Validity of the Bottle Buoyancy Model for Body Fat Determination

International Journal of Exercise Science 10(1): 87-96, 2017. We investigated a modification of the bottle buoyancy (BB) method in comparison to single frequency, bioelectric impedance analysis (BIA) as a valid noninvasive method of percent body fat (%BF) determination. Twenty-eight participants (15 men, 13 women), in counterbalanced-order, completed the BB, BIA, and computerized hydrostatic densitometry (HD) methods. We elected to modify the BB method using a 12.15 L container with participants hugging the container in an upright position. Consistency measures of intraclass correlation coefficient (ICC), typical error (TE), coefficient of variation (CV) and total error of measurement (TEM) are reported. Our modification of the BB resulted in less “bobbing” than described in the previous method, and took ~5 to 15 min per participant to complete. Group values (%BF) did not differ (p \u3e 0.05) for BB (20.7 ± 6.6), BIA (21.0 ± 9.7), and HD (20.2 ± 7.2). Strong measurement agreement was observed between BB and HD (ICC: 0.95, TE: 1.80 %BF, CV: 10.7%, TEM: 1.77 %BF). Agreement between BIA and HD (ICC: 0.85, TE: 3.35 %BF, CV: 19.6%, TEM: 3.29 %BF) was lower than BB. Our modification of the BB method resulted in similar measurement consistency with the originating method. The BB method appears to represent a valid surrogate measure of %BF, superior to that observed with BIA

New views on how population-intrinsic and community-extrinsic processes interact during the vole population cycles

Based on evidence from a series of recent studies linking behaviour to demography in experimental vole populations we propose how intrinsic and extrinsic factors interact through the various phases of the multi-annual population cycles of voles and lemmings. We hypothesise that population growth in the increase phase of the cycle is enhanced by a high degree of space sharing (sociality) among reproductive females who share resource patches, especially during winter. These social females enjoy a high reproductive output due to good resource conditions, and facilitation provided by communal thermoregulation, breeding and defence of weanlings towards infanticidal conspecifics. We hypothesise on the other hand that the crash phase is initiated and enhanced by predation of adult males that leads to a series of cascading events involving infanticidal behaviour by immigrant males, increased mortality of adult social females, and inversely density-dependent and/or disturbance-induced dispersal. These events further enhance predation-induced mortality and thus a negative feed-back loop to the rate of the crash. In this framework we may explain how extrinsic factors such as predation and winter resource distribution contribute to transitions between docile and aggressive behaviours, and how this transition is spatially synchronised by inversely density-dependent dispersal that may act to mediate a rapidly spreading wave throughout the population. We propose that innate differences among rodent species in their propensities for different social organizations also determine their propensity for exhibiting multi-annual cycles as well as other cycle-related phenomena such as shape of the population cycles and spatial synchrony. We provide a set of testable predictions for further empirical evaluation

The role of colonization in the dynamics of patchy populations of a cyclic vole species

This is the postprint version of the article. The published article can be located at www.springerlink.comThe crash phase of vole populations with cyclic dynamics regularly leads to vast areas of uninhabited habitats. Yet although the capacity for cyclic voles to re-colonize such empty space is likely to be large and predicted to have become evolved as a distinct life history trait, the processes of colonization and its effect on the spatio-temporal dynamics have been little studied. Here we report from an experiment with root voles (Microtus oeconomus) specifically targeted at quantifying the process of colonization of empty patches from distant source patches and its resultant effect on local vole deme size variation in a patchy landscape. Three experimental factors: habitat quality (1), predation risk (2) and inter-patch distance (3) were employed among 24 habitat patches in a 100x300 m experimental area. The first born cohort in the spring efficiently colonized almost all empty patches irrespective of the degree of patch isolation and predation risk, but dependent on habitat quality. Just after the initial colonization wave the deme sizes in patches of the same quality were underdispersed relative to Poission variance, indicating regulated (density-dependent) settlement. Towards the end of the breeding season local demographic processes acted to smooth out the initial post colonization differences among source and colonization patches, and among patches of initially different quality. However, at this time demographic stochasticity had also given rise to a large (overdispersed) variation in deme sizes that may have contributed to overshadow the effect of other factors. The results of this experiment confirmed our expectation that the space-filling capacity of voles is large. The costs associated with transience appeared to be so low, at least at the spatial scale considered in this experiment, that such costs is not likely to substantially constrain habitat selection and colonization in the increase phase of cyclic patchy populations.2014-09-3

