Possible Explanations For Variation Research Articles

Efficacy of labile carbon addition to reduce fast‐growing, invasive non‐native plants: A review and meta‐analysis

Abstract Elevated soil nitrogen (N) resulting from pollution, fertilizer and woody encroachment in grasslands enhances invasion pressures from weedy plant species. Sawdust, sucrose and other labile carbon (C) sources can be used as a soil amendment to combat the growth of fast‐growing, invasive non‐native plants by immobilizing soil N. Here, we present a systematic review of 83 publications, and a meta‐analysis from 48 publications. Using hierarchical mixed‐effects meta‐analytic models, we synthesized 655 responses from native plants and 486 responses from non‐native weeds to quantify the overall effect of C addition. We explored the possible explanations for variation in effect, such as differences in study conditions and how C was applied. Carbon addition studies were almost exclusively reported from the United States, Australia and Canada (93%). The majority of papers (63%) did not include any cost information. Overall, C addition significantly decreased non‐native weed abundance, but did not significantly affect native plant abundance. A C application rate of at least 210 g C m−2 year−1 (5 Mg sucrose ha−1 year−1 or 4.6 Mg sawdust ha−1 year−1) decreased non‐native weed abundance, but a rate of 2110–3000 g C m−2 year−1 (50–71 Mg sucrose ha−1 year−1 or 46–65 Mg sawdust ha−1 year−1) was required to significantly increase native plant abundance. Carbon addition was most effective in the western USA and southeastern Australia, and when used to suppress non‐native grasses (annual or perennial) and annual forbs. Simultaneous seeding of native species prevented an overall decrease in native plant abundance. Synthesis and application. When there is a nearby and inexpensive source of C available, we recommend C addition with simultaneous seeding of native species to control invasive non‐native grasses and annual forbs in semi‐arid and arid regions of the western USA and southeast Australia. In contrast to other weed control measures, especially herbicide, C addition does not significantly harm native perennial plants. Future studies should implement longer‐term monitoring, establish larger plots and include cost analysis to improve guidance for land managers.

Integrating phylogenetic and functional data in microbiome studies.

Microbiome functional data are frequently analyzed to identify associations between microbial functions (e.g. genes) and sample groups of interest. However, it is challenging to distinguish between different possible explanations for variation in community-wide functional profiles by considering functions alone. To help address this problem, we have developed POMS, a package that implements multiple phylogeny-aware frameworks to more robustly identify enriched functions. The key contribution is an extended balance-tree workflow that incorporates functional and taxonomic information to identify functions that are consistently enriched in sample groups across independent taxonomic lineages. Our package also includes a workflow for running phylogenetic regression. Based on simulated data we demonstrate that these approaches more accurately identify gene families that confer a selective advantage compared with commonly used tools. We also show that POMS in particular can identify enriched functions in real-world metagenomics datasets that are potential targets of strong selection on multiple members of the microbiome. These workflows are freely available in the POMS R package at https://github.com/gavinmdouglas/POMS. Supplementary data are available at Bioinformatics online.

Welding Fume Exposure and Health Risk Assessment in a Cohort of Apprentice Welders.

Welding fumes vary in composition depending on the materials and processes used, and while health outcomes in full-time welders have been widely studied, limited research on apprentices exists. Besides, few data are available for metals such as vanadium and antimony. This study aimed to look at individual metals present in welding fumes in the learning environment of apprentice welders. Forty-three welders and 41 controls were chosen from trade programmes at the Northern Alberta Institute of Technology. Ambient and personal air samples were collected at days 0, 1, 7, and 50 of their training and analysed for mass and metal concentrations using Inductively Coupled Plasma Mass Spectrometry. Results showed increases in particle and metal concentrations as apprentices progressed throughout their education and that concentrations at day 50 were similar to levels found in the literature for professional welders. Variable concentrations indicate that some individuals may not properly use the local exhaust ventilation system. Other possible explanation for variations are the position of the sampler on the shoulder, the time spent welding and in each welding position, and the skills of the welders. Strong relationships were observed between particle and metal concentrations, suggesting that these relationships could be used to estimate metal exposure in welders from particle exposure. Welding processes were the most important determinant of exposure in apprentice welders, with Metal Core Arc Welding producing the largest particle concentrations followed by oxyacetylene cutting, and Gas Metal Arc Welding. Health risk assessment showed that welder apprentices are at risk for overexposure to manganese, which suggests that professional welders should be monitored for manganese as they are exposed more than apprentices. Training in proper positioning of local exhaust ventilation system and proper use of respirators are recommended in training facilities.

