Potential Underestimation Research Articles

A Comparison of Manual and Automatic Methods for Calculating Cumulative Dose-Volume Histogram Parameters in Cervical Cancer Radiotherapy

Background: The cumulative dose-volume histogram (DVH) parameters for organs at risk (OAR) and the target volume, obtained from external beam radiotherapy (EBRT) and brachytherapy (BT), are commonly calculated manually in clinical practice. Objectives: This study aims at comparing the manual and automatic methods for calculating cumulative DVH parameters of OAR and the target volume in patients with cervical cancer. Methods: The cumulative DVH of EBRT and BT methods for target volume and OAR, including rectum, bladder, and sigmoid was calculated manually, using the EQD2 (equivalent dose in 2 Gy fractions) formula. In the automatic method, dosimetric data were collected as DICOM files and entered into SagiPlan® BT software. Using the BED/EQD2 summation feature, the BT and EBRT plans were summed, and the cumulative DVH parameters were extracted. The results were compared with the manual method. Results: In 32 cervical cancer samples, dosimetric comparisons showed significant differences between manual (EQD2) and automatic (SagiPlan®) calculations for rectum (mean dose 69.15 vs. 71.92 Gy, P < 0.01), bladder (mean dose 81.87 vs. 84.47 Gy, P < 0.01), and sigmoid (mean dose 69.84 vs.73.15 Gy, P < 0.01). However, the cumulative dose to the target tissue was similar between the two methods (mean dose 86.9 vs. 86.91, P = 0.21). Automatic calculations indicated higher doses of the OARs, suggesting potential underestimation by manual methods. Conclusions: In clinical practice, when designing BT planning for cervical cancer, it is recommended to input the patient’s EBRT design data into the planning software to determine the cumulative dose received by the target and OARs.

Victimization, immigration status, and psychosocial well-being: A representative study among finnish adolescents.

Immigrant adolescents seem to be at risk for victimization and being victimized in adolescence is related to risk factors regarding mental health. This study compared the frequency and type of victimization experiences among immigrant and native Finnish adolescents and tested whether these experiences mediate the relationship between immigration status and psychosocial well-being. Additionally, willingness to disclose victimization experiences in anonymous questionnaires was compared between the groups. In this computer-based study a population-based sample of 5607 Finnish adolescents was used (Mage=15.23, SDage=0.42, Range 15 to 16years; 49.8% girls, 48.5% boys), of which 11.7% were immigrants. Twelve lifetime victimization experiences were assessed, and psychosocial well-being was measured with Strengths and Difficulties Questionnaire. Descriptive statistics, crosstabulation and t-tests were used to report victimization experiences and participants' willingness to share them in an anonymous questionnaire. The relationship between immigration status and psychosocial well-being was investigated with mediation analysis, victimization experiences as mediator. Findings revealed that immigrant adolescents experienced more victimization, particularly in the form of property crimes, hate crimes, and physical and sexual abuse, than native adolescents. Victimization experiences were found to mediate the impact of immigration status on psychosocial well-being. Moreover, immigrant adolescents were less likely to disclose victimization experiences. The results suggest a potential underestimation of the prevalence of victimization experiences in immigrant adolescents, which warrants further investigation. As these experiences play an important role in the relationship between immigrant status and psychosocial well-being, the findings endorse assessing adverse experiences, as well as safe disclosure when planning psychosocial support and treatment for immigrant adolescents.

Collagenase injection versus limited fasciectomy surgery to treat Dupuytren's contracture in adult patients in the UK: DISC, a non-inferiority RCT and economic evaluation.

