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LiGAPS-Beef (Livestock simulator for Generic analysis of Animal Production Systems – Beef cattle) is a generic, mechanistic model designed to quantify potential and feed-limited growth, which provides insight in the biophysical scope to increase beef production (i.e. yield gap). Furthermore, it enables identification of the bio-physical factors that define and limit growth, which provides insight in management strategies to mitigate yield gaps. The aim of this paper, third in a series of three, is to evaluate the performance of LiGAPS-Beef with independent experimental data. After model calibration, independent data were used from six experiments in Australia, one in Uruguay and one in the Netherlands. Experiments represented three cattle breeds, and a wide range of climates, feeding strategies and cattle growth rates. The mean difference between simulated and measured average daily gains (ADGs) was 137 g/day across all experiments, which equals 20.1% of the measured ADGs. The root mean square error was 170 g/day, which equals 25.0% of the measured ADGs. LiGAPS-Beef successfully simulated the factors that defined and limited growth during the experiments on a daily basis (genotype, heat stress, digestion capacity, energy deficiency and protein deficiency). The simulated factors complied well to the reported occurrence of heat stress, energy deficiency and protein deficiency at specific periods during the experiments. We conclude that the level of accuracy of LiGAPS-Beef is acceptable, and provides a good basis for acquiring insight in the potential and feed-limited production of cattle in different beef production systems across the world. Furthermore, its capacity to identify factors that define or limit growth and production provides scope to use the model for yield gap analysis.
The expected increase in the global demand for livestock products calls for insight in the scope to increase actual production levels across the world. This insight can be obtained by using theoretical concepts of production ecology. These concepts distinguish three production levels for livestock: potential (i.e. theoretical maximum) production, which is defined by genotype and climate only; feed-limited production, which is limited by feed quantity and quality; and actual production. The difference between the potential or limited production and the actual production is the yield gap. The objective of this paper, the first in a series of three, is to present a mechanistic, dynamic model simulating potential and feed-limited production for beef cattle, which can be used to assess yield gaps. A novelty of this model, named LiGAPS-Beef (Livestock simulator for Generic analysis of Animal Production Systems – Beef cattle), is the identification of the defining factors (genotype and climate) and limiting factors (feed quality and available feed quantity) for cattle growth by integrating sub-models on thermoregulation, feed intake and digestion, and energy and protein utilisation. Growth of beef cattle is simulated at the animal and herd level. The model is designed to be applicable to different beef production systems across the world. Main model inputs are breed-specific parameters, daily weather data, information about housing, and data on feed quality and quantity. Main model outputs are live weight gain, feed intake and feed efficiency (FE) at the animal and herd level. Here, the model is presented, and its use is illustrated for Charolais and Brahman × Shorthorn cattle in France and Australia. Potential and feed-limited production were assessed successfully, and we show that FE of herds is highest for breeds most adapted to the local climate conditions. LiGAPS-Beef also identified the factors that define and limit growth and production of cattle. Hence, we argue the model has scope to be used as a tool for the assessment and analysis of yield gaps in beef production systems.
The model LiGAPS-Beef (Livestock simulator for Generic analysis of Animal Production Systems – Beef cattle) has been developed to assess potential and feed-limited growth and production of beef cattle in different areas of the world and to identify the processes responsible for the yield gap. Sensitivity analysis and evaluation of model results with experimental data are important steps after model development. The first aim of this paper, therefore, is to identify which parameters affect the output of LiGAPS-Beef most by conducting sensitivity analyses. The second aim is to evaluate the accuracy of the thermoregulation sub-model and the feed intake and digestion sub-model with experimental data. Sensitivity analysis was conducted using a one-at-a-time approach. The upper critical temperature (UCT) simulated with the thermoregulation sub-model was most affected by the body core temperature and parameters affecting latent heat release from the skin. The lower critical temperature (LCT) and UCT were considerably affected by weather variables, especially ambient temperature and wind speed. Sensitivity analysis for the feed intake and digestion sub-model showed that the digested protein per kg feed intake was affected to a larger extent than the metabolisable energy (ME) content. Sensitivity analysis for LiGAPS-Beef was conducted for ¾ Brahman×¼ Shorthorn cattle in Australia and Hereford cattle in Uruguay. Body core temperature, conversion of digestible energy to ME, net energy requirements for maintenance, and several parameters associated with heat release affected feed efficiency at the herd level most. Sensitivity analyses have contributed, therefore, to insight which parameters are to be investigated in more detail when applying LiGAPS-Beef. Model evaluation was conducted by comparing model simulations with independent data from experiments. Measured heat production in experiments corresponded fairly well to the heat production simulated with the thermoregulation sub-model. Measured ME contents from two data sets corresponded well to the ME contents simulated with the feed intake and digestion sub-model. The relative mean absolute errors were 9.3% and 6.4% of the measured ME contents for the two data sets. In conclusion, model evaluation indicates the thermoregulation sub-model can deal with a wide range of weather conditions, and the feed intake and digestion sub-model with a variety of feeds, which corresponds to the aim of LiGAPS-Beef to simulate cattle in different beef production systems across the world.
