scholarly journals Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas

Ibis ◽  
2007 ◽  
Vol 149 ◽  
pp. 2-13 ◽  
Author(s):  
RICHARD T. HOLMES
Keyword(s):  
Population Change ◽  
Experimental Studies ◽  
Neotropical Migrants ◽  
Migratory Songbirds ◽  
Wintering Areas

scholarly journals Forest fragmentation in the temperate zone and its effects on migratory songbirds

1994 ◽  
Vol 4 (2-3) ◽  
pp. 233-249 ◽  
Author(s):  
Scott K. Robinson ◽  
David S. Wilcove
Keyword(s):  
Forest Fragmentation ◽  
Tropical Deforestation ◽  
Temperate Zone ◽  
Breeding Habitat ◽  
Neotropical Migrants ◽  
Population Declines ◽  
Migratory Songbirds

SummaryAlthough much attention has been paid to the impacts of tropical deforestation on populations of Neotropical migrants, fragmentation of breeding habitat may be an equally serious problem for many of these birds. Populations of many migrant songbirds have been declining in recent decades, especially within small woodlots. Censuses from woodlots of different sizes also consistently show that many migrant songbirds are area-sensitive, i.e. they are absent from all but the largest woodlots in a region. In contrast, long-term censuses from large, unfragmented forests show few consistent patterns of decline in Neotropical migrants. Population declines are therefore linked to forest fragmentation because they are most pronounced in small, isolated woodlots.

Masonry: the brittle or plastic material?

2019 ◽  
pp. 22-28
Keyword(s):  
Plastic Material ◽  
Experimental Studies ◽  
Point Of View ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
Base Materials ◽  
Stress States ◽  
Creep Deformations ◽  
Structural Point

The results of experimental studies of masonry on the action of dynamic and static (short-term and long-term) loads are presented. The possibility of plastic deformations in the masonry is analyzed for different types of force effects. The falsity of the proposed approach to the estimation of the coefficient of plasticity of masonry, taking into account the ratio of elastic and total deformations of the masonry is noted. The study of the works of Soviet scientists revealed that the masonry under the action of seismic loads refers to brittle materials in the complete absence of plastic properties in it in the process of instantaneous application of forces. For the cases of uniaxial and plane stress states of the masonry, data on the coefficient of plasticity obtained from the experiment are presented. On the basis of experimental studies the influence of the strength of the so-called base materials (brick, mortar) on the bearing capacity of the masonry, regardless of the nature of the application of forces and the type of its stress state, is noted. The analysis of works of prof. S. V. Polyakov makes it possible to draw a conclusion that at the long application of the load, characteristic for the masonry are not plastic deformations, but creep deformations. It is shown that the proposals of some authors on the need to reduce the level of adhesion of the mortar to the brick for the masonry erected in earthquake-prone regions in order to improve its plastic properties are erroneous both from the structural point of view and from the point of view of ensuring the seismic resistance of structures. It is noted that the proposal to assess the plasticity of the masonry of ceramic brick walls and large-format ceramic stone with a voidness of more than 20% is incorrect, and does not meet the work of the masonry of hollow material. On the basis of the analysis of a large number of research works it is concluded about the fragile work of masonry.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

scholarly journals Understanding sex differences in long-term blood pressure regulation: insights from experimental studies and computational modeling

2019 ◽  
Vol 316 (5) ◽  
pp. H1113-H1123 ◽  
Author(s):  
Sameed Ahmed ◽  
Rui Hu ◽  
Jessica Leete ◽  
Anita T. Layton
Keyword(s):  
Blood Pressure ◽  
Sex Differences ◽  
Computational Models ◽  
Experimental Studies ◽  
Pressure Control ◽  
Blood Pressure Regulation ◽  
Pressure Regulation ◽  
Physiological Processes ◽  
Key Players

Sex differences in blood pressure and the prevalence of hypertension are found in humans and animal models. Moreover, there has been a recent explosion of data concerning sex differences in nitric oxide, the renin-angiotensin-aldosterone system, inflammation, and kidney function. These data have the potential to reveal the mechanisms underlying male-female differences in blood pressure control. To elucidate the interactions among the multitude of physiological processes involved, one may apply computational models. In this review, we describe published computational models that represent key players in blood pressure regulation, and highlight sex-specific models and their findings.

scholarly journals Implementation Intentions to Reduce Smoking: A Systematic Review of the Literature

2020 ◽  
Author(s):  
Charlotte J Hagerman ◽  
Rebecca K Hoffman ◽  
Sruthi Vaylay ◽  
Tonya Dodge
Keyword(s):  
Systematic Review ◽  
Implementation Intentions ◽  
Experimental Studies ◽  
Implementation Intention ◽  
Promising Tool ◽  
Current Systematic Review ◽  
Long Term Follow Up ◽  
Positive Effect

