1,153 research outputs found
Mixed Model-Based Hazard Estimation.
We propose a new method for estimation of the hazard function from a set of censored failure time data, with a view to extending the general approach to more complicated models. The approach is based on a mixed model representation of penalized spline hazard estimators. One payoff is the automation of the smoothing parameter choice through restricted maximum likelihood. Another is the option to use standard mixed model software for automatic hazard estimation.Non-parametric regression; Restricted maximum likelihood; Variance component; Survival analysis.
Gas hydrate concentration estimates from chlorinity, electrical resistivity and seismic velocity
Gas hydrate beneath the N. Cascadia continental slope off Vancouver Island occurs as a regional diffuse layer above the BSR and as local high concentrations in large vent or upwelling structures. Regional concentrations of gas hydrate beneath the N. Cascadia continental slope off Vancouver Island have been estimated earlier using multichannel seismic, seafloor electrical, and IODP Leg 146 downhole data. The concentrations of between 15 and 30% of pore saturation in a 100 m thick layer above the BSR are much higher than estimated elsewhere where there is good data, especially the Blake Ridge and central Cascadia off Oregon on ODP Leg 204. Although both of these other studies involved different sediment environments, a careful re-evaluation of the N. Cascadia estimates seemed desirable. We have re-evaluated the methods used to calculate the gas hydrate concentrations from pore-water chlorinity (salinity), electrical resistivity, and seismic velocity, describing in detail the assumptions and uncertainties. Use of the pore-water chlorinity/salinity and electrical resistivity directly have low reliability because of the effect on the no-hydrate reference of hydrate formation and dissociation, and the effect of pore fluid freshening by clay dehydration. At ODP Site 889/890 hydrate concentrations range from 5–10% to 30–40%, depending on the no-hydrate reference salinity used. Use of core salinity data along with the downhole and seafloor electrical resistivity data allows calculation of both the in situ reference salinity and the hydrate concentrations. The most important uncertainty in this method is the relation between resistivity and porosity, i.e., Archie’s Law parameters. Significantly different relations were determined from the ODP Leg 146 core and downhole log data, the log data resistivity-porosity relation giving much lower concentrations. Finally, seismic velocities from sonic-logs and multichannel data can be used to calculate gas hydrate concentrations, if an appropriate no-hydrate velocity-depth profile can be estimated. A velocity-hydrate concentration relation is also required. Depending on which no-hydrate/no-gas velocity baseline is used, estimated hydrate concentrations range from as low as 5% to above 25% saturation. In spite of having three nearly independent methods of estimating hydrate concentrations, it is concluded that the data allow regional concentrations in the 100 m layer above the BSR from less than 5% to over 25% saturation (3-13% of sediment volume). ODP drilling in the region scheduled for the fall of 2005 should help resolve the uncertainties
Mechanical nociceptive threshold testing in Bos indicus bull calves
The aim of this prospective, controlled, randomised trial was to develop a technique for mechanical nociceptive threshold testing (NTT) to assess pain in Bos indicus bull calves undergoing surgical castration. Analgesia was provided by 0.5 mg/kg subcutaneous (SC) meloxicam (M) and/or 2 mg/kg of intra-testicular and SC (at the surgery sites) lidocaine (L). Forty-eight Brahman bull calves at 6–8 months of age were divided into six study groups, each with eight animals: no surgery control; surgical castration (C) without analgesia; C and Mpre-op; C and Mpost-op; C, L and Mpost-op; C and L. Mechanical NTT was performed the day before surgery (Day –1) and on Days 1, 2, 6, 10 and 13 after surgery. A handheld manual pneumatic device with a 1-mm (diameter) blunt pin was used to deliver a mechanical stimulus to a maximum of 27 Newtons either side of the most dorsal aspect of the sacrum. The most frequent responses to the mechanical stimulus were lifting or kicking of the leg on the same side as the stimulus (31%) and stepping away from the stimulus (24.9%). Data were analysed with a mixed effect linear model with the nociceptive threshold (NT) as the response variable and day and analgesic treatment as predictors (P < 0.05 was considered significant). For all groups, there was a trend towards decreasing NT over the study period but there were no significant differences between groups. Step down model selection with day, batch and treatment terms revealed a significant effect of day (P < 0.001) and batch (P = 0.007). Mechanical NTT for assessment of pain in Bos indicus bull calves requires further refinement to determine if this is a useful method of pain assessment