Dupuytren's contracture is caused by nodules and cords which pull the fingers towards the palm of the hand. Treatments include limited fasciectomy surgery, collagenase injection and needle fasciotomy. There is limited evidence comparing limited fasciectomy with collagenase injection. To compare whether collagenase injection is not inferior to limited fasciectomy when treating Dupuytren's contracture. Pragmatic, two-arm, unblinded, randomised controlled non-inferiority trial with a cost-effectiveness evaluation and nested qualitative and photographic substudies. Thirty-one National Health Service hospitals in England and Scotland. Patients with Dupuytren's contracture of ≥ 30 degrees who had not received previous treatment in the same digit. Collagenase injection with manipulation 1-7 days later was compared with limited fasciectomy. The primary outcome was the Patient Evaluation Measure score, with 1 year after treatment serving as the primary end point. A difference of 6 points in the primary end point was used as the non-inferiority margin. Secondary outcomes included: Unité Rhumatologique des Affections de la Main scale; Michigan Hand Outcomes Questionnaire; recurrence; extension deficit and total active movement; further care/re-intervention; complications; quality-adjusted life-year; resource use; and time to function recovery. Online central randomisation, stratified by the most affected joint, and with variable block sizes allocates participants 1 : 1 to collagenase or limited fasciectomy. Participants and clinicians were not blind to treatment allocation. Between 31 July 2017 and 28 September 2021, 672 participants were recruited (n = 336 per group), of which 599 participants contributed to the primary outcome analysis (n = 285 limited fasciectomy; n = 314 collagenase). At 1 year (primary end point) there was little evidence to support rejection of the hypothesis that collagenase is inferior to limited fasciectomy. The difference in Patient Evaluation Measure score at 1 year was 5.95 (95% confidence interval 3.12 to 8.77; p = 0.49), increasing to 7.18 (95% confidence interval 4.18 to 10.88) at 2 years. The collagenase group had more complications (n = 267, 0.82 per participant) than the limited fasciectomy group (n = 177, 0.60 per participant), but limited fasciectomy participants had a greater proportion of 'moderate'/'severe' complications (5% vs. 2%). At least 54 participants (15.7%) had contracture recurrence and there was weak evidence suggesting that collagenase participants recurred more often than limited fasciectomy participants (odds ratio 1.39, 95% confidence interval 0.74 to 2.63). At 1 year, collagenase had an insignificantly worse quality-adjusted life-year gain (-0.003, 95% confidence interval -0.006 to 0.0004) and a significant cost saving (-£1090, 95% confidence interval -£1139 to -£1042) than limited fasciectomy with the probability of collagenase being cost-effective exceeding 99% at willingness to pay thresholds of £20,000-£30,000 per quality-adjusted life-year. At 2 years, collagenase was both significantly less effective (-0.048, 95% confidence interval -0.055 to -0.040) and less costly (-£1212, 95% confidence interval -£1276 to -£1147). The probability of collagenase being cost-effective was 72% at the £20,000 threshold but limited fasciectomy became the optimal treatment at thresholds over £25,488. The Markov model found the probability of collagenase being cost-effective at the lifetime horizon dropped below 22% at thresholds over £20,000. Semistructured qualitative interviews found that those treated with collagenase considered the outcome to be acceptable, though not perfect. The photography substudy found poor agreement between goniometry and both participant and clinician taken photographs, even after accounting for systematic differences from each method. Impacts of the COVID-19 pandemic resulted in longer waits for Dupuytren's contracture treatment, meaning some participants could not be followed up for 2 years. This resulted in potential underestimation of Dupuytren's contracture recurrence and/or re-intervention rates, which may particularly have impacted the clinical effectiveness and long-term Markov model findings. Among adults with Dupuytren's contracture, collagenase delivered in an outpatient setting is less effective but more cost-saving than limited fasciectomy. Further research is required to establish the longer-term implications of both treatments. Recurrence and re-intervention usually occur after 1 year, and therefore follow-up to 5 years or more could resolve whether the differences observed in the Dupuytren's interventions surgery versus collagenase trial to 2 years worsen. Current Controlled Trials ISRCTN18254597. This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 15/102/04) and is published in full in Health Technology Assessment; Vol. 28, No. 78. See the NIHR Funding and Awards website for further award information.

A multivariate statistical framework for mixed storm types in compound flood analysis

Abstract. In coastal regions, compound flooding can arise from a combination of different drivers, such as storm surges, high tides, excess river discharge, and rainfall. Compound flood potential is often assessed by quantifying the dependence and joint probabilities of flood drivers using multivariate models. However, most of these studies assume that all extreme events originate from a single population. This assumption may not be valid for regions where flooding can arise from different generation processes, e.g., tropical cyclones (TCs) and extratropical cyclones (ETCs). Here we present a flexible copula-based statistical framework to assess compound flood potential from multiple flood drivers while explicitly accounting for different storm types. The proposed framework is applied to Gloucester City, New Jersey, and St. Petersburg, Florida, as case studies. Our results highlight the importance of characterizing the contributions from TCs and non-TCs separately to avoid potential underestimation of the compound flood potential. In both study regions, TCs modulate the tails of the joint distributions (events with higher return periods), while non-TC events have a strong effect on events with low to moderate joint return periods. We show that relying solely on TCs may be inadequate when estimating compound flood risk in coastal catchments that are also exposed to other storm types. We also assess the impact of non-classified storms that are not linked to either TCs or ETCs in the region (such as locally generated convective rainfall events and remotely forced storm surges). The presented study utilizes historical data and analyzes two populations, but the framework is flexible and can be extended to account for additional storm types (e.g., storms with certain tracks or other characteristics) or can be used with model output data including hindcasts or future projections.

