Cycle Variability Research Articles

Towards Optimized ARMGs’ Low-Carbon Transition Investment Decision Based on Real Options

As a critical node of the global transportation network, ports have great potential in promoting transportation emission reduction. Promoting the low-carbon transition of ports by using clean energy is effective. Using hydrogen energy in automated container terminals (ACTs) has become popular in port emission-reduction research. The research object is the main port equipment—the automated rail-mounted container gantry crane (ARMG). This research designs a staged investment decision-making scheme for ARMGs’ hydrogen energy transition. The Internet of Things (IoT) architecture in ACTs collects ARMG equipment operation and carbon emission data. It provides a basis for data acquisition in ARMGs’ hydrogen energy transition. Furthermore, ports can adopt big data technology to analyze the correlation between equipment operation and carbon emissions. Finally, the digital twin platform will visualize the ARMG equipment operation and carbon emission behavior to remote operators. These advanced technologies can achieve status monitoring and simulation prediction, which will support ARMGs’ hydrogen energy transition. However, the ARMGs’ hydrogen energy transition has a long cycle, large investment, and strong variability. Ports should make staged investment decisions based on the digital twin platform’s status monitoring and simulation prediction analysis results. Therefore, this research establishes an optimization model for ARMGs’ low-carbon transition investment decision based on the real options method, and analyzes the staged investment scale and timing of ARMGs’ hydrogen energy transition. The results provide a popularized decision-making scheme for the low-carbon transition of ports’ equipment, which could facilitate the low-carbon transition of ports’ equipment.

Effects of direct injection and mixture enleament on the combustion of hydrous ethanol and an ethanol-gasoline blend in an optical engine

Ethanol is a renewable fuel and can be used in electric hybrid vehicles concepts, especially for countries capable of producing such fuel in a sustainable way. A strategy to enhance these concepts is the use of lean-burn combustion, which is an effective way to improve the fuel economy from spark-ignition engines, while obtaining low pollutant emissions. However, these improvements are complicated to achieve in a practical way because lean combustion has low rates of reaction, extinction, and misfire cycles, leading to cyclical variability for the engine operation. The drawback becomes even greater when lean combustion is associated with commercial ethanol fuels and direct injection. Therefore, the objective of the present work is to provide an experimental analysis of spray guided direct injection with commercial fuels used in a consolidated market for the use of ethanol such as the Brazilian one, in particular hydrous ethanol (E95W05) and ethanol-gasoline blends (E27G73). The experiments were conducted in an optically accessible spark-ignition engine and the lean combustion effects on engine cycle variability, performance, flame morphology, and exhaust emissions were assessed. In general, the results indicated that combustion instabilities can be correlated from thermodynamic and optical analyses. Flame instabilities for E95W05 were associated with the lower flame propagation speed caused by the temperature reduction during lean combustion. Additionally, exhaust emissions contained the presence of unburned ethanol which increased when combustion became leaner. Moreover, the lower flame propagation speed was one of the factors responsible for reducing engine performance and increasing combustion variability. The results indicated that vaporization was a relevant phenomenon affecting ethanol combustion in the direct injection mode. The cooling effect of fuel vaporization presented itself as a powerful means for the reduction of NOx and aldehydes, even for the lean operation. Higher emissions of CO and THC were also observed for the engine operating with E95W05 when compared to E27G73. The results of the present work showed that special attention must be paid to the use of commercial fuel with a high ethanol content in spray-guided direct injection engines, especially during lean-burn combustion, in order to not compromise the performance nor increase pollutant emissions.

Reliability and Variability of Lower Limb Muscle Activation as Indicators of Familiarity to Submaximal Eccentric Cycling.

