Asynchronous Responses Research Articles

A visco-hyperelastic constitutive model of hydrogel considering the coupling effect between segment motion and interchain slippage

Segment motion induces interchain slippage, leading to a complex coupling between hyperelastic and viscoelastic behaviors in hydrogels. Traditional models, which treat these behaviors separately and introduce a coupling free energy, struggle to capture this visco-hyperelastic coupling mechanism accurately. In this work, we develop a visco-hyperelastic constitutive model incorporating viscoelastic contributions into the general hyperelastic free energy to capture the coupling mechanism. The model introduces both the end-to-end distance and the envelope radius to describe the three-dimensional chain conformation. A joint probability distribution of these two parameters is used to capture the relationship between the chain conformation and the chain distribution. We also propose a two-level macro-micro transition framework to link the evolution of end-to-end distance and envelope radius to macroscopic deformations. In the first level of such macro-micro transition, the elongation of individual chains in various directions within the network is mapped to the overall chain elongation. In the second level, both interchain slippage and total chain elongation are incorporated into the overall deformation of the polymer network. A comparison between our predicted results with our experimental data demonstrates the predictability of the new model. Finally, the modeling results show that the interchain slippage always involves two sequential stages, i.e., orientation and relative slippage; and the increasing strain rate enhances the asynchronous responses between segment motion and relative slippage due to multichain interactions, making the viscoelastic responses of hydrogel more obvious.

Negative density dependence promotes persistence of a globally rare yet locally abundant plant species Oenothera coloradensis

Identifying the mechanisms underlying the persistence of rare species has long been a motivating question for ecologists. Classical theory implies that community dynamics should be driven by common species, and that natural selection should not allow small populations of rare species to persist. Yet, a majority of the species found on Earth are rare. Consequently, several mechanisms have been proposed to explain their persistence, including negative density dependence, demographic compensation, vital rate buffering, asynchronous responses of subpopulations to environmental heterogeneity, and fine‐scale source‐sink dynamics. Persistence of seeds in a seed bank, which is often ignored in models of population dynamics, can also buffer small populations against collapse. We used integral projection models (IPMs) to examine the population dynamics of Oenothera coloradensis, a rare, monocarpic perennial forb, and determine whether any of five proposed demographic mechanisms for rare species persistence contribute to the long‐term viability of two populations. We also evaluate how including a discrete seed bank stage changes these population models. Including a seed bank stage in population models had a significantly increased modeled O. coloradensis population growth rate. Using this structured population model, we found that negative density‐dependence was the only supported mechanism for the persistence of this rare species. We propose that high micro‐site abundances within a spatially heterogeneous environment enables this species to persist, allowing it to sidestep the demographic and genetic challenges of small population size that rare species typically face. The five mechanisms of persistence explored in our study have been demonstrated as effective strategies in other species, and the fact that only one of them had strong support here supports the idea that globally rare species can employ distinct persistence strategies. This reinforces the need for customized management and conservation strategies that mirror the diversity of mechanisms that allow rare species persistence.

Periodontal Ligament Reactions to Orthodontic Force: A Transcriptomic Study on Maxillary and Mandibular Human Premolars.