Abdominal Compared With Coronary Artery Calcification and Incident Cardiovascular Events and Mortality in Black Adults.

Black adults show heightened cardiovascular risk compared with other groups despite comparable or lower coronary artery calcium (CAC) scores, indicating potential cardiovascular risk underestimation by CAC. Abdominal aortic calcification (AAC), preceding CAC, may predict cardiovascular events better in Black adults who are prone to early atherosclerotic cardiovascular disease and excess events at low CAC scores. We included 2551 participants from the JHS (Jackson Heart Study) visit 2 examination (2005-2008) without cardiovascular disease, followed through 2016. Cox regression estimated hazard ratios for incident cardiovascular events defined as a composite of myocardial infarction, stroke, heart failure, and all-cause mortality. The predictive value of CAC and AAC, when added to the American College of Cardiology/American Heart Association cardiovascular risk algorithm (pool cohort equation), was assessed. Mean age was 57±10 years; 66% were women. Over a follow-up period of 12.6 years, 287 (11.3%) cardiovascular events and 360 (14.1%) mortality cases were observed. Adjusting for demographic and clinical variables, each 2-fold increase in CAC and AAC was associated with cardiovascular events (CAC: hazard ratio, 1.10 [95% CI, 1.06-1.13]; AAC: hazard ratio, 1.10 [95% CI, 1.06-1.13]) and all-cause mortality CAC: hazard ratio, 1.04 [95% CI, 1.01-1.08]; AAC: hazard ratio, 1.05 [95% CI, 1.01-1.08]). The incremental value of CAC (0.17 [95% CI, 0.08-0.23]) and AAC (0.15 [95% CI, 0.07-0.29]) to the pool cohort equation by net reclassification index was comparable. Notably, 45% of participants with 0 CAC showed some degree of AAC. Each 2-fold increase in AAC was associated with an increased risk of cardiovascular events (hazard ratio, 1.07 [95% CI, 1.01-1.19]) but not all-cause mortality among participants with 0 CAC. AAC is comparable to CAC in predicting cardiovascular events and all-cause mortality among Black adults, potentially valuable when CAC is absent.

Abstract 4129273: Severe Mitral Regurgitation from Impella-associated Mitral Chordae Rupture with Successful Transcatheter Edge-to-edge Repair

Background: Limited data exists describing Impella-related mechanical mitral valve complications. Diagnosis and management can be challenging due to potential underestimation of mitral regurgitation severity from Impella and acute clinical deterioration upon removal. We present a case of successful mitral transcatheter edge-to-edge repair (TEER) for acute severe MR secondary to Impella-related mitral chordae rupture resulting in acute pulmonary edema post-Impella removal. Case Summary: A 37-year-old male smoker presented with chest pain complicated by cardiac arrest due to ventricular fibrillation. Spontaneous circulation could not be restored, requiring veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Coronary angiography revealed total occlusion of the proximal left anterior descending artery, which was successfully stented. Transfemoral Impella CP was placed for left ventricular venting under fluoroscopy (Panel A) with TTE showing no complications. In the intensive care unit, the Impella was advanced under TTE guidance; its tip was found to be positioned deep at the base of the posteromedial pupillary muscle without suction alarms or ventricular arrhythmias on the following day (Panel B). Several days later, TTE revealed new eccentric MR with hyperdynamic left ventricular motion (Panel C). The patient remained hemodynamically stable after VA-ECMO decannulation with Impella at P4. Following Impella removal, he developed repeated flash pulmonary edema despite aggressive fluid removal attributed to acute severe MR secondary to a flail P3 leaflet with ruptured chordae tendineae confirmed by transesophageal echocardiography (Panel D). Given the patient's poor surgical candidacy with a STS score of 13.2%, the team proceeded with mitral TEER, successfully reducing MR severity from severe to mild with a single NT Mitraclip ® across the medial commissure (Panel E). His post-operative cardiac course was uneventful without recurrence of pulmonary edema. Discussion: Irreversible mechanical damage to the mitral valve apparatus caused by Impella placement and repositioning is a rare, potentially fatal complication requiring emergent intervention. Mitral TEER can be a viable salvage option for poor surgical candidates.

