Long-term Monitoring Campaign Research Articles

Net primary production annual maxima in the North Atlantic projected to shift in the 21st century

Abstract. Shifts in the day of peak net primary production (NPP) were detected in different biogeochemical provinces of the North Atlantic (25–65° N). Most provinces displayed a shift toward earlier peak NPP, with the largest change points in the 21st century and in the northern parts of the domain. Furthermore, the occurrences of the first day with a mixed-layer depth (MLD) shallower than 40 m and the day of peak NPP are positively correlated over most of the domain. As was the case for the day of peak NPP, the largest change points for the day of MLD shallower than 40 m occur around or after the year 2000. Daily output from two fully coupled CMIP6 Earth system models, EC-Earth3-CC and NorESM2-LM, for the period 1750–2100 and under the SSP5-8.5 scenario, were used for the analysis. The ESM NPP data were compared with estimates derived from Carbon, Absorption and Fluorescence Euphotic-resolving (CAFE) satellite-based data. The ESMs showed significant differences from the CAFE model, though the timing of peak NPP was well captured for most provinces. The largest change points in the day of peak NPP occur earlier in EC-Earth3-CC than in NorESM2-LM. Although SSP5-8.5 is a scenario with very high warming, EC-Earth3-CC generates change points for most provinces in the early part of the 21st century, before the warming has deviated far from lower-emissions scenarios. NorESM2-LM displays the largest change points centered around the mid 21st century, with two out of eight provinces displaying the largest change point before the year 2050. The early timing of the detected shifts in some provinces in both ESMs suggests that similar shifts could already have been initiated or could start in the near future. This highlights the need for long-term monitoring campaigns in the North Atlantic.

Observations of Titan’s Stratosphere during Northern Summer: Temperatures, CH3CN and CH3D Abundances

Titan’s atmospheric composition and dynamical state have previously been studied over numerous epochs by both ground- and space-based facilities. However, stratospheric measurements remain sparse during Titan’s northern summer and fall. The lack of seasonal symmetry in observations of Titan’s temperature field and chemical abundances raises questions about the nature of the middle atmosphere’s meridional circulation and evolution over Titan’s 29 yr seasonal cycle that can only be answered through long-term monitoring campaigns. Here, we present maps of Titan’s stratospheric temperature, acetonitrile (or methyl cyanide; CH3CN) abundance, and monodeuterated methane (CH3D) abundance following Titan’s northern summer solstice obtained with Band 9 (∼0.43 mm) Atacama Large Millimeter/submillimeter Array observations. We find that increasing temperatures toward high southern latitudes, currently in winter, resemble those observed during Titan’s northern winter by the Cassini mission. Acetonitrile abundances have changed significantly since previous (sub)millimeter observations, and we find that the species is now highly concentrated at high southern latitudes. The stratospheric CH3D content is found to range between 4 and 8 ppm in these observations, and we infer the CH4 abundance to vary between ∼0.9% and 1.6% through conversion with previously measured D/H values. A global value of CH4 = 1.15% was retrieved, lending further evidence to the temporal and spatial variability of Titan’s stratospheric methane when compared with previous measurements. Additional observations are required to determine the cause and magnitude of stratospheric enhancements in methane during these poorly understood seasons on Titan.

Monitoring arthropods under the scope of LIFE-SNAILS project: I - Santa Maria Island baseline data with implementation of the Index of Biotic Integrity.