Orthodontic force (OF) induces a variety of reactions in the periodontal ligament (PDL) that could potentially account for individual variability regarding orthodontic tooth movement (OTM). This study investigates the transcriptomic profile of human PDL tissue subjected to OF invivo for 7 and 28 days, additionally comparing the differences between maxillary and mandibular PDL. Healthy patients requiring orthodontic premolar extractions were randomly assigned to one of three groups: control (CG) where no OF was applied, 7 days and 28 days, where premolars were extracted either 7 or 28 days after the application of a 50-100 g OF. Total RNA was extracted from the PDL tissue and analyzed via RNA-seq. Differentially expressed genes (DEGs) were identified using a false discovery rate and fold change threshold of < 0.05 and ≥ 1.5 respectively. Functional and Protein-Protein Interaction analysis were performed. After 7 days of OF, the reaction of PDL to OF is characterized by cell responses to stress, increased bone resorption, inflammation and immune response, and decreased bone formation. In contrast, after 28 days, bone regeneration is more prominent, and processes of bone homeostasis, immune response, and cell migration are present. The response of maxillary and mandibular PDL was different. Bone resorption was observed in the maxilla at 7 and 28 days, while in the mandible expression of cell proliferation and transcriptional activity were predominant after 28 days of OF. The early reaction of the PDL to OF corresponds with increased bone resorption and decreased bone formation. After 28 days, bone formation became more prominent. The maxillary and mandibular PDL present asynchronous responses during OTM. These findings enhance our comprehension of the mechanisms underlying the origin-specific responses of PDL to different lengths of OF, which is potentially relevant in the development of personalized therapeutic strategies.

8704 A DREADD-base Chemogenetic Approach to Quiz the Impact of the Delta Cell Input on Islet Hormone Secretion

Abstract Disclosure: D. Hakim Rodriguez: None. A. Tamayo: None. R. Rodriguez Diaz: None. E. Pereira: None. O. Alcazar: None. M. Makhmutova: None. The utilization of DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) that are gated by clozapine-N-oxide (CNO) enables the selective stimulation of genetically specified cell types in vivo. This chemogenetic technology has been successfully applied in various in vivo studies, including those using mice, to remotely control GPCR signaling in specific cells, such as neurons, glia cells, pancreatic β-cells, or cancer cells. Utilizing DREADDs in the study of pancreatic islets, particularly in the somatostatin-producing δ-cells, could offer insights into the complex role of this hormone. Somatostatin is known to inhibit the secretion of other islet hormones, such as insulin and glucagon, but the detailed mechanisms of its action have not been fully elucidated. To address this, we generated mice enabling the expression of either the activator-DREADD Gq or the inhibitor-DREADD Gi in the mouse somatostatin secreting cells, including the islet δ-cell. Immunohistochemical staining of pancreas sections showed that DREADD were expressed and translocated to the membrane of the islet δ-cells. Perifusion experiments with isolated islets showed that δ-cells responded to CNO stimulation as expected. Islets bearing the DREADD Gq secreted somatostatin in a dose-dependent manner, while somatostatin secretion was inhibited in those expressing DREADD Gi. Secretion of insulin and glucagon were modulated upon activation or inhibition of δ-cells via CNO/DREADD manipulation. CNO-driven pulses of somatostatin stimulation caused asynchronous off responses of neighboring α-and β-cells during the time lapses of somatostatin secretion falloff, resulting in a net increment in the magnitude of both insulin and glucagon secretion. Meanwhile, inhibition of somatostatin secretion surprisingly unleashed glucagon secretion in non-permissive 16mM glucose. These results encouraged us to explore the potential application of DREADD tools in isolated human islets. We will discuss our current approaches whilst using viral vectors to drive the expression of DREADDs in human δ-cells and its impact in the overall islet secretory output. Presentation: 6/2/2024

Divergent sensitivity of primary producers and benthic invertebrates to hydrological alteration in floodplain lakes

