Time Lag In Response Research Articles

Analyzing moisture-heat coupling in a wheat-soil system using data-driven vector autoregression model.

Soil temperature and moisture have a close relationship, the accurate controlling of which is important for crop growth. Mechanistic models built by previous studies need exhaustive parameters and seldom consider time stochasticity and lagging effect. To circumvent these problems, this study designed a data-driven stochastic model analyzing soil moisture-heat coupling. Firstly, three vector autoregression models are built using hourly data on soil moisture and temperature at the depth of 10, 30, and 90 cm. Secondly, from impulse response functions, the time lag and intensity of two variables’ response to one unit of positive shock can be obtained, which describe the time length and strength at which temperature and moisture affect each other, indicating the degree of coupling. Thirdly, Granger causality tests unfold whether one variable’s past value helps predict the other’s future value. Analyzing data obtained from Shangqiu Experiment Station in Central China, we obtained three conclusions. Firstly, moisture’s response time lag is 25, 50, and 120 h, while temperature’s response time lag is 50, 120, and 120 h at 10, 30, and 90 cm. Secondly, temperature’s response intensity is 0.2004, 0.0163, and 0.0035 °C for 1% variation in moisture, and moisture’s response intensity is 0.0638%, 0.0163%, and 0.0050% for 1 °C variation in temperature at 10, 30, and 90 cm. Thirdly, the past value of soil moisture helps predict soil temperature at 10, 30, and 90 cm. Besides, the past value of soil temperature helps predict soil moisture at 10 and 30 cm, but not at 90 cm. We verified this model by using data from a different year and linking it to soil plant atmospheric continuum model.

Mixing data modelling method for response of water environment quality to economic development

Environmental Kuznets Curve (EKC) is one of the main tools to analyze the response relationship between water environmental quality and economic development. In classical EKC curve modeling process, the environmental index time series and economic index time series must be the same frequency. Because basin water-quality in China has been gradually monitored and released with high frequency, and most macroeconomic indicators are on annual basis, therefore, by the construction of three classes mix data polynomial equation of EKC curve, the mixing data modeling method of the response relationship between water quality and economic development is proposed to adapt to the situation. The mix data model not only avoids destroying original information due to simple low-frequency measurement of high frequency water quality data using classical model, but also through direct mining of high frequency water quality data, the lag time of water environment quality response to economic development can be obtained. To verify the validity of the model, according to the monitoring and statistical data of 2009-2017, a prefecture level city in Henan province of Haihe River Basin is taken as the research object, and EKC three classes mix data polynomial equation of chemical oxygen demand (COD) concentration and ammonia nitrogen concentration is established.