Socially informed dispersal in a territorial cooperative breeder

Dispersal is a key process governing the dynamics of socially and spatially structured populations, and involves three distinct stages: emigration, transience, and settlement. At each stage, individuals have to make movement decisions, which are influenced by social, environmental, and individual factors. Yet, a comprehensive understanding of the drivers that influence such decisions is still lacking, particularly for the transient stage during which free-living individuals are inherently difficult to follow.Social circumstances such as the likelihood of encountering conspecifics can be expected to strongly affects decision making during dispersal, particularly in territorial species where encounters with resident conspecifics are antagonistic. Here we analyzed the movement trajectories of 47 dispersing coalitions of Kalahari meerkats (Suricata suricatta) through a landscape occupied by constantly monitored resident groups, while simultaneously taking into account environmental and individual characteristics.We used GPS locations collected on resident groups to create a geo-referenced social landscape representing the likelihood of encountering resident groups. We used a step-selection function to infer the effect of social, environmental and individual covariates on habitat selection during dispersal. Lastly, we created a temporal mismatch between the social landscape and the dispersal event of interest to identify the temporal scale at which dispersers perceive the social landscape.Including information about the social landscape considerably improved our representation of the dispersal trajectory, compared to analyses that only accounted for environmental variables. The latter were only marginally selected or avoided by dispersers. Before leaving their natal territory, dispersers selected areas frequently used by their natal group. In contrast, after leaving their natal territory, they selectively used areas where they were less likely to encounter unrelated groups. This pattern was particularly marked in larger dispersing coalitions and when unrelated males were part of the dispersing coalition.Our results suggest that, in socially and spatially structured species, dispersers gather and process social information during dispersal, and that reducing risk of aggression from unrelated resident groups outweighs benefits derived from conspecific attraction. Finally, our work underlines the intimate link between the social structure of a population and dispersal, which affect each other reciprocally

Modelling the effects of ionising radiation on a vole population from the Chernobyl Red forest in an ecological context

A novel mathematical model was developed to study the historical effects of ionising radiation from the 1986 Chernobyl accident on a vole population. The model uses an ecosystem approach combining radiation damages and repair, life history and ecological interactions. The influence of reproduction, mortality and factors such as ecosystem resource, spatial heterogeneity and migration are included. Radiation-induced damages are represented by a radiosensitive ‘repairing pool’ mediating between healthy, damaged and radio-adapted animals. The endpoints of the model are repairable radiation damage (morbidity), impairment of reproductive ability and mortality. The focus of the model is the Red Forest, an area some 3 km west of the Chernobyl Nuclear Power Plant. We simulated ecosystem effects of both current exposures and historical doses, including transgenerational effects and adaptation. The results highlight the primary role of animal mobility in stabilising the vole population after the accident, the importance of ecosystem recovery, the time evolution of the repairing and fecundity pools and the impact of adaptation on population sustainability. Using this model, we found dose rate tipping points for mortality and morbidity, along with a limiting migration rate for population survival and the limiting size of the most contaminated region not entailing loss of survival. Our ecosystem approach to radioecological modelling enables an exploration of the impact of radiation in an ecological context, consistent with the available observations. Model predictions indicate that population sensitivity in our exposure scenario does not contradict the benchmarks currently considered in risk assessments for wildlife. The model can be used to support advice on the extent to which historical doses and other ecological factors may influence different exposure modelling scenarios. The approach could easily be adapted to accommodate other stressors, thereby contributing to the evaluation of the regulatory benchmarks used in non-radiological risk assessment

Vole population cycles and the role of colonisation

The multiannual population cycles in small rodents have triggered an intense debate between proponents of population-intrinsic and community-extrinsic factors as the cycle generating mechanisms. A well-known challenge is the apparent absence of vole individuals during the low phase of the population cycle and the fact that most studies addressing vole and lemming behaviour and demography are conducted at high to moderate population densities. Overall this thesis aim to (1) present new insight for the least studied phase(s)of the vole population cycles: specifically the role of colonisation processes in the transition from small isolated populations in the low-phase to the spatially extensively distributed populations in the peak phase of the cycle, and (2) provide an updated view on how population-intrinsic and community-extrinsic processes may interact during the vole population cycles. The first experiment documented that colonisation is a beneficial strategy in female bank voles (Myodes glareolus) compared to immigration. The second experiment demonstrated that the first born cohort of root voles (Microtus oeconomus) emigrating in early summer have large capacity for colonising spatially scattered habitat patches – a capacity that explains the fast recolonistation of empty habitat space following crashes in cyclic populations. These experimental results also gave evidence for presence of social fences around high quality habitats at low population density. Hence, in the increase phase voles seem to actively search for vacant habitats and settle in them conditional on habitat quality and population density. An observational study of a riparian mainland-island root vole metapopulation confirmed that such patchy populations with cyclic dynamics may be subject to extensive occupancy dynamics. However, owing to high capacities for dispersal and habitat tracking, voles rapidly colonised the high quality islands across the entire metapopulation landscape that previously had gone extinct due to demographic (small population size) and environmental (high water levels) stochasticity. In total, the experimental and observational studies show that spatially scattered (sub)populations that have survived the crash phase are able to provide colonists to remote habitat patches embedded in hostile matrix and thus pave the way to a new increase and peak phase. The updated view on the causes of population cycles in voles emphasises the important role of dispersal (colonisation) and sociality in all phases of the cycle. It is not claimed that intrinsic mechanisms, either alone or in interactions with extrinsic factors, are necessary for generating multiannual cycles. Rather that the interaction between extrinsic and intrinsic factors likely contribute to shape rodent population dynamics, and that different innate propensities for sociality and dispersal among different rodent species may be related to interspecific variation in topology of the cycles (i.e. cycle shape and amplitude) and degree of spatial population synchrony

