scholarly journals Tree cover change proves stability and instability in tropical ecosystems

2021 ◽  
Author(s):  
Chandrakant Singh ◽  
Ruud van der Ent ◽  
Lan Wang-Erlandsson ◽  
Ingo Fetzer
Keyword(s):  
Storage Capacity ◽  
Temporal Dynamics ◽  
Root Zone ◽  
Tree Cover ◽  
Tropical Ecosystems ◽  
Forest Resilience ◽  
Stability And Instability ◽  
Temporal Aspects ◽  
Time Substitution ◽  
The Relationship

Terrestrial tropical ecosystems’ resilience is determined predominantly based on space-for-time substitution, which assumes that the current ‘static’ frequency distribution of ecosystems’ tree cover structure across space also holds across time. However, dynamic and temporal aspects are increasingly important to explicitly account for under ongoing rapid climate change. Here, we empirically study ecosystem stability and instability using remote sensing-derived tree cover change (ΔTC) over the last two decades. We find that considerable ΔTC predominantly takes place in intermediate tree cover ecosystems (i.e., areas with 30-60% tree cover), whereas high (>75%) and low (<10%) tree cover ecosystems only experience limited ΔTC. Our results further suggest that root zone storage capacity, which defines the adaptive capacity of the ecosystem to absorb water stress perturbations, does mediate the relationship between ecosystems’ stability and ΔTC by instigating investment in ecosystems subsoil structure. Based on these analyses, we propose a modified forest resilience metric using both precipitation and root zone storage capacity, which reveals that the Congo rainforests are more resilient than if only precipitation is considered. This study emphasises the importance of temporal dynamics and adaptation of ecosystems in inferring and assessing the risk of forest-savannah transitions under change.

The visual arrays task…visual storage capacity or attention control?

2019 ◽  
Author(s):  
Jessie Martin ◽  
Jason S. Tsukahara ◽  
Christopher Draheim ◽  
Zach Shipstead ◽  
Cody Mashburn ◽  
...  
Keyword(s):  
Working Memory ◽  
Storage Capacity ◽  
Working Memory Capacity ◽  
Memory Capacity ◽  
Attention Control ◽  
Data Sets ◽  
Independent Data ◽  
Visual Storage ◽  
Design Selection ◽  
The Relationship

**The uploaded manuscript is still in preparation** In this study, we tested the relationship between visual arrays tasks and working memory capacity and attention control. Specifically, we tested whether task design (selection or non-selection demands) impacted the relationship between visual arrays measures and constructs of working memory capacity and attention control. Using analyses from 4 independent data sets we showed that the degree to which visual arrays measures rely on selection influences the degree to which they reflect domain-general attention control.

Auf der Suche nach der Zeit als narratologische Analysekategorie. Mit Beispielen aus der setsuwa-Literatur

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sebastian Balmes
Keyword(s):  
Classical Theory ◽  
Historical Development ◽  
Textual Analysis ◽  
Cognitive Theory ◽  
Temporal Dynamics ◽  
Narrative Text ◽  
Narrative Discourse ◽  
Time Concepts ◽  
The Relationship ◽  
Gerard Genette

Abstract There are three levels on which time is constitutive for narrative discourse: a) without time events as well as the story world cannot be conceived; b) time is needed to tell a story; c) the recipient of a narrative text makes temporal connections by recalling something that happened earlier in the story or the way in which something has been told, or by wondering how the narrative will continue. An examination of these levels shows, however, that the underlying time concepts or temporalities differ significantly. In most narratological studies, the focus lies on the relationship between ‘narrated time’ and ‘narrating time’ (Günther Müller, “Die Bedeutung der Zeit in der Erzählkunst,” 1947), pertaining to what Gérard Genette (“Discours du récit,” 1972) has systematized under the categories of ‘order,’ ‘duration,’ and ‘frequency.’ While a textual analysis based on these concepts may lead to promising results, there are also limitations to this approach. Using examples from Japanese twelfth- to thirteenth-century setsuwa literature, I demonstrate that Meir Sternberg’s (“Telling in Time (II): Chronology, Teleology, Narrativity,” 1992) cognitive theory based on reception and centered around the temporal dynamics of suspense, curiosity, and surprise provides a useful toolkit to make sense of narratives where ‘classical’ theory fails. The application on a tale from Konjaku monogatari shū (24:11) has implications for our understanding of the transmission of the story and allows us to reject one existing theory of the historical development of the tale.

