scholarly journals Age-Independent Adult Mortality in a Long-Lived Herb

Diversity ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 187 ◽  
Author(s):  
Edelfeldt ◽  
Lindell ◽  
Dahlgren
Keyword(s):  
General Pattern ◽  
Cost Of Reproduction ◽  
Mortality Rates ◽  
Adult Mortality ◽  
Trade Offs ◽  
Age Dependent ◽  
Annual Mortality ◽  
Age Independent ◽  
Long Term Studies

Relative to mammals and birds, little is known about the mortality trajectories of perennial plants, as there are few long-term demographic studies following multiple yearly cohorts from birth to death. This is particularly important because if reproductively mature individuals show actuarial senescence, current estimations of life spans assuming constant survival would be incorrect. There is also a lack of studies documenting how life history trade-offs and disturbance influence the mortality trajectories of plants. We conducted Bayesian survival trajectory analyses (BaSTA) of a 33-year individual-based dataset of Pulsatilla vulgaris ssp. gotlandica. Mortality trajectories corresponded to “Type III” survivorship patterns, with rapidly decreasing annual mortality rates for young plants, but with constant mortality for reproductively mature individuals. We found trade-off effects resulting in a cost of growth for non-reproductive plants but no apparent cost of reproduction. Contrarily to our expectation, young plants that had previously shrunk in size had a lower mortality. However, accounting for trade-offs and disturbance only had minor effects on the mortality trajectories. We conclude that BaSTA is a useful tool for assessing mortality patterns in plants if only partial age information is available. Furthermore, if constant mortality is a general pattern in polycarpic plants, long-term studies may not be necessary to assess their age-dependent demography.

scholarly journals Dynamics of Tropical Forest Twenty-Five Years after Experimental Logging in Central Amazon Mature Forest

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 89 ◽  
Author(s):  
Márcio Amaral ◽  
Adriano Lima ◽  
Francisco Higuchi ◽  
Joaquim dos Santos ◽  
Niro Higuchi
Keyword(s):  
Tropical Forest ◽  
Mortality Rates ◽  
Selective Logging ◽  
Managed Forests ◽  
Tropical Regions ◽  
Striking Increase ◽  
Natural Dynamics ◽  
Annual Mortality ◽  
Long Term Studies

Long-term studies of the dynamics of managed forests in tropical regions are lacking. This study aimed to evaluate the dynamics of a tropical forest, over a 25-year period, that was experimentally logged in 1987 and 1988 and submitted to three different cutting intensities. All trees with diameter at breast height (DBH) ≥ 10 cm have been measured annually since 1990. The three logging intensities that were applied were: light (T1)-trees harvested with DBH ≥ 55 cm; medium (T2)-DBH ≥ 50 cm; and heavy (T3)-DBH ≥ 40 cm. Control plots (T0) were also monitored. The highest mean annual mortality rates (1.82% ± 0.38), recruitment rates (2.93% ± 0.77) and diameter increments (0.30 ± 0.02 cm) occurred in the T3 treatment. Shifts in dynamics of the forest were mainly caused by a striking increase in a fast-growing pioneer species and their high mortality rates. The loss in stocking caused by mortality was greater than to that of replacement by recruitment. The results demonstrated that selective logging altered the natural dynamics of the forest through increased: mortality rates, recruitment and growth rates of the residual trees.

The age structure of a striped maple population

1979 ◽  
Vol 9 (4) ◽  
pp. 504-508 ◽  
Author(s):  
David E. Hibbs
Keyword(s):  
Structure Analysis ◽  
High Mortality ◽  
Age Structure ◽  
Mortality Rates ◽  
Population Age Structure ◽  
Survivorship Curve ◽  
Age Dependent ◽  
Gap Phase ◽  
Annual Mortality

Cohort and population age structure analysis showed that, after the initially high mortality rates of the 1st year (87.5%), striped maple seedlings (Acerpensylvanicum L.) underwent practically no mortality until the age of 15. Annual mortality was up (3.8%) between the ages of 16 and 40, then dropped to a lower level (1.6%). Mortality was age dependent and generally density independent. The survivorship curve agrees well with a pattern that could be expected of a species whose strategy is gap phase replacement.

Comparative mortality rates of Bos indicus and Bos taurus cattle in central Queensland

1973 ◽  
Vol 13 (61) ◽  
pp. 127 ◽  
Author(s):  
JE Frisch
Keyword(s):  
Birth Weight ◽  
First Generation ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Mortality Rates ◽  
Adult Mortality ◽  
The Difference ◽  
Annual Mortality ◽  
Zebu Breed ◽  
Zebu Cows

