In structural dynamics a structure’s dynamic properties are often determined from its frequency-response functions (FRFs). Commonly, FRFs are determined by measuring a structure’s response while it ...is subjected to controlled excitation. Impact excitation performed by hand is a popular way to perform this step, as it enables rapid FRF acquisition for each individual excitation location. On the other hand, the precise location of impacts performed by hand is difficult to estimate and relies mainly on the experimentalist’s skills. Furthermore, deviations in the impact’s location and direction affect the FRFs across the entire frequency range. This paper proposes the use of ArUco markers for an impact-pose estimation for the use in FRF acquisition campaign. The approach relies on two dodecahedrons with markers on each face, one mounted on the impact hammer and another at a known location on the structure. An experimental setup with an analog trigger is suggested, recording an image at the exact time of the impact. A camera with a fixed aperture is used to capture the images, from which the impact pose is estimated in the structure’s coordinate system. Finally, a procedure to compensate for the location error is presented. This relies on the linear dependency of the FRFs in relation to the impact offset.
In this paper the belt-drive model using an absolute nodal coordinate formulation is presented. Using this approach the damping forces are usually neglected and only the elastic forces are taken into ...account. The aim of this paper is to introduce a damping mechanism into the belt-drive model and to verify it against experimental data. Different damping mechanisms are proposed for the damping of the longitudinal and bending deformations and several experiments were conducted in order to obtain the damping properties. Good agreement between the numerical result and the experimentally obtained data was found. Finally, the applicability of the belt-drive model was presented in a comparison with the pinned–pinned beam model.
The effect of tick infestations on body weight and various blood parameters was monitored in juvenile northern brown bandicoots (Isoodon macrourus) after release into tick-infested or tick-free ...enclosures. Three species of ticks were observed in the enclosures, Haemaphysalis humerosa, Ixodes tasmani and Ixodes holocyclus. Bandicoots released into tick-infested enclosures showed a reduced growth rate (1.8 versus 2.5 g/day increase in body weight), a reduced haematocrit value (27.4 versus 40.0%) and an increased number of white blood cells when compared with bandicoots released into tick-free enclosures. These results suggest that tick infestations may influence the health of juvenile I. macrourus.
The possum is a seasonally breeding marsupial which gives birth in Queensland from March through to September. To ascertain whether this seasonality in breeding is manifest in the male reproductive ...system, body weight and plasma testosterone concentrations were examined in five possums. Plasma testosterone concentrations fluctuated throughout the year and a seasonal cycle was observed, with a peak in testosterone concentration in March and a nadir in September. Body weights fluctuated in a similar manner. Statistical analysis suggested that the annual plasma testosterone profile correlated well with the rate of change of daylength.
1. The adult possums showed a circadian rhythm of body temperature with a peak in temperature around midnight and a nadir at noon. 2. The young possum within the pouch displayed a circadian rhythm ...with the highest temperatures during the day and the lowest in the early evening. 3. Although the body temperature of the young possum exceeded that of the mother occassionally, for the major part of the 24 hr the body temperature of the young was lower than that of the mother. 4. The young possum could maintain a steady body temperature between 140 and 167 days post partum. A circadian rhythm of temperature was observed between 157-190 days post partum. 5. All adipose tissue examined with the light and electron microscope had the morphology of white adipose tissue.
This study aimed at comparing the effects of a traditional finishing roughage-based diet and a higher energy diet, on growth, carcass characteristics, and feeding behaviour of Slovenian Cika and ...Simmental bulls (20 per breed). The experimental diets were: extensive (EXT) based on grass silage, and semi-intensive (S-INT) in which a part of the roughage was replaced with maize silage and sunflower meal. Each diet was fed ad libitum to 10 Cika (547 days old) and 10 Simmental (442 days old) bulls housed in group pens of five animals each. Growth performance was similar in both breeds, but Cika reached commercial finishing 1 month earlier than Simmental (139 vs 167 days; P = 0.016). Bulls fed S-INT had higher final weight (645.3 vs 590.1 kg; P = 0.05), average daily growth (1.05 vs 0.83 kg; P = 0.026), and feed intake (11.7 vs 10.6 kg dry matter (DM)/day; P < 0.001) than EXT bulls. Regardless of breed and diet, bulls ate 77–80% of the daily DM in the first 8 h after feed delivery. Bulls fed EXT showed longer standing (406.4 vs 355.8 min; P < 0.001) and eating (217.2 vs 155.3 min; P < 0.001) and shorter ruminating (77.5 vs 92.9 min; P < 0.001) times than S-INT bulls during the first 8 h of feed delivery. Cika bulls had lower full reticulo-rumen weights relative to slaughter weights (8.7 vs 10.7%; P = 0.002) than Simmental. The positive findings obtained with Cika cattle should encourage farmers to finish their young Cika male stocks for beef production, thus contributing to the maintenance of this animal genetic resource, and also to increase the energy density of the grass-based finishing diets by feeding supplements.