Biological, Ecological, and Distributional Aspects of Two Native Species of Lucilia Genus (Diptera: Calliphoridae) of Forensic Interest in Yungas Environments of Argentina

2020 ◽  
Vol 57 (6) ◽  
pp. 1700-1711
Author(s):  
X Acosta ◽  
A X González-Reyes ◽  
N D Centeno ◽  
J A Corronca
Keyword(s):  
Native Species ◽  
Temporal Dynamics ◽  
Synergistic Effects ◽  
Habitat Preferences ◽  
Warm Season ◽  
Sun Exposure ◽  
Late Summer ◽  
Cold Season ◽  
Tree Cover ◽  
Native Habitats

Abstract This study determined the spatial and temporal dynamics of two native neotropical species flies of forensic interest, belonging to the Lucilia (Robineau-Desvoidy) genus. The study focused on their abundance and reproductive behaviors associated with different habitats and phenological parameters. In the Province of Salta, Argentina, monthly samplings were performed over 1 yr in urban, rural, and native habitats, at morning, mid-day, and afternoon periods, controlling the oviposition of captured specimens. Environmental variables were also assessed: cloudiness, precipitation, relative humidity, temperature, and tree cover. Lucilia purpurascens (Walker) appeared to be associated with native habitats, whereas Lucilia ochricornis (Wiedemann) was mainly associated with rural habitats, exhibiting distinct habitat preferences. Two ecotones were also identified: rural–urban and rural–native, suggesting rural habitats promoted habitable conditions at its margins. Both species were recorded at the end of winter to the middle of autumn, with an initial peak in early spring, and a second peak at late summer. These peaks were associated with the highest numbers of laid eggs. Lucilia purpurascens preferred high tree coverings, whereas L. ochricornis resisted areas with intermediate sun, suggesting limited sun exposure was important. The latter was also associated with daily flight activities; during the warm season, the densest catches occurred at morning and afternoon periods, whereas during the cold season, they occurred at mid-day. Climatic variables explained 77% of variability in terms of abundance and oviposition. Synergistic effects were observed between these variables, suggesting that these variables conditioned insect distribution and reproduction, and not just temperature per se.

#MeToo, Networked Acknowledgment, and Connective Action: How “Empowerment Through Empathy” Launched a Social Movement

2019 ◽  
pp. 089443931986488 ◽  
Author(s):  
Jiyoun Suk ◽  
Aman Abhishek ◽  
Yini Zhang ◽  
So Yun Ahn ◽  
Teresa Correa ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Computational Approaches ◽  
Part Of Speech Tagging ◽  
Part Of Speech ◽  
Personal Experiences ◽  
Connective Action ◽  
News Event ◽  
The Relationship ◽  
Speech Tagging ◽  
Do So

How did efforts that prompted the sharing of personal experiences of sexual violence and harassment around #MeToo coalesce into calls for action across a range of institutions and communities? We argue that sharing experiences of trauma in digital spaces created a network of acknowledgment, which supported and sustained nascent #MeToo activism based on the logic of connective action. This article attempts to (a) understand the temporal dynamics of these different discourses within the #MeToo movement on Twitter, (b) reveal the accounts animating these discourses and the most prominent themes within them, and (c) model the overtime relationship between these discourses and their relationship to major news event and #MeToo revelations. To do so, we analyze a 1% sample of tweets from the 5-month period following the revelations about Harvey Weinstein in early October 2017, employing a range of computational approaches, including part-of-speech tagging, dependency analysis, hashtags extraction, and retweet network analysis—to identify key discourses, actors, and themes. We then conduct time series analysis to identify the relationship between the two discourses and predict how the ebbs and flows of each discourse are shaped by news events.

scholarly journals Effects of Initial Epidemic Conditions, Sporulation Rate, and Spore Dispersal Gradient on the Spatio-Temporal Dynamics of Plant Disease Epidemics

1998 ◽  
Vol 88 (10) ◽  
pp. 1000-1012 ◽  
Author(s):  
X.-M. Xu ◽  
M. S. Ridout
Keyword(s):  
Spatial Pattern ◽  
Power Law ◽  
Temporal Dynamics ◽  
Initial Conditions ◽  
Disease Incidence ◽  
Disease Status ◽  
Spatio Temporal ◽  
Disease Epidemics ◽  
Sporulation Rate ◽  
The Relationship

