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Review: Biological determinants of between-animal variation in feed efficiency of growing beef cattle
- G. Cantalapiedra-Hijar, M. Abo-Ismail, G. E. Carstens, L. L. Guan, R. Hegarty, D. A. Kenny, M. McGee, G. Plastow, A. Relling, I. Ortigues-Marty
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Animal’s feed efficiency in growing cattle (i.e. the animal ability to reach a market or adult BW with the least amount of feed intake), is a key factor in the beef cattle industry. Feeding systems have made huge progress to understand dietary factors influencing the average animal feed efficiency. However, there exists a considerable amount of animal-to-animal variation around the average feed efficiency observed in beef cattle reared in similar conditions, which is still far from being understood. This review aims to identify biological determinants and molecular pathways involved in the between-animal variation in feed efficiency with particular reference to growing beef cattle phenotyped for residual feed intake (RFI). Moreover, the review attempts to distinguish true potential determinants from those revealed through simple associations or indirectly linked to RFI through their association with feed intake. Most representative and studied biological processes which seem to be connected to feed efficiency were reviewed, such as feeding behaviour, digestion and methane production, rumen microbiome structure and functioning, energy metabolism at the whole body and cellular levels, protein turnover, hormone regulation and body composition. In addition, an overall molecular network analysis was conducted for unravelling networks and their linked functions involved in between-animal variation in feed efficiency. The results from this review suggest that feeding and digestive-related mechanisms could be associated with RFI mainly because they co-vary with feed intake. Although much more research is warranted, especially with high-forage diets, the role of feeding and digestive related mechanisms as true determinants of animal variability in feed efficiency could be minor. Concerning the metabolic-related mechanisms, despite the scarcity of studies using reference methods it seems that feed efficient animals have a significantly lower energy metabolic rate independent of the associated intake reduction. This lower heat production in feed efficient animals may result from a decreased protein turnover and a higher efficiency of ATP production in mitochondria, both mechanisms also identified in the molecular network analysis. In contrast, hormones and body composition could not be conclusively related to animal-to-animal variation in feed efficiency. The analysis of potential biological networks underlying RFI variations highlighted other significant pathways such as lipid metabolism and immunity and stress response. Finally, emerging knowledge suggests that metabolic functions underlying genetic variation in feed efficiency could be associated with other important traits in animal production. This emphasizes the relevance of understanding the biological basis of relevant animal traits to better define future balanced breeding programmes.
P147: Clinical characteristics and system factors of elderly treated for agitation in the emergency department: a data driven approach
- R. Tam, K. McGregor, A. Maneshi, H. Gangatharan, M. Woo, I. Guan, K. Bradshaw, M. Bouchard, C. Meyers
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- Journal:
- Canadian Journal of Emergency Medicine / Volume 20 / Issue S1 / May 2018
- Published online by Cambridge University Press:
- 11 May 2018, p. S109
- Print publication:
- May 2018
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Introduction: Aligning health systems appropriately to the needs of the elderly is an urgent global priority, according to the WHO. In Canada, ED length of stay has risen 16% for elderly patients in the last year. Agitation requiring chemical restraint is a common, high-risk problem for elderly in the ED. Improving outcomes in this heterogeneous population remain difficult due to inability to effectively identify and evaluate delirium, frailty, multi-morbidity, and incompatibility with the ED system. A data-driven approach to complex health problems is a recognized emerging tool for healthcare innovation. New opportunities for targeted quality improvement in the ED will be uncovered by identifying the clinical characteristics of elderly patients with agitation, and the system process factors that influence their outcomes. Methods: We studied 400 patients in a case-control study at two tertiary-care EDs over five years. Patients were randomly selected if age was greater than 75 years. 200 cases of patients who received an intravenous dose of haloperidol, midazolam and/or lorazepam were selected as a surrogate data marker for having agitation. Controls were randomly matched by age and ED diagnosis. Standardized clinical, systems and process variables were collected. We conducted a univariate analysis. Results: Elderly given intravenous medications for agitation had increased mortality (OR 3.8 CI: 1.6-10.7, p<0.001) and ED length of stay (27 vs. 15 hours, p<0.001). No statistical significance was found in clinical characteristics, CTAS scores, PRISMA7 frailty scores nor sentinel or return visits. There was no statistical difference in median hospital length of stay (8 vs. 6 days, p<0.70). No differences were found in median time from ED physician seeing a patient to first consultant request (73 vs. 83 mins, p=0.75). The largest time intervals contributing to ED length of stay were from first consultant request to hospital request (15 vs. 12 hours, p=0.056) and hospitalization delay (13 vs. 7 hours, p=0.45). Conclusion: Identification of high-risk elderly patients for targeted intervention through a data-driven approach is feasible and informative. Traditional clinical characteristics remain unhelpful in identifying and evaluating outcomes in elderly with agitation. We have identified a process factor that is clinically relevant and pragmatic to evaluate in our ED system. Future research focused on optimizing systems process factors to improve quality of elderly care should be prioritized.
Photoelastic Waveguides Formed by Interfacial Reactions on Semiconductor Heterostructures
- L. S. Yu, Z F. Guan, F. Deng, Q.Z. Liu, S. A. Pappert, P. K. L. Yu, S. S. Lau, J. Redwing, J. Geisz, T. F. Kuech, H. Kattelus, I. Suni
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- MRS Online Proceedings Library Archive / Volume 326 / 1993
- Published online by Cambridge University Press:
- 21 February 2011, 251
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- 1993
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Lateral confinement of carriers and photons in semiconductor heterostructures is an important feature in modern electronic and optoelectronic devices. A number of techniques have been invented to induce lateral confinement with varying degrees of success and processing requirements. One of simplest but least commonly used technique is to utilize the strain induced effect (or the photoelastic effect) to cause confinement. While the concept is simple, the control of stress in the stressor layers is rather difficult in practice, without resorting to complicated selective growth of strained layers. We have investigated the controlled introduction of stable stresses into semiconductor heterostructures using a simple scheme of interfacial reactions between a metal and the substrate. Since the volumetric change for a given reaction is fixed, the induced stress in the structure is independent of the deposition method or the deposition system, as long as the deposited film is fully reacted to form a compound. The stability of the stress depends on the stability of the compound. We have made low-loss (~ ldB/cm at 1.53 μm) photoelastic waveguides in GaAs/AlGaAs and other layered structures by reacting Ni and other metals, with an underlying semiconductor. In the case Ni on GaAs/AlGaAs, the dominant stressor compound is N3GaAs, and the waveguide characteristics are thermally stable up to 600°C. Other photoelastic optical devices are also demonstrated.