Effect of Bast Fibre Crops and Their Biochemicals on Nutritional Indices of Spilosoma Obliqua (Walker)

This study is on the nutritional efficiency of the host plants viz., Corchorus olitorius, C. capsularis, Hibiscus cannabinus, H. sabdariffa, Crotoloria juncea and Boemheria nivea and their biochemical influences on Bihar hairy caterpillar Spilosoma obliqua (Walker) (Lepidoptera: Arctiidae). The results revealed that the nutritional and biochemical parameters varied significantly with the infested and uninfested host plants. The growth rate of 5th instar larvae varied from 13.06 mg/ day in B. nivea to 17.90 mg/ day in C. olitorius; it was 14.80 ± 0.69, 16.74 ± 0.74, 14.94 ± 0.29 and 15.06 ± 0.26 mg/ day on C. capsularis, H. cannabinus, H. sabdariffa, C. juncea and B. nivea, respectively. Thus, C. olitorius appeared to be the most suitable food source for growth and development of S. obliqua. Peroxidase and polyphenol oxidase were elicited by the infestation of S. obliqua indicating their role in insect defence. Higher phenol and peroxidase content in the host plants adversely affected the food utilization indices. This is the possible explanation for variation in food consumption and development of S. obliqua; and it might be due to significant differences in the biochemical contents of the evaluated bast fibre crops.

Empirical Investigations of the Instrument Response for Distributed Acoustic Sensing (DAS) across 17 Octaves

ABSTRACT With the potential of high temporal and spatial sampling and the capability of utilizing existing fiber-optic infrastructure, distributed acoustic sensing (DAS) is in the process of revolutionizing geophysical ground-motion measurements, especially in remote and urban areas, where conventional seismic networks may be difficult to deploy. Yet, for DAS to become an established method, we must ensure that accurate amplitude and phase information can be obtained. Furthermore, as DAS is spreading into many different application domains, we need to understand the extent to which the instrument response depends on the local environmental properties. Based on recent DAS response research, we present a general workflow to empirically quantify the quality of DAS measurements based on the transfer function between true ground motion and observed DAS waveforms. With a variety of DAS data and reference measurements, we adapt existing instrument-response workflows typically in the frequency band from 0.01 to 10 Hz to different experiments, with signal frequencies ranging from 1/3000 to 60 Hz. These experiments include earthquake recordings in an underground rock laboratory, hydraulic injection experiments in granite, active seismics in agricultural soil, and icequake recordings in snow on a glacier. The results show that the average standard deviations of both amplitude and phase responses within the analyzed frequency ranges are in the order of 4 dB and 0.167π radians, respectively, among all experiments. Possible explanations for variations in the instrument responses include the violation of the assumption of constant phase velocities within the workflow due to dispersion and incorrect ground-motion observations from reference measurements. The results encourage further integration of DAS-based strain measurements into methods that exploit complete waveforms and not merely travel times, such as full-waveform inversion. Ultimately, our developments are intended to provide a quantitative assessment of site- and frequency-dependent DAS data that may help establish best practices for upcoming DAS surveys.

Commentary on Freeman et al. (2019): Why does cannabis potency still vary across European countries?

Although the potency of cannabis has increased in almost every European country between 2006 and 2016, substantial differences among countries persist, with important public health consequences. Possible explanations for variations across Europe in the cannabis market include tastes (demand-side) and enforcement or input price differences (supply-side). Freeman et al. 4 contribute new observations to this puzzle of varying equilibria in national markets. They present data on the potency of cannabis [as measured by the percentage of tetrahydrocannabinol (THC)] in 21 European countries during the period 2006–16. For all but two countries, potency of herbal cannabis increases during that period, mostly by a substantial amount. There is reason to believe that there are common factors at work here, and Freeman and collaborators suggest that there has been an improvement in technology for cannabis production. However, in 2016, visual inspection of the fitted graphs for herbal cannabis (4, Fig. S2) suggests a range of average potencies almost as broad as in 2006. Putting aside the Netherlands, with its quasi-legal market for cannabis and unchanging potency of 15%, the 2016 range is approximately 3–15%, whereas in 2006 it was approximately 0.5–10%. Similar patterns can be observed for cannabis resin (4, Fig. S1). There is little evidence of a convergence or harmonizing across markets. As with purity in the cocaine and heroin markets, cannabis potency is a product decision by producers, which partially reflects customer taste. The variation in potency probably matters for public health, as Freeman et al. note, because user titration is imperfect; those who consume very high-potency cannabis may consume more THC. Thus, it would be useful to investigate what factors drive potency variation. To my knowledge, no such effort has been published. It is not necessary to rely on national-level data for such research. There may well be similar variation among cities within countries that would allow exploration of these hypotheses where city-level data are available. The fact that almost all European nations have experienced an increase in potency does not lessen the significance of the national variation; it merely deepens the puzzle. None.