A stochastic model that simulates the spread of disease over space and time was developed to study the effects of initial epidemic conditions (number of initial inocula and their spatial pattern), sporulation rate, and spore dispersal gradient on the spatio-temporal dynamics of plant disease epidemics. The spatial spread of disease was simulated using a half-Cauchy distribution with median dispersal distance μ (units of distance). The rate of temporal increase in disease incidence (βI, per day) was influenced jointly by μ and by the sporulation rate λ (spores per lesion per day). The relationship between βI and μ was nonlinear: the increase in βI with increasing μ was greatest when μ was small (i.e., when the dispersal gradient was steep). The rate of temporal increase in disease severity of diseased plants (βS) was affected mainly by λ: βS increased directly with increasing λ. Intraclass correlation (κt), the correlation of disease status of plants within quadrats, increased initially with disease incidence, reached a peak, and then declined as disease incidence approached 1.0. This relationship was well described by a power-law model that is consistent with the binary form of the variance power law. The amplitude of the model relating κt to disease incidence was affected mainly by μ: κt decreased with increasing μ. The shape of the curve was affected mainly by initial conditions, especially the spatial pattern of the initial inocula. Generally, the relationship of spatial autocorrelation (ρt,k), the correlation of disease status of plants at various distances apart, to disease incidence and distance was well described by a four-parameter power-law model. ρt,k increased with disease incidence to a maximum and then declined at higher values of disease incidence, in agreement with a power-law relationship. The amplitude of ρt,k was determined mainly by initial conditions and by μ: ρt,k decreased with increasing μ and was lower for regular patterns of initial inocula. The shape of the ρt,k curve was affected mainly by initial conditions, especially the spatial pattern of the initial inocula. At any level of disease incidence, autocorrelation declined exponentially with spatial lag; the degree of this decline was determined mainly by μ: it was steeper with decreasing μ.

Changes in root zone storage capacity and their effects on river discharge and gross primary production

2020 ◽  
Author(s):  
Rodolfo Nóbrega ◽  
David Sandoval ◽  
Colin Prentice
Keyword(s):  
Land Cover ◽  
Primary Production ◽  
Mass Balance ◽  
Land Cover Change ◽  
Storage Capacity ◽  
Root Zone ◽  
Gross Primary Production ◽  
Terrestrial Ecosystem ◽  
Ecosystem Models ◽  
Stress Functions

&lt;p&gt;Root zone storage capacity (R&lt;sub&gt;z&lt;/sub&gt;) is a parameter widely used in terrestrial ecosystem models that estimate the amount of soil moisture available for transpiration. However, R&lt;sub&gt;z&lt;/sub&gt; is subject to large uncertainty, due to the lack of data on the distribution of soil properties and the depth of plant roots that actively take up water. Our study makes use of a mass-balance approach to investigate R&lt;sub&gt;z&lt;/sub&gt; in different ecosystems, and changes in water fluxes caused by land-cover change. The method needs no land-cover or soil information, and uses precipitation (P) and evapotranspiration (ET) time series to estimate the seasonal water deficit. To account for some of the uncertainty in ET, we use different methods for ET estimation, including methods based on satellite estimates, and modelling approaches that back-calculate ET from other ecosystem fluxes. We show that reduced ET due to land-cover change reduces R&lt;sub&gt;z&lt;/sub&gt;, which in turn increases baseflow in regions with a strong rainfall seasonality. This finding allows us to analyse the trade-off between gross primary production and hydrological fluxes at river basin scales. We also consider some ideas on how to use mass-balance R&lt;sub&gt;z&lt;/sub&gt; in water-stress functions as incorporated in existing terrestrial ecosystem models.&lt;/p&gt;

scholarly journals Relationship of the BOLD Signal with VEP for Ultrashort Duration Visual Stimuli (0.1 to 5 ms) in Humans

2009 ◽  
Vol 30 (2) ◽  
pp. 449-458 ◽  
Author(s):  
Barış Yeşilyurt ◽  
Kevin Whittingstall ◽  
Kâmil Uğurbil ◽  
Nikos K Logothetis ◽  
Kâmil Uludağ
Keyword(s):  
Brain Function ◽  
Temporal Dynamics ◽  
Visual Stimulation ◽  
Impulse Response Function ◽  
Blood Oxygenation ◽  
Context Dependency ◽  
Oxygenation Level ◽  
Relationship Of ◽  
The Relationship ◽  
The Brain

There is currently a great interest to combine electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to study brain function. Earlier studies have shown different EEG components to correlate well with the fMRI signal arguing for a complex relationship between both measurements. In this study, using separate EEG and fMRI measurements, we show that (1) 0.1 ms visual stimulation evokes detectable hemodynamic and visual-evoked potential (VEP) responses, (2) the negative VEP deflection at ∼80 ms (N2) co-varies with stimulus duration/intensity such as with blood oxygenation level-dependent (BOLD) response; the positive deflection at ∼120 ms (P2) does not, and (3) although the N2 VEP–BOLD relationship is approximately linear, deviation is evident at the limit of zero N2 VEP. The latter finding argues that, although EEG and fMRI measurements can co-vary, they reflect partially independent processes in the brain tissue. Finally, it is shown that the stimulus-induced impulse response function (IRF) at 0.1 ms and the intrinsic IRF during rest have different temporal dynamics, possibly due to predominance of neuromodulation during rest as compared with neurotransmission during stimulation. These results extend earlier findings regarding VEP–BOLD coupling and highlight the component- and context-dependency of the relationship between evoked potentials and hemodynamic responses.

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