Why models underestimate West African tropical forest primary productivity

Tropical forests dominate terrestrial photosynthesis, yet there are major contradictions in our understanding due to a lack of field studies, especially outside the tropical Americas. A recent field study indicated that West African forests have among the highest forests gross primary productivity (GPP) yet observed, contradicting models that rank them lower than Amazonian forests. Here, we show possible reasons for this data-model mismatch. We found that biometric GPP measurements are on average 56.3% higher than multiple global GPP products at the study sites. The underestimation of GPP largely disappears when a standard photosynthesis model is informed by local field-measured values of (a) fractional absorbed photosynthetic radiation (fAPAR), and (b) photosynthetic traits. Remote sensing products systematically underestimate fAPAR (33.9% on average at study sites) due to cloud contamination issues. The study highlights the potential widespread underestimation of tropical forests GPP and carbon cycling and hints at the ways forward for model and input data improvement.

Quantifying low-value care in Germany: An observational study using statutory health insurance data from 2018 to 2021.

Low-value care refers to medical services whose benefits do not outweigh the costs and potential harm. This study estimates the prevalence, distribution, and associated costs of 24 low-value care services within the German public healthcare system. Large-scale retrospective observational study using statutory health insurance data provided by the Techniker Krankenkasse (TK) spanning from 2018 to 2021 covering approximately 11.1 million insured individuals annually. The prevalence of 24 low-value service indicators, which were identified through a systematic review and expert consultations was calculated. To address uncertainties in distinguishing between appropriate and low-value care, both broad (potential overestimation) and narrow definitions (potential underestimation) were applied to all suitable indicators, providing a range within which the true extent of low-value care is expected to lie. Between 2019 and 2021, 1.6 million patients were identified as having received at least one low-value service, using the 24 indicators. Of all 10.6 million delivered services (cases) examined, on average per year, 1.1 million cases (broad definition) and 0.43 million cases (narrow definition) were classified as low-value, corresponding to 10.4% and 4.0%, respectively. Costs incurred by the identified services were approximately 15.5 million euros (broad definition) and 9.9 million euros (narrow definition) annually. Despite the limitations of German statutory health insurance data, considerable low-value care was found within several of the 24 low-value-indicators. The findings highlight the necessity for targeted interventions to mitigate low-value care in Germany, guiding healthcare policy and practice to enhance quality and safety effectively.

Automatic landslide prioritization at regional scale through PS-InSAR cluster analysis and socio-economic impacts

The present study is part of an initiative to revise the PAI landslide inventories for post-seismic reconstruction in the Central Apennines (Italy), affected by the 2016-2017 seismic sequence. We introduce an innovative automated workflow for classifying and prioritizing landslide-prone areas using multi-sensor Persistent Scatterers (PS). This approach aims to support post-seismic reconstruction efforts by government institutions through a comprehensive and up-to-date ranking of landslides. The methodology integrates post-seismic multi-sensor interferometric datasets, advanced clustering techniques, and socio-economic factors to establish a standard procedure for monitoring hazardous areas and prioritizing resource allocation. Key findings demonstrate the efficacy of the method in identifying critical regions that require immediate intervention, thereby enhancing the effectiveness of field inspections and territorial planning activities. Our multi-sensor analysis reveals that approximately 6% of landslides are not detectable by interferometric technique, 45% show stability with no detected deformation via PS data, and 19% are accurately mapped with deformation confined within their boundaries. Notably,30% of analyzed landslides exhibit displacement beyond their mapped perimeters, indicating potential expansion or underestimation of their extent. The integration of data from multiple sources provides a more robust understanding of potential risks across the study area, promoting a structured approach to hazard management that ensures interventions are both scientifically grounded and economically justified.