Increases in Variation of Barbell Kinematics Are Observed with Increasing Intensity in a Graded Back Squat Test.

The purpose of the current study was two-fold: (1) To examine the variation in velocity and power with increasing intensity in the back squat among subjects; and (2) To explore individual subject characteristics as possible explanations for variations of velocity in the back squat. Fourteen recreationally trained male subjects with experience in the back squat agreed to participate in the study (age = 25.0 ± 2.6 years, height = 178.9 ± 8.1 cm, body mass = 88.2 ± 15.8 kg). One-repetition maximums (1RM) were performed for each subject on force platforms with four linear position transducers attached to the barbell. The 1RM assessment was immediately preceded by warm-up sets at 65%, 75%, 85%, and 95% of estimated 1RM for 5, 3, 2, and 1 repetitions, respectively. Mean concentric velocity (MCV) and mean power were recorded for each intensity condition and were analyzed using Pearson correlation to determine the relationship between each variable and relative intensity (%1RM). Statistically significant negative relationships existed between %1RM and MCV (r = −0.892) and mean power (r = −0.604). Between-subject coefficient of variation tended to increase as %1RM increased for both MCV and mean power. These results suggest that MCV is superior to mean power as an indicator of relative intensity in the back squat. Additionally, the between-subject variation observed at higher intensities for MCV and mean power support the use of velocity ranges by strength and conditioning coaches.

Different frequencies of Porphyromonas gingivalis infection in cancers of the upper digestive tract

The high incidence rate of multiple carcinomas in the upper digestive tract is often explained in terms of involvement of the same underlying risk factors. It has been reported that the oral bacterium Streptococcus anginosus is associated with esophageal, gastric, and pharyngeal cancers. We previously reported occurrence of Porphyromonas gingivalis (P. gingivalis) DNA in esophagus cancer. In this study, the presence of P. gingivalis in specimens of various types of cancer from the upper digestive tract was investigated. Here we report that P. gingivalis was preferentially and frequently present in specimens of esophageal cancer as well as in those from dysplasia of the esophagus but rarely in matched noncancerous portions and are quite low or absent in cancers from the cardia or stomach. Therefore, it led us to propose that, the microorganism does not survive in conditions of high acidity. We then investigate the pH dependence of survival of P. gingivalis as well as the acid tolerance of it. We found that, exposure to acidic buffers of a wide range of pH values led to a decline in colony forming units of P. gingivalis, thus, providing a possible explanation for variations in frequencies of P. gingivalis infection in this study.

Reconciling niches and neutrality in a subalpine temperate forest

AbstractThe Unified Neutral Theory of Biodiversity has been put forth to explain species coexistence in forests worldwide, but its assumption of species equivalence has been met with much debate. Theoretical advancements have reconciled the opposing concepts of neutral and niche theories as two ends of a continuum, improving our understanding of global patterns in diversity and community assembly. However, the relative importance of niche and neutral processes remains understudied in temperate forests. To determine the balance of niche and neutral processes in climatically limited subalpine temperate forests, we established the Utah Forest Dynamics Plot, a 13.64‐ha plot comprising 27,845 stems ≥1 cm diameter at breast height (1.37 m) representing 17 species at 3100 m elevation on the Colorado Plateau. We examined the fit of niche‐ and neutral‐based models to the species abundance distribution (SAD), and tested three underlying assumptions of neutral theory. The neutral model was a poor fit to the SAD, but we did not find the alternative model to provide a better fit. Using spatial analyses, we tested the neutral assumptions of functional equivalence, ecological equivalence, and habitat generality. Half of species analyzed were characterized by non‐neutral recruitment processes, and the two most abundant species exhibited asymmetric competitive and facilitative interactions with each other. The assumption of habitat generality was strongly contradicted, with all common species having habitat preferences. We conclude niche‐based processes play the dominant role in structuring subalpine forest communities, and we suggest possible explanations for variation in the relative importance of niche vs. neutral processes along ecological gradients.

Is righting response lateralized in two species of freshwater turtles?