Submaximal eccentric (ECC) cycling exercise is commonly used in research studies. No previous study has specified the required time naïve participants take to familiarize with submaximal ECC cycling. Therefore, we designed this study to determine whether critical indicators of cycling reliability and variability stabilize during 15 min of submaximal, semi-recumbent ECC cycling (ECC cycling). Twenty-two participants, aged between 18–51 years, volunteered to complete a single experimental session. Each participant completed three peak eccentric torque protocol (PETP) tests, nine countermovement jumps and 15 min of submaximal (i.e., 10% peak power output produced during the PETP tests) ECC cycling. Muscle activation patterns were recorded from six muscles (rectus femoris, RF; vastus lateralis, VL; vastus medialis, VM; soleus, SOL; medial gastrocnemius, GM; tibialis anterior, TA), during prescribed-intensity ECC cycling, using electromyography (EMG). Minute-to-minute changes in the reliability and variability of EMG patterns were examined using intra-class correlation coefficient (ICC) and variance ratios (VR). Differences between target and actual power output were also used as an indicator of familiarization. Activation patterns for 4/6 muscles (RF, VL, VM and GM) became more consistent over the session, the RF, VL and VM increasing from moderate (ICC = 0.5–0.75) to good (ICC = 0.75–0.9) reliability by the 11th minute of cycling and the GM good reliability from the 1st minute (ICC = 0.79, ICC range = 0.70–0.88). Low variability (VR ≤ 0.40) was maintained for VL, VM and GM from the 8th, 8th and 1st minutes, respectively. We also observed a significant decrease in the difference between actual and target power output (χ2 14 = 30.895, p = 0.006, W = 0.105), expressed primarily between the 2nd and 3rd minute of cycling (Z = -2.677, p = 0.007). Indicators of familiarization during ECC cycling, including deviations from target power output levels and the reliability and variability of muscle activation patterns stabilized within 15 min of cycling. Based upon this data, it would be reasonable for future studies to allocate ∼ 15 min to familiarize naïve participants with a submaximal ECC cycling protocol.

Bilateral Feedback in Oscillator Model Is Required to Explain the Coupling Dynamics of Hes1 with the Cell Cycle

Biological processes are governed by the expression of proteins, and for some proteins, their level of expression can fluctuate periodically over time (i.e., they oscillate). Many oscillatory proteins (e.g., cell cycle proteins and those from the HES family of transcription factors) are connected in complex ways, often within large networks. This complexity can be elucidated by developing intuitive mathematical models that describe the underlying critical aspects of the relationships between these processes. Here, we provide a mathematical explanation of a recently discovered biological phenomenon: the phasic position of the gene Hes1’s oscillatory expression at the beginning of the cell cycle of an individual human breast cancer stem cell can have a predictive value on how long that cell will take to complete a cell cycle. We use a two-component model of coupled oscillators to represent Hes1 and the cell cycle in the same cell with minimal assumptions. Inputting only the initial phase angles, we show that this model is capable of predicting the dynamic mitosis to mitosis behaviour of Hes1 and predicting cell cycle length patterns as found in real-world experimental data. Moreover, we discover that bidirectional coupling between Hes1 and the cell cycle is critical within the system for the data to be reproduced and that nonfixed asymmetry in the interactions between the oscillators is required. The phase dynamics we present here capture the complex interplay between Hes1 and the cell cycle, helping to explain nongenetic cell cycle variability, which has critical implications in cancer treatment contexts.

P-429 The prevalence and assessment of uterine natural killer cells (uNK) by Immunohistochemistry (IHC) in women undergoing IVF