2000-2015年宁夏草地净初级生产力时空特征及其气候响应

PDF HTML阅读 XML下载 导出引用 引用提醒 2000-2015年宁夏草地净初级生产力时空特征及其气候响应 DOI: 10.5846/stxb201801220171 作者: 作者单位: 宁夏大学西北土地退化与生态系统恢复省部共建国家重点实验室培育基地,宁夏大学西北土地退化与生态系统恢复省部共建国家重点实验室培育基地,宁夏大学西北土地退化与生态系统恢复省部共建国家重点实验室培育基地,宁夏大学西北土地退化与生态系统恢复省部共建国家重点实验室培育基地,宁夏大学西北土地退化与生态系统恢复省部共建国家重点实验室培育基地,宁夏大学西北土地退化与生态系统恢复省部共建国家重点实验室培育基地,宁夏大学西北土地退化与生态系统恢复省部共建国家重点实验室培育基地,宁夏大学西北土地退化与生态系统恢复省部共建国家重点实验室培育基地 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41661003）；宁夏高等学校一流学科（生态学）建设项目（NXYLXK2017B06）；中国科学院西部之光人才计划项目（XAB2017AW01） Spatiotemporal characteristics of grassland net primary production in Ningxia Province from 2000 to 2015 and its response to climate change Author: Affiliation: Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China,Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China,Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China,Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China,Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China,Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China,Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China,Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:草地是宁夏陆地生态系统的重要组成部分，估算其净初级生产力（NPP）对宁夏草地可持续利用与管理至关重要。采用MODIS数据和CASA模型对2000-2015年间宁夏草地生态系统NPP进行了估算，通过一元线性回归趋势分析、Hurst指数等方法研究草地NPP的时空变化规律及未来演变趋势，并分析草地NPP与气象因子的相关性。结果表明：（1）基于CASA模型的宁夏草地NPP模拟精度高，其估算值与实测多年草地NPP均值具有良好的线性关系（R=0.93，P < 0.01），与MOD17产品的草地NPP空间分布基本一致。（2）近16 a宁夏草地年均NPP为148.28 g C m-2 a-1，且存在波动上升的趋势，其线性增长率为3.84 g C m-2 a-1（P < 0.01）。（3）宁夏草地NPP整体处于上升趋势，草地NPP增长的草地面积达98%，且其增率自南向北递减；宁夏草地NPP的Hurst指数在0.27-0.81之间，均值为0.53，大部分草地的NPP变化趋势具有较强同向持续性。（4）在年时间尺度上，宁夏草地NPP主要受降水量的影响，与气温的相关性较弱；在月时间尺度上，生长季草地NPP与月总降水量的相关性高，且不存在时间滞后响应现象，而与月均温的响应则存在1个月的时间滞后性，宁夏大面积分布的干草原与荒漠草原NPP对气温响应滞后是导致这一现象发生的主要原因。 Abstract:Net primary productivity (NPP) is an important indicator of terrestrial ecosystems and accurately estimating NPP is fundamental in terrestrial carbon cycle research. Ningxia Province is dominated by grassland and the estimation of grassland NPP can provide a scientific basis for the sustainable use of grassland resources and the improvement of grassland management. In this study, the grassland ecosystem NPP in Ningxia Province was estimated using a Carnegie-Ames-Stanford Approach (CASA) model and Moderate Resolution Imaging Spectroradiometer (MODIS) data from 2000 to 2015. To study the spatiotemporal characteristics and future evolution trend of grassland NPP, the correlation between the grassland NPP and meteorological factors was analyzed using a simple linear regression model and the Hurst index. The results showed that the CASA model accurately simulated the grassland NPP in Ningxia Province. The correlation coefficient between estimated NPP by the CASA model and measured NPP was 0.93 (P < 0.01), and the spatial characteristics of the estimated NPP image were similar to that of the NPP image of MOD17. In the whole province, the average annual grassland NPP estimated by the CASA model was 148.28 g C m-2 a-1 during 2000-2015. Meanwhile, the average annual grassland NPP increased with fluctuations during the past 16 years and the linear growth rate was 3.84 g C m-2 a-1 (P < 0.01). Regarding the spatial variation of grassland NPP in Ningxia Province, the NPP in 98% of the grassland increased during the past 16 years and this increasing rate decreased from South to North. The Hurst index of grassland NPP in the past 16 years ranged from 0.27 to 0.81 and the mean value was 0.53, which indicated the grassland NPP will maintain the same trend of change in the future. At an annual scale, the average grassland NPP in Ningxia Province was mainly affected by annual precipitation, and had a weak correlation with the average annual temperature. At a monthly scale, there was also a weak relationship between the grassland NPP and temperature in the growing season; however, the monthly total precipitation exerted an important influence on the grassland NPP accumulation. Furthermore, there was a one-month time lag in the monthly NPP response to mean temperature, but this phenomenon did not exist between the monthly NPP and total precipitation. The main reason for this phenomenon was possibly the hysteresis response to temperature in the steppe and desert grasslands, which were the main types of grassland in Ningxia Province. 参考文献 相似文献 引证文献

Response characteristics of water level dynamic of the Baiyangdian Wetland to climate change and human activities

Water level dynamics of Wetlands are influenced by both climate change and human activities. Understanding the influence characteristics is important for the management of wetland water resources and ecology. Based on the water level dynamic and precipitation of the Baiyangdian Wetland, and the NPI index, the paper analyzes the response characteristics of the water level dynamic to the precipitation, and the teleconnections between the water level dynamic and the NPI by adopting method of wavelet analysis. Results show that climate change plays an important role on the response of the water level dynamic to the precipitation and also to the NPI, and human activities can significantly change the response characteristics. The response time lags of the water level dynamics to the NPI is longer than that of the water level dynamics to the precipitations, which indicates that the wetland precipitation might be partially influenced by the NPI. The knowledge of the response characteristics obtained in the paper is beneficial for water conservancy and control of the wetland, and is favorable for the sustainable development of its eco-environment.

Point of View Telemedicine at Point of Care.