The lifestyle recommendations of the World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) are primarily intended for cancer prevention. In the absence of specific recommendations for cancer survivors, we investigated adherence of colorectal cancer (CRC) survivors to the WCRF/AICR lifestyle recommendations and associations with health-related quality of life (HRQoL). The cross-sectional part of the Energy for life after ColoRectal cancer (EnCoRe) study was conducted in 155 CRC survivors (stage I-III), 2–10 years post diagnosis. Dietary intake, physical activity and general body fatness were measured by 7-d food diaries, by questionnaires and accelerometers and BMI, respectively. Adherence to each of the ten WCRF/AICR recommendations was scored as 0 (no/low adherence), 0·5 (moderate adherence) or 1 point (complete adherence), and summed into an overall adherence score (range: 0–10). HRQoL, disability and distress were assessed by validated questionnaires. Associations of the overall WCRF/AICR adherence score with HRQoL outcomes were analysed by confounder-adjusted linear regression. The mean adherence score was 5·1 (sd 1·4, range: 1·5–8·5). In confounder-adjusted models, a higher adherence score was significantly associated with the HRQoL dimension better physical functioning (β per 1 point difference in score: 2·6; 95 % CI 0·2, 5·1) and with less fatigue (β: −3·3; 95 % CI −6·4, −0·1). In conclusion, higher adherence of CRC survivors to WCRF/AICR lifestyle recommendations for cancer prevention was associated with better physical functioning and with less fatigue. This study adds to the limited knowledge on adherence to lifestyle behaviours in CRC survivors and relationships with quality of life. Prospective studies are needed to investigate longitudinal associations.
As new work on the proper motions (PMs) of the Large Magellanic Cloud (LMC) has come out, our view of the history of the Magellanic Clouds has evolved. We now believe they are on their first infall into the Milky Way (MW), having been tidally bound at the start of infall (though not necessarily now). Combining these observations with initial PMs of the Small Magellanic Cloud (SMC) suggests a new formation mechanism of the Magellanic Stream through the stripping of material from the SMC. However, large uncertainties remain in the exact mass of the LMC. We present a measurement of the systemic proper motions of the SMC from astrometry with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST), covering a ~3 year baseline of 30 fields with background QSOs. We find these motions to be μW = −0.82 ± 0.06 mas/yr and μN = −1.23 ± 0.07 mas/yr. Combining these measurements with previous efforts in studying the Clouds will help constrain their interactions with each other and the MW, including the mass of the LMC and the MW, as well as provide new insight into the internal dynamics of the SMC.
Genetic variation in Lactuca serriola, the closest wild relative of cultivated lettuce, was studied across Europe from the Czech Republic to the United Kingdom, using three molecular marker systems, simple sequence repeat (SSR, microsatellites), AFLP and nucleotide-binding site (NBS) profiling. The ‘functional’ marker system NBS profiling, targeting disease resistance genes of the NBS/LRR family, did not show marked differences in genetic diversity parameters to the other systems. The autogamy of the species resulted in low observed heterozygosity and high population differentiation. Intra-population variation ranged from complete homogeneity to nearly complete heterogeneity. The highest genetic diversity was found in central Europe. The SSR results were compared to SSR variation screened earlier in the lettuce collection of the Centre for Genetic Resources, the Netherlands (CGN). In the UK, practically only a single SSR genotype was found. This genotype together with a few other common SSR genotypes comprised a large part of the plants sampled on the continent. Among the ten most frequent SSR genotypes observed, eight were already present in the CGN collection. Overall, the CGN collection appears to already have a fair representation of genetic variation from NW Europe. The results are discussed in relation to sampling strategies for improving genebank collections of crop wild relatives.
