Although sound production requires energy, it has been unclear how much singing increases metabolic rate in passerine birds. We measured the rate of oxygen consumption of two breeds of canary that ...sang inside a respirometry chamber. Metabolic rate increased with the proportion of time that birds spent singing. Average metabolic rate during singing at 15–20°C was 1.05–1.07 times that of standing quietly in the same temperature range or 2.2–2.6 times basal metabolic rate (BMR). Whether an increase in metabolic rate during song of this order would represent a fitness cost to free-living passerine birds would depend upon the circumstances. Singing rather than perching during the day would raise metabolic rate only slightly. Singing at night or at dawn, instead of sleeping with a metabolic rate closer to BMR, would cause a greater increase in metabolism. Birdsong could act as a condition-dependent signal, since birds that are easily able to achieve energy balance could afford the cost of singing, but those close to their energy limits might not. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
Animals often face complex and changing food environments. While such environments are challenging, an animal should make an association between a food type and its properties (such as the presence ...of a nutrient or toxin). We use information theory concepts, such as mutual information, to establish a theory for the development of these associations. In this theory, associations are assumed to maximize the mutual information between foods and their consequences. We show that associations are invariably imperfect. An association’s accuracy increases with the length of a feeding session and the relative frequency of a food type but decreases as time delay between consumption and postingestive consequence increases. Surprisingly, the accuracy of an association is independent of the number of additional food types in the environment. The rate of information transfer between novel foods and a forager depends on the forager’s diet. In light of this theory, an animal’s diet may have two competing goals: first, the provision of an appropriate balance of nutrients, and second, the ability to quickly and accurately learn the properties of novel foods. We discuss the ecological and behavioral implications of making associational errors and contrast the timescale and mechanisms of our theory with those of existing theory.
In-situ diffraction study of Ba2In2O5 SPEAKMAN, S. A; RICHARDSON, J. W; MITCHELL, B. J ...
Solid state ionics,
08/2002, Letnik:
149, Številka:
3-4
Journal Article
Abstract
Background
Device impedance for subcutaneous ICDs (S-ICDs) may rise over time reflecting changes in tissue electrical conduction due to fibrosis from the natural foreign body response, ...increasing the risk of defibrillation failure. A biologic envelope optimized for S-ICDs may mitigate fibrosis and encourages angiogenesis around the device possibly decreasing impedance rise over time. The S-ICD system performs routine low-voltage Z-lead (LVZ) impedance testing (impedance between shocking coil and can) that may provide insight into the impedance changes on device functionality and efficacy over time.
Purpose
Explore early and late impedance changes over time in S-ICDs implanted with and without envelopes using periodic LVZ measurements.
Methods
30 patients received S-ICDs (15 with envelope) between 1/2017 and 3/2021, after excluding those with device complications, uncontrolled comorbidities, or recent cardiac surgery. Impedance data was recorded at initial implantation. LVZ impedance data was extracted from the wireless remote monitoring system, trended over 0–4 years post implant, and analyzed blinded to patient information.
Results
24 patients (12 envelope) had evaluable implant and chronic data sets. Baseline clinical characteristics were similar between groups. Impedance in general was higher in the envelope group at initial implantation (LVZ mean 89 Ω vs 74 Ω) and throughout the first year. Comparing envelope to no envelope, the initial average shock impedance was 87.3±30.50 vs 66.7±10.40, followed by an average low-V impedance drop of 29 Ω vs 17 Ω during the first month, with a recovery to 109 Ω vs 91 Ω at 30 months post implant. After 30 months, impedance trends demonstrated a modest linear increase up to 48 months in the no envelope group in comparison with a modest decrease in the envelope group (sample sizes too small to determine significance) (Figure 1).
Conclusion
The results demonstrate periodic LVZ testing in the S-ICD monitoring system can reliably trend changes in system impedance over time. Impedance measurements within the first 6–7 months (and most markedly within the first 3 months) appear to be transiently lower than the values seen after this timepoint suggesting that early impedance measurements may not predict steady-state impedance. Further studies are needed to explore the impact of envelope use and the S-ICD impedance changes beyond 30 months.
Funding Acknowledgement
Type of funding sources: None.
Our understanding of complex marine ecosystem dynamics is often hindered by significant uncertainties and issues of representativeness associated with models and observations. Both observations and ...models provide a limited view of real-world complexities depending on what is specifically measured or simulated. When used together, they provide the ability to gain a broader understanding of important ecological processes. How to properly integrate models and observations while utilizing the advantages of both approaches remains a challenge. In this paper, we draw attention to commonly overlooked limitations of both observations and models, and use examples to illustrate potential strategies to mitigate bias, properly interpret results, and help improve both models and observations. We emphasize that proper validation of all data sources (models and observations) is necessary in all marine ecosystem studies, with a careful assessment of the spatio-temporal scales that the data represent.