Floodplain lake ecosystems are hydrologically dynamic and biologically important. Their ecosystem functioning is complex due to the concurrent influence of multiple anthropogenic stressors. Paleolimnological studies focused on a single biotic proxy might lead to biased results, as multiple trophic levels may show different responses to the same driver. In this study, multiple proxies including chlorophyll and carotenoid pigments (indicators of phytoplankton) and chironomids (indicators of invertebrates) were analyzed in a 210Pb dated sediment core from Luhu Lake (Yangtze floodplain, China). Using these indicators, we investigated how different trophic levels respond to external driving forces (i.e., hydrological alteration represented by K/Al ratios and nutrient influxes indicated by TP) in floodplain lakes. Sedimentary pigments showed that algal production increased in Luhu Lake after the 2000s. The chironomid community shifted from a fauna dominated by Microchironomus tener-type to an assemblage characterized by macrophyte-dwelling taxa (e.g., Tanytarsus, Paratanytarsus, Paratanytarsus penicillatus-type) after the 1970s. Finally, nutrient-tolerant taxa (e.g., Microchironomus tabarui-type) increased in abundance after the 1990s. Redundancy analysis and hierarchical partitioning analysis showed that the increases in algal production were mainly correlated with anthropogenic nutrient influxes, followed by hydrological alteration. In contrast, the transition in the chironomid communities were mainly associated with hydrological alteration, followed by food sources. Our study revealed asynchronous responses of phototrophs and benthic invertebrates to hydrological alteration, highlighting the necessity of analyzing multiple trophic levels to obtain a sophisticate understanding of long-term ecosystem evolution in lotic floodplain lakes which are influenced by multiple stressors. These findings will provide valuable information for the sustainable development, as well as the conservation and restoration of floodplain lakes.

Campanian Ignimbrite tephra reveals asynchronous vegetation responses to abrupt climate change in the eastern Mediterranean region

The timing and rate of ecosystem response to abrupt climate change is a product of numerous complex interactions between biotic and abiotic drivers. Palaeoecological studies from long sedimentary records, particularly those that span periods of dynamic climate such as the last glacial cycle, can help to contextualise ecosystem responses to climate variability through time. Detailed studies that compare proxy data from multiple sites, with high chronological precision, have the potential to ascribe mutual climate drivers, and, therefore, track spatiotemporal variability in ecosystem responses. Here, we interrogate the vegetation impact of past climate change in the eastern Mediterranean, using three sub-centennially resolved pollen archives from Greece. The widespread Campanian Ignimbrite (CI/Y-5; ca. 39.85 ka BP) tephra marker is used as an isochron to directly correlate pollen records from Ioannina (NW Greece), Tenaghi Philippon (NE Greece), and Megali Limni (NE Aegean). Our results reveal spatiotemporal variability in the timing of vegetation response in the Mediterranean to climate forcing across Heinrich Stadial 4 (40.2–38.3 ka BP), a period of known abrupt climatic change. We identify a decline in tree pollen in all three sites, likely related to the onset of enhanced regional aridity, with vegetation at Tenaghi Philippon responding prior to the CI/Y-5, in contrast to at Megali Limni and Ioannina, where much of the vegetation change occurs following tephra deposition.

Interacting within an asynchronous online interprofessional education workshop focused on social determinants of health

BackgroundMeaningful interprofessional education (IPE) involves students from at least two professions interacting to learn with, about, and from one another. Our objective was to describe a novel online approach used to create meaningful IPE within a social determinants of health (SDoH) workshop. Interprofessional education activityThis online workshop integrated four different professions' perspectives on SDoH (social-work, public-health, nursing, and pharmacy). Each six-student interprofessional team was assigned a local neighborhood. This week-long workshop had numerous activities (pre- and post-workshop quizzes, a SDoH-primer video, video self-introduction to teammates, a windshield questionnaire with two subsequent clinical cases, a post-workshop reflection, and post-workshop evaluation). For discussion, asynchronous video-based responses were used instead of traditional text-based discussion-boards. DiscussionQuantitatively comparing quiz scores, students' SDoH knowledge increased with this workshop. Qualitatively from evaluations, most students found this workshop helpful and meaningful. Supporting use of video-based responses, many students' favorite aspect was interacting and collaborating within their interprofessional teams, although some students desired synchronous activities instead. Faculty facilitators confirmed that meaningful IPE interactions occurred. ImplicationsIn short, students from multiple health-professions learned SDoH-content and, using video-based responses, interacted asynchronously during this online workshop. This report demonstrated one tool available to help facilitate meaningful IPE asynchronously. This asynchronous, online IPE workshop appears to be a promising format to be integrated with other in-person IPE sessions.