Wide angle seismic recordings from the 2002 Georgia Basin Geohazards Initiative, Northwestern Washington and British Columbia
This report describes the acquisition and processing of shallow-crustal wide-angle seismicreflection and refraction data obtained during a collaborative study in the Georgia Strait, western Washington and southwestern British Columbia. The study, the 2002 Georgia Strait Geohazards Initiative, was conducted in May 2002 by the Pacific Geoscience Centre, the U.S. Geological Survey, and the University of Victoria. The wide-angle recordings were designed to image shallow crustal faults and Cenozoic sedimentary basins crossing the International Border in southern Georgia basin and to add to existing wide-angle recordings there made during the 1998 SHIPS experiment. We recorded, at wide-angle, 800 km of shallow penetration multichannel seismic-reflection profiles acquired by the Canadian Coast Guard Ship (CCGS) Tully using an air gun with a volume of 1.967 liters (120 cu. in.). Prior to this reflection survey, we deployed 48 Refteks onshore to record the airgun signals at wide offsets. Three components of an oriented, 4.5 Hz seismometer were digitally recorded at all stations. Nearly 160,300 individual air gun shots were recorded along 180 short seismic reflection lines. In this report, we illustrate the wide-angle profiles acquired using the CCGS Tully, describe the land recording of the air gun signals, and summarize the processing of the land recorder data into common-receiver gathers. We also describe the format and content of the archival tapes containing the SEGY-formated, common-receiver gathers for the Reftek data. Data quality is variable but the experiment provided useful data from 42 of the 48 stations deployed. Three-fourths of all stations yielded useful first-arrivals to source-receiver offsets beyond 10 km: the average maximum source-receiver offset for first arrivals was 17 km. Six stations yielded no useful data and useful firstarrivals were limited to offsets less than 10 km at five stations. We separately archived our recordings of 86 local and regional earthquakes ranging in magnitude from 0.2 to 4.3 and 16 teleseisms ranging in magnitude 5.5 to 6.5
Qualitative Behavioural Assessment of Bos indicus cattle after surgical castration
There are various methods to perform castration of cattle, but surgical castration is the most common. Although it is well documented that surgical procedures inflict pain, analgesic use is usually omitted for surgical castration of production animals in Australia. This study compares the behavioural responses of castrated cattle (C) with non-castrated (NC) controls, and C with those castrated and given lignocaine and meloxicam (CLM) for analgesia. Brahman bull calves (n = 8 for each treatment) were filmed in the morning pre- (day -1) and post- (day +1) castration in the paddock and feed yard (‘context’ of observation). Over four sessions, volunteer observers viewed the video footage for Qualitative Behaviour Analysis (QBA) using the Free Choice Profiling methodology comparing C and NC cattle, and C and CLM cattle under both contexts. The QBA consensus profiles explained 37.4% (C vs. NC) and 40.6% (C vs. CLM) of variation among observers for paddock sessions and 34.7% (C vs. NC) and 38.7% (C vs. CLM) for feed yard sessions. Significant treatment x day interaction effects were recorded in the paddock (P = 0.007 and P < 0.001) and yard (P =  0.004 and P =  0.025) contexts for comparisons between NC vs C, and C vs CLM respectively. Compared to NC, post-castration C cattle were described as more ‘bored’/’lethargic’ and ‘alone’ (paddock) and were more ‘calm’/’relaxed’ and ‘relaxed’/’lonely’ (yard). Similarly, compared to CLM, post-castration C cattle were described as more ‘docile’/’chilled’ and ‘curious’/’aware’ (paddock) and were less ‘hungry’/’alert’ (yard). There was only one correlation between qualitative and quantitative behaviour scoring; ruminating showed significant correlation with one dimension in each context, that reflected a positive emotion (‘calm, relaxed’). The comparison between C vs. NC suggest that C were less active and less engaged with their environment compared to the NC group following castration. The C vs. CLM comparison suggests a more subtle response whereby analgesia was associated with more positive valence (higher scores on ‘calm/comfortable’, and ‘hungry/alert’ dimensions) following castration. The interpretation of findings requires careful consideration of the emotional responses given these calves were unhabituated and reactive to their surroundings. These results suggest the body language of Bos indicus cattle may reveal indicators of pain, and that the administration of analgesia may be beneficial at the time of castration. The study highlights the complexities and challenges of identifying pain responses in Brahman cattle