Neural-tube defects (NTD) are common congenital malformations that can lead to severe disability or even death. Periconceptional supplementation with the B-vitamin folic acid has been demonstrated to prevent 50–70% of NTD cases. Since the identification of the first genetic risk factor of NTD, the C677T single-nucleotide polymorphism (SNP) in the methylenetetrahydrofolate reductase (MTHFR) gene, and the observation that elevated plasma homocysteine levels are associated with NTD, research has focused on genetic variation in genes encoding for enzymes of folate metabolism and the closely-related homocysteine metabolism. In the present review relevant SNP in genes that code for enzymes involved in folate transport and uptake, the folate cycles and homocysteine metabolism are summarised and the importance of these SNP discussed in relation to NTD risk.
Rotation characteristics in gait and passive rotation of the lower limbs were evaluated retrospectively in 105 patients with diplegic cerebral palsy (65 males, 40 females; mean age 13y [SD 6y 9mo]; range 4y 4mo–40y 5mo). Of 105 patients, 22 (20.9%) required crutches, sticks, tripods, or a K-walker for their daily ambulation. Twelve (11.5%) patients used a wheelchair or buggy for community distances, e.g. shopping. Significant differences in rotational characteristics were found at the pelvis, hip, knee, and foot between left and right legs. Patients who were more affected on the right (group R, n=33) or the left side (group L, n=39) were re-evaluated. There was also a group of patients who were not asymmetrically affected (group S, n=33). In group L, maximum passive internal rotation was significantly greater on the left side, while no difference between the sides was found in group R. Peak internal rotation in gait was significantly higher on the right side in group R, but did not differ significantly between the sides in group L. Right hindfoot–thigh angle and transmalleolar axis were more external on the right, irrespective of which leg was more affected. These findings may have implications for the early non-operative management of limb posture in infants with diplegia and the surgical management of established lower extremity malrotation.
Background and objective: To determine the minimal oxygen delivery and pump flow that can maintain systemic oxygen uptake during normothermic (37°C) pulsatile and non-pulsatile cardiopulmonary bypass in dogs. Methods: Eighteen anaesthetized dogs were randomly assigned to receive either non-pulsatile (Group C; n = 9) or pulsatile bypass flow (Group P; n = 9). Oxygen delivery was reduced by a progressive decrease in pump flow, while arterial oxygen content was maintained constant. In each animal, critical oxygen delivery was determined from plots of oxygen uptake vs. oxygen delivery and from plots of blood lactate vs. oxygen delivery using a least sum of squares technique. Critical pump flow was determined from plots of lactate vs. pump flow. Results: At the critical point, oxygen delivery obtained from oxygen uptake was 7.7 ± 1.1 mL min−1 kg−1 in Group C and 6.8 ± 1.8 mL min−1 kg−1 in Group P (n.s.). These values were similar to those obtained from lactate measurements (Group C: 7.8 ± 1.6 mL min−1 kg−1; Group P: 7.6 ± 2.0 mL min−1 kg−1). Critical pump flows determined from lactate measurements were 55.6 ± 13.8 mL min−1 kg−1 in Group C and 60.8 ± 13.9 mL min−1 kg−1 in Group P (n.s.). Conclusions: Oxygen delivery values greater than 7–8 mL min−1 kg−1 were required to maintain oxygen uptake during normothermic cardiopulmonary bypass with either pulsatile or non-pulsatile blood flow. Elevation of blood lactate levels during bypass helps to identify inadequate tissue oxygen delivery related to insufficient pump flow.
Background. Data on the efficacy and safety of methylphenidate in adults with attention deficit/hyperactivity disorder (ADHD) are lacking in Europe. This study was undertaken to report on the efficacy and safety of methylphenidate in an adult out-patient population with ADHD, and to compare results with US data.