Settling into uncertainty and risk amidst the COVID-19 pandemic and the war in Ukraine

ABSTRACT This study explores the process of navigating instability arising from sudden, co-occurring crises in the 2020s. We focus on the combined impact of the COVID-19 pandemic and the war in Ukraine on growing material and relational uncertainty and risk among Polish citizens, accumulating in the loss of ontological security. To showcase the practical and narrative presence of risk at the micro-level, we operationalize the broad theorization of risk society using the categorization of material, relational and subjective dimensions within the ‘unsettling events’ model proposed by Kilkey and Ryan. We reconceptualize the third pillar, positioning subjectivity as a meta-category. Moreover, we extend the application of the framework of unsettling events, treating the Polish situation as a case study for examining societies facing compounding catastrophes.The analyzed qualitative longitudinal data comprised 70 in-depth interviews about the pandemic and conducted with Polish young adults (ages 18–35) and their parents in 2021; and asynchronous responses from 43 study participants collected shortly after the Russian attack on Ukraine in 2022. Considering intergenerational and temporal lens, we identify the dominant patterns of meaning that interviewees attributed to the pandemic and war, thereby revealing materialities of unsettlement, relational gains and losses, and the erosion of ontological security. .

Match-play, training workloads and sensorimotor and neuromuscular performance of elite young soccer players

Purpose: The purpose of this study was to assess sensorimotor and neuromuscular performance capabilities over an in-season microcycle in early-career professional soccer players and to examine the relationship with training and match-play workload. Methods: Sensorimotor and neuromuscular performance capabilities (isometric knee extensor: force replication error, peak force, electromechanical delay, rate of force development) of 12 professional soccer players were assessed over a 7-day period. Training and match-play workload was also recorded over the same period for each player (high-intensity running distance). Fluctuations in sensorimotor and neuromuscular performance and workload variables were analysed. Results: There was evidence of fluctuations in sensorimotor and neuromuscular performance capability over the microcycle that reached statistical (p &lt; .005) and practical (18.1% [baseline-to-peak]) significance alongside heterogeneity in training and match workload (264% [coefficient of variation], p &lt; .0005). Some temporal congruence among fluctuating patterns of intra-microcycle training and match-play load and concomitant electromechanical delay performance was noted (p &lt; .005). Asynchronous responses were observed for peak force, but rate of force development and force replication error capabilities were unchanged during the microcycle. Conclusion: While some neuromuscular performance capabilities fluctuate over an in-season microcycle and are influenced partially by high-intensity running workload, sensorimotor performance capabilities were unchanged during the microcycle.

Long-term warming increased carbon sequestration capacity in a humid subtropical forest.

Tropical and subtropical forests play a crucial role in global carbon (C) pools, and their responses to warming can significantly impact C-climate feedback and predictions of future global warming. Despite earth system models projecting reductions in land C storage with warming, the magnitude of this response varies greatly between models, particularly in tropical and subtropical regions. Here, we conducted a field ecosystem-level warming experiment in a subtropical forest in southern China, by translocating mesocosms (ecosystem composed of soils and plants) across 600 m elevation gradients with temperature gradients of 2.1°C (moderate warming), to explore the response of ecosystem C dynamics of the subtropical forest to continuous 6-year warming. Compared with the control, the ecosystem C stock decreased by 3.8% under the first year of 2.1°C warming; but increased by 13.4% by the sixth year of 2.1°C warming. The increased ecosystem C stock by the sixth year of warming was mainly attributed to a combination of sustained increased plant C stock due to the maintenance of a high plant growth rate and unchanged soil C stock. The unchanged soil C stock was driven by compensating and offsetting thermal adaptation of soil microorganisms (unresponsive soil respiration and enzyme activity, and more stable microbial community), increased plant C input, and inhibitory C loss (decreased C leaching and inhibited temperature sensitivity of soil respiration) from soil drying. These results suggest that the humid subtropical forest C pool would not necessarily diminish consistently under future long-term warming. We highlight that differential and asynchronous responses of plant and soil C processes over relatively long-term periods should be considered when predicting the effects of climate warming on ecosystem C dynamics of subtropical forests.