Laterality has been found in a variety of reptiles. In turtles, one important behaviour is the righting response. Here, we studied laterality of righting response of two species of freshwater turtles, the Painted Turtle (Chrysemys picta) and the Eastern Musk Turtle (Sternotherus odoratus). We found evidence of individual-level laterality in righting response inC. picta, but notS. odoratus. Neither species showed evidence of population-level laterality in righting response. Our results suggest that there is variation in the extent of laterality of righting response in turtles. Possible explanations for variation in laterality of righting response in turtles include shell shape and use of terrestrial habitats. However, more species of turtles need to be examined to demonstrate any general patterns in laterality of righting response in turtles.

Sero-epidemiology of Peste des petits ruminants virus infection in Turkana County, Kenya.

BackgroundPeste des petits ruminants (PPR) is a contagious viral disease of small ruminants. Serum samples from sheep (n = 431) and goats (n = 538) of all ages were collected in a cross-sectional study in Turkana County, Kenya. The objective was to estimate the sero-prevalence of PPR virus (PPRV) infection and associated risk factors in both species.PPRV competitive enzyme-linked immuno-sorbent assay (c-ELISA) analysed the presence of antibodies in the samples. All analyses were conducted for each species separately. Multivariable logistic regression models were fitted to the data to assess the relationship between the risk factors and PPRV sero-positivity. Mixed-effect models using an administrative sub-location as a random effect were also fitted to adjust for possible clustering of PPRV sero-positivity. Intra-cluster correlation coefficients (ρ) that described the degree of similarity among sero-positive responses for each species in each of the six administrative divisions were estimated.ResultsGoats had a significantly higher sero-prevalence of 40% [95% confidence interval (CI): 36%, 44%] compared to sheep with 32% [95% CI: 27%, 36%] (P = 0.008). Combined sero-prevalence estimates were heterogeneous across administrative divisions (n = 6) (range 22% to 65%) and even more across sub-locations (n = 46) (range 0% to 78%). Assuming that PPRV antibodies are protective of infection, a large pool of PPRV susceptible middle age group (>6 months and < 24 months) in both species was estimated. This was based on the low sero-prevalence in this group in goats (14% [95% CI: 10%, 20%]) and in sheep (18% [95% CI: 13%, 25%]). Regression analysis returned significant risk factors across species: in sheep - vaccination status, age and administrative division; in goats - sex, age, administrative division and sex*age interaction. The intra-sub-location correlation coefficients varied widely across divisions (range <0.001 to 0.42) and across species within divisions.ConclusionsBiological, spatial and socio-ecological factors are hypothesized as possible explanations for variation in PPRV sero-positivity in the Turkana pastoral ecosystem.

Explaining variation in emergency admissions: a mixed-methods study of emergency and urgent care systems

BackgroundRecent increases in emergency admission rates have caused concern. Some emergency admissions may be avoidable if services in the emergency and urgent care system are available and accessible. A set of 14 conditions, likely to be rich in avoidable emergency admissions, was identified by expert consensus.ObjectiveWe aimed to understand variation in avoidable emergency admissions between different emergency and urgent care systems in England.MethodsThe design was a sequential mixed-methods study in three phases. In phase 1 we calculated an age- and sex-adjusted avoidable admission rate for 2008–11. We located routine data on characteristics of emergency and urgent care systems and used linear regression to explain variation in avoidable admissions rates in 150 systems. In phase 2 we undertook in-depth case studies in six systems to identify further factors. A key part of these case studies was interviews with commissioners, service providers and patient representatives, totalling 82 interviews. In phase 3 we returned to the linear regression to test further factors identified in the case studies.ResultsThe 14 conditions accounted for 3,273,395 admissions in 2008–11 (22% of all emergency admissions). The mean age- and sex-adjusted admission rate was 2258 per year per 100,000 population, with a 3.4-fold variation between systems (1268–4359). Characteristics of the population explained the majority of variation: deprivation explained 72% of variation, with urban/rural status explaining 3% more. Systems serving populations with high levels of deprivation and in urban areas had high rates of potentially avoidable admissions. Interviewees described the complexity of deprivation, representing high levels of morbidity, low awareness of alternative services to emergency departments and high expressed need for immediate access to urgent care. Factors related to emergency departments (EDs), hospitals, emergency ambulance services and general practice explained a further 10% of variation in avoidable admissions. Systems with high, potentially avoidable, admission rates had high rates of acute beds (suggesting supply-induced demand), high rates of attendance at EDs (which have been associated with poor perceived access to general practice), high rates of conversion from ED attendances to admissions, and low rates of non-transport to emergency departments by emergency ambulances. The six case studies revealed further possible explanations of variation: there was variation in how hospitals coded admissions; some systems focused proactively on admission avoidance whereas others were more interested in hospital discharge, for example use of multidisciplinary teams based at acute trusts; there were different levels of integration between different services such as health and social care, and acute and community trusts; and some systems faced more challenging problems around geographical boundaries operating for different services in the system. Interviewees often described admission as the easy or safe option.ConclusionsDeprivation explained most of the variation in avoidable admission rates. Research is needed to understand the complex relationship between deprivation and avoidable admission, and to develop interventions tailored to avoid admissions from deprived communities. Standardisation of coding of admissions would reduce variation.FundingThe National Institute for Health Research Health Service and Research Delivery programme.