IntroductionThe use of telemedicine by deployed healthcare providers to improve patient care has been increasing in recent foreign conflicts and humanitarian missions. These efforts have mostly been limited to email consultation with long response lag times. The United States Military has developed several modalities of telemedicine for use in austere environments, ranging from video conferencing, email, and store-and-forward technology. As of now, these efforts have required large pieces of equipment and many technical support personnel and have a delayed response time. Our study aimed to test the overall feasibility of use, the effects on time to intervention, and user confidence in a highly portable, real-time video set-up to aid in teleconsultations at the early stages of care for a simulated traumatic injury.Materials and methodsSubjects or operators taking direct care of the simulated patient were junior emergency medicine (EM) residents or military trained medics. Video teleconsultation was completed by either senior EM residents in their final year of training or board-certified EM physicians. The subjects taking direct care of the simulated patient were blinded to whether their video device was actively sending images or not. All participants communicated verbally using hand-held radios. The total number of interventions and time to event analysis was completed and survey data were collected, assessing confidence levels on procedures performed and patient care. ResultsWe demonstrated the accessibility, ease of use, and overall practicality of this telemedicine platform. A trend was found towards decreased time to evacuation for patients with a live video feed. Alternatively, the data showed no significant difference in the addition of video as opposed to solely radio in terms of the number of interventions, time to interventions, or operator or teleconsultant confidence in the care delivered or procedures performed.ConclusionsThis study demonstrated the overall feasibility and ease of use of a highly portable telemedicine platform with live video capabilities. A trend was found toward earlier evacuation decisions when using the live video. Follow-up studies may consider examining more challenging simulations or prolonged field care utilization of this technology.

Flow Cytometric Analysis of Platelet Function in Patients on Antiplatelet Therapy and Suspected Thrombocytopathy

Background: Light transmission aggregometry (LTA) is still the most used test for the identification and diagnosis of platelet function defects (PFD). Disadvantages of LTA include its laborious nature, the large volumes of blood required and the relative insensitivity to small changes in platelet function. We investigated if the flow cytometry-based whole blood platelet activation test (WB-PACT) correlates with LTA or could be used as a complimentary test.Methods: WB-PACT quantifies αIIbβ3 activation and P-selectin expression in response to 3 agonists and VWF binding to platelets in response to ristocetin. In total, 212 patients (51 on dual antiplatelet therapy (acetylsalicylic acid and ADP receptor antagonist), 161 suspected for bleeding diathesis) were tested. For WB-PACT parameters, the 2.5th, 10th and 25th percentiles were determined in 56 healthy donors to score the patient samples. For LTA, maximal aggregation, disaggregation and prolongation of the lagtime in response to 4 agonists and ristocetin was scored. Patients with at least one parameter lower than the 10th percentile measured with WB-PACT in healthy donors or at least one value deviating from the normal range measured with LTA were diagnosed with PFD. A bleeding score (BS) was calculated with the ISTH/SSC bleeding assessment tool (Rodeghiero et al., JTH, 2010).Results: A moderate correlation between LTA versus WB-PACT was found with a R of 0.60 (Figure 1). In total, 95 patients were diagnosed with PFD by both tests (κ=0.40, Table 1) and BS were recorded for 28/95 patients. Of these 28 patients, 25% had an elevated BS (adapted according to gender and age: >5 in women, >3 in men and >2 in children) and 36% had a BS>3. BS were recorded for 30/38 and 22/24 patients who were diagnosed with PFD according to WB-PACT only and LTA only, respectively. Interestingly, 27% of patients with PFD according to WB-PACT had an elevated BS and 40% had a BS>3. For LTA, only 13% of patients with PFD had an elevated BS and 13% had a BS>3.Conclusions: Flow cytometric analysis of platelet function by WB-PACT gives additional value to LTA to determine PFD. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Effects of Transgenerational Plasticity on Morphological and Physiological Properties of Stoloniferous Herb Centella asiatica Subjected to High/Low Light.