Seasonal patterns of carbon and water flux responses to precipitation and solar radiation variability in a subtropical evergreen forest, South China

Precipitation and energy are vital factors profoundly affecting carbon and water fluxes in subtropical forest ecosystems. However, knowledge of the seasonality of ecosystem productivity and water fluxes and their dominant controlling factors remains understudied. Based on 12 years (2003–2014) of eddy-covariance measurements, we examined how the seasonal carbon flux components and evapotranspiration respond to climatic variability in a subtropical forest ecosystem. Our results showed that both the magnitude and the percentage of gross ecosystem productivity (GEP) and ecosystem respiration (Reco) in winter increased. The enhanced GEP during winter and dampened Reco in summer and autumn were not sufficient to compensate for the decreased GEP in spring, summer and autumn, and simultaneously increased Reco in spring and winter. Thus, net ecosystem productivity (NEP) slightly diminished during the study period, and the majority of annual net carbon gains occurred in winter and spring with high water use efficiency. In addition, solar radiation predominantly contributed to GEP in spring and winter, while soil moisture is the main contributor in summer. ET greatly determined the GEP in autumn due to both were well-coupled. The vapor pressure deficit (VPD) was a major driver of Reco in summer and autumn inferred that Reco largely depends on substrate availability. However, Reco was mainly attributed to the soil environmental conditions (moisture and temperature) in spring and winter. Our results highlighted that the different extents and asynchronous responses of ecosystem carbon assimilation and respiration to altered energy and moisture availability determined the seasonal patterns of carbon and water fluxes, thus having important implications for assessing or projecting subtropical forest ecosystem responses to current climate change.

Changing climate and reorganized species interactions modify community responses to climate variability

While an array of ecological mechanisms has been shown to stabilize natural community dynamics, how the effectiveness of these mechanisms-including both their direction (stabilizing vs. destabilizing) and strength-shifts under a changing climate remains unknown. Using a 35-y dataset (1985 to 2019) from a desert stream in central Arizona (USA), we found that as annual mean air temperature rose 1°C and annual mean precipitation reduced by 40% over the last two decades, macroinvertebrate communities experienced dramatic changes, from relatively stable states during the first 15 y of this study to wildly fluctuating states highly sensitive to climate variability in the last 10 y. Asynchronous species responses to climatic variability, the primary mechanism historically undergirding community stability, greatly weakened. The emerging climate regime-specifically, concurrent warming and prolonged multiyear drought-resulted in community-wide synchronous responses and reduced taxa richness. Diversity loss and new establishment of competitors reorganized species interactions. Unlike manipulative experiments that often suggest stabilizing roles of species interactions, we found that reorganized species interactions switched from stabilizing to destabilizing influences, further amplifying community fluctuations. Our study provides evidence of climate change-induced modifications of mechanisms underpinning long-term community stability, resulting in an overall destabilizing effect.

