Variability in individual rates of aggression in wild gray seals: fine-scale analysis reveals importance of social and spatial stability

Aggressive interactions are costly for individuals in time, energy, or physical damage, and in polygynous mating systems, there is high variability in the rates and intensity of aggression across individuals and within breeding seasons. However, examinations into the drivers of this variability are often conducted in isolation, in non-wild systems, or the predictor variables in question, for example, dominance, are averaged across large spatial, social, or temporal scales. The aim of this study was to adopt a fine spatial and temporal scale approach to investigate the factors associated with inter-individual variation in aggression in wild, breeding male gray seals within three consecutive breeding seasons. To do this, we fit models examining if the daily frequency of aggression and probability of escalated aggression for males was best explained by factors such as dominance score, proximity to competitors or females, local social stability, and the occurrence of stochastic environmental events. Stability of neighbor identities was the strongest correlate of reduced male aggression. Dominance status did not correlate with aggression at the daily scale, with the exception of one period after a natural disturbance to the breeding colony where dominant males had relatively reduced rates of aggression. These findings emphasize the importance of local social stability in explaining inter-individual variation in aggression in a wild population and suggest that factors associated with aggression are context dependent in relation to the natural environment. Furthermore, we highlight the utility of a fine temporal scale and incorporating spatial parameters when investigating variability in aggression in wild systems

Assessing the utility and limitations of accelerometers and machine learning approaches in classifying behaviour during lactation in a phocid seal

Background Classifying behaviour with animal-borne accelerometers is quickly becoming a popular tool for remotely observing behavioural states in a variety of species. Most accelerometry work in pinnipeds has focused on classifying behaviour at sea often quantifying behavioural trade-offs associated with foraging and diving in income breeders. Very little work to date has been done to resolve behaviour during the critical period of lactation in a capital breeder. Capital breeding phocids possess finite reserves that they must allocate appropriately to maintain themselves and their new offspring during their brief nursing period. Within this short time, fine-scale behavioural trade-offs can have significant fitness consequences for mother and offspring and must be carefully managed. Here, we present a case study in extracting and classifying lactation behaviours in a wild, breeding pinniped, the grey seal (Halichoerus grypus). Results Using random forest models, we were able to resolve 4 behavioural states that constitute the majority of a female grey seals’ activity budget during lactation. Resting, alert, nursing, and a form of pup interaction were extracted and classified reliably. For the first time, we quantified the potential confounding variance associated with individual differences in a wild context as well as differences due to sampling location in a largely inactive model species. Conclusions At this stage, the majority of a female grey seal’s activity budget was classified well using accelerometers, but some rare and context-dependent behaviours were not well captured. While we did find significant variation between individuals in behavioural mechanics, individuals did not differ significantly within themselves; inter-individual variability should be an important consideration in future efforts. These methods can be extended to other efforts to study grey seals and other pinnipeds who exhibit a capital breeding system. Using accelerometers to classify behaviour during lactation allows for fine-scale assessments of time and energy trade-offs for species with fixed stores

Interpreting scores on multiple sclerosis-specific patient reported outcome measures (the PRIMUS and U-FIS)

BACKGROUND: The PRIMUS is a Multiple Sclerosis (MS)-specific suite of outcome measures including assessments of QoL (PRIMUS QoL, scored 0-22) and activity limitations (PRIMUS Activities, scored 0-30). The U-FIS is a measure of fatigue impact (scored 0-66). These measures have been fully validated previously using an MS sample with mixed diagnoses. The aim of the present study was to validate the measures further in a specifically Relapse Remitting MS (RRMS) sample and to provide preliminary evidence of the responder definitions (RD; also known as minimal important difference) for these instruments. METHODS: Data were derived from a multi-country efficacy trial of MS patients with assessments at baseline and 12 months. Baseline data were used to assess the internal reliability and validity of the measures. Both anchor-based and distribution-based approaches were employed for estimating RD. Anchor-based estimates were based on published RD values for the EQ-5D and were assessed for those improving and deteriorating separately. Distribution-based estimates were based on standard error of measurement (SEM), change score equivalent to 0.30, and change score equivalent to 0.50, effect sizes (ES). RESULTS: The sample included 911 RRMS patients (67.3% female, age mean (SD) 36.2 (8.4) years, duration of MS mean (SD) 4.8 (5.2) years). Results showed that the PRIMUS and U-FIS had good internal consistency. Appropriate correlations were observed with comparator instruments and both measures were able to distinguish between participants based on Expanded Disability Status Scale scores and time since diagnosis. The anchor-based and distribution-based RD estimates were: PRIMUS Activities range = 1.2-2.3, PRIMUS QoL range = 1.0-2.2, and U-FIS range = 2.4-7.0. CONCLUSIONS: The results show that the PRIMUS and U-FIS are valid instruments for use with RRMS patients. The analyses provide preliminary information on how to interpret scores on the scales. These data will be useful for assessing treatment efficacy and for powering clinical studies. TRIAL REFERENCE NUMBER: ClinicalTrials.gov Identifier NCT00340834