Abstract Study question What is the prevalence of raised uNK cells in an IVF population? Identifying demographic factors that are predictive of a raised uNK result? Summary answer The prevalence of uNK was high for those with RIF and history of miscarriage. Age was the only statistically significant factor for predicting positive results. What is known already uNK cells play two important roles in implantation; regulation of trophoblastic invasion and spiral artery modelling. Both these crucial mechanisms are required for bringing about a state of endometrial receptivity. The current evidence is centred on raised uNK status in women undergoing IVF being associated with a detrimental pregnancy outcome. This could be either due to NK cells being cytotoxic to embryo endometrium complex or causing aberrant placentation. Their exact function is unclear and the prevalence has only been determined in small observational studies. Study design, size, duration This was a prospective analysis of 203 patients who had uNK testing through immunohistochemistry and subsequently embarked on IVF treatment. Patients undergoing both fresh and frozen in vitro fertilisation (IVF) cycles at NURTURE fertility, Nottingham, UK were approached over a period of 6 months at different stages of their fertility history. Participants/materials, setting, methods uNK biopsy was arranged one month before undergoing IVF to ensure results before embryo transfer. The procedure was carried out in the mid-luteal phase of the menstrual cycle (day 19-24). Samples were fixed and analyzed by IHC. The age, BMI, timing of the biopsy, cause of infertility was recorded. The details of the subsequent IVF cycle, embryo quality, and pregnancy outcome were also collected prospectively. The data was analyzed using SPSS version 25. Main results and the role of chance The prevalence of raised uNK status was noted to be 61.6% (CI 54.9-68.3) in the IVF population. Furthermore the prevalence in women with no previous IVF treatment (primary infertility) was also high 66.7% (CI 54.4-78.9). One of the main strengths of this work was women were recruited from a highly successful IVF center. The clinical pregnancy rates are 2-3 fold higher than the national average e.g. 65% for women aged under 35 versus 29% respectively (HFEA 2018). This is mainly due to stringent laboratory processes leading to the creation of optimal quality embryos and their transfer. Therefore if IVF did not result in a pregnancy, then endometrial receptivity or adverse maternal immunology could be contributory factors. Although the prevalence of raised uNK status was high for those with RIF and a history of miscarriage, there were only statistically significant associations found for age in terms of predicting a positive result. Therefore IHC has to be complimented with another technique such as flow cytometry to determine if uNK is significant in implantation and pregnancy success. Limitations, reasons for caution uNK status is influenced by hormonal, menstrual cycle variability, pathogenic and laboratory interpretation. Therefore to gauge an accurate assessment of whether immune cells are implicated in pregnancy, a functional aspect of study or repeat sampling in the same cycle is required. Wider implications of the findings It is known that immune cell function declines with age. They may also be detrimental to pregnancy outcomes and contribute to the age-related decline in fertility. Designing a randomized controlled trial whereby patients tested for uNK are allocated to therapy such as prednisolone. This may address both issues. Trial registration number N/A

Ballistocardiogram suppression in concurrent EEG-MRI by dynamic modeling of heartbeats.

The ballistocardiogram (BCG), the induced electric potentials by the head motion originating from heartbeats, is a prominent source of noise in electroencephalography (EEG) data during magnetic resonance imaging (MRI). Although methods have been proposed to suppress the BCG artifact, more work considering the variability of cardiac cycles and head motion across time and subjects is needed to provide highly robust correction. Here, a method called “dynamic modeling of heartbeats” (DMH) is proposed to reduce BCG artifacts in EEG data recorded inside an MRI system. The DMH method models BCG artifacts by combining EEG points at time instants with similar dynamics. The modeled BCG artifact is then subtracted from the EEG recording to suppress the BCG artifact. Performance of DMH was tested and specifically compared with the Optimal Basis Set (OBS) method on EEG data recorded inside a 3T MRI system with either no MRI acquisition (Inside‐MRI), echo‐planar imaging (EPI‐EEG), or fast MRI acquisition using simultaneous multi‐slice and inverse imaging methods (SMS‐InI‐EEG). In a steady‐state visual evoked response (SSVEP) paradigm, the 15‐Hz oscillatory neuronal activity at the visual cortex after DMH processing was about 130% of that achieved by OBS processing for Inside‐MRI, SMS‐InI‐EEG, and EPI‐EEG conditions. The DMH method is computationally efficient for suppressing BCG artifacts and in the future may help to improve the quality of EEG data recorded in high‐field MRI systems for neuroscientific and clinical applications.