Potential Causes of Iatrogenic Intraoperative Bleeding During C1 Surgeries: A CT 3D Rendering Study

BackgroundIatrogenic intraoperative bleeding during C1 surgeries is difficult to manage. PurposeTo investigate the potential causes of iatrogenic intraoperative bleeding in atlas surgeries. Study designThis was a retrospective study, observational cohort of patients with DICOM. Patient SampleHigh-resolution head and neck computed tomography angiography (CTA) images from 551 subjects were included. Outcome MeasuresPonticulus posticus (POPO), vertebral artery (VA), venous plexus communication. MethodsThree dimension rendering was utilized in the present study. Potential arterial bleeding was evaluated based on the variation in the VA and the polymorphism of the POPO over the groove for VA (GVA). The communication of the venous plexus in the occipitoatlantal region was investigated to assess the venous hemorrhage. ResultsAmong the 551 atlases examined, POPOs were identified on 155 sides, resulting in a prevalence of 14.07% (155/1102). These POPOs (n = 155) were reclassified into four types: tiny spur (54.84%), long spur (7.10%), ossified bridge (30.32%), and ossified canal (7.74%). In 42.92% (473/1102) of cases, the VA did not directly contact the sulci of the GVA, creating space for the passage of the rich venous plexus that drained intracranial venous blood outflow to various extracranial layers. Moreover, in 12.7% of the subjects, the study revealed the presence of additional foramens in the posterior lamina of C1, which served as a conduit for the communicating vein ConclusionThe potential underestimation of polymorphism in POPOs and VAs can lead to arterial bleeding, whereas a lack of understanding of the intricate condylar emissary venous plexus can result in venous hemorrhage. To mitigate iatrogenic hemorrhage during C1 surgeries, a preoperative HEAD AND NECK CTA is recommended, and heightened caution should be exercised during dissection in the lateral half of the C1 lamina. Furthermore, unknown causes of intraoperative bleeding may arise during the posterior C1 approach; modifications should be considered based on the specific circumstances encountered.

Effect of Different Irrigated Crop Successions on Soil Carbon and Nitrogen–Phosphorus–Potassium Budget Under Mediterranean Conditions

Sustainability in agroecosystems relies on the optimized use of resources to achieve consistent yields while maintaining or improving soil health. The monitoring of soil quality is crucial when changes from rainfall-fed to irrigated crop systems occur. The objective of this study was to assess the impact of different crop successions in the Mediterranean area under irrigation and different technical practices. The soil nitrogen–phosphorous–potassium (NPK) and soil organic carbon (SOC) balances were observed in four fields with irrigated annual crops in a two-year succession timeframe, namely, sunflower–maize (P1), sunflower–clover (P2), maize–sunflower (P3), and alfalfa–alfalfa (P4). The SOC and nutrient balance, integrating the total irrigation, mineral fertilizers, and exported yield, was calculated for each farm. Except for maize–sunflower succession (P3), all fields presented a negative SOC balance at the end of the two-year crop succession, indicating losses from 2.84 to 4.91 Mg SOC ha−1 y−1. While in N-fixing plants the soil N decreased, in the remaining crops a surplus was observed, possibly leading to future N losses. The continuous depletion of soil P revealed a potential underestimation of this nutrient. Soil K appears to be related to specific crop management practices, namely, crop residue incorporation after harvest. In annual irrigated crops under Mediterranean conditions, crop succession can induce soil fertility degradation if conservation practices are absent.

Plug method allows measurement of apical and lateral growth of fen brown mosses

ABSTRACT Introduction: A reliable method for measuring brown moss production helps us to understand the functioning of fen peatlands and to quantify their peat formation rate. However, traditional methods based on height increment are not suitable for measuring the growth rate of brown mosses with numerous lateral branches. Methods: The growth rate of common brown moss species in temperate and boreal fens was measured using two methods: (i) the marking method – a moss shoot was marked with oil paint and its growth increment measured from the mark (in the laboratory and in the field); and (ii) the plug method – a fragment of a moss colony was ‘plugged' (i.e. cored), weighed and replanted in a small basket for a year, then weighed again; a similar and bottomless basket was fixed in the moss colony as a control. Key results and discussion: Despite promising laboratory results, the marking method gave low shoot survival in the field, probably due to the restriction of external water transport along the shoots. No differences in shoot elongation were found between the plug method and the control. The plug method comprises the measurement of both apical and lateral growth, and the authors of the present study therefore recommend it for measuring the growth of brown mosses with numerous lateral branches. Considering only the elongation of the top shoots leads to an underestimation of growth by 50% and consequently to an underestimation of the peat-forming potential of brown mosses.