Environmentally induced transgenerational plasticity can increase success of progeny and thereby be adaptive if progeny experiences the similarly parental environment. The ecological and evolutionary significance of transgenerational plasticity in plant has been studied mainly in the context of sexual generations. A pot experiment using the stoloniferous herb Centella asiatica was conducted to investigate the effects of high/low light treatment experienced by parental ramets (F0 generation) on morphological and physiological properties of offspring ramets (F2 generation) as well as growth performance. Light environment experienced by parental ramets (F0 generation) significantly influenced petiole length, specific petiole length, internode length of stolon, leaf area, specific leaf area (SLA), leaf nitrogen and chlorophyll contents, potential maximum net photosynthetic rate (Pmax) in offspring ramets subjected to parental or non-parental environments even after they were detached from the parental ramets. Potential maximum net photosynthetic rate (Pmax) of offspring ramets (F2 generation) from parental ramets (F0 generation) subjected to low light treatment was significantly greater than that of offspring ramets (F2 generation) from parental ramets (F0 generation) subjected to high light treatment. Potential maximum net photosynthetic rate (Pmax) of offspring ramets (F2 generation) subjected to parental light environment was greater than that of offspring ramets (F2 generation) subjected to non-parental light environment. The greatest biomass accumulation and total stolon length were observed in offspring ramets (F2 generation) subjected to low light treatment as parental ramets (F0 generation) experienced. When parental ramets (F0 generation) were subjected to low light treatment, biomass accumulation and total stolon length of offspring ramets (F2 generation) experiencing parental light environment were significantly greater than those of offspring ramets (F2 generation) experiencing non-parental light environment. Opposite pattern was observed in offspring ramets (F2 generation) from parental ramets subjected to high light treatment. Our work provides evidence that transgenerational plasticity through both morphological and physiological flexibility was triggered across vegetative generations for stoloniferous herb C. asiatica subjected to high/low light treatment. The transgenerational plasticity can allow offspring ramets to present adaptive phenotype early without lag time in response to the current environment. Thus, it is very important for clonal plants in adapting temporally and spatially heterogeneous habitats.

Vegetation trends over eleven years on mountain summits in NW Argentina.

As global climate change leads to warmer and dryer conditions in the central Andes, alpine plant communities are forced to upward displacements following their climatic niche. Species range shifts are predicted to have major impacts on alpine communities by reshuffling species composition and abundances. Using a standardized protocol, we surveyed alpine plant communities in permanent plots on four high Andean summits in NW Argentina, which range from 4,040 to 4,740 m a.s.l. After a baseline survey in 2006–2008, we resurvey the same plots in 2012, and again in 2017. We found a significant decrease in plant cover, species richness, and diversity across the elevation gradient in the three censuses and a strong decrease in soil temperature along the elevation gradient. We found a high plant community turnover (37%–49%) among censuses, differentiating according to summits and aspects; major changes of community turnover were observed in the lowest summit (49%) and on the northern (47%) and western (46%) aspects. Temporal patterns in community changes were represented by increases in plant cover in the highest summit, in species richness in the lower summit, and in diversity (Shannon index) in the four summits, over time, together with increase in small herbs and non‐tussock grasses. We suggest that the observed trend in plant community dynamics responds to short‐term temperature and precipitation variability, which is influenced by El Niño Southern Oscillation (ENSO), and due to time lags in plant community response, it may take much longer than one decade for the observed trends to become stables and statistically significant. Our study provides an important foundation for documenting more profound changes in these subtropical alpine plant communities as global climate change continues.

Initial Response Lag time in Flat versus Non-Flat Beam Frameless Image Guided Trigeminal Radiosurgery

Radiosurgery is an established option in trigeminal neuralgia. Irrespective of devices used, the pain relief with radiosurgery occurs after a lag time of about 6-8wks. Recent introduction of FFF beams with dose rates around 2000mu/mt results in abbreviated beam-on time (BOT) - 12mts & overall treatment time (OTT) - 22-28 mts. Purpose of this study is to analyse the pain response lag time in trigeminal radiosurgery using unflat beams (@dose rate 2000) and flat beams (@dose rate 600). Twenty consecutive patients aged between 33-88 yrs with Trigeminal neuralgia (Typical -17, Atypical-3) underwent double reinforced mask immobilisation, CT (0.725mm post contrast axial) and MR simulation (0.75mm 3D space, 3-D TOF sequences). Following rigid fusion, a single isocenter was positioned at either RGZ or the DREZ along the symptomatic trigeminal nerve to deliver doses of 75-80 gy prescribed to 90% isodose line. All patients underwent treatment on a C-arm linac with 5mm stereotactic cones, 9 arcs with 3D-CBCT image guidance for positional accuracy. Sub-mm and sub-degree precision all through treatment was achieved using 6-DOF robotics & intra-fraction imaging after every 4000 mu delivery. 10 consecutive pts who underwent treatment with Unflat beams were compared with retrospective cohort of 10 patients who underwent treatment with flat beams. The pain outcome of patient, Lag time for response, pain recurrence, and treatment-related complications were evaluated. Cox regression analyses was used to evaluate the time to response and the duration of pain relief in relation to the type of beams used. Using the Barrow Neurological Index (BNI) pain score, 9 cases (90%) and 8 cases (80%) of unflat and flat beams Radiosurgery achieved treatment success (BNI pain score I–IIIb) within first 2months. However the Median time to initial response after the Radiosurgery was significantly shorter in the unflat beam cohort (mean 2.5 weeks) than in the Flat beam cohort (mean 6.4 weeks) (p=0.044). There were 5 pts in BNI 1 & 2 within first 1 month post radiosurgery for unflat beams. Frequency of facial numbness was lower in the Unflat beams compared to the Flat beams (0%, 10%). Faster treatments are associated with less patient mobility and increased delivery accuracy. Prolonged duration of radiosurgery amplifies the impact of Increased submm mobility of the nerve in the prepontine cistern, factor never considered, & which might negatively affect the amount of clinically relevant fibers receiving the minimal radiation dose necessary to block excessive sensory information. To the best of our knowledge, this is the first study reported in literature which looked into the impact of the abbreviated treatment times on pain outcomes using unflat beams for trigeminal radiosurgery. Larger study is initiated to study the effects of dose rates on pain outcomes.