Method. A double-blind randomized cross-over trial comparing methylphenidate and placebo in 45 adults with ADHD with childhood onset was performed in a dose–titration design. Methylphenidate was titrated from 0·5 mg/kg per day in week 1 up to 1·0 mg/kg per day in week 3.
Results. Response rates using methylphenidate varied between 38 and 51%, and using placebo between 7 and 18% (p<0·05), depending on outcome measure used. Although the overall percentage of subjects having any side effect on both methylphenidate and placebo was rather high, side effects on methylphenidate over and above those on placebo were few and mild.
Conclusions. Methylphenidate proves to be an effective and well tolerated treatment for symptoms of ADHD in adults in the short term. Future research should study the long-term response and clarify the impact of gender, co-morbidity, socio-economic status and IQ on response rates in adults with ADHD.
The purpose of the study was to investigate whether jaw reflexes evoked by selective stimulation of periodontal ligament mechanoreceptors are susceptible to modulation by remote noxious stimulation. Experiments were performed on 10 volunteer subjects. Skin surface recordings were made from the jaw-closing masseter muscle. The subjects activated the muscle to approximately 10% of maximum by biting on a rubber impression of their molar teeth while they received visual feedback of the electromyogram (EMG) of the muscle. Reflexes were produced by the application of gentle mechanical stimuli to an upper central incisor tooth. The stimuli were in the form of ‘ramp and hold’ forces with a 5 ms rise-time and a 1.5 N plateau which lasted 350ms. The resulting reflexes were recorded both under control conditions and while the subjects received a remote noxious stimulus (immersion of a hand in water at 3°C). In all 10 subjects, the stimuli produced a single period of inhibition of masseteric activity (latency, 12.8±0.4 ms; duration, 18.1±1.3 ms; means ± S.E.M.), which was usually followed by a period of increased masseteric activity. The period of inhibition constituted a downward wave in full-wave rectified, averaged signals. The integrals of such waves were significantly smaller (by 17±6.5 %; P = 0.027; Student's t test) when the reflex was evoked during remote noxious stimulation rather than under control conditions. As such reflexes are believed to play a modulatory role during normal oral function, this finding may be relevant to disorders of mastication associated with pain.
Although brain volume changes are found in schizophrenia, only a limited number of structural magnetic resonance imaging studies have exclusively examined antipsychotic-naïve patients.
To comprehensively investigate multiple brain structures in a single sample of patients who were antipsychotic-naïve.
Twenty antipsychotic-naïve patients with first-episode schizophrenia and 20 healthy comparison subjects were included. Intracranial, total brain, frontal lobe, grey and white matter, cerebellar, hippocampal, parahippocampal, thalamic, caudate nucleus and lateral and third ventricular volumes were measured. Repeated-measures analyses of (co)variance were conducted with intracranial volume as covariate.
Third ventricle volume enlargement was found in patients compared with the healthy subjects. No differences were found in other brain regions.
These findings suggest that some brain abnormalities are present in the early stages of schizophrenia. Moreover, it suggests that brain abnormalities reported in patients with chronic schizophrenia develop in a later stage of the disease and/or are medication induced.
Our intent in publishing this collection of essays is to introduce historians to a set of quantitative and qualitative social science methods that have genuine, and as yet un- or under-explored, utility for historical inquiry. Believing that the potency of any methodology is best displayed through the analysis of actual historical cases, we called for our contributors to demonstrate their chosen method's logic and applicability by grounding their exposition in concrete historical happenings. Though we also asked them to use as expository vehicles historical cases that are significant on their own terms and of clear relevance to social historians, the essays’ actual substantive pay-off is apt to be less important than their ability to display in an accessible fashion when, why and how the application of various formal methods may generate deeper, more satisfying explanations and interpretations of historical happenings.
Admittedly, a call to contemporary historians to reconsider the possible value to them of formal social science methodologies comes at a peculiar time in our intellectual life. Analytical formalism in history seems on the wane, and, at best, social science and history have shared a checkered and uneasy relationship over the last century and a half. Early sociology, for example, borrowed from, leaned on, or in other ways was in conversation with history, even if some of the discipline's founders paradoxically used history in an ahistorical manner; that is, as a “storehouse of samples” in Barrington Moore's apt phrase, a mere testing ground for grand sociological theory rather than something to be comprehended in its own right.