The database we introduce is a pivotal component of the LIFE SNAILS project (Support and Naturalisation in Areas of Importance for Land Snails). This initiative is dedicated to safeguarding three endangered species of terrestrial molluscs, specifically, two snails (Oxychilusagostinhoi Martins 1981 and Leptaxisminor Backhuys, 1975) and a semi-slug (Plutoniaangulosa (Morelet, 1860)), all of which are single island endemics from Santa Maria Island and face significant threats towards their populations.In this study, we established a comprehensive database derived from a long-term arthropod monitoring campaign utilising SLAM (Sea, Land, Air, Malaise) traps. Although molluscs were not the primary focus, our findings serve as a credible proxy for evaluating the overall habitat quality for endemic invertebrates, with arthropods serving as principal indicators. From September to December of 2022, a total of 11 SLAM traps were installed and monitored monthly in eleven sites of mixed forests of Santa Maria Island. Based on the 33 available samples (11 sites x 3 sampling periods), we recorded a total of 118 taxa of arthropods (of which 94 were identified at species or subspecies level), belonging to three classes, 14 orders and 62 families. From the 94 identified taxa, a total of 21 species were endemic, 31 native non-endemic, 32 introduced and 10 indeterminate. We also provide additional information of the habitat quality (Index of Biotic Integrity), including general habitat and dominant species composition.We registered three new records to the Island, the native bug Piezodoruslituratus (Fabricius, 1794) (Hemiptera, Pentatomidae), the Azorean endemic beetle Phloeosinusgillerforsi Bright, 1987 (Coleoptera, Curculionidae) and the exotic ant Hypoponerapunctatissima (Roger, 1859) (Hymenoptera, Formicidae) and one new record for the Azores Archipelago, the native beetle Cephenniumvalidum Assing & Meybohm, 2021 (Coleoptera, Staphylinidae, Scydmaeninae).This publication not only contributes to the conservation of highly threatened endemic molluscs, through an assessment of habitat quality, based on arthropod communities and habitat description (e.g. native or exotic vegetation), but also provides an updated inventory of arthropods from Santa Maria Island.

Long-Term Optical Monitoring of Broad-Line AGNs (LoTerm AGN): Case Study of NGC 3516

Properties of the broad line region (BLR) in active galactic nuclei (AGNs) are commonly used to estimate the mass of the supermassive black hole (SMBH) that powers an AGN. However, the understanding of the physics behind the BLR remains incomplete. The AGNs exhibit strong optical variability, observed in the change of the profiles and fluxes of broad emission lines. Utilizing this variability provides an opportunity to constrain the physics of the BLR, and understand the interplay of the BLR with SMBH and surrounding regions. Here, we present the long-term monitoring campaign of a sample of the known broad-line AGNs (identified as LoTerm AGN). The aim of this study is to show the importance of sustained and dedicated campaigns that continually collect spectroscopic data of the known AGNs over extended timescales, providing unique insight into the origin and structure of the BLR. LoTerm AGN is a collaborative network of seven moderate-size telescopes equipped for spectroscopy. We focus on the recent spectral data of the known changing-look AGN, NGC 3516. Specifically, we examine the broad hydrogen Balmer Hα line observed in the period 2020–2023, demonstrating that this AGN remains active with the BLR signatures observed in the spectra. No significant change in the broad line profile of Hα line is observed during this recent period.

Long-Term Monitoring Campaign of LED Street Lighting Systems: Focus on Photometric Performances, Maintenance and Energy Savings

The renovation of public lighting installations by replacing the traditional systems with LED technologies and introducing smart lighting control systems is a policy widely adopted to contain energy consumption and expenditure. Additionally, the long-term monitoring of the depreciation of the new lighting systems is a crucial issue. The aim of this study is to report the results of in-field measurements of new LED lighting systems in the city of Turin (Italy). A method was defined to assess: (i) energy performance (through data from the remote-control system); (ii) photometric performance (through in-field measurement campaigns); and (iii) depreciation of the photometric performance over a period of approximately 5 years. Results demonstrated that the new LED systems allow us to achieve an average energy saving of 51% compared to the ex-ante condition, improving the photometric performances and compiling the standard requirements by lowering the over-illumination levels. Moreover, the measured depreciation of the LED systems over time was compared with the predicted depreciation, estimated based on the calculation method proposed in Standards BS 5489-1:2020 and ISO/CIE TS 22012:2019. The results obtained showed that the measured depreciation of the photometric performance was closer to the predicted depreciation trend according to BS 5489-1:2020 (variations between 0% and 4%), while greater variations (between 17% and 23%) emerged considering the ISO/CIE TS 22012:2019.