Reproductive ecology of Agave colorata: the importance of nectar-feeding bats and the germination consequences of self-pollination

Agave colorata is a paniculate agave distributed along the migratory route of the nectar-feeding bat Leptonycteris yerbabuenae. In this paper, we evaluate the importance of nectar-feeding bats in the reproduction of A. colorata in a population in Sonora, Mexico, and describe the germination consequences of self-pollination. We estimated abundance using five plots and set pollination treatments to evaluate the importance of bats. We recorded 14.8 ± 6.8 plants/400 m2, with a bimodal size distribution. Flowers are protandrous and visited mainly (> 20 visits/plant/30 min) by L. yerbabuenae. Pollination exclusion experiments showed that flowers excluded from diurnal visitors had maximum fruit set values (0.49 ± 0.42), while the autonomous self-pollination treatment had the lowest value (0.03 ± 0.06). Similarly, the greatest number of viable seeds per fruit was recorded in the diurnal exclusion treatment, while the greatest number of empty seeds was observed in the self-pollination treatment. Fruit set values among untreated plants varied from 32 to 54%, with a mean value of 41.8%. Seeds derived from self-pollination had a narrower window of opportunity for germination compared to seeds derived from nocturnal pollination. Self-pollinated seeds had lower germination, rate of germination or lag time in response to light, osmotic potential and heat shock treatments, compared to other pollination treatments, revealing an inbreeding cost. Overall, our results show that L. yerbabuenae is the likely major pollinator of the studied A. colorata population. However, under pollinator limitation A. colorata may produce seeds by autonomous self-pollination, at a cost expressed as lower germination.

Thermoregulatory response of Brangus heifers to naturally occurring heat exposure on pasture.

Heat stress is a cause of major economic losses to cattle producers, especially in tropical and subtropical environments. The objectives of this study were to assess the phenotypic variability in core body temperature and sweating rate and to evaluate the effect of coat type, temperament, and BW on core body temperature and sweating rate in Brangus heifers. During August and September of 2016, 725 Brangus heifers were evaluated on pasture in four separate groups (n = 200, 189, 197, and 139). Environmental measurements of dry bulb temperature (Tdb) and relative humidity (RH) were measured every 15 min during the entire time of data collection and the temperature-humidity index (THI) was used to quantify heat-stress potential. Coat score, sweating rate, chute score, exit score, and live weight were recorded as the animals passed through the chute. Vaginal temperature was recorded every 5 min for five consecutive days. There was significant variation in vaginal temperature between heifers in the same environmental conditions (σ2u = 0.049), suggesting opportunities for selective improvements. A repeatability of 0.47 and 0.44 was estimated for sweating rate and vaginal temperature, respectively, suggesting that one measurement would be able to adequately describe the sweating capacity or ability to control the body temperature of an individual. Vaginal temperature increased as THI increased, with approximately 1 h lag time in the animal's response. Vaginal temperature (-0.047 °C, P = 0.015) and sweating rate were lower (-5.49 ± 2.12 g/(m2·h), P < 0.01) for heifers that demonstrated a calmer behavior in the chute. Animals with shorter, smoother hair coats had significantly lower vaginal temperatures when compared to animals with longer hair coats (P < 0.01). Also, heavier heifers in this study maintained lower (P < 0.0001) vaginal temperature than the lighter heifers. Our results showed that hair coat, temperament, and weight influenced vaginal temperature regulation.

Physiological response of 10 phytoplankton species exposed to macondo oil and the dispersant, Corexit.