Accuracy and reliability of injury coding in the national Dutch Trauma Registry

Objective: Injury coding is well known for lack of completeness and accuracy. The objective of this study was to perform a nationwide assessment of accuracy and reliability on Abbreviated Injury Scale (AIS) coding by Dutch Trauma Registry (DTR) coders and to determine the effect on Injury Severity Score (ISS). Additionally, the coders' characteristics were surveyed.Methods: Three fictional trauma cases were presented to all Dutch trauma coders in a nationwide survey (response rate 69%). The coders were asked to extract and code the cases' injuries according to the AIS manual (version 2005, update 2008). Reference standard was set by three highly experienced coders. Summary statistics were used to describe the registered AIS codes and ISS distribution. The primary outcome measures were accuracy of injury coding and inter-rater agreement on AIS codes. Secondary outcome measures were characteristics of coders: profession, work setting, experience in injury coding and training level in injury coding.Results: The total number of different AIS codes used to describe 14 separate injuries in the three cases was 89. Mean accuracy per AIS code was 42.2% (range 2.4-92.7%). Mean accuracy on number of AIS codes was 23%. Overall inter-rater agreement per AIS code was 49.1% (range 2.4-92.7%). The number of assigned AIS codes varied between 0 and 18 per injury. Twenty-seven percentage of injuries were overlooked. ISS was correctly scored in 42.4%. In 31.7%, the AIS coding of the two more complex cases led to incorrect classification of the patient as ISS = 16. Half (47%) of the coders had no (para)medical degree, 26% were working in level I trauma centers, 37% had less than 2 years of experience and 40% had no training in AIS coding.Conclusions: Accuracy of and inter-rater agreement on AIS injury scoring by DTR coders is limited. This may in part be due to the heterogeneous backgrounds and training levels of the coders. As a result of the inconsistent coding, the number of major trauma patients in the DTR may be over- or underestimated. Conclusions based on DTR data should therefore be drawn with caution.Trauma Surger

Reactive stress-coping styles show more variable reproductive expenditure and fitness outcomes

Stress-coping styles dictate how individuals react to stimuli and can be measured by the integrative physiological parameter of resting heart-rate variability (HRV); low resting HRV indicating proactive coping styles, while high resting HRV typifies reactive individuals. Over 5 successive breeding seasons we measured resting HRV of 57 lactating grey seals. Mothers showed consistent individual differences in resting HRV across years. We asked whether proactive and reactive mothers differed in their patterns of maternal expenditure and short-term fitness outcomes within seasons, using maternal daily mass loss rate to indicate expenditure, and pup daily mass gain to indicate within season fitness outcomes. We found no difference in average rates of maternal daily mass loss or pup daily mass gain between proactive and reactive mothers. However, reactive mothers deviated more from the sample mean for maternal daily mass and pup daily mass gain than proactive mothers. Thus, while proactive mothers exhibit average expenditure strategies with average outcomes, expenditure varies much more among reactive mothers with more variable outcomes. Overall, however, mean fitness was equal across coping styles, providing a mechanism for maintaining coping style diversity within populations. Variability in reactive mothers’ expenditures and success is likely a product of their attempts to match phenotype to prevailing environmental conditions, achieved with varying degrees of success

Can We Rely on the Dermatology Life Quality Index as a Measure of the Impact of Psoriasis or Atopic Dermatitis?

The Dermatology Life Quality Index (DLQI) is a widely used health-related quality of life measure. However, little research has been conducted on its dimensionality. The objectives of the current study were to apply Rasch analysis to DLQI data to determine whether the scale is unidimensional, to assess its measurement properties, test the response format, and determine whether the measure exhibits differential item functioning (DIF) by disease (atopic dermatitis versus psoriasis), gender, or age group. The results show that there were several problems with the scale, including misfitting items, DIF by disease, age, and gender, disordered response thresholds, and inadequate measurement of patients with mild illness. As the DLQI did not benefit from the application of Rasch analysis in its development, it is argued that a new measure of disability related to dermatological disease is required. Such a measure should use a coherent measurement model and ensure that items are relevant to all potential respondents. The current use of the DLQI as a guide to treatment selection is of concern, given its inadequate measurement properties

Observations of aerosols over Southern California coastal waters

To characterize the background aerosol in air off the California coast, observations of suspended particles were made in the summer and fall of 1970 on San Nicolas Island (SNI), located about 130 km west-south-west of Los Angeles. Measurements of the physical and chemical properties of aerosols showed that the particles are a complex mixture of material from marine and continental origins. The Aitken nuclei population averaged 2400 cm−3, while the particles >0.5 μm diameter averaged 20–100 cm−3. The average total mass concentration of aerosol evaluated from 22 samples was 29.8 μg m−3, but the refined fraction defined as particles ~< 3.5 μm diameter was 40% of this level. The averages of the chemical analysis of 13 samples revealed that 11% of the aerosol sampled at a 200 m height above the ocean was sea salt, while approximately 20% evidently was soil dust, as indicated by silicates. Over 25% of the suspended material was found to be sulfate, nitrate or ammonium, which are constituents believed to be produced primarily from gaseous transformation reactions in the atmosphere. More than 20% of the sampled material was volatile in nature and is believed to be partly water. The ratio for the average chlorine to sodium concentrations from the analysis of 13 different samples was 2.4 compared with 1.8 for sea water. This high ratio supports other limited results for unpolluted air from offshore sources taken in this geographical region. The anomaly is believed to be linked with chemical reactions transforming gaseous chlorine compounds into condensed material. Comparison was made between the aerosol sampled on San Nicolas Island and the “natural” background contribution of the Los Angeles smog aerosol, as estimated elsewhere assuming contributions solely from sea salt and soil dust. The calculated background and the composition of the SNI aerosol were qualitatively similar, with the principal differences showing in Ca, Zn, SO4− and NO3−. Further comparison with aerosol analyzed from Pasadena illustrated the major contribution of localized pollution to the chemical properties of the particles, particularly in the concentrations of Mu, Ca, Br, Fe, Pb, SO4− and NO3−