution when sows are sound and lame

Mesoscopic modeling of a two-phase flow in the presence of boundaries: the Contact Angle

We present a mesoscopic model, based on the Boltzmann Equation, for the interaction between a solid wall and a non-ideal fluid. We present an analytic derivation of the contact angle in terms of the surface tension between the liquid-gas, the liquid-solid and the gas-solid phases. We study the dependency of the contact angle on the two free parameters of the model, which determine the interaction between the fluid and the boundaries, i.e. the equivalent of the wall density and of the wall-fluid potential in Molecular Dynamics studies. We compare the analytical results obtained in the hydrodynamical limit for the density profile and for the surface tension expression with the numerical simulations. We compare also our two-phase approach with some exact results for a pure hydrodynamical incompressible fluid based on Navier-Stokes equations with boundary conditions made up of alternating slip and no-slip strips. Finally, we show how to overcome some theoretical limitations connected with a discretized Boltzmann scheme and we discuss the equivalence between the surface tension defined in terms of the mechanical equilibrium and in terms of the Maxwell construction.Comment: 29 pages, 12 figure

Evaluation of mechanical and thermal nociception as objective tools to measure painful and nonpainful lameness phases in multiparous sows

The objective of this study was to quantify pain sensitivity differences using mechanical nociception threshold (MNT) and thermal nociception threshold (TNT) tests when sows were in painful and nonpainful transient lameness phases. A total of 24 mixed parity crossbred sows (220.15 ± 21.23 kg) were utilized for the MNT test, and a total of 12 sows (211.41 ± 20.21 kg) were utilized for the TNT test. On induction day (D0), all sows were anesthetized and injected with Amphotericin B (10mg/mL) in the distal interphalangeal joint space in both claws of one randomly selected hind limb to induce transient lameness. Three days were compared: (1) D-1 (sound phase, defined as 1 d before induction), (2) D+1 (most lame phase, defined as 1 d after induction), and (3) D+6 (resolution phase, defined as 6 d after induction). After completion of the first round, sows were given a 7-d rest period and then the procedures were repeated with lameness induced in the contralateral hind limb. During the MNT test, pressure was applied perpendicularly to 3 landmarks in a randomized sequence for each sow: 1) middle of cannon on the hind limb (cannon), 2) 1 cm above the coronary band on the medial hind claw (medial claw), and 3) 1 cm above the coronary band on the lateral hind claw (lateral claw). During the TNT test, a radiant heat stimulus was directed 1 cm above the coronary band. The data were analyzed using the MIXED procedure in SAS with sow as the experimental unit. Differences were analyzed between sound and lame limbs on each day. For the MNT test, pressure tolerated by the lame limb decreased for every landmark (P \u3c 0.05) when comparing D-1 and D+1. The sound limb tolerated more pressure on D+1 and D+6 than on baseline D-1 (P \u3c 0.05). Thermal stimulation tolerated by the sound limb did not change over the 3 d (P \u3e 0.05). However, the sows tolerated less heat stimulation on their lame limb on D+1 compared to D-1 levels (P \u3c 0.05). Both MNT and TNT tests indicated greater pain sensitivity thresholds when sows were acutely lame