Personal comfort models in long-term monitoring using physiological data from wearable sensors

Personal Comfort Models (PCMs) propose a new approach for human-centric comfort studies overcoming the one-size-fits-all of the conventional models. This research addresses the development of PCMs based on a seven-month long-term monitoring campaign including continuous environmental and physiological data collection through wearables and daily survey submission about subjects’ sensations. To tackle the influence of subjects’ environmental exposure history, time series of environmental data of different durations were used to predict individuals’ perception via Machine Learning models with Support Vector Machine and Random Forest methods. The accuracy and F1-score values of seven different PCMs were confronted for each subject and for the whole group (nine people). The number of datapoints per subject and their answers’ consistency during time affected the models’ accuracy, and the inclusion of physiological signals improved the models’ performance. When considering the whole dataset, the comfort model accuracy decreases supporting that individual subjectivity have an important impact in the environmental perception prediction.

Measuring radon concentration and investigation of it’s effects on lung cancer

The second most significant etiological factor contributing to the development of lung cancer, following tobacco smoking, is the presence of radon gas. Hence, the assessment of indoor radon levels within residential structures assumes paramount importance within the realm of public health. The primary objective of this investigation is to quantify the concentration of radon gas within the premises of Balikesir University Health Education and Research Hospital as well as the Faculty of Medicine Education building situated in the city of Balikesir. Furthermore, this research endeavors to ascertain the potential risk of lung cancer associated with these measured radon concentrations. To this end, an extensive, long-term (2–3 months) radon monitoring campaign was executed by strategically positioning Columbia Resin-39 (CR-39) solid-state nuclear track detectors at 28 distinct locations. The overarching aim of this effort is to comprehensively assess the health hazards posed to both staff and students and subsequently institute any requisite mitigating measures. The lowest measured value of the measured radon gas concentration is 6 Bq/m3, the highest measured value is 60 ± 8 Bq/m3. The average measurement value is 21.96 ± 3.16 Bq/m3. The measurement results were determined to be lower than the allowed radon activity concentration value in the “Radiation Safety Directive.

Performance of lagoon and constructed wetland systems for tertiary wastewater treatment and potential of reclaimed water in agricultural irrigation

Climate change poses challenges to agricultural water resources, both in terms of quantity and quality. As an adaptation measure, the new European Regulation (EU) 2020/741 establishes different water quality classes for the use of reclaimed water in agricultural irrigation. Italy is also working on the definition of a new regulation on reclaimed water reuse for agricultural irrigation (in substitution of the current one) that will also include the specific requirements imposed by the European one. Nature-based Solutions (NBS) can be a cost-effective and environmentally friendly way to facilitate water reclamation and reuse. The present study reports the outcomes of a long-term monitoring campaign of two NBS (e.g., a constructed wetland (CW) and a lagoon system (LS)) comparing influent and effluent concentrations of different contaminants (e.g., E. coli, BOD5, TSS, TN and TP) with the threshold values imposed by the new regulations. The results showed that in both the case studies, E. coli (about 100 CFU 100 mL−1) and BOD5 (lower than 25 mg L−1) mean effluent concentration need to be further reduced in reclaimed water to be suitable for unlimited reuse. As a negative aspect, in both the monitored NBS, an increase in TSS mean concentration in the effluent was observed, up to 40 mg L−1 in the case of the LS, making reclaimed water unsuitable for agricultural reuse. The CW has proven to be more effective in nitrogen removal (the effluent mean concentration was 3.4 mg L−1), whereas the LS was better at phosphorus removal (with an effluent mean concentration of 0.4 mg L−1). Based on the results, recommendations were made to further improve the performance of both systems in order to have adequate water quality, even for class A. Furthermore, the capacity of reclaimed water to meet crop water and nutrient needs was analyzed, and total nitrogen removal rate coefficients were calculated for the design of future LSs.