A study was made over several years of lifetime mortality rates of both purebred Bos taurus and Bos indicus breeds and of several generations of crosses between the breeds. Of 4,678 calves born during the period, 4.7 per cent died at or within one week of birth. A further 2.3 per cent of those remaining died before weaning and a further 1.1 per cent died from weaning to 15 months. Sixteen of 22 calves born as twins were perinatal mortalities. Perinatal losses were highest in purebred Zebus (Africander and Brahman) and in first generation Brahman crossbred (BX) calves. Africander crossbreds (AX) generally had the lowest mortality rates of all crossbreds at each stage of the life cycle. Perinatal mortalities were however high in both F1 AX and F1 BX calves born to primiparous purebred British (Hereford and Shorthorn) heifers. Over all crossbred generations, perinatal mortalities were highest in calves from 3-year-old heifers and decreased with age of dam. More males (4.7 per cent) than females (2.9 per cent) died at or near birth. Mortalities in F1 BX males (10.3 per cent) were the highest of all groups. Relatively high or low birth weight was associated with high perinatal mortalities in the crossbreeds. Losses of stock after weaning were generally higher in the British breed-types than in the Zebu breed-types with the greatest differences in adult mortality rates. Annual mortality rates of breeding cows of each breed were studied over a similar period. 9,537 cow years were involved in the study. Mortality rates of both purebred and crossbred British cows were higher than for purebred and crossbred Zebu cows. One contributing cause was the difference in numbers of cows of each breed that died while calving. In all, 1.4 per cent of British crossbred calvings resulted in the death of the cow compared with 0.6 and 0.3 per cent for comparable AX and BX cows. Losses were negligible in purebred Zebus. Mortality rates in adults generally increased slowly with age and were highest in 8 - 10-year-old cows.

What is the optimum solar proxy for long-term ionospheric studies?

2021 ◽  
Author(s):  
Jan Laštovička
Keyword(s):  
Solar Activity ◽  
Ionizing Radiation ◽  
Sunspot Number ◽  
General Pattern ◽  
Data Series ◽  
Lyman Alpha ◽  
Yearly Average ◽  
Selection Of ◽  
Long Term Studies

<p>For long-term studies as ionospheric trends investigations we have to use proxies of solar activity, because homogenous and sufficiently long data series of solar ionizing radiation are not available. Here I deal with selection of the optimum solar proxy for yearly average and monthly median values near noon (11-13 LT). Six solar proxies are used, F10.7, F30, Mg II, He II, Fα (solar H Lyman alpha flux) and R (sunspot number), foF2 from European ionosondes Juliusruh, Pruhonice and Rome, and foE from Chilton and Juliusruh over the period 1976-2019. For yearly values Mg II is the optimum proxy (but it is available only since late 1978) for foF2, with F30 being the second best. For foE the optimum proxy appears to be F10.7. For monthly medians of January, April, July and October the general pattern is the same as for yearly values.</p>

Age structure, mortality and breeding in a population of agile wallabies (Macropus agilis)

2008 ◽  
Vol 56 (6) ◽  
pp. 431 ◽  
Author(s):  
Simon C. Stirrat
Keyword(s):  
Sex Ratio ◽  
Age Structure ◽  
Mortality Rates ◽  
Adult Mortality ◽  
Study Data ◽  
Life Table Analysis ◽  
Wet Season ◽  
Age Classes ◽  
Table Analysis ◽  
Annual Mortality

Aspects of the demography of the agile wallaby (Macropus agilis) were investigated in an overabundant population in East Point Reserve, Darwin. The maximum wet-season population size was relatively stable for several years before, and during, this study. Data suggest that the population fluctuated in size seasonally. Life table analysis indicated that mortality of animals up to 18 months old (including pouch young and young-at-foot) was high compared with adult mortality rates. After 18 months of age, mortality rates of males increased throughout life whereas those of females declined slightly and were relatively stable in older age classes. Females reproduced throughout the year, but more large pouch young were observed in the wet season than at other times of the year. The sex ratio of the population was female-biased, probably a result of higher mortality of males in the dry season. Predation by dogs was documented but contributed a relatively small fraction of total annual mortality.

scholarly journals Omitting age-dependent mosquito mortality in malaria models underestimates the effectiveness of insecticide-treated nets

2021 ◽  
Author(s):  
Melissa Alexis Iacovidou ◽  
Priscille Barreaux ◽  
Matthew B Thomas ◽  
Erin E Gorsich ◽  
Kat S Rock
Keyword(s):  
Mathematical Models ◽  
Mortality Rates ◽  
Vectorial Capacity ◽  
Insecticide Treated Nets ◽  
Mosquito Mortality ◽  
Age Dependent ◽  
Vector Borne ◽  
Mortality Function ◽  
The Impact ◽  
Age Independent