The Political Economy of Russian Gubernatorial Election and Appointment

Political and economic outcomes depend, in part, on the quality of the officials making policy. Many scholars argue that the free and fair elections are the best method for selecting competent officials. Others, however, argue that elections can lead to the selection of amateurs, demagogues, and political sycophants. Under this view, sub-national officials should be appointed by centralized planners who are insulated from local popular pressures. In this paper, we use original data on the biographies of Russian regional governors to determine whether the backgrounds of governors elected between 1992 and 2004 differ from the backgrounds of appointed governors post-2004. We find that the two groups are surprisingly similar on many dimensions. Elected and appointed governors have similar career backgrounds, ages, educational profiles, and ethnicities. But there are some important differences as well. Elected governors, are more likely to have held elected office and be from the region where they serve. Appointed governors are also more likely to be federal bureaucrats, hold a graduate degree, and have education in economics. Finding that the selection mechanism explains only a small portion of the variance in governor backgrounds, we conclude the paper by speculating on other possible explanations for variation in governor background.

The Political Economy of Russian Gubernatorial Election and Appointment

Political and economic outcomes depend, in part, on the quality of the officials making policy. Some argue that free elections are the best method for selecting competent officials. Others argue that elections lead to the selection of amateurs and demagogues. We use original data on the biographies of Russian regional governors to examine the backgrounds of elected and appointed governors. Elected governors are more likely to be locals. Appointed governors are more likely to be federal bureaucrats or hold a graduate degree. We conclude the paper by speculating on other possible explanations for variation in governor background.

Status of prevalence study on multimorbidity of chronic disease in China: systematic review.

It is imperative to provide a more uniform method to improve the validity of prevalence studies on multimorbidity. However, the status of prevalence studies on multimorbidity of chronic disease is still yet to be confirmed in China. The objective of the present systematic review was to evaluate the variance across prevalence studies and to explore possible explanations for variations in China. Published literature was obtained from four databases. The studies that described the prevalence of multimorbidity on chronic disease based on the general population were considered. We assessed the risk of bias by a preplanned checklist referring to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology). The heterogeneity among eligible studies was estimated by I(2) statistic and P-value using MetaAnalyst software. Nine studies were eligible for this systematic review. The prevalence of multimorbidity among the population aged 60 years or more ranged from 6.4% (95% CI 5.1-8.0) to 76.5% (95%CI 73.6-79.2). However, just two of nine studies could be judged as having a low risk of bias. It was shown that key items introducing the risk of bias included inconsistent sampling method, lacking of uniform measure indices and data source based on self-report. Heterogeneity test showed I(2) = 50% (P < 0.001), which showed there was substantial variation among individual studies. Therefore, only a narrative summary rather than meta-analysis was carried out. Marked methodology heterogeneity exists among prevalence studies on multimorbidity. Suggested methodological aspects that should be considered in future studies include sampling method, measure indices of multimorbidity and data source.

Investigating variations in implementation fidelity of an organizational-level occupational health intervention.

The workplace has been suggested as an important arena for health promotion, but little is known about how the organizational setting influences the implementation of interventions. The aims of this study are to evaluate implementation fidelity in an organizational-level occupational health intervention and to investigate possible explanations for variations in fidelity between intervention units. The intervention consisted of an integration of health promotion, occupational health and safety, and a system for continuous improvements (Kaizen) and was conducted in a quasi-experimental design at a Swedish hospital. Implementation fidelity was evaluated with the Conceptual Framework for Implementation Fidelity and implementation factors used to investigate variations in fidelity with the Framework for Evaluating Organizational-level Interventions. A multi-method approach including interviews, Kaizen notes, and questionnaires was applied. Implementation fidelity differed between units even though the intervention was introduced and supported in the same way. Important differences in all elements proposed in the model for evaluating organizational-level interventions, i.e., context, intervention, and mental models, were found to explain the differences in fidelity. Implementation strategies may need to be adapted depending on the local context. Implementation fidelity, as well as pre-intervention implementation elements, is likely to affect the implementation success and needs to be assessed in intervention research. The high variation in fidelity across the units indicates the need for adjustments to the type of designs used to assess the effects of interventions. Thus, rather than using designs that aim to control variation, it may be necessary to use those that aim at exploring and explaining variation, such as adapted study designs.