Long-Term Thermal Comfort Monitoring via Wearable Sensing Techniques: Correlation between Environmental Metrics and Subjective Perception

The improvement of comfort monitoring resources is pivotal for a better understanding of personal perception in indoor and outdoor environments and thus developing personalized comfort models maximizing occupants' well-being while minimizing energy consumption. Different daily routines and their relation to the thermal sensation remain a challenge in long-term monitoring campaigns. This paper presents a new methodology to investigate the correlation between individuals' daily Thermal Sensation Vote (TSV) and environmental exposure. Participants engaged in the long-term campaign were instructed to answer a daily survey about thermal comfort perception and wore a device continuously monitoring temperature and relative humidity in their surroundings. Normalized daily profiles of monitored variables and calculated heat index were clustered to identify common exposure profiles for each participant. The correlation between each cluster and expressed TSV was evaluated through the Kendall tau-b test. Most of the significant correlations were related to the heat index profiles, i.e., 49% of cases, suggesting that a more detailed description of physical boundaries better approximates expressed comfort. This research represents the first step towards personalized comfort models accounting for individual long-term environmental exposure. A longer campaign involving more participants should be organized in future studies, involving also physiological variables for energy-saving purposes.

High Indoor Rn Concentration Mitigation in a Heritage Building: Case Study Analysis of the Applied Constructive Measures

Indoor radon (Rn) concentration is pointed out by the World Health Organization (WHO) as the second leading cause of lung cancer. Adopting mitigation measures based on ventilation procedures is an effective solution for most cases. However, the occurrence of abnormal concentrations of indoor Rn in heritage buildings, where most interventions are restricted, may lead to alternative remediation techniques. In these cases, constructive mitigation measures, such as the use of barrier membranes on the floor or specific coating mortars on the walls, can be adequate solutions. In the current investigation, two constructive measures were applied and analyzed sequentially. The preliminary long-term monitoring campaign registered extremely high indoor Rn concentration measurements. The application of a barrier membrane covering the floor of the test compartment allowed a 90% reduction in the average Rn concentration, but it nevertheless remained substantially above the recommended value of 300 Bq·m−3. Subsequently, a coating mortar was applied on the walls. The combined measures contributed to a total reduction of 94% in the average indoor Rn concentration, which remains slightly above the recommended exposure limit. Despite the verified reduction and the apparent effectiveness of the measures, it is still necessary to carry out more monitoring campaigns to test their general applicability.

Deep X-Ray and Radio Observations of the First Outburst of the Young Magnetar Swift J1818.0−1607

Swift J1818.0−1607 is a radio-loud magnetar with a spin period of 1.36 s and a dipolar magnetic field strength of B ∼ 3 × 1014 G, which is very young compared to the Galactic pulsar population. We report here on the long-term X-ray monitoring campaign of this young magnetar using XMM-Newton, NuSTAR, and Swift from the activation of its first outburst in 2020 March until 2021 October, as well as INTEGRAL upper limits on its hard X-ray emission. The 1–10 keV magnetar spectrum is well modeled by an absorbed blackbody with a temperature of kT BB ∼ 1.1 keV and apparent reduction in the radius of the emitting region from ∼0.6 to ∼0.2 km. We also confirm the bright diffuse X-ray emission around the source extending between ∼50″ and ∼110″. A timing analysis revealed large torque variability, with an average spin-down rate −2.3 × 10−11 Hz2 that appears to decrease in magnitude over time. We also observed Swift J1818.0−1607 with the Karl G. Jansky Very Large Array on 2021 March 22. We detected the radio counterpart to Swift J1818 measuring a flux density of S v = 4.38 ± 0.05 mJy at 3 GHz and a half-ringlike structure of bright diffuse radio emission located at ∼90″ to the west of the magnetar. We tentatively suggest that the diffuse X-ray emission is due to a dust-scattering halo and that the radio structure may be associated with the supernova remnant of this young pulsar, based on its morphology.

Confined Spaces in Buildings with High Indoor Radon Concentration: A Case Study Analysis with the Application of Constructive Remediation Measures