Environmental hormesis in living systems: The role of hormetic trade-offs

Hormesis (low-dose stimulation and high-dose inhibition) can be accompanied by hormetic trade-offs, that is, stimulation of some traits and inhibition (trade-off 1) or invariability (trade-off 2) of others. Currently, trade-off options and their biological significance are insufficiently studied. Therefore, the review analyses trade-off types, their relationship with asynchronous stress responses of indicators, the importance of trade-offs for preconditioning, hormesis transgenerational effects, fitness, and evolution. The analysis has shown that hormetic trade-offs 1 and 2 can be observed in evolutionarily distant groups of organisms and at different biological levels (cells, individuals, populations, and communities) with abiotic and biotic stressors, as well as various pollutants. Trade-offs 1 and 2 are found both between different functional traits (e.g., self-maintenance and reproduction in animals, growth and defense in plants), and between the endpoints of the same functional trait (e.g., seed weight and seed number in plants). Asynchronous responses of indicators to a low-dose stressor can lead to hormetic trade-offs in two cases: 1) these indicators have different responses (hormesis, inhibition or zero reaction) in the same dose range; 2) these indicators have hormetic responses with different hormetic zones. Trade-offs can have a positive, negative or zero effect on preconditioning, offspring, and fitness of the population. Trade-offs can potentially affect evolution in two ways: 1) the creation of trends in genotype selection; 2) participation in the assimilation of phenotypic adaptations in the genotype through the Baldwin effect (selection of mutations copying adaptive phenotypes).

The effect of prestimulus low-frequency neural oscillations on the temporal perception of audiovisual speech.

Perceptual integration and segregation are modulated by the phase of ongoing neural oscillation whose frequency period is broader than the size of the temporal binding window (TBW). Studies have shown that the abstract beep-flash stimuli with about 100 ms TBW were modulated by the alpha band phase. Therefore, we hypothesize that the temporal perception of speech with about hundreds of milliseconds of TBW might be affected by the delta-theta phase. Thus, we conducted a speech-stimuli-based audiovisual simultaneity judgment (SJ) experiment. Twenty human participants (12 females) attended this study, recording 62 channels of EEG. Behavioral results showed that the visual leading TBWs are broader than the auditory leading ones [273.37 ± 24.24 ms vs. 198.05 ± 19.28 ms, (mean ± sem)]. We used Phase Opposition Sum (POS) to quantify the differences in mean phase angles and phase concentrations between synchronous and asynchronous responses. The POS results indicated that the delta-theta phase was significantly different between synchronous and asynchronous responses in the A50V condition (50% synchronous responses in auditory leading SOA). However, in the V50A condition (50% synchronous responses in visual leading SOA), we only found the delta band effect. In the two conditions, we did not find a consistency of phases over subjects for both perceptual responses by the post hoc Rayleigh test (all ps > 0.05). The Rayleigh test results suggested that the phase might not reflect the neuronal excitability which assumed that the phases within a perceptual response across subjects concentrated on the same angle but were not uniformly distributed. But V-test showed the phase difference between synchronous and asynchronous responses across subjects had a significant phase opposition (all ps < 0.05) which is compatible with the POS result. These results indicate that the speech temporal perception depends on the alignment of stimulus onset with an optimal phase of the neural oscillation whose frequency period might be broader than the size of TBW. The role of the oscillatory phase might be encoding the temporal information which varies across subjects rather than neuronal excitability. Given the enriched temporal structures of spoken language stimuli, the conclusion that phase encodes temporal information is plausible and valuable for future research.

Plasmonic-Magnetic Active Nanorheology for Intracellular Viscosity.

We demonstrate active plasmonic systems where plasmonic signals are repeatedly modulated by changing the orientation of nanoprobes under an external magnetic field, which is a prerequisite for in situ active nanorheology in intracellular viscosity measurements. Au/Ni/Au nanorods act as "nanotransmitters", which transmit the mechanical motion of nanorods to an electromagnetic radiation signal as a periodic sine function. This fluctuating optical response is transduced to frequency peaks via Fourier transform surface plasmon resonance (FTSPR). As a driving frequency of the external magnetic field applied to the Au/Ni/Au nanorods increases and reaches above a critical threshold, there is a transition from the synchronous motion of nanorods to asynchronous responses, leading to the disappearance of the FTSPR peak, which allows us to measure the local viscosity of the complex fluids. Using this ensemble-based method with plasmonic functional nanomaterials, we measure the intracellular viscosity of cancer cells and normal cells in a reliable and reproducible manner.