Business cycle characteristics of Mediterranean economies: a secular trend and cycle dynamics perspective

AbstractThis study analyzes business cycle characteristics for all 20 major contemporaneous economies bordering the Mediterranean Sea based on annual real gross domestic product series for the period from 1960 to 2019. The region we investigate corresponds to the Mare Internum region of the Imperial Roman Empire during the Nerva-Antonine and early Severan dynasty, i.e., at the time of the maximum extent of the Roman Empire around 100 to 200 CE. The covered area encircles the Mediterranean, including economies now belonging to the European Union as well as acceding countries, Turkey, and the Middle East and North African economies. Using a components-deviation-cycle approach, we assess level trends and relative volatility of output. We also quantify the contribution of various factors to the business cycle variability within a region. We find cyclic commonalities and idiosyncrasies are related to ancient and colonial history and to contemporaneous trade relationships. Caliphate and Ottoman Empire membership as well as colonial rule in the twentieth century and contemporary Muslim share of population are the most promising predictors of business cycle commonalities in the region.

Menstrual Cycle Effects on Sleep.

Sleep and circadian rhythms are altered in association with the hormonal changes in the menstrual cycle and in the presence of menstrual-associated disorders. The magnitude of the effect varies, particularly for self-reported sleep quality, which worsens in some, but not all, women when premenstrual symptoms emerge. Importantly, women with polycystic ovary syndrome (PCOS) have an increased risk for sleep-disordered breathing (SDB), which should be treated to mitigate health impacts. Potential menstrual cycle variability in sleep quality, as well as upper airway resistance, should be considered when evaluating reproductive-age women. For research purposes, the impact of the menstrual cycle phase should be kept in mind when data are collected and, ideally, the phase should be documented. When comparing women with men, women of reproductive age should be studied in the early-mid follicular phase before there is potential influence from ovarian hormones.

Remote Sensing Phenology of the Brazilian Caatinga and Its Environmental Drivers

The Caatinga is the largest nucleus of Seasonally Dry Tropical Forests (SDTF) in the Neotropics. The leafing patterns of SDTF vegetation are adapted to the current environmental and climate variability, but the impacts of climate change tend to alter plants’ phenology. Thus, it is necessary to characterise phenological parameters and evaluate the relationship between vegetation and environmental drivers. From this information, it is possible to identify the dominant forces in the environment that trigger the phenological dynamics of the Caatinga. In this way, remote sensing represents an essential tool to investigate the phenology of vegetation, particularly as it has a long series of vegetation monitoring and allows relationships with different environmental drivers. This study has two objectives: (i) estimate phenological parameters using an Enhanced Vegetation Index (EVI) time-series over 20 years, and (ii) characterise the relationship between phenologic dynamics and environmental drivers. TIMESAT software was used to determine four phenological parameters: Start Of Season (SOS), End Of Season (EOS), Length Of Season (LOS), and Amplitude (AMPL). Boxplots, Pearson’s, and partial correlation coefficients defined relationships between phenologic dynamics and environmental drivers. The non-parametric test of Fligner–Killeen was used to test the interannual variability in SOS and EOS. Our results show that the seasonality of vegetation growth in the Caatinga was different in the three experimental sites. The SOS was the parameter that presented the greatest variability in the days of the year (DOY), reaching a variation of 117 days. The sites with the highest SOS variability are the same ones that showed the lowest EOS variation. In addition, the values of LOS and AMPL are directly linked to the annual distribution of rainfall, and the longer the rainy season, the greater their values are. The variability of the natural cycles of the environmental drivers that regulate the ecosystem’s phenology and the influence on the Caatinga’s natural dynamics indicated a greater sensitivity of the phenologic dynamics to water availability, with precipitation being the limiting factor of the phenologic dynamics. Highlights: The EVI time series was efficient in estimating phenological parameters. The high variability of the start of season (SOS) occurred in sites with low variability of end of the season (EOS) and vice versa. The precipitation and water deficit presented a higher correlation coefficient with phenological dynamics. Length of Season (LOS) and amplitude (AMPL) are directly linked to the annual distribution of rainfall.