Radon is an increasingly common concern, mainly when it is found indoors exposing the users of the space to radiation. As a gas, radon is an element produced due to uranium decay; it emanates naturally from soil and is considered by the World Health Organization as the second most common cause of lung cancer. Several methodologies are available for mitigating the indoor radon concentration, with distinct improvements and efficiencies that need to be proved with on-site testing. The case study here presented analyzes the effect of applying a barrier membrane, covering the pavement of a ground floor room located in a historic building with a high occupancy rate, on an abnormal radon concentration evidenced by experimental data. After the barrier membrane installation, a new long-term monitoring campaign (3 months) was carried out to assess indoor radon concentration. The obtained results showed that the barrier membrane lowered the indoor radon concentration by 90%. However, the radon exposure level remained higher than the recommended level to enable safe occupation and the regular use of space. Nevertheless, as the reduction in the radon concentration was very significant by the adoption of a barrier membrane, the combination of this technical solution with other mitigation methodologies, namely including the adoption of mechanical ventilation procedures, can become a very efficient solution for radon remediation, reducing the number of air changes per hour (ACH) from 30–60 to 4–6.

Multidisciplinary long-term survey of Manila clam grown in farming sites subjected to different environmental conditions

In recent years recurrent bivalve mass mortalities considerably increased around the world, causing the collapse of natural and farmed populations. Venice Lagoon has historically represented one of the major production areas of the Manila clam Ruditapes philippinarum in Europe. However, in the last 20 years a 75 % decrease in the annual production has been experienced. While climate change and anthropogenic interventions may have played a key role in natural and farmed stocks reductions, no studies investigated at multiple levels the environmental stressors affecting farmed Manila clam to date.In this work we carried out a long-term monitoring campaign on Manila clam reared in four farming sites located at different distances from the southern Venice Lagoon inlet, integrating (meta)genomic approaches (i.e. RNA-seq; microbiota characterization), biometric measurements and chemical-physical parameters. Our study allowed to characterize the molecular mechanisms adopted by this species to cope with the different environmental conditions characterizing farming sites and to propose hypotheses to explain mortality events observed in recent years. Among the most important findings, the disruption of clam's immune response, the spread of Vibrio spp., and the up-regulation of molecular pathways involved in xenobiotic metabolism suggested major environmental stressors affecting clams farmed in sites placed close to Chioggia's inlet, where highest mortality was also observed.Overall, our study provides knowledge-based tools for managing Manila clam farming on-growing areas. In addition, the collected data is a snapshot of the time immediately before the commissioning of MoSE, a system of mobile barriers aimed at protecting Venice from high tides, and will represent a baseline for future studies on the effects of MoSE on clams farming and more in general on the ecology of the Venice Lagoon.

Effect of wind and wave properties in modal parameter estimates of an idling offshore wind turbine from long-term monitoring data

In the long-term, the modal properties of Offshore Wind Turbines (OWT) exhibit significant variations due to constant changes in environmental and operational conditions. These variations have a substantial effect on the wind turbine loads and will lead, for instance, to large uncertainty in fatigue and useful life predictions. Due to the numerous sources of uncertainty, it is difficult to judge how independent environmental or operational parameters influence the modal properties of OWTs. In this work, we make a systematic analysis of the modal parameter estimates extracted from a long-term monitoring campaign in an OWT from the DanTysk wind farm while in its idling condition. We cluster the dataset of vibration responses of the idling OWT into bins of wind and wave characteristics, in order to isolate the effect of the different sources of uncertainty affecting the OWT modal properties. Once the trends in the data are confirmed, we use a simple linear regression model to extrapolate the damping estimates for zero wind speed and wave excitation, thus providing an estimate of the mean and standard errors of the OWT structural damping in the first fore-aft and side-to-side tower bending modes.

One-year spatiotemporal variations of air pollutants in a major chemical-industry park in the Yangtze River Delta, China by 30 miniature air quality monitoring stations