Pairwise comparisons of ten porcine tissues identify differential transcriptional regulation at the gene, isoform, promoter and transcription start site level

The transcriptome is the absolute set of transcripts in a tissue or cell at the time of sampling. In this study RNA-Seq is employed to enable the differential analysis of the transcriptome profile for ten porcine tissues in order to evaluate differences between the tissues at the gene and isoform expression level, together with an analysis of variation in transcription start sites, promoter usage, and splicing.Totally, 223 million RNA fragments were sequenced leading to the identification of 59,930 transcribed gene locations and 290,936 transcript variants using Cufflinks with similarity to approximately 13,899 annotated human genes. Pairwise analysis of tissues for differential expression at the gene level showed that the smallest differences were between tissues originating from the porcine brain. Interestingly, the relative level of differential expression at the isoform level did generally not vary between tissue contrasts. Furthermore, analysis of differential promoter usage between tissues, revealed a proportionally higher variation between cerebellum (CBE) versus frontal cortex and cerebellum versus hypothalamus (HYP) than in the remaining comparisons. In addition, the comparison of differential transcription start sites showed that the number of these sites is generally increased in comparisons including hypothalamus in contrast to other pairwise assessments.A comprehensive analysis of one of the tissue contrasts, i.e. cerebellum versus heart for differential variation at the gene, isoform, and transcription start site (TSS), and promoter level showed that several of the genes differed at all four levels. Interestingly, these genes were mainly annotated to the “electron transport chain” and neuronal differentiation, emphasizing that “tissue important” genes are regulated at several levels. Furthermore, our analysis shows that the “across tissue approach” has a promising potential when screening for possible explanations for variations, such as those observed at the gene expression levels.

Call Variation in Tufted Titmice (Baeolophus bicolor) in a Distress Context: Potential Sex Differences

Tufted titmice, Baeolophus bicolor, produce calls in the contexts related to threat and approach of, and capture by, a predator. In titmice, these calls transition from the chick-a-dee call, used in a wide range of social contexts, to ‘distress’ calls that are produced by birds when captured and held by a predator or human observer. A recent study indicated that titmice modify the note composition of their calls in the presence of such threatening stimuli. Here, we tested whether female and male titmice differed in their calling behavior, as relatively few sex differences have been documented in calls shared by female and male songbirds. Individual titmice were captured in walk-in treadle traps, and we gradually increased the level of fear or arousal by approaching and finally capturing the bird in the hand. Male titmice produced more chick-a-dee calls than females as the level of threat increased, up to the point of capturing the bird in the hand. Furthermore, the note composition of calls produced by males differed from that of calls produced by females. A limitation to our study is that our method did not allow us to rule out the possibility that size or dominance differences, rather than sex, were the main reason for the differences in calling we detected. However, increased size generally was not associated with increased calling. We discuss some possible explanations for variation in distress calling behavior in titmice.

It’s the weather, stupid! Individual participation in collective May Day demonstrations

We investigate the possible explanations for variations in aggregate levels of participation in large-scale political demonstrations. A simple public choice inspired model is applied to data derived from the annual May Day demonstrations of the Danish labor movement and socialist parties taking place in Copenhagen in the period 1980–2011. The most important explanatory variables are variations in the weather conditions and consumer confidence, while political and socio-economic conditions exhibit no robust effects. As such accidental or non-political factors may be much more important for collective political action than usually acknowledged and possibly make changes in aggregate levels of political support seem erratic and unpredictable.

It’s the Weather, Stupid! Individual Participation in Collective May Day Demonstrations

We investigate the possible explanations of variations in aggregate levels of participation in large-scale political demonstrations. A simple public choice inspired model is applied to data derived from the annual May Day demonstrations of the Danish labour movement and socialist parties taking place in Copenhagen in the period 1980-2009. The most important explanatory variables are variations in the weather conditions. Political and socio-economic conditions exhibit few or no robust effects.