Relationship between Tissue Gliding of the Lateral Thigh and Gait Parameters after Trochanteric Fractures.

Trochanteric fractures lead to severe functional deficits and gait disorders compared to femoral neck fractures. This study aims to investigate gait parameters related to gliding between tissues (gliding) after trochanteric fracture (TF) surgery. This study implemented a cross-sectional design and was conducted amongst patients who underwent TF surgery (n = 94) approximately three weeks post-trochanteric fracture surgery. The following parameters were evaluated: (1) gliding between tissues; (2) lateral femoral pain during loading; (3) maximum gait speed; (4) stride time variability and step time asymmetry as measures of gait cycle variability; (5) double stance ratio and single stance ratio for assessment of stance phase, (6) jerk; and (7) Locomotor rehabilitation index as a measure of force changes during gait. The gliding coefficient was significantly correlated with lateral femoral pain (r = 0.517), jerk root mean square (r = −0.433), and initial contact-loading response jerk (r = −0.459). The jerk of the force change value during gait was also effective in understanding the characteristics of the gait in the initial contact-loading response in patients with trochanteric fractures. Additionally, gliding is related not only to impairments such as pain but also to disabilities such as those affecting gait.

Hormonal regulation of ovarian follicle growth in humans: Model-based exploration of cycle variability and parameter sensitivities

We present a modelling and simulation framework for the dynamics of ovarian follicles and key hormones along the hypothalamic-pituitary–gonadal axis throughout consecutive human menstrual cycles. All simulation results (hormone concentrations and ovarian follicle sizes) are in biological units and can easily be compared to clinical data. The model takes into account variability in follicles’ response to stimulating hormones, which introduces variability between cycles. The growth of ovarian follicles in waves is an emergent property in our model simulations and further supports the hypothesis that follicular waves are also present in humans. We use Approximate Bayesian Computation and cluster analysis to construct a population of virtual subjects and to study parameter distributions and sensitivities. The model can be used to compare and optimize treatment protocols for ovarian hyperstimulation, thus potentially forming the integral part of a clinical decision support system in reproductive endocrinology.

Solar Cycle and Seasonal Variability of Martian Ionospheric Irregularities from Mars Atmosphere and Volatile Evolution Observations

Spacecraft observations around Mars show that ionospheric irregularities occur frequently in the Martian ionosphere. In this study, Mars Atmosphere and Volatile Evolution data (the region is below ∼200 km) during 2015 January to 2021 March were used to revisit the statistical characteristics of ionospheric irregularities and the comparison of irregularities in Martian years with higher or lower solar activity phase of solar cycle. Results show that the characteristics of the irregularities with a larger length scale associated with the magnetic field and solar zenith angle are similar to the previous studies. Moreover, our results show that the occurrence rate of irregularities exhibits dawn and dusk asymmetry, and the occurrence rate at dusk is higher than that at dawn. In addition, results demonstrate that the occurrence rate of irregularities is higher in Martian years with higher solar activity than Martian years with lower solar activity, which means that the solar cycle might play an important role in the formation of irregularity events. Further studies show that the solar zenith angle (SZA) and altitude at the maximum occurrence rate depend on the level of solar activity. The SZA and altitude of the maximum occurrence rate are smaller in the Martian year with higher solar activity than the lower. We also found that the rate of events is lower during the day than the terminator in the ionospheric dynamo region. By contrast, in the regions where both electrons and ions are magnetized, events have a higher rate during the day than the terminator. Furthermore, the seasonal variation of the irregularity events was also presented in this study. Results show that the occurrence rate in the dynamo region with 80° < SZA < 150° in MY34 and MY35 show an incremental trend from spring to winter, but this trend is not obvious in MY33.