Asynchronous responses of microbial CAZymes genes and the net CO2 exchange in alpine peatland following 5 years of continuous extreme drought events

Peatlands act as an important sink of carbon dioxide (CO2). Yet, they are highly sensitive to climate change, especially to extreme drought. The changes in the net ecosystem CO2 exchange (NEE) under extreme drought events, and the driving function of microbial enzymatic genes involved in soil organic matter (SOM) decomposition, are still unclear. Herein we investigated the effects of extreme drought events in different periods of plant growth season at Zoige peatland on NEE and microbial enzymatic genes of SOM decomposition after 5 years. The results showed that the NEE of peatland decreased significantly by 48% and 26% on average (n = 12, P < 0.05) under the early and midterm extreme drought, respectively. The microbial enzymatic genes abundance of SOM decomposition showed the same decreasing trend under early and midterm extreme drought, but an increasing trend under late extreme drought. The microbial community that contributes to these degradation genes mainly derives from Proteobacteria and Actinobacteria. NEE was mainly affected by soil hydrothermal factors and gross primary productivity but weakly correlated with SOM enzymatic decomposition genes. Soil microbial respiration showed a positive correlation with microbial enzymatic genes involved in the decomposition of labile carbon (n = 18, P < 0.05). This study provided new insights into the responses of the microbial decomposition potential of SOM and ecosystem CO2 sink function to extreme drought events in the alpine peatland.

Bushfire‐Induced Water Balance Changes Detected by a Modified Paired Catchment Method

AbstractWhile bushfires are often regarded as a vital trigger that alters the partitioning of hydrological fluxes, their role in water balance changes remains poorly quantified, especially in regions where the impacts of frequent bushfires and climate variability overlap. Here, we estimated the fire‐induced water balance changes based on a modified paired catchment method that considers the partial effect of annual precipitation differences. In the application for eight forested catchments impacted by the 2009 Victorian Bushfires with multiple burned areas (12%–89%), we found that evapotranspiration declined by 33 ± 20 mm yr−1 (mean ± standard deviation) and streamflow increased by 68 ± 32 mm yr−1 during the post‐fire decade. For the interannual changes within this decade, the decline in evapotranspiration due to fires gradually recovered after the first year since bushfires, while the increase in streamflow mostly peaked in the second or third year and diminished in subsequent years. We surmised that such asynchronous responses of the two fluxes to bushfires occurred with the initial increase and the later decrease in terrestrial water storage. Averaged for the post‐fire decade, there seems to be an overall decline in terrestrial water storage for burned catchments relative to unburned catchments.

Asynchronous functional linear regression models for longitudinal data in reproducing kernel Hilbert space.

Motivated by the analysis of longitudinal neuroimaging studies, we study the longitudinal functional linear regression model under asynchronous data setting for modeling the association between clinical outcomes and functional (or imaging) covariates. In the asynchronous data setting, both covariates and responses may be measured at irregular and mismatched time points, posing methodological challenges to existing statistical methods. We develop a kernel weighted loss function with roughness penalty to obtain the functional estimator and derive its representer theorem. The rate of convergence, a Bahadur representation, and the asymptotic pointwise distribution of the functional estimator are obtained under the reproducing kernel Hilbert space framework. We propose a penalized likelihood ratio test to test the nullity of the functional coefficient, derive its asymptotic distribution under the null hypothesis, and investigate the separation rate under the alternative hypotheses. Simulation studies are conducted to examine the finite-sample performance of the proposed procedure. We apply the proposed methods to the analysis of multitype data obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study, which reveals significant association between 21 regional brain volume density curves and the cognitive function. Data used in preparation of this paper were obtained from the ADNI database (adni.loni.usc.edu).