Smitteisolasjon i somatiske avdelinger: Hva oppleves som mest belastende for pasientens psykiske helse under isolasjonsregimet, og hvordan kan dette forebygges av sykepleier

Introduksjon: Smittevern i somatiske avdelinger medfører ofte isolasjon av pasienten for å bryte smittekjeden. Dette kan oppleves som belastende for pasienten av ulike årsaker. Hensikt: Økt kunnskap rundt hvilke faktorer som virker mest belastende for pasienten i isolasjonssituasjonen vil lettere kunne bidra til å finne riktige forebyggende sykepleietiltak. Metode: Litteraturstudie, med 7 vitenskapelige artikler som primærkilder. Artikkelen er kritisk vurdert, analysert og deretter sammenfattet og underbygget av faglitteratur og teoretisk perspektiv. Benyttede søkeord: Patient isolation, Infection control, Psychological stress, Source isolation, Experience, Infected, Infection isolation, MRSA, Psychological. Hovedresultat: Deltakerne i studiene opplever manglende informasjon om egen helsetilstand og behandling, og utilstrekkelig pleietilbud som mest belastende. Flere opplever økende depressive symptomer som virker å tilta i takt med tiden i isolat. Konklusjon: Økt kunnskap hos pasient og sykepleier kan bidra til økt følelse av trygghet og kontroll hos den isolerte pasienten. Dette avhenger av tilstrekkelig informasjon ut ifra pasientens behov og forutsetninger. På samme måte gjelder dette også pleietilbudet. Pasienten må føle å ha samme rettigheter og tilbud som pasienter utenfor isolat. Dette er konkrete områder å jobbe utafra for å kunne oppnå gode forebyggende tiltak, rettet mot negative reaksjoner som for eksempel depresjon

Sammenhengen mellom Sosial Støtte, Frykt for Covid-19 og Jobbtilfredshet blant Norske Arbeidstakere

Med utgangspunkt i Event Systems Theory (EST) og jobbkrav-ressursmodellen (JD-R) var hensikten med denne studien å undersøke sammenhengen mellom sosial støtte på arbeidsplassen, frykt for Covid-19 og jobbtilfredshet blant norske arbeidstakere. Studien konkluderte med at det virket til å være en sammenheng mellom sosial støtte og jobbtilfredshet for ansatte innen to ulike norske næringer, mens frykt for Covid-19 kun så ut til å ha sammenheng med jobbtilfredshet for ansatte innen den ene næringen. I studien ble det benyttet bekvemmelighetsutvalg som metode for å rekruttere respondenter til å besvare et digitalt spørreskjema. Totalt besvarte 629 respondenter spørreskjemaet som ble distribuert via en lenke i et informasjonsskriv. Dataene ble samlet inn og klargjort i et datasett som var utgangspunkt for studiens statistiske analyser. Resultatene fra to hierarkiske regresjonsanalyser fant en positiv signifikant sammenheng mellom sosial støtte fra kollegaer og ledere med økt opplevelse av jobbtilfredshet for ansatte innen to ulike norske næringer. Derimot ble det funnet en negativ signifikant sammenheng mellom frykt for Covid-19 og jobbtilfredshet kun for ansatte innen den ene næringen. Funnene fra denne studien kan bidra til å gi et bilde på jobbtilfredshet blant norske arbeidstakere under pandemien, samt å inspirere til videre forskning på frykt for Covid-19 og jobbtilfredshet. Studien fastslår ingen kausale forhold, det oppfordres derfor til videre forskning med longitudinelt design for å forstå kausale forhold ved frykt og jobbtilfredshet og effekt av disse over tid