The Effects of Solar Cycle Variability on Nanodust Dynamics in the Inner Heliosphere: Predictions for Future STEREO A/WAVES Measurements

AbstractThe collisional grinding of interplanetary meteoroids should continually produce grains over a wide range of sizes, including down to the nanometer‐size regime. Once generated, nanodust grains are subject to interplanetary electromagnetic forces from the solar wind due to their relatively large charge‐to‐mass ratios, resulting in complex and highly time‐dependent dynamics. Here, we use the coupled Wang‐Sheeley‐Arge solar corona and Enlil solar wind models together with a nanodust charging and dynamics model to explore the behavior and variability of nanodust dynamics in the inner heliosphere (&lt;1 au) both within and across multiple solar cycles. In particular, we quantify the relative accessibility of these grains to 1 au across solar cycles 23 and 24, including focusing and defocusing heliospheric conditions. Finally, we qualitatively compare our model results with STEREO A (STA)/WAVES observations and identify correlations between the STA/WAVES single‐hit rate and the relative flux of &gt;10 nm grains. Using solar cycle 23 as a proxy for the behavior of solar cycle 25, since both solar cycles share the same defocusing‐to‐focusing transition, we predict the relative flux of nanodust grains in the future and identify times at which nanodust impacts may reappear in the STA/WAVES data set. Continued analysis of future STA/WAVES observations will provide an important test of this prediction, either bolstering or weakening the interpretation of electromagnetically accelerated nanodust grains as the source of single‐hit events in the STA/WAVES Time Domain Sampler data set.

Etonogestrel Administration Reduces the Expression of PHOX2B and Its Target Genes in the Solitary Tract Nucleus.

Heterozygous mutations of the transcription factor PHOX2B are responsible for Congenital Central Hypoventilation Syndrome, a neurological disorder characterized by inadequate respiratory response to hypercapnia and life-threatening hypoventilation during sleep. Although no cure is currently available, it was suggested that a potent progestin drug provides partial recovery of chemoreflex response. Previous in vitro data show a direct molecular link between progestins and PHOX2B expression. However, the mechanism through which these drugs ameliorate breathing in vivo remains unknown. Here, we investigated the effects of chronic administration of the potent progestin drug Etonogestrel (ETO) on respiratory function and transcriptional activity in adult female rats. We assessed respiratory function with whole-body plethysmography and measured genomic changes in brain regions important for respiratory control. Our results show that ETO reduced metabolic activity, leading to an enhanced chemoreflex response and concurrent increased breathing cycle variability at rest. Furthermore, ETO-treated brains showed reduced mRNA and protein expression of PHOX2B and its target genes selectively in the dorsal vagal complex, while other areas were unaffected. Histological analysis suggests that changes occurred in the solitary tract nucleus (NTS). Thus, we propose that the NTS, rich in both progesterone receptors and PHOX2B, is a good candidate for ETO-induced respiratory modulation.

Multiarea Brain Activation and Gait Deterioration During a Cognitive and Motor Dual Task in Individuals With Parkinson Disease.

In people with Parkinson disease (PD), gait performance deteriorating during dual-task walking has been noted in previous studies. However, the effects of different types of dual tasks on gait performance and brain activation are still unknown. The purpose of this study was to investigate cognitive and motor dual-task walking performance on multiarea brain activity in individuals with PD. Twenty-eight participants with PD were recruited and performed single walking (SW), walking while performing a cognitive task (WCT), and walking while performing a motor task (WMT) at their self-selected speed. Gait performance including walking speed, stride length, stride time, swing cycle, temporal and spatial variability, and dual-task cost (DTC) was recorded. Brain activation of the prefrontal cortex (PFC), premotor cortex (PMC), and supplementary motor areas (SMA) were measured using functional near-infrared spectroscopy during walking. Walking performance deteriorated upon performing a secondary task, especially the cognitive task. Also, a higher and more sustained activation in the PMC and SMA during WCT, as compared with the WMT and SW, in the late phase of walking was found. During WMT, however, the SMA and PMC did not show increased activation compared with during SW. Moreover, gait performance was negatively correlated with PMC and SMA activity during different walking tasks. Individuals with mild to moderate PD demonstrated gait deterioration during dual-task walking, especially during WCT. The SMA and PMC were further activated in individuals with PD when performing cognitive dual-task walking.Supplemental Digital Content is Available in the Text.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A383 ).