Synergistic effects of straw and earthworm addition on microbial diversity and microbial nutrient limitation in a subtropical conservation farming system

Conservation farming systems with straw return and no-tillage are recommended as effective methods for soil quality improvement, and they are often accompanied by increases in soil fauna populations. Recently, attempts have been made to improve the soil fertility in conservation agriculture through enhanced bioturbation by adding earthworms to no-till fields. However, the mechanisms associated with the responses in terms of soil functions, such as microbial diversity and microbial nutrient metabolism, to the synergistic effects of biotic and abiotic factors remain unclear. In this study, plow layer and plow pan soils were collected from subtropic cropland, and a full factorial microcosm experiment was conducted to quantify the effects of straw mulching and adding earthworms on the soil nutrient contents, microbial diversity, and extracellular enzymatic activities. The results showed that the single application of straw significantly increased the soil organic carbon (C), the ratio of C to nitrogen (N), and the ratio of C to phosphorus (P) in the plow layer soil (p < 0.05). The combined addition of straw and earthworms significantly increased the microbial diversity (Observed species, Chao 1 and Shannon), C/N/P-acquiring enzymatic activities, and microbial C limitation (p < 0.05), but decreased the microbial P limitation (p < 0.05) in the plow pan soil. Adding straw or earthworms did not affect the soil nutrient content in the plow pan soil (p > 0.05), microbial diversity, C-acquiring enzymatic activities, and microbial C and P limitations in the plow layer soil (p > 0.05). Structural equation models indicated that straw mulching indirectly affected the soil microbial diversity and microbial nutrient limitation through the buffering effects of aggregate stability and the C/P ratio in the plow layer soil. By contrast, the soil microbial activities were directly influenced by straw and earthworm addition in the plow pan soil. These findings indicate that earthworms enhanced soil microbial metabolism when straw was added by improving the substrate availability, and the soil physicochemical properties determined the asynchronous responses of the soil functions to land management. We suggest that the combined addition of organic matter and earthworms can improve the quality of soil in infertile land.

Spanning scales: The airborne spatial and temporal sampling design of the National Ecological Observatory Network

Abstract1. Each year, the National Ecological Observatory Network's (NEON) Airborne Observation Platform (AOP) collects high‐resolution hyperspectral imagery, discrete and waveform lidar, and digital photography at a subset of 81 terrestrial and aquatic research sites throughout the United States. These open remote sensing data, together with NEON in situ sensor measurements and field observations, enable researchers to characterize ecological processes at multiple spatial and temporal scales.2. Here we describe the sampling design for the AOP that aims to meet the diverse research needs of the ecological science community within the operational constraints affecting airborne data collection. Our spatial sampling protocol captures NEON instrumented systems, field plots and environmental gradients around each site while considering the context of airspace restrictions and remote sensing instrument capabilities. We use time series of moderate resolution imaging spectroradiometer (MODIS) satellite and PhenoCam near‐surface observations to define temporal sampling windows based on vegetation peak foliar greenness. We developed a probabilistic model based on MODIS reflectance imagery and Monte Carlo simulation to estimate sampling durations for cloud‐free data collection at each site.3. Agreement in the estimated phenophase transition dates between MODIS Enhanced Vegetation Index and PhenoCam Green Chromatic Coordinate varied by vegetation class. Results from both sensors show that some vegetation classes have relatively consistent interannual peak greenness start‐ and end‐dates, while others experience high year‐to‐year variability in green‐up and senescence. In addition to phenological variability among sites, certain vegetation forms demonstrate distinct, asynchronous responses to climate, resulting in non‐overlapping peak greenness periods within a single site. Results from flight campaigns showed that the cloud‐likelihood model underestimated actual cloud conditions by 13%–26%, depending on the probability used.4. Where interannual or intra‐site phenology is highly variable or clouds are a persistent problem, it becomes challenging to schedule domain deployments so that all sites are flown in cloud‐free conditions while their vegetation communities are in peak greenness. Despite limitations, application of cloud and peak greenness models to airborne sampling results in significant improvements to AOP data quality. Although most applicable to airborne sampling with hyperspectral and lidar instruments in piloted aircraft, these methods may be a valuable resource to deployment of Unmanned Aerial Vehicles for ecological research.