COVID-19 Vaccination Strategies Considering Hesitancy Using Particle-Based Epidemic Simulation

Vaccine hesitancy is one of the critical factors in achieving herd immunity and suppressing the COVID-19 epidemic. Many countries face this as an acute public health issue that diminishes the efficacy of their vaccination campaigns. Epidemic modeling and simulation can be used to predict the effects of different vaccination strategies. In this work, we present an open-source particle-based COVID-19 simulator with a vaccination module capable of taking into account the vaccine hesitancy of the population. To demonstrate the efficacy of the simulator, we conducted extensive simulations for the province of Lecco, Italy. The results indicate that the combination of both high vaccination rate and low hesitancy leads to faster epidemic suppression.

The influence of particle size of Enogen Feed corn and conventional yellow dent corn on nursery and finishing pig performance, carcass characteristics and stomach morphology

Enogen Feed corn is a variety developed by Syngenta Seeds (Downers Grove, IL) that has been genetically modified to contain an α-amylase enzyme trait (SYT-EFC). Originally, Enogen feed corn was developed for the ethanol industry due to its reduction in viscosity of the corn mash, thus eliminating the need to add a liquid form of the α-amylase enzyme. However, there is potential application for Enogen Feed corn to be used in livestock diets due to the increase in α-amylase enzyme potential to increase starch digestibility. A more common method of increasing starch digestibility in corn is to finely grind it to reduce particle size. This increases the surface area and allows for greater interaction with digestive enzymes. We hypothesized that pigs fed Enogen feed corn potentially could achieve similar gain:feed ratio (G:F) at larger particle sizes than conventional corn because of the differences in starch digestibility. In Exp. 1, a total of 360 pigs (DNA 200 × 400, Columbus, NE; initially 6.6 ± 0.1 kg BW) were used with 5 pigs per pen and 12 pens per treatment. Treatments were arranged in a 2 × 3 factorial with main effects of corn source (Enogen Feed corn or conventional yellow dent corn) and ground corn particle size (300, 600, or 900 µm). Overall, there was a corn source × particle size interaction (linear, P = 0.027) for G:F. There was no effect due to particle size when pigs were fed conventional yellow dent corn, but in pigs fed Enogen Feed corn, G:F increased with decreasing particle size. Neither corn source nor particle size affected (P > 0.05) overall average daily gain (ADG) or average daily feed intake (ADFI). In Exp. 2, a total of 323 pigs (241 × 600; DNA, Columbus, NE; initially 50.0 ± 1.3 kg) were used with 9 pigs per pen and 6 pens per treatment. Treatments were identical as Exp. 1. Overall, corn source had no effect on finishing pig ADG, ADFI or G:F. For corn particle size, ADG and G:F increased (linear, P < 0.014) and ADFI decreased (P = 0.043) as particle size decreased. For stomach morphology, there was a tendency for a corn source × particle size interaction (P = 0.055) for keratinization score with keratinization increasing linearly (P = 0.001) as particle size of the corn decreased for yellow dent corn with no change in keratinization score as particle size decreased for Enogen Feed corn. In summary, reducing corn particle size improved G:F with no major differences observed between corn sources for overall pig performance.

133 Influence of Particle Size of Enogen Feed Corn and Conventional Yellow Dent Corn on Nursery and Finishing Pig Performance, Carcass Characteristics and Stomach Morphology

Two studies evaluated the effect of particle size of Enogen® Feed corn (Syngenta Seeds, LLC, Downers Grove, IL) and conventional yellow dent corn on nursery and finishing pig performance, carcass characteristics and stomach morphology. In Exp. 1, 360 nursery pigs (DNA 200×400, Columbus, NE; initially 6.6±0.1 kg BW) were used with 5 pigs per pen and 12 pens per treatment. Treatments were arranged in a 2×3 factorial with main effects of corn source (Enogen Feed corn or conventional yellow dent corn) and ground corn particle size (300, 600, or 900 µm). Overall, there was a corn source×particle size interaction (linear, P = 0.027) for G:F ratio. There was no difference due to particle size when pigs were fed conventional yellow dent corn, but in pigs fed Enogen Feed corn, G:F increased with decreasing particle size. Neither corn source nor particle size affected (P > 0.05) ADG or ADFI. In Exp. 2, 323 finishing pigs (241′600; DNA, Columbus, NE; initially 50.0±1.3 kg) were used with 8 or 9 pigs per pen and 6 pens per treatment. Treatments were arranged identical to Exp. 1. Overall, corn source did not elicit differences in ADG, ADFI or G:F (P > 0.05). For corn particle size, ADG and G:F increased (linear, P ≤ 0.014) and ADFI decreased (P = 0.043) as particle size decreased. For carcass characteristics, there was a tendency (linear, P = 0.093) for increased HCW and increased (linear, P = 0.023) carcass yield as corn particle size decreased. For stomach morphology, there was a tendency for a corn source×particle size interaction (P = 0.055) for keratinization score with keratinization increasing linearly (P = 0.001) as particle size decreased for yellow dent corn with no change in keratinization score as particle size decreased for Enogen Feed corn. In summary, reducing corn particle size improved G:F with no major differences observed between corn sources for overall pig performance.