Fine chemical industrial park (FCIP) is a major source of atmospheric pollutants in China. A long-term high spatial resolution monitoring campaign on air pollutants had been firstly conducted in a major FCIP in Yangtze River Delta (YRD) from December 2019 to November 2020. The grid-based monitoring platform consisting of 30 miniature air quality monitoring stations (AQMSs) provided comprehensive coverage of a FCIP, and long-term monitoring studies solved the problem of lack of clarity about pollution sources in industrial parks. Overall, NO2 pollution was particularly high in the pharmaceutical industry, while TVOCs and O3 pollution were most serious in the textile dyeing industry, with PM pollution much higher in the metal smelting industry than in other industries, and in the leather industry, O3 pollution was relatively severe. The spatial and temporal variations of air pollutants showed that higher PM, CO and NO2 concentrations were revealed in winter while lower in summer due to better meteorological diffusion conditions. TVOCs concentrations were higher with an average of 1954 ppb in summer possibly due to their increased volatilization from their sources at higher ambient temperatures. O3 concentrations were at their peaks in spring (88.8 μg m−3) and early fall (78.5 μg m−3). The daily trends of O3 precursors (TVOCs and NO2) were clearly negatively correlated with O3, and they showed bimodal peaks due to anthropogenic activities, plant emissions, lowering of the mixed boundary layer, etc. The O3 formed in FCIP was judged to be NO2-limited during the monitoring period based on the ratios of NO2 to TVOCs. Therefore, the effective strategy to reduce O3 formation in FCIP is to decrease the ambient NO2 concentration. Based on Pearson correlation coefficients, it appeared that WS promoted O3 formation through long-term transport and that high air temperatures also contributed to O3 formation in the environment. It was also stated in the study that the closer the residential area is to the industrial sources, the more significant the correlation. Thus, the results of this study will also be helpful for policymakers to design pollutant control strategies for different industries to mitigate the impact of pollutants on human health.

Total and methylmercury concentrations in nocturnal migratory birds passing through Mount Ailao, Southwest China

Despite growing concerns over mercury (Hg) accumulation in birds in recent decades, little is known about Hg exposure in nocturnal migratory birds. Here, total mercury (THg) and methylmercury (MeHg) were detected in the feathers of nocturnal migratory birds (n = 286, belonging to 46 species) passing through Mount Ailao in Southwest China. The stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were also determined to clarify the effects of trophic position, foraging guild, and foraging behavior on Hg bioaccumulation. Our results show that the THg and MeHg concentrations varied by two orders of magnitude among all nocturnal migratory birds investigated, with the lowest values (THg: 0.056 mg kg−1; MeHg: 0.038 mg kg−1) in the Asian koel (Eudynamys scolopaceus) and the highest (THg: 12 mg kg−1; MeHg: 7.8 mg kg−1) in the hair-crested drongo (Dicrurus hottentottus). Waterbirds showed higher δ15N values and higher THg and MeHg concentrations than songbirds, and the Hg concentrations in piscivorous species were significantly higher than those in herbivores, omnivores, and insectivores. Significant effects of foraging guilds (Kruskal–Wallis one-way ANOVA, p < 0.001) and foraging behaviors (Kruskal–Wallis one-way ANOVA, p < 0.001) on the Hg concentrations in migratory bird feathers were detected. A risk assessment indicated that approximately 7.0% of individuals were at moderate (2.4–5.0 mg kg−1) to high (>5.0 mg kg−1) risk of Hg exposure, and were therefore vulnerable to adverse physiological and behavioral effects. A long-term monitoring campaign during the migratory period is highly recommended to better understand the bioaccumulation of Hg in these nocturnal migratory bird populations over time.

Underwater Anthropogenic Noise Pollution Assessment in Shallow Waters on the South-Eastern Coast of Spain

Anthropogenic noise is a growing threat to marine life due to the incrementation of human activity in the marine environment. In Europe, the Directive 2008/56/EC of the European Parliament and of the Council was published with the aim of establishing a framework for community action in the field of marine environmental policy. The directive introduces underwater acoustic energy, as detailed in Descriptor 11, and stipulates that the member states should set the threshold levels at which a good environmental status can be achieved by means of long-term monitoring campaigns. This research presents the results of a long-term underwater noise monitoring campaign with a duration of three years in the port of Cartagena located on the south-eastern coast of Spain, focusing on the monthly and annual variation patterns of low-frequency continuous noise. The acquired data are classified according to the source of the acoustic noise into shipping, other anthropogenic, and natural noise measurements. These three groups of measurements are processed in order to obtain one-third octave band levels centered at 63 and 125 Hz, as well as the overall bandwidth of unweighted Sound Pressure Level (SPL). The analysis of the measurements shows an increase in the annual average overall band of 4 and 3 dB of the natural and shipping noise, respectively, from 2013 to 2015. This monitoring campaign provides accurate acoustic values to establish threshold levels to achieve good environmental status and recommendations to conduct monitoring programs and regulations to control underwater noise pollution.