Culture experiments were conducted on ten phytoplankton species to examine their biological and physiological responses during exposure to oil and a combination of oil and dispersant. The species tested included a range of taxa typically found in the Gulf of Mexico such as cyanobacteria, chlorophytes, and diatoms. Cultures were exposed to Macondo surrogate oil using the water accommodated fraction (WAF), and dispersed oil using a chemically enhanced WAF (CEWAF) and diluted CEWAF, to replicate conditions following the Deepwater Horizon spill in the Gulf of Mexico. A range of responses were observed, that could broadly class the algae as either "robust" or "sensitive" to oil and/or dispersant exposure. Robust algae were identified as Synechococcus elongatus, Dunaliella tertiolecta, two pennate diatoms Phaeodactylum tricornutum and Navicula sp., and Skeletonema grethae CCMP775, and were largely unaffected by any of the treatments (no changes to growth rate or time spent in lag phase relative to controls). The rest of the phytoplankton, all centric diatoms, exhibited at least some combination of reduced growth rates or increased lag time in response to oil and/or dispersant exposure. Photophysiology did not have a strong treatment effect, with significant inhibition of photosynthetic efficiency (Fv /Fm ) only observed in the CEWAF, if at all. We found that the effects of oil and dispersants on phytoplankton physiology were species-dependent, and not always detrimental. This has significant implications on how oil spills might impact phytoplankton community structure and bloom dynamics in the Gulf of Mexico, which in turn impacts higher trophic levels.

The roles of channels and hillslopes in rainfall/run‐off lag times during intense storms in a steep catchment

AbstractThe response time (lag time) between rainfall input and run‐off output in headwater catchments is a key parameter for flood prediction. Lag times are expected to be controlled by run‐off processes, both on hillslopes and in channels. To demonstrate these effects on peak lag times within a 4.5‐km2 catchment, we measured stream water levels at up to 16 channel locations at 1‐min intervals and compared the lag times with topographic indices describing the length and gradient of the hillslope and channel flow path. We captured storm events with a total precipitation of 38–198 mm and maximum hourly precipitation intensity of 9–90 mm/hr. There were positive relationships between lag time and flow path length as well as the ratio of the flow path length and the square root of the gradient of channels for the most intense storms, demonstrating that channel flow paths generally defined the variation in lag times. Topographic analysis showed that hillslope flow path lengths were similar among locations, whereas channel flow path length increased almost one order of magnitude with a 100‐fold increase in catchment area. Thus, the relative importance of hillslope flow path decreased with increasing catchment area. Our results indicate that the variation in lag times is small when hillslopes are sufficiently wet; thus, catchment‐scale variation in lag times can be explained almost entirely by channel processes. Detailed topographic channel information can improve prediction of flood peak timing, whereas hillslopes can be treated as homogeneous during large flood events.

Atmospheric QBO and ENSO indices with high vertical resolution from GNSS radio occultation temperature measurements

Abstract. We provide atmospheric temperature variability indices for the tropical troposphere and stratosphere based on global navigation satellite system (GNSS) radio occultation (RO) temperature measurements. By exploiting the high vertical resolution and the uniform distribution of the GNSS RO temperature soundings we introduce two approaches, both based on an empirical orthogonal function (EOF) analysis. The first method utilizes the whole vertical and horizontal RO temperature field from 30∘ S to 30∘ N and from 2 to 35 km altitude. The resulting indices, the leading principal components, resemble the well-known patterns of the Quasi-Biennial Oscillation (QBO) and the El Niño–Southern Oscillation (ENSO) in the tropics. They provide some information on the vertical structure; however, they are not vertically resolved. The second method applies the EOF analysis on each altitude level separately and the resulting indices contain information on the horizontal variability at each densely available altitude level. They capture more variability than the indices from the first method and present a mixture of all variability modes contributing at the respective altitude level, including the QBO and ENSO. Compared to commonly used variability indices from QBO winds or ENSO sea surface temperature, these new indices cover the vertical details of the atmospheric variability. Using them as proxies for temperature variability is also of advantage because there is no further need to account for response time lags. Atmospheric variability indices as novel products from RO are expected to be of great benefit for studies on atmospheric dynamics and variability, for climate trend analysis, as well as for climate model evaluation.

