The objective of this systems-scale study was to investigate grazing season timeframes on pasture and milk production and on milk processability of dairy systems with compact spring-calving dairy ...cows grazing white clover (Trifolium repens L.) based grassland. Fifty-four primiparous and multiparous Holstein-Friesian dairy cows were used in a one-factor study with 3 systems (n = 18) and repeated over 2 yr (2008/09 and 2009/10). The 3 systems were: early spring calving with annual fertilizer N input of 100 kg·ha−1 applied in spring (ES100N; 2.1 cows·ha−1; grazing February to November), early spring calving without fertilizer N (ES0N; 1.6 cows·ha−1; grazing February to November) and late spring calving without fertilizer N (LS0N; 1.53 cows·ha−1; grazing April to January). Annual pasture production was affected by an interaction between grazing system and year: Mean annual pasture yields for 2008 and 2009 were ES100N; 10.35 and 9.88, ES0N; 8.88 and 8.63, LS0N; 9.18 and 10.31 t of dry matter (DM)·ha−1 (SEM 0.39). LS0N had higher pasture DM yield in 2009 due to higher clover DM production and biological N fixation compared with the other systems. Clover stolon and root mass in the following February was correlated with stolon and root mass in the previous November with 64% of stolon mass present on LS0N in February (R2 = 0.84). There were no detectable differences in per-lactation milk yield (6,335 kg·cow−1), fat, protein and lactose yields (271, 226, 297 kg·cow−1, respectively), cow liveweight (585 kg) or body condition score (3.02). Although winter grazing favored subsequent clover DM production, biological N fixation and pasture DM production, delaying calving date in spring and extending lactation into the following winter led to inefficient use of this pasture by the grazing herd and lowered the quality of late-lactation milk for processing purposes. Hence, a mean calving date in mid- to late-February is recommended for zero-fertilizer N input clover-based grassland.
Accurate estimation of herbage mass (HM) is essential for optimising grass utilisation and increasing profit for pasture-based livestock agriculture. The rising plate meter (RPM) is used for ...predicting HM based on average compressed sward height (CSH). Sampling resolution and distribution are primary parameters in determining spatial heterogeneity of HM. There is no definitive sampling protocol for the RPM. The objectives of this study were to: investigate spatial variation of HM within pastures, determine the number of RPM measurements required to accurately predict mean HM, and assess the precision of the RPM in terms of measurement repeatability. Intensive CSH measurements and HM reference cuts were carried out on controlled plots and grazed paddocks over two grazing seasons. Sward heterogeneity was estimated as the coefficient of variation (CV) of CSH and compared to empirically derived ‘true’ sward heterogeneity in terms of HM CV. Retrospective analysis simulations were performed to identify the effect of various reduced measurement resolutions on estimated mean CSH error. Repeated measures analysis was performed on grass samples to determine RPM measurement system precision. Results indicated that pasture heterogeneity varied by 36% across the growing season and was affected by grazing, fertilisation, sward composition and seasonality. Mean CSH could be estimated to within 5% relative prediction error by recording 24 measurements per ha in a random stratified manner. The standard deviation of RPM measurement repeatability was calculated to be 4.34 mm. The findings of this study will be used to inform the implementation of a more optimum grass measurement protocol.
•A grass measurement optimisation tool (GMOT) was developed.•Random stratified sampling, GPS and a genetic algorithm were employed.•GMOT outputs include predicted measurement survey value, cost, ...error and time.•GMOT outputs enable optimal grass measurement by performing 8 measurements ha−1.•The GMOT is applicable to a range of pasture measurement technologies.
Accurate and efficient estimation of herbage mass is essential for optimising grass utilisation and increasing profit for pasture farming. There is no definitive sampling protocol for grass measurement on Irish pastures. This paper presents the Grass Measurement Optimisation Tool (GMOT), designed to generate measurement protocols that optimise for time and accuracy. The GMOT was designed in the form of a decision support tool that generates interactive paddock maps that guide the farmer on how to optimally measure their pastures in a random stratified manner based on GPS co-ordinates, resulting in accurate non-biased estimations of mean herbage mass. Rising plate meter (RPM) measurements and reference herbage cuts were performed on trial plots and grazed paddocks over three years. Measurement routes were optimised using a genetic algorithm based on a traveling salesman problem. Actual survey error was estimated in terms of relative prediction error using Monte Carlo simulations that combined measurement and calibration error distributions for the RPM. Cost benefit analysis was conducted to evaluate the feasibility of using the GMOT on Irish grasslands. Actual error for the RPM decreased from 37% to 26% as measurement rates increased from 1 to 8 ha−1 and reductions in error were negligible (<1%) as measurements increased from 8 to 32 ha−1. Calibration error was the largest source of error (25.9%) compared to measurement error (8%). Optimal measurement value was achieved by performing 8 measures ha−1 and further increasing the measurement rate resulted in diminishing returns. The GMOT is compatible with a range of pasture measurement technologies.