Abstract Implementation intentions are a goal-setting technique in which an individual commits to perform a particular behavior when a specific context arises. Recently, researchers have begun studying how implementation intention (II) interventions can facilitate antismoking efforts. The current systematic review synthesized results of experimental studies that tested the effect of an II intervention on smoking cognitions and behavior. Of 29 reviewed articles, 11 studies met inclusion criteria. Nine studies (81.8%) tested an II intervention as a cessation tool for current smokers, whereas two tested II interventions as a tool to prevent smoking among predominantly nonsmoking adolescents. A majority of the studies (66.7%) testing II interventions as a cessation tool reported a positive effect on cessation at long-term follow-up. Of the two studies testing II interventions as a tool for prevention, one study found a positive effect on long-term follow-up. Methodology varied between the studies, highlighting the discrepancies between what researchers consider “implementation intentions” to be. II interventions are a promising tool for antismoking efforts, but more research is necessary to determine the best methodology and the populations for whom this intervention will be most effective. Implications Brief, free, and easily scalable, II interventions to prevent smoking are highly attractive for antismoking efforts. This review outlines the circumstances under which II interventions have demonstrated effectiveness in helping people resist smoking cigarettes. We illuminate gaps in the existing literature, limitations, methodological discrepancies between studies, and areas for future study.

Manipulating Environmental Commitment: A Replication and Extension

2021 ◽  
pp. 003329412110126
Author(s):  
Eric D. Wesselmann ◽  
Shane W. Boyd ◽  
Jordan A. Arellanes ◽  
Alexander Driskell ◽  
Matthew S. Hesson-McInnis
Keyword(s):  
Natural Environment ◽  
Behavioral Intentions ◽  
Subjective Experience ◽  
Experimental Studies ◽  
Environmental Commitment

Environmental commitment, the subjective experience of dependence on the natural environment, is marked by a long-term orientation and psychological attachment towards the natural environment. The current research replicates and extends previous research on temporarily increasing environmental commitment ( Davis et al., 2009 ). We employed Davis et al.’s manipulation in two experimental studies (one laboratory, one online): we asked participants to spend time writing either about ways in which they are interdependent with the natural environment (high commitment manipulation) or unconnected with the environment (low commitment manipulation). In both studies we replicated the key finding that reflecting on one’s interdependence with the environment increases commitment. We extended the previous research by finding evidence that this commitment effect was mediated by satisfaction with one’s relationship to the environment. We did not replicate the original findings that the interdependence manipulation influences environmental behavioral intentions.

scholarly journals Increasing frequency of low summer precipitation synchronizes dynamics and compromises metapopulation stability in the Glanville fritillary butterfly

2015 ◽  
Vol 282 (1806) ◽  
pp. 20150173 ◽  
Author(s):  
Ayco J. M. Tack ◽  
Tommi Mononen ◽  
Ilkka Hanski
Keyword(s):  
Population Dynamics ◽  
Population Change ◽  
Temporal Dynamics ◽  
Summer Precipitation ◽  
Life History Stage ◽  
General Effect ◽  
Spatial Synchrony ◽  
Glanville Fritillary Butterfly ◽  
Spatio Temporal

Climate change is known to shift species' geographical ranges, phenologies and abundances, but less is known about other population dynamic consequences. Here, we analyse spatio-temporal dynamics of the Glanville fritillary butterfly ( Melitaea cinxia ) in a network of 4000 dry meadows during 21 years. The results demonstrate two strong, related patterns: the amplitude of year-to-year fluctuations in the size of the metapopulation as a whole has increased, though there is no long-term trend in average abundance; and there is a highly significant increase in the level of spatial synchrony in population dynamics. The increased synchrony cannot be explained by increasing within-year spatial correlation in precipitation, the key environmental driver of population change, or in per capita growth rate. On the other hand, the frequency of drought during a critical life-history stage (early larval instars) has increased over the years, which is sufficient to explain the increasing amplitude and the expanding spatial synchrony in metapopulation dynamics. Increased spatial synchrony has the general effect of reducing long-term metapopulation viability even if there is no change in average metapopulation size. This study demonstrates how temporal changes in weather conditions can lead to striking changes in spatio-temporal population dynamics.

Harvest rate of sooty shearwaters (Puffinus griseus) by Rakiura Māori: a potential tool to monitor population trends?

2004 ◽  
Vol 31 (3) ◽  
pp. 319 ◽  
Author(s):  
Jane Catherine Kitson
Keyword(s):  
New Zealand ◽  
Cross Section ◽  
Large Scale ◽  
Population Change ◽  
Population Trends ◽  
Harvest Rate ◽  
General Index ◽  
Careful Screening ◽  
Potential Tool

Sooty shearwaters (tītī, muttonbird, Puffinus griseus) are highly abundant migratory seabirds, which return to breeding colonies in New Zealand. The Rakiura Māori annual chick harvest on islands adjacent to Rakiura (Stewart Island), is one of the last large-scale customary uses of native wildlife in New Zealand. This study aimed to establish whether the rate at which muttonbirders can extract chicks from their breeding burrows indicates population trends of sooty shearwaters. Harvest rates increased slightly with increasing chick densities on Putauhinu Island. Birders' harvest rates vary in their sensitivities to changing chick density. Therefore a monitoring panel requires careful screening to ensure that harvest rates of the birders selected are sensitive to chick density, and represents a cross-section of different islands. Though harvest rates can provide only a general index of population change, it can provide an inexpensive and feasible way to measure population trends. Detecting trends is the first step to assessing the long-term sustainability of the harvest.

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