First signs of macroinvertebrate recovery following enhanced restoration of boreal streams used for timber floating

Although ecological restoration generally succeeds in increasing physical heterogeneity, many projects fail to enhance biota. Researchers have suggested several possible explanations, including insufficient restoration intensity, or time-lags in ecological responses that prevent detection of significant changes in short-term monitoring programs. This study aims to evaluate whether benthic macroinvertebrate communities responded to an expanded set of stream restoration measures within a study period of one to five years after completion of the restoration project. We studied 10 forest streams in northern Sweden that were channelized in the past for timber floating. Managers subjected six of these streams to habitat restoration, on each of these we selected two reaches, located in close proximity but differing in restoration intensity. In "basic" restored reaches, the restoration managers broke up the channelized banks and returned cobbles and small boulders to the main channel. In "enhanced" restoration reaches, they added additional large wood and boulders to reaches previously subjected to basic restoration, and rehabilitated gravel beds. The remaining four streams were not restored, and thus represent the baseline impacted (channelized) condition. We surveyed stream benthic assemblages before the enhanced restoration (year 2010) and three times afterward between 2011 and 2015. Five years after restoration, macroinvertebrate assemblages at the enhanced restored reaches were more differentiated from channelized conditions than those at basic-restored reaches. This reflected increased relative abundances of the insect orders Ephemeroptera and Trichoptera and the bivalve molluscs Sphaeriidae and decreased relative abundances of Chironomidae (Diptera). Analysis of functional traits provided further insights on the mechanistic explanations driving the recovery, e.g., indicating that the augmented channel retention capacity at enhanced restored reaches favored taxa adapted to slow flow conditions and more effectively retained passive aquatic dispersers. The increased restoration intensity in enhanced restored reaches has resulted in shifts in the composition of benthic macroinvertebrate assemblages, including increases in more sensitive taxa. These shifts became fully apparent five years after the enhanced restoration. Our results emphasize the value of longer-term monitoring to assess ecological responses following restoration, and of undertaking additional restoration as a valuable management option for previously restored sites that failed to achieve biotic recovery.

Information Theoretic Approach to Discovering Causalities in the Solar Cycle

Abstract The causal parameters and response lag times of the solar cycle dynamics are investigated with transfer entropy, which can determine the amount of information transfer from one variable to another. The causal dependency of the solar cycle parameters is bidirectional. The transfer of information from the solar polar field to the sunspot number (SSN) peaks at lag time (τ) ∼ 30–40 months, but thereafter it remains at a persistently low level for at least 400 months (∼3 solar cycles) for the period 1906–2014. The latter may lend support to the idea that the polar fields from the last three or more solar cycles can affect the production of the SSN of the subsequent cycle. There is also a similarly long-term information transfer from the SSN to the polar field. Both the meridional flow speed and flux emergence (proxied by the SSN) transfer information to the polar field, but one transfers more information than the other, depending on the lag times. The meridional flow speed transfers more information than the SSN to the polar field at τ ∼ 28–30 months and at τ ∼ 90–110 months, which may be consistent with some flux transfer dynamo models and some surface flux transport models. However, the flux emergence transfers more information than the meridional flow to the polar field at τ ∼ 60–80 months, which may be consistent with a recently developed surface flux transport model. The transfer of information from the meridional flow to the SSN peaks at τ ∼ 110–120 months (∼1 solar cycle).

Climatic suitability, isolation by distance and river resistance explain genetic variation in a Brazilian whiptail lizard.

Spatial patterns of genetic variation can help understand how environmental factors either permit or restrict gene flow and create opportunities for regional adaptations. Organisms from harsh environments such as the Brazilian semiarid Caatinga biome may reveal how severe climate conditions may affect patterns of genetic variation. Herein we combine information from mitochondrial DNA with physical and environmental features to study the association between different aspects of the Caatinga landscape and spatial genetic variation in the whiptail lizard Ameivula ocellifera. We investigated which of the climatic, environmental, geographical and/or historical components best predict: (1) the spatial distribution of genetic diversity, and (2) the genetic differentiation among populations. We found that genetic variation in A. ocellifera has been influenced mainly by temperature variability, which modulates connectivity among populations. Past climate conditions were important for shaping current genetic diversity, suggesting a time lag in genetic responses. Population structure in A. ocellifera was best explained by both isolation by distance and isolation by resistance (main rivers). Our findings indicate that both physical and climatic features are important for explaining the observed patterns of genetic variation across the xeric Caatinga biome.