To provide a detailed genomic-epidemiological description of a complex multi-ward SARS-CoV-2 outbreak, which originated in the crowded emergency department (ED) in our hospital during the third wave ...of the COVID-19 pandemic, and was elucidated promptly by local whole-genome sequencing (WGS).
SARS-CoV-2 was detected by reverse transcriptase real-time polymerase chain reaction on viral RNA extracted from nasopharyngeal swabs. WGS was performed using an Oxford MinION Mk1C instrument following the ARTIC v3 sequencing protocol. High-quality consensus genomes were assembled with the artic-ncov2019 bioinformatics pipeline and viral phylogenetic trees were built, inferred by maximum-likelihood. Clusters were defined using a threshold of 0–1 single nucleotide polymorphisms (SNPs) between epidemiologically linked sequences.
In April 2021, outbreaks of COVID-19 were declared on two wards at University Hospital Limerick after 4 healthcare-associated SARS-CoV-2 infections were detected by post-admission surveillance testing. Contact tracing identified 12 further connected cases; all with direct or indirect links to the ED ‘COVID Zone’. All sequences were assigned to the Pangolin B.1.1.7 lineage by WGS, and SNP-level analysis revealed two distinct but simultaneous clusters of infections. Repeated transmission in the ED was demonstrated, involving patients accommodated on trolleys in crowded areas, resulting in multiple generations of infections across three inpatient hospital wards and subsequently to the local community. These findings informed mitigation efforts to prevent cross-transmission in the ED.
Cross-transmission of SARS-CoV-2 occurred repeatedly in an overcrowded emergency department. Viral WGS elucidated complex viral transmission networks in our hospital and informed infection, prevention and control practice.
Nitinol׳s superelastic properties permit self-expanding stents to be crimped without plastic deformation, but its nonlinear properties can contribute towards stent buckling. This study investigates ...the axial buckling of a prototype tracheobronchial nitinol stent design during crimping, with the objective of eliminating buckling from the design. To capture the stent buckling mechanism a computational model of a radial force test is simulated, where small geometric defects are introduced to remove symmetry and allow buckling to occur. With the buckling mechanism ascertained, a sensitivity study is carried out to examine the effect that the transitional plateau region of the nitinol loading curve has on stent stability. Results of this analysis are then used to redesign the stent and remove buckling. It is found that the transitional plateau region can have a significant effect on the stability of a stent during crimping, and by reducing the amount of transitional material within the stent hinges during loading the stability of a nitinol stent can be increased.
Opioids have played in a key role in cardiac anesthesia and analgesia since the early years of cardiac surgery. Today, opioids continue to be the primary mode for analgesia in cardiac surgery, yet ...there is considerable variability in the choice, dose and route of used. A history of the use of opioids in cardiothoracic anesthesia is presented, followed by an examination of the differences among current opioids in use and of outcome variables important in cardiac anesthesia, such as postoperative analgesia, extubation times, fast-track cardiac anesthesia, chronic neuropathic pain, and cardioprotection. Topical issues such as the role of perioperative opioid use in the global opioid crisis, opioid-sparing techniques and novel opioids in development are also discussed.
Extraction of coffee solubles from roast and ground coffee is a highly complex process, depending on a large number of brewing parameters. We consider a recent, experimentally validated, model of ...coffee extraction, describing extraction from a coffee bed using a double porosity model, which includes dissolution and transport of coffee. It was shown that this model can accurately describe coffee extraction in two situations: extraction from a dilute suspension of coffee grains and extraction from a packed coffee bed. Despite being based on some simplifying assumptions, this model can only be solved numerically. In this paper we consider asymptotic solutions of the model describing extraction from a packed coffee bed. Such solutions can explicitly relate coffee concentration to the process parameters. For an individual coffee grain, extraction is controlled by a rapid dissolution of coffee from the surface of the grain, in conjunction with a slower diffusion of coffee through the intragranular pore network to the grain surface. Extraction of coffee from the bed also depends on the speed of advection of coffee from the bed. We utilize the small parameter resulting from the ratio of the advection timescale to the grain diffusion timescale to construct asymptotic solutions using the method of matched asymptotic expansions. The asymptotic solutions are compared to numerical solutions and data from coffee extraction experiments. The asymptotic solutions depend on a small number of dimensionless parameters and so are useful to quickly fit extraction curves and investigate the influence of various process parameters on the extraction.