Temperature time series forecasting in The Optimal Challenges in Irrigation (TO CHAIR)
Predicting and forecasting weather time series has always been a difficult field of research analysis with a very slow progress rate over the years. The main challenge in this project—The Optimal Challenges in Irrigation (TO CHAIR)—is to study how to manage irrigation problems as an optimal control problem: the daily irrigation problem of minimizing water consumption. For that it is necessary to estimate and forecast weather variables in real time in each monitoring area of irrigation. These time series present strong trends and high-frequency seasonality. How to best model and forecast these patterns has been a long-standing issue in time series analysis. This study presents a comparison of the forecasting performance of TBATS (Trigonometric Seasonal, Box-Cox Transformation, ARMA errors, Trend and Seasonal Components) and regression with correlated errors models. These methods are chosen due to their ability to model trend and seasonal fluctuations present in weather data, particularly in dealing with time series with complex seasonal patterns (multiple seasonal patterns). The forecasting performance is demonstrated through a case study of weather time series: minimum air temperature.publishe
Animal welfare and the use of procedural documents: Limitations and refinement
Increased scrutiny of animal welfare in wildlife management has seen a recent proliferation in the use of procedural documents (standard operating procedures, codes of practice etc.). Some procedural documents are presumed to represent 'best practice' methods, whereby adherence to prescribed inputs is explicitly purported to generate humane outcomes. However, the relationship between what is done to animals (inputs) and what they experience (outputs), as assessed by animal-based measures, has received little attention. Procedural documents are commonly developed in the absence of empirical animal-based measures, creating uncertainty in animal welfare outcomes. Prescribed procedures are valuable as guidelines for standardising methodology, but the development of 'welfare standards' that focus on desired thresholds for animal-based measures offers many advantages for improving animal welfare. Refinement of the use of procedural documents in wildlife management is required to ensure they generate desirable outcomes for animals, and do not preclude the development of improved methods
Lesinurad, a novel, oral compound for gout, acts to decrease serum uric acid through inhibition of urate transporters in the kidney.
BackgroundExcess body burden of uric acid promotes gout. Diminished renal clearance of uric acid causes hyperuricemia in most patients with gout, and the renal urate transporter (URAT)1 is important for regulation of serum uric acid (sUA) levels. The URAT1 inhibitors probenecid and benzbromarone are used as gout therapies; however, their use is limited by drug-drug interactions and off-target toxicity, respectively. Here, we define the mechanism of action of lesinurad (Zurampic®; RDEA594), a novel URAT1 inhibitor, recently approved in the USA and Europe for treatment of chronic gout.MethodssUA levels, fractional excretion of uric acid (FEUA), lesinurad plasma levels, and urinary excretion of lesinurad were measured in healthy volunteers treated with lesinurad. In addition, lesinurad, probenecid, and benzbromarone were compared in vitro for effects on urate transporters and the organic anion transporters (OAT)1 and OAT3, changes in mitochondrial membrane potential, and human peroxisome proliferator-activated receptor gamma (PPARγ) activity.ResultsAfter 6 hours, a single 200-mg dose of lesinurad elevated FEUA 3.6-fold (p < 0.001) and reduced sUA levels by 33 % (p < 0.001). At concentrations achieved in the clinic, lesinurad inhibited activity of URAT1 and OAT4 in vitro, did not inhibit GLUT9, and had no effect on ABCG2. Lesinurad also showed a low risk for mitochondrial toxicity and PPARγ induction compared to benzbromarone. Unlike probenecid, lesinurad did not inhibit OAT1 or OAT3 in the clinical setting.ConclusionThe pharmacodynamic effects and in vitro activity of lesinurad are consistent with inhibition of URAT1 and OAT4, major apical transporters for uric acid. Lesinurad also has a favorable selectivity and safety profile, consistent with an important role in sUA-lowering therapy for patients with gout
Mitigation of electroencephalographic and cardiovascular responses to castration in Bos indicus bulls following the administration of either lidocaine or meloxicam
Objective
To investigate the mitigating effects of administration of local or systemic meloxicam on the electroencephalographic (EEG) and cardiovascular responses during surgical castration of Bos indicus bull calves.