A novel perspective to calibrate temporal delays in cerebrovascular reactivity using hypercapnic and hyperoxic respiratory challenges

Redistribution of blood flow across different brain regions, arising from the vasoactive nature of hypercapnia, can introduce errors when examining cerebrovascular reactivity (CVR) response delays. In this study, we propose a novel analysis method to characterize hemodynamic delays in the blood oxygen level dependent (BOLD) response to hypercapnia, and hyperoxia, as a way to provide insight into transient differences in vascular reactivity between cortical regions, and across tissue depths. A pseudo-continuous arterial spin labeling sequence was used to acquire BOLD and cerebral blood flow simultaneously in 19 healthy adults (12 F; 20 ± 2 years) during boxcar CO2 and O2 gas inhalation paradigms. Despite showing distinct differences in hypercapnia-induced response delay times (P < 0.05; Bonferroni corrected), grey matter regions showed homogenous hemodynamic latencies (P > 0.05) once calibrated for bolus arrival time derived using non-vasoactive hyperoxic gas challenges. Longer hypercapnic temporal delays were observed as the depth of the white matter tissue increased, although no significant differences in response lag were found during hyperoxia across tissue depth, or between grey and white matter. Furthermore, calibration of hypercapnic delays using hyperoxia revealed that deeper white matter layers may be more prone to dynamic redistribution of blood flow, which introduces response lag times ranging between 1 and 3 s in healthy subjects. These findings suggest that the combination of hypercapnic and hyperoxic gas-inhalation MRI can be used to distinguish between differences in CVR that arise as a result of delayed stimulus arrival time (due to the local architecture of the cerebrovasculature), or preferential blood flow distribution. Calibrated response delays to hypercapnia provide important insights into cerebrovascular physiology, and may be used to correct response delays associated with vascular impairment.

A Multi-Sensor Approach for Assessing Mangrove Biophysical Characteristics in Coastal Odisha, India

Mangroves around the world play a major role in coastal ecosystem processes by mitigating erosion and serving as a barrier against storm surges. India holds approximately 5% of the world’s mangroves, over half of which are found along its east coast. Situated in the state of Odisha, Chilika Lagoon and Bhitarkanika Wildlife Sanctuary are two wetlands of local importance in need of effective management. This study demonstrated the use of Terra, Landsat, and Sentinel-1 satellite data for spatio-temporal monitoring of mangrove health at these two sites. Several indices, including Normalized Difference Vegetation Index and Enhanced Vegetation Index, were examined to develop biophysical prediction tools and derive a 17-year time-series (from 2000 to 2016) of leaf chlorophyll (CHL), Leaf Area Index (LAI), and Gross Primary Productivity (GPP). The long-term analysis revealed phenological patterns in the biophysical characteristics such as high values during wet season and low values during the dry season. Correlations between biophysical characteristics and meteorological factors revealed a time lag exists in response to precipitation and associated runoff. In contrast, surface temperature did not show any lag in response time. This study also utilized Sentinel-1 radar data for the first time for Odisha mangroves to show seasonal variability in LAI, GPP, and CHL. The results from radar data were consistent with optical sensors and proved useful for capturing the rainy season, where data were limited due to cloud cover. This study revealed the advantages of using a multi-sensor approach for monitoring mangrove health and defining future monitoring protocols.

Stump extraction in the surrounding landscape: Predatory saproxylic beetles are more negatively affected than lower trophic levels

Abstract To harvest more biofuel from forests, tree stumps are sometimes extracted after clearcutting. Species in different organism groups rely on deadwood, and biofuel extraction reduces their substrate. Our aim was to investigate the potential landscape effects of stump extraction, and compare the effects among trophic levels of deadwood-dependent (saproxylic) beetles. We sampled saproxylic beetle species in clearcut stumps using bark sieving. We did the study in 2013 in 49 clearcuts (1–4 years old) in three regions in central Sweden where stump extraction had been performed for six years prior to sampling. We selected landscape buffers with 500 m, 1000 m, and 2000 m radius with different intensities of stump extraction (0–100%). We show for the first time, based on empirical data, that increasing stump extraction can affect deadwood-dependent species at the landscape level. On average, obligate predators were more negatively affected than cambivores and facultative predators. The 34 studied saproxylic beetle species showed varied responses to stump extraction in the surrounding landscape, including stable (no response), negative, or positive responses. Positive responses could be due to a crowding effect, indicating a time-lagged response to habitat loss. Since stump extraction in the study area started just six years prior to sampling, time-lags in population-level responses could be expected. The age of the sampled clearcuts influenced the abundance of eleven species, but other local factors had little effect on abundance. Our results suggest that if stump extraction is widely introduced, deadwood retention—planned for both spatial and temporal continuity—should be an integrated part of intensified forest management. We suggest monitoring the long-term effects of stump extraction.