Anemia is an important global health challenge. We investigate anemia prevalence among Indigenous Shuar of Ecuador to expand our understanding of population-level variation, and to test hypotheses ...about how anemia variation is related to age, sex, and market integration.
Hemoglobin levels were measured in a total sample of 1650 Shuar participants (ages 6 months to 86 years) from 46 communities between 2008 and 2017 to compare anemia prevalence across regions characterized by different levels of market integration.
Shuar anemia rates among children under 15 years (12.2%), adult women (10.5%), and adult men (5.3%) were less than half of those previously documented in other neo-tropical Indigenous populations. Anemia prevalence did not vary between more traditional and market integrated communities (OR = 0.47, p = .52). However, anemia was negatively associated with body mass index (OR = 0.47, p = .002).
Compared to other South American Indigenous populations, anemia prevalence is relatively low among Shuar of Ecuador and invariant with market integration. Understanding this pattern can provide valuable insights into anemia prevention among at-risk populations.
Objectives
Little research exists documenting levels of intestinal inflammation among indigenous populations where exposure to macroparasites, like soil‐transmitted helminths (STHs), is common. ...Reduced STH exposure is hypothesized to contribute to increased prevalence of elevated intestinal inflammation in wealthy nations, likely due to coevolutionary histories between STHs and human immune systems that favored anti‐inflammatory pathways. Here, we document levels of intestinal inflammation and test associations with STH infection among the Shuar of Ecuador, an indigenous population undergoing socioeconomic/lifestyle changes that influence their hygienic environment. We predict that fecal calprotectin (FC; a measure of intestinal inflammation) will be lower in STH infected individuals and that FC will be negatively associated with infection intensity.
Methods
Stool samples to analyze FC levels and STH infection were collected from 69 Shuar participants (ages 5–75 years). Children (<15 years) and adults (15+ years) were analyzed separately to understand the role of exposure in immune system development and the intestinal inflammatory response.
Results
Two species of STH were present: Ascaris lumbricoides and Trichuris trichiura. The relationships between infection and intestinal inflammation were age‐ and species‐specific. While no significant relationships were found among adults, children who were singly infected with T. trichiura had lower FC levels than uninfected children. Infection intensity was not significantly associated with FC in children or adults.
Conclusions
These preliminary results provide limited support for our hypotheses, documenting tentative age‐ and species‐specific associations between FC and infection status. Findings may point to the importance of species‐specific STH exposure during immune system development.
Background: Market integration (MI)-increasing production for and consumption from a market-based economy-is drastically altering traditional ways of life and environmental conditions among ...indigenous Amazonian peoples. The effects of MI on the biology and health of Amazonian children and adolescents, however, remain unclear.
Aim: This study examines the impact of MI on sub-adult body size and nutritional status at the population, regional and household levels among the Shuar of Amazonian Ecuador.
Subjects and methods: Anthropometric data were collected between 2005-2014 from 2164 Shuar (aged 2-19 years) living in two geographic regions differing in general degree of MI. High-resolution household economic, lifestyle and dietary data were collected from a sub-sample of 631 participants. Analyses were performed to investigate relationships between body size and year of data collection, region and specific aspects of household MI.
Results: Results from temporal and regional analyses suggest that MI has a significant and overall positive impact on Shuar body size and nutritional status. However, household-level results exhibit nuanced and heterogeneous specific effects of MI underlying these overarching relationships.
Conclusion: This study provides novel insight into the complex socio-ecological pathways linking MI, physical growth and health among the Shuar and other indigenous Amazonian populations.
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