Development of adequate diving capabilities is crucial for survival of seal pups and may depend on age and body size. We tracked the diving behavior of 20 gray seal pups during their first 3 mo at ...sea using satellite relay data loggers. We employed quantile analysis to track upper limits of dive duration and percentage time spent diving, and lower limits of surface intervals. When pups first left the breeding colony, extreme (ninety-fifth percentile) dive duration and percentage time spent diving were positively correlated with age, but not mass, at departure. Extreme dive durations and percentage time spent diving peaked at
d of age at values comparable with those of adults, but were not sustained. Greater peaks in extreme percentage time spent diving occurred in pups that had higher initial values, were older at their peak, and were heavier at departure. Pups that were smaller and less capable divers when they left the colony improved extreme dive durations and percentage time spent diving more rapidly, once they were at sea. Minimum survival time correlated positively with departure mass. Pups that were heavier at weaning thus benefitted from being both larger and older at departure, but smaller pups faced a trade-off. While age at departure had a positive effect on early dive performance, departure mass impacted on peak percentage time spent diving and longer-term survival. We speculate that once small pups have attained a minimum degree of physiological development to support diving, they would benefit by leaving the colony when younger but larger to maximize limited fuel reserves, rather than undergoing further maturation on land away from potential food resources, because poor divers may be able to “catch up” once at sea.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Energy intake (EI) and physical activity energy expenditure (PAEE) are key modifiable determinants of energy balance, traditionally assessed by self-report despite its repeated demonstration of ...considerable inaccuracies. We argue here that it is time to move from the common view that self-reports of EI and PAEE are imperfect, but nevertheless deserving of use, to a view commensurate with the evidence that self-reports of EI and PAEE are so poor that they are wholly unacceptable for scientific research on EI and PAEE. While new strategies for objectively determining energy balance are in their infancy, it is unacceptable to use decidedly inaccurate instruments, which may misguide health-care policies, future research and clinical judgment. The scientific and medical communities should discontinue reliance on self-reported EI and PAEE. Researchers and sponsors should develop objective measures of energy balance.
Bioautography on thin-layer chromatograms was used to isolate six antifungal sesquiterpenes and three bisbibenzyls from
Bazzania trilobata. Their antifungal activities were compared by microtiter ...plate tests. Furthermore gymnomitr-8(12)-en-4-one and the new coumarin 7,8-dihydroxy-coumarin-7-
O-β-
d-glucuronide were isolated.
A dichloromethane and a methanol extract of the liverwort
Bazzania trilobata showed antifungal activity against the phytopathogenic fungi
Botrytis cinerea,
Cladosporium cucumerinum,
Phythophthora infestans,
Pyricularia oryzae and
Septoria tritici. Bioautography on thin-layer chromatograms was used to isolate six antifungal sesquiterpenes: 5- and 7-hydroxycalamenene, drimenol, drimenal, viridiflorol, gymnomitrol and three bisbibenzyls: 6
′,8
′-dichloroisoplagiochin C, isoplagiochin D and 6
′-chloroisoplagiochin D. Furthermore we report the isolation of gymnomitr-8(12)-en-4-one and the new coumarin 7,8-dihydroxycoumarin-7-
O-β-
d-glucuronide. Their structures have been elucidated based on extensive NMR spectral evidence.
Muller et al. 1 have provided a strong critique of the Genome-Wide Association Studies (GWAS) of body-mass index (BMI), arguing that the GWAS approach for the study of BMI is flawed, and has provided ...us with few biological insights. They suggest that what is needed instead is a new start, involving GWAS for more complex energy balance related traits. In this invited counter-point, we highlight the substantial advances that have occurred in the obesity field, directly stimulated by the GWAS of BMI. We agree that GWAS for BMI is not perfect, but consider that the best route forward for additional discoveries will likely be to expand the search for common and rare variants linked to BMI and other easily obtained measures of obesity, rather than attempting to perform new, much smaller GWAS for energy balance traits that are complex and expensive to measure. For GWAS in general, we emphasise that the power from increasing the sample size of a crude but easily measured phenotype outweighs the benefits of better phenotyping.
A resource acquisition–allocation model is developed to examine the trade-off between reproduction and somatic protection. Unlike previous studies, resource intake is not assumed to be constrained: ...instead, resource intake is free to vary, with increased intake being associated with an increased risk of somatic damage. This gives rise to an optimal resource intake as well as an optimal allocation strategy. This paper studies the relative importance of acquisition and allocation strategies in regulating acquisition-related mortality. Under the optimal allocation strategy mortality rate increases with age, in accordance with the disposable soma theory of aging. Contrary to the usual interpretation of the disposable soma theory, this increase in mortality can arise from an increase in the resource acquisition effort rather than a decrease in the resources allocated to protection. At early ages resource acquisition is found to be the primary path for regulating life history costs, whilst allocating resources to protection becomes more important later in life. Models for targeted and non-targeted damage repair are considered and the robustness of our results to the structure and parameterization of the model is discussed. The results from our models are discussed in light of published data. Resource acquisition is shown to be a potentially important mechanism for controlling somatic damage which deserves further study.
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