Understanding the Effects of Cardamom Cultivation on Its Local Environment Using Novel Systems Thinking Approach-the Case of Indian Cardamom Hills

Intensive cardamom cultivation in Indian Cardamom hills (ICH) has been related to severe ecological and environmental implications that can challenge the long-term sustainability of cardamom. This research study and analysis proposes a novel system approach for sustainable agroecological production of cardamom in southern India. The effects of intensive cardamom cultivation on its forest environment had been significant. A considerable increase in surface air temperature was observed in the ICH during the last three decades (1990–2020). The climate of the Cardamom hill reserves (CHR) has a very high variability of daily cycles (surface air temperature and relative humidity) compared to low variability of yearly cycles, which helped minor and major pests and diseases occur and spread throughout the season. The current hydrothermal condition of the soil fostered the occurrence of soil insect pests, resulting in higher pesticide use. Epiphytes peculiar to the CHR forest have been eliminated due to repeated, intense shade lopping of each tree. Variability occurred in cardamom growth and development and yield can be attributed to changes in the microclimatic environment prevailing in the micro habitats of the sloping hillsides. This study has revealed the possible link and various dimensions between the intensive growing practices that were positively reflected in its local climate and production system. The 75% shade level under the cardamom canopy influences the cardamom microclimatic conditions, the relative humidity close proximity with panicles was maximum (88.9%), and the mean air temperature was minimum (18.4°C). On the contrary, the relative humidity at canopy top was reduced (78.7%) but the mean air temperature was still high (27.4°C). This study also suggests that future energy transfers in the CHR production system must be understood for improving the long-term agricultural sustainability of cardamom cultivation in the ICH.

Stable Isotope Oscillations in Whale Baleen Are Linked to Climate Cycles, Which May Reflect Changes in Feeding for Humpback and Southern Right Whales in the Southern Hemisphere

Baleen whales that undertake extensive long-distance migrations away from reliable food sources must depend on body reserves acquired prior to migration. Prey abundance fluctuates, which has been linked in some regions with climate cycles. However, where historically these cycles have been predictable, due to climate change they are occurring at higher frequencies and intensities. We tested if there were links between variability in whale feeding patterns and changes in climate cycles including the El Niño-Southern Oscillation (ENSO), Southern Annular Mode (SAM), and Indian Ocean Dipole (IOD). To reconstruct feeding patterns we used the values of bulk stable isotopes of nitrogen (δ15N) and carbon (δ13C) assimilated within the baleen plates of 18 humpback and 4 southern right whales between 1963 and 2019, then matched them with climate anomalies from the time in which the section of baleen grew. We show that variability in stable isotope values within baleen for both humpback and southern right whales is linked with shifts in climate cycles and may imply changes in feeding patterns due to resource availability. However, these relationships differed depending on the oceanic region in which the whales feed. In the western Pacific, Southern Ocean feeding humpback whales had elevated nitrogen and carbon stable isotope values during La Niña and positive SAM phases when lagged 4 years, potentially reflecting reduced feeding opportunities. On the other hand, in the Indian Ocean the opposite occurs, where lower nitrogen and carbon stable isotope values were found during positive SAM phases at 2–4-year lag periods for both Southern Ocean feeding humpback and southern right whales, which may indicate improved feeding opportunities. Identifying links between stable isotope values and changes in climate cycles may contribute to our understanding of how complex oscillation patterns in baleen are formed. As projections of future climate scenarios emphasise there will be greater variability in climate cycles and thus the primary food source of baleen whales, we can then use these links to investigate how long-term feeding patterns may change in the future.