Abstract
Funding Acknowledgements
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): EU Horizon 2020 SME Instrument.
Background
Epicardial ganglionated plexi (GP) play a ...significant role in the initiation and maintenance of atrial fibrillation. However, modulation of this effect, through GP ablation, has had limited success; outcomes being confounded by unnecessary atrial tissue ablation and inability to access and ablate all of the atrial GPs. Selective pulsed field ablation (PFA) of GPs, using epicardial access, provides the opportunity to better identify the role of GP ablation in the treatment of atrial fibrillation.
Purpose
This study aimed to assess the safety and feasibility of selective GP ablation in patients undergoing elective coronary artery bypass grafting (CABG). It was hypothesized that GP ablation would provide an acute extension of atrial tissue refractoriness, which constitutes its antiarrhythmic effect.
Methods
Using a monopolar, monophasic PFA system, atrial GPs were ablated in nineteen patients with or without atrial fibrillation, undergoing CABG. The Oblique Sinus GP, Right Superior GP, Transverse Sinus GP, Left Superior GP and Ligament of Marshall GP were each ablated with up to sixty PFA pulses of 1000 V amplitude and 100 µs pulse width. Atrial Effective Refractory Period (AERP) was measured before and after all GP ablations, at the left atrial appendage (LAA) and on the right atrium (RA). Patients were monitored through to discharge for post-operative atrial fibrillation (POAF).
Results
Complete ablation of the GPs was performed in nineteen patients (aged 63.4 ± 6.6 years, 63.1% male) immediately after sternotomy. Electric field pulses were ECG-gated, with energy delivery during the ventricular refractory period. All GP sites were successfully accessed and ablated; all patients progressed immediately to their planned elective surgery and were discharged on schedule. Procedure time, for all GP ablations and AERP measurements was in the range 35-45 minutes. Thirteen valid pre- and post-ablation datasets were obtained. AERP (LAA and RA combined) increased upon GP ablation on average by 23% (220 ± 46 ms pre-ablation versus 269 ± 59 ms post-ablation, p = 0.002). Four patients experienced POAF; there was no evident correlation between POAF and AERP data. Only three of the enrolled patients had a prior history of AF; none of these exhibited AF on 24-hour Holter monitoring at 3-month follow-up.
Conclusions
Selective epicardial PFA of GPs is feasible and safe. An acute increase in atrial tissue refractoriness is promising but further studies are required to see how this translates to longer term outcomes in symptomatic AF patients and in a percutaneous epicardial access setting.
Real time intraoperative transoesophageal echocardiograpgy (TOE) has an expanding role in peri-operative management and surgical decision making.
Studies of the effect of transoesophageal ...echocardiography (TOE) on intraoperative decision making commonly emphasise major changes in operative plans. We examined more subtle effects using a novel scale, recording influences on management as follows: Level 1: TOE had no effect on management, confirmed and quantified known pathology. Level 2: TOE altered hemodynamic and/or anesthetic management. Level 3: TOE evaluated the adequacy of surgical intervention/or repair. Level 4: TOE led to an alteration in the surgical plan. We compared the impact of TOE as an aid to intra-operative management in coronary artery bypass cases with other types of cardiac surgery.
Retrospective, observational study in a single centre, university-affiliated hospital included 319 patients undergoing cardiac surgery and suitable for TOE. TOE was performed in each patient before and after the institution of cardiopulmonary by-pass. Normal and abnormal echocardiographic findings as well as immediate outcomes of the surgical procedure were recorded using a standard database form. Instances where TOE lead to alteration in operative management were documented. The findings were also compared with those documented on preoperative echocardiography.
In 141 CABG patients TOE had a level 1 impact in 73%, level 2 impact in 11.6%, levels 3 and 4 in 7% and 7.8% respectively. In 178 non CABG patients these values were 2%, 1.6%, (p < 0.05), 72.4% (p < 0.05) and 23.6% (p < 0.05) respectively.
The impact of TOE in CABG procedures, while significantly less than that in non-CABG surgical procedures, remains substantial.
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