The first seven months of the 2020 X-ray outburst of the magnetar SGR J1935+2154

ABSTRACT The magnetar SGR J1935+2154 underwent a new active episode on 2020 April 27–28, when a forest of hundreds of X-ray bursts and a large enhancement of the persistent flux were detected. For the first time, a radio burst with properties similar to those of fast radio bursts and with a X-ray counterpart was observed from this source, showing that magnetars can power at least a group of fast radio bursts. In this paper, we report on the X-ray spectral and timing properties of SGR J1935+2154 based on a long-term monitoring campaign with Chandra, XMM–Newton, NuSTAR, Swift, and NICER covering a time-span of ∼7 months since the outburst onset. The broad-band spectrum exhibited a non-thermal power-law component (Γ ∼ 1.2) extending up to ∼20–25 keV throughout the campaign and a blackbody component with temperature decreasing from ∼1.5 keV at the outburst peak to ∼0.45 keV in the following months. We found that the luminosity decay is well described by the sum of two exponential functions, reflecting the fast decay (∼1 d) at the early stage of the outburst followed by a slower decrease (∼30 d). The source reached quiescence about ∼80 d after the outburst onset, releasing an energy of ∼6 × 1040 erg during the outburst. We detected X-ray pulsations in the XMM–Newton data sets and derived an average spin-down rate of ∼3.5 × 10−11 s s−1 using the spin period measurements derived in this work and three values reported previously during the same active period. Moreover, we report on simultaneous radio observations performed with the Sardinia Radio Telescope. No evidence for periodic or single-pulse radio emission was found.

Long-term radio monitoring of the neutron star X-ray binary Swift J1858.6−0814

ABSTRACT We present the results of our long-term radio monitoring campaign at 1.3 GHz (MeerKAT) and 15.5 GHz (Arcminute Microkelvin Imager – Large Array, AMI-LA) for the outburst of the recently discovered neutron star X-ray binary Swift J1858.6−0814. Throughout the outburst, we observe radio emission consistent with a quasi-persistent, self-absorbed jet. In addition, we see two flares at MJD 58427 and 58530. The second flare allows us to place constraints on the magnetic field and minimum energy of the jet at 0.2 G and 5 × 1037 erg, respectively. We use the multifrequency radio data in conjunction with data from Swift-BAT (Burst Alert Telescope) to place Swift J1858.6−0814 on the radio/X-ray correlation. We find that the quasi-simultaneous radio and BAT data make Swift J1858.6−0814 appear to bridge the gap in the radio/X-ray plane between atoll and Z sources. Furthermore, AMI-LA observations made while Swift J1858.6−0814 was in the soft state have allowed us to show that the radio emission during the soft state is quenched by at least a factor of 4.

Quantification of influence of monitoring duration on measured traffic action effects on fatigue of RC deck slabs of road bridges

The safety of existing bridges may be assessed using data from monitoring. The fatigue damage induced during observation period is extrapolated to the total service duration of a structure, and the reserve capacity is estimated. However, due to the randomness of road traffic, there exists a risk of underestimation of damage using a short-term monitoring campaign. This paper analyses the influence of monitoring duration on the obtained results using datasets collected during two long-term (>3 years) dynamic monitoring campaigns. Two road bridges with different nature of traffic are considered: (a) a heavily loaded two-lane highway viaduct and (b) a road viaduct with a bi-directional traffic. The deck slabs of both bridges are monitored using strain gauges installed on reinforcement bars. The daily, seasonal, year-to-year and COVID-19 lockdown-induced variations of measured action effects and calculated equivalent fatigue damage are discussed. The resampling method is used for simulation of possible short-term monitoring campaigns during the period considered, with different order of heavy vehicles arriving. The Extreme Value Theory serves to answer what is the required monitoring duration for reliable results. Possible ways of considering the monitoring duration in the fatigue damage calculation are discussed, and the methodology for damage extrapolation proposed.