Nontarget Screening Exhibits a Seasonal Cycle of PM2.5 Organic Aerosol Composition in Beijing.

The molecular composition of atmospheric particulate matter (PM) in the urban environment is complex, and it remains a challenge to identify its sources and formation pathways. Here, we report the seasonal variation of the molecular composition of organic aerosols (OA), based on 172 PM2.5 filter samples collected in Beijing, China, from February 2018 to March 2019. We applied a hierarchical cluster analysis (HCA) on a large nontarget-screening data set and found a strong seasonal difference in the OA chemical composition. Molecular fingerprints of the major compound clusters exhibit a unique molecular pattern in the Van Krevelen-space. We found that summer OA in Beijing features a higher degree of oxidation and a higher proportion of organosulfates (OSs) in comparison to OA during wintertime, which exhibits a high contribution from (nitro-)aromatic compounds. OSs appeared with a high intensity in summer-haze conditions, indicating the importance of anthropogenic enhancement of secondary OA in summer Beijing. Furthermore, we quantified the contribution of the four main compound clusters to total OA using surrogate standards. With this approach, we are able to explain a small fraction of the OA (∼11-14%) monitored by the Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM). However, we observe a strong correlation between the sum of the quantified clusters and OA measured by the ToF-ACSM, indicating that the identified clusters represent the major variability of OA seasonal cycles. This study highlights the potential of using nontarget screening in combination with HCA for gaining a better understanding of the molecular composition and the origin of OA in the urban environment.

On the F3 layer occurrence and drift over the equatorial location of Thiruvananthapuram

A study has been carried out on various aspects of occurrence as well as vertical drift of F3 layer over the magnetic equatorial location of Thiruvananthapuram [8.5 0N; 77 0E; dip lat of 0.5 0N] in India for the period from 1990−2009 using ionosonde observations. Diurnally, F3 layer occurrence exhibits a double peak pattern with maximum occurrence in the pre-noon, followed by a broad peak in the post-noon hours. The F3 layer exhibits a seasonal pattern of occurrence which is prominent only during low solar activity periods. The solar cycle variability of F3 layer occurrence is brought out in the present study using data from solar cycle 22 and 23. Further it is clear from the present analysis that F3 layer occurrence is high during periods of lower geomagnetic activity with Ap less than 20. The present study brings out an important aspect that there is no significant difference in the occurrence percentage of pre-noon F3 layers during solar cycle 22 and 23, while the post-noon F3 layer occurrence increases during the deep solar minimum periods at the end of solar cycle 23. The role of Counter Electrojet and the ensuing thermosphere-ionosphere coupling processes are proposed to be the reason for the above stated features of occurrence. The seasonal as well as solar activity dependence of the vertical drift of F3 layers is also brought out. The influence of thermospheric winds in determining the drift velocity is revealed.

Occurrence features of Intermediate Descending Layers [IL] over the equatorial location of Thiruvananthapuram

A study has been carried out on the various aspects of occurrence of Intermediate Descending Layers [IL] on the bottom side of the F region over the magnetic equatorial location of Thiruvananthapuram [8.5 0 N; 77 0 E; dip lat of 0.5 0 N] in India for the period from 2000−2008 using ionosonde observations. Diurnally, the IL occurrence exhibits a double peak pattern with maximum occurrence in the post noon [15–17 IST], followed by early morning [7–9 IST]. The IL has a solsticial maximum [both summer and winter] probability of occurrence [∼70% during 2006 and 20% during 2002] with minima during equinoxes [∼10% during 2002 and 40% during 2006]. The solar cycle variability of IL is brought out in the present study using data from solar cycle 23. The occurrence is found to be high during solar minimum period [70%] and low during solar maximum period [10%]. The diurnal and seasonal behaviour of IL parameters like the peak frequency and the base height are also reported in this study. The role of gravity waves in determining the above stated features of occurrence is being proposed.