Study design
Prospective, randomized, experimental study.
Animals
Thirty-six 6–8 month-old Bos indicus bull calves, with a mean ± standard deviation weight of 237 ± 19 kg.
Methods
Animals were randomly allocated to three groups of 12 (group L, 260 mg of 2% lidocaine subcutaneously and intratesticularly 5 minutes prior to castration; group M, 0.5 mg kg−1 of meloxicam subcutaneously 30 minutes prior to castration; group C, no pre-operative analgesia administered). Anaesthesia was induced and maintained with halothane (0.9–1.1%) in oxygen. Electroencephalogram, heart rate (HR) and mean blood pressure (MAP) were recorded for 300 seconds prior to (baseline, B) and from the start of surgery (first testicle incision, T1). HR and MAP were compared at 10 second intervals for 90 seconds from the start of T1. Median frequency (F50), spectral edge frequency (F95) and total power of the EEG (Ptot) were analysed using area under the curve comparing T1 to B.
Results
All EEG variables were significantly different between B and T1 (p ≤ 0.0001). No differences in F50 were found between groups during T1 (p = 0.6491). F95 and Ptot were significantly different between group L and groups C and M during T1 (p = 0.0005 and 0.0163, respectively). There were transient significant changes in HR and MAP in groups L and M compared to group C during the 20–50 second periods.
Conclusions
The EEG changes indicate nociceptive responses in all three groups during surgical castration, greater in group L compared to groups C and M. Both analgesics attenuated the peracute cardiovascular response. Lidocaine and meloxicam administered prior to castration attenuated these responses in Bos indicus bull calves.
Clinical relevance
These findings provide support for the pre-operative administration of lidocaine and potentially meloxicam for castration in Bos indicus bull calves
A Case-control Study of Haemorrhagic Septicaemia in Buffaloes and Cattle in Karachi, Pakistan, in 2012
A retrospective epidemiological case–control study was performed in Karachi, Pakistan, from January to April 2013. The owners of 217 dairy cattle and buffalo farms from six different locations in Karachi were interviewed. The aim of the study was to identify risk factors associated with the presence of haemorrhagic septicaemia (HS). Farms with a history of at least one instance of sudden death in a dairy animal during 2012 and a positive clinical HS diagnosis (made by local veterinarians) were defined as cases. Farms having no history of sudden deaths in 2012 were defined as controls. Univariable analyses were initially conducted, and factors with P ≤ 0.25 were offered to a multivariable logistic regression model to identify putative risk factors. The final multivariable logistic model contained five factors. Vaccination was found to be a protective factor (OR = 0.22) along with the length of time cattle were kept on farm (months). For every extra month cattle were kept, the odds of HS disease were reduced by a factor of 0.9. In contrast, for every extra animal in a herd, the risk of infection increased by a factor of 1.01. Supplying underground water and the presence of foot and mouth disease on the farm increased the risk by 2.90 and 2.37, respectively. To understand the epidemiology of HS in Karachi dairy herds, more in-depth research is required to study the risk and protective factors identified in this survey and to evaluate risk mitigation strategies, where possible
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