Mathematical models of vector-borne infections, including malaria, often assume age-independent mortality rates of vectors, despite evidence that many insects senesce. In this study we present survival data on insecticide-resistant Anopheles gambiae s.l. from field experiments in Côte d’Ivoire. We fit a constant mortality function and two age-dependent functions (logistic and Gompertz) to the data from mosquitoes exposed (treated) and not exposed (control) to insecticide-treated nets (ITNs), to establish biologically realistic survival functions. This enables us to explore the effects of insecticide exposure on mosquito mortality rates, and the extent to which insecticide resistance might impact the effectiveness of ITNs. We investigate this by calculating the expected number of infectious bites a mosquito will take in its lifetime, and by extension the vectorial capacity. Our results show that the predicted vectorial capacity is substantially lower in mosquitoes exposed to ITNs, despite the mosquitoes in the experiment being highly insecticide-resistant. The more realistic age-dependent functions provide a better fit to the experimental data compared to a constant mortality function and, hence, influence the predicted impact of ITNs on malaria transmission potential. In models with age-independent mortality, there is a reduction of 56.52% ( [[EQUATION]] 14.66) for the vectorial capacity under exposure compared to no exposure. However, the two age-dependent functions predicted a larger reduction due to exposure: for the logistic function the reduction is 74.38% ( [[EQUATION]] 9.93) and for the Gompertz 74.35% ( [[EQUATION]] 7.11), highlighting the impact of incorporating age in the mortality rates. These results further show that multiple exposures to ITNs had a considerable effect on the vectorial capacity. Overall, the study highlights the importance of including age dependency in mathematical models of vector-borne disease transmission and in fully understanding the impact of interventions.

Implications of Long-Term Studies of Three Model Preschool Programs for Head Start

2008 ◽  
Author(s):  
Lawrence J. Schweinhart ◽  
Elena V. Malofeeva ◽  
Lawrence J. Schweinhart ◽  
Michelle M. Englund ◽  
Arthur J. Reynolds ◽  
...  
Keyword(s):  
Head Start ◽  
Preschool Programs ◽  
Long Term Studies

Primary varicose veins

Phlebologie ◽  
2010 ◽  
Vol 39 (03) ◽  
pp. 133-137
Author(s):  
H. Partsch
Keyword(s):  
Varicose Veins ◽  
Compression Therapy ◽  
Daily Practice ◽  
Clinical Severity ◽  
Compression Stockings ◽  
Primary Varicose Veins ◽  
The Cost ◽  
Convincing Data ◽  
Long Term Studies

SummaryBackground: Compression stockings are widely used in patients with varicose veins. Methods: Based on published literature three main points are discussed: 1. the rationale of compression therapy in primary varicose veins, 2. the prescription of compression stockings in daily practice, 3. studies required in the future. Results: The main objective of prescribing compression stockings for patients with varicose veins is to improve subjective leg complaints and to prevent swelling after sitting and standing. No convincing data are available concerning prevention of progression or of complications. In daily practice varicose veins are the most common indication to prescribe compression stockings. The compliance depends on the severity of the disorder and is rather poor in less severe stages. Long-term studies are needed to proof the cost-effectiveness of compression stockings concerning subjective symptoms and objective signs of varicose veins adjusted to their clinical severity. Conclusion: Compression stockings in primary varicose veins are able to improve leg complaints and to prevent swelling.

Diatoms and aquatic palynomorphs in the sediments of the Eurasian Arctic seas and their significance for paleooceanological investigations in the Arctic

2019 ◽  
pp. 246-251
Author(s):  
Yelena I. Polyakova ◽  
Yekaterina I. Novichkova ◽  
Tatiana S. Klyuvitkina ◽  
Elizaveta A. Agafonova ◽  
Irina M. Kryukova
Keyword(s):  
Bering Sea ◽  
Surface Sediments ◽  
Sea Water ◽  
The Arctic ◽  
Marginal Filter ◽  
Arctic Seas ◽  
Hydrological Parameters ◽  
The Arctic Ocean ◽  
Long Term Studies

Presented the results of long-term studies of diatoms and aquatic palynomorphs in surface sediments of the Arctic seas and the possibility of their use for the reconstructions of paleocirculation water masses, advection of Atlantic and Bering sea water into the Arctic ocean, changes in the river runoff to the seas, sedimentary processes in the marginal filter of the largest rivers, seasonal sea ice cover and other hydrological parameters.

Aspects of the Evolution of the Romanian Tourists’ Preferences Concerning the Domestic Tourist Destinations

2019 ◽  
Vol 10 (1) ◽  
pp. 21-28
Author(s):  
Aniela Bălăcescu ◽  
Radu Șerban Zaharia
Keyword(s):  
Logistic Model ◽  
Local Level ◽  
Medium Term ◽  
Tourist Destinations ◽  
Tourism Management ◽  
Production And Consumption ◽  
On Line ◽  
The One ◽  
Long Term Studies

Abstract Tourist services represent a category of services in which the inseparability of production and consumption, the inability to be storable, the immateriality, and last but not least non-durability, induces in tourism management a number of peculiarities and difficulties. Under these circumstances the development of medium-term strategies involves long-term studies regarding on the one hand the developments and characteristics of the demand, and on the other hand the tourist potential analysis at regional and local level. Although in the past 20 years there has been tremendous growth of on-line booking made by household users, the tour operators agencies as well as those with sales activity continue to offer the specific services for a large number of tourists, that number, in the case of domestic tourism, increased by 1.6 times in case of the tour operators and by 4.44 times in case of the agencies with sales activity. At the same time, there have been changes in the preferences of tourists regarding their holiday destinations in Romania. Started on these considerations, paper based on a logistic model, examines the evolution of the probabilities and scores corresponding to the way the Romanian tourists spend their holidays on the types of tourism agencies, actions and tourist areas in Romania.

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