PSIV-15 Influence of Particle Size of Enogen Feed Corn and Conventional Yellow Dent Corn on Lactating Sow Performance

A total of 107 sows (Line 241; DNA, Columbus, NE) across 4 batch farrowing groups were used to evaluate the effects of corn source and particle size on sow and litter performance. Treatments were arranged in a 2×2 factorial with main effects of corn source (Enogen® Feed corn (Syngenta Seeds, Downers Grove, IL) or conventional yellow dent corn) and ground corn particle size (600 or 900 µm). Sows were blocked by parity and BW upon arrival to the farrowing house. There were approximately 27 sows per treatment, sow was considered the experimental unit, dietary treatment was a fixed effect, and sow group and block were used as random effects. Main effects of corn source and particle size as well as their interactions were tested. From farrowing to weaning, there was a tendency for a source×particle size interaction (P=0.065) for sow BW change. Sows fed 900 µm Enogen Feed corn had decreased BW loss compared to sows fed other treatments which were similar in BW loss. There was a source×particle size interaction (P=0.048) for lactation ADFI with sows fed 900 µm conventional yellow dent corn having lower feed intake than the sows fed 600 µm conventional yellow dent corn, whereas sows fed 900 µm Enogen Feed corn had greater feed intake compared to the sows fed 600 µm Enogen Feed corn. There was a tendency for a particle size main effect (P<0.10) for litter ADG (2,849 vs 2,635 g/d) and total litter gain (45.7 vs 42.3 kg), with sows fed corn ground to 600 µm having increased litter ADG and total litter gain compared to sows fed corn ground to 900 µm. In summary, there were few differences in sow or litter characteristics among corn sources. Reducing particle size of both corn sources tended to increase litter ADG and weaning weights.

Influence of particle size of Enogen Feed corn and conventional yellow dent corn on lactating sow performance

Enogen Feed corn is a variety developed by Syngenta Seeds (Downers Grove, IL) that has been genetically modified to contain an α-amylase enzyme trait (SYT-EFC). Originally, Enogen feed corn was developed for the ethanol industry, due to its properties for reducing the viscosity of its corn mash. There is potential application for Enogen Feed corn to be used in livestock diets due to the potential for the increase in α-amylase enzyme to increase the starch digestibility. Because of this, it may be possible to increase particle size of ground Enogen Feed corn and maintain the same starch digestibility as finely ground conventional yellow dent corn. Therefore, our hypothesis was that an interaction between corn source and particle size would exist, such that performance of sows fed fine ground conventional yellow dent corn would be similar to sows fed coarse ground Enogen Feed corn. A total of 107 sows (Line 241; DNA, Columbus, NE) across 4 batch farrowing groups were used to evaluate sow and litter performance. Treatments were arranged in a 2 × 2 factorial with main effects of corn source (Enogen Feed corn or conventional yellow dent corn) and ground corn particle size (600 or 900 µm). From farrowing to weaning, there was a tendency for a corn source × particle size interaction (P = 0.065) in sow body weight change. Sows fed 900 µm Enogen Feed corn had decreased body weight loss compared to sows fed other treatments which were similar in weight loss. For sow ADFI from farrowing to weaning, there was a corn source × particle size interaction (P = 0.048) with sows fed 900 µm conventional yellow dent corn having lower feed intake than the sows fed 600 µm conventional yellow dent corn, whereas sows fed 900 µm Enogen Feed corn had greater feed intake compared to the sows fed 600 µm Enogen Feed corn. There was a tendency for a particle size main effect (P < 0.10) for litter ADG and total litter gain, with sows fed corn ground to 600 µm having increased litter ADG and total litter gain compared to sows fed corn ground to 900 µm. In summary, there were few differences in sow or litter characteristics among those fed Enogen Feed corn or conventional yellow dent corn. Reducing particle size of both corn sources tended to increase litter ADG and weaning weights.

Towards an Integrated Computational Model for Additive Manufacturing Process: Heat Source-Particle Interaction and Effective Thermal Conductivity of Powder Bed

An integrated computational modeling frame work is under development for the electron beam based additive manufacturing process to establish the fundamental correlation among material properties, process parameters and thermal and mechanical performances of the final manufactured components such as residual stresses. This paper focuses on the investigation of beam-powder interaction in mesoscale, the kinetics of the powder sintering, and the effective thermal property of the powder bed as a function of powder size distribution.