Influence of Terrigenious Inorganic Nitrogen on Marine Nitrogen Cycle Reconstruction Inferred from Sedimentary Bulk Nitrogen Isotope

This study reevaluates the application of sedimentary bulk nitrogen isotopes (δ15NTN) as proxies for reconstructing past marine nitrogen dynamics, traditionally assumed to reflect organic nitrogen (δ15NON) derived from marine productivity. Employing a novel method that utilizes persulfate oxidation to convert organic nitrogen (ON) and ammonium into nitrate, followed by nitrate reduction to nitrous oxide via denitrifying bacteria, we quantified and characterized both ON and inorganic nitrogen (IN) across diverse environments, including soils, rivers, lakes, and marine sediments. We found that IN, primarily sourced from clay-fixed ammonium via riverine and dust inputs, constitutes 30 % to 50 % of total nitrogen (TN) in marine sediments. Our findings reveal that δ15N values of IN are typically 2 ‰ to 5 ‰ lower than those of δ15NON, resulting in a − 0.5 ‰ to −2 ‰ negative shift in marine δ15NTN. This significant isotopic deviation necessitates a reevaluation of nitrogen cycle interpretations inferred from δ15NTN, especially regarding the potential underestimation of nitrate utilization in nitrate-rich regions and the overestimation of nitrogen fixation in oligotrophic oceans.

Effectiveness of newborn infant parasympathetic evaluation (NIPE) index for guiding intraoperative fentanyl administration in children under 2 years: a randomized controlled trial.

Assessing pain in infants and neonates is challenging due to their inability to communicate verbally. While validated subjective tools exist, they rely on interpreting the child's behavior, leading to potential inconsistencies and underestimation of pain. Based on heart rate variability, the newborn infant parasympathetic evaluation (NIPE) index offers a more objective approach to pain assessment in children under 2 years. Although promising, research on its effectiveness during surgery under general anesthesia remains limited and inconclusive. This study compared the effectiveness of NIPE-guided fentanyl administration to traditional vital signs (heart rate and mean arterial pressure) in managing pain during surgery in children under 2 years. Seventy children undergoing head, neck, or upper extremity surgery were randomized into group N (NIPE) or group C (Control) with 35 participants in each group. Both groups received standardized anesthesia and monitoring, including NIPE. Group N received fentanyl when NIPE scores fell below 50, while group C received fentanyl upon a 20% increase in heart rate or mean arterial pressure (MAP). Postoperative pain was assessed using the Face, Legs, Activity, Cry, and Consolability (FLACC) scores, alongside fentanyl consumption, sedation levels, and potential side effects. Both groups exhibited similar outcomes in terms of postoperative pain scores, fentanyl consumption, sedation levels, and absence of side effects (postoperative respiratory depression or nausea and vomiting). Additionally, intraoperative NIPE scores, heart rate, and MAP were comparable between the groups. There are strong correlations between both groups in terms of NIPE scores (r = 0.735, p < 0.0001), heart rate (r = 0.630, p < 0.0001), and MAP (r = 0.846, p < 0.0001). In both group C and group N, the NIPE scores reveal strong negative correlations with heart rate (r = -0.610, p < 0.0001, and r = -0.674, p < 0.0001) and MAP (r = -0.860, p < 0.0001, and r = -0.756, p < 0.0001). NIPE-guided intraoperative fentanyl administration was not superior to heart rate/MAP-guided administration, as both achieved similar pain management outcomes in this study. However, NIPE may offer a more practical and precise approach, as it is an objective tool with a defined threshold. These findings suggest NIPE's promise as a valuable tool for managing pain in children under 2 years undergoing surgery. However, confirmation of its widespread effectiveness requires further research with larger, multicenter studies encompassing procedures with a broader spectrum of pain severity.

Estimating daily road traffic pollution in Hong Kong using CFD modelling: Validation and application

Road traffic is a major source of urban air pollution, exposing residents to harmful levels of pollutants, particularly in densely populated urban centers. In this study, Computational Fluid Dynamics (CFD) modelling is applied to investigate the impact of road traffic emissions on air pollution within a dense urban environment. The model, applied in Mong Kok, Hong Kong, incorporates high-resolution traffic activity, meteorological, and background concentration data. It demonstrates strong agreement with roadside measurements, deviating by 18.8 % for NOx, 15.5 % for CO, and 0.7 % for PM10, with potential underestimation linked to unmodeled NOx-O3 photochemistry during midday hours (12:00–17:00). Results reveal that local road traffic significantly increases background NOx levels (41 % average increase), highlighting the importance of dispersion modelling for accurate pollution assessments. Traffic-induced increases in CO and PM10 background levels are less pronounced. Two applications demonstrate the model's utility. Firstly, analysis of daily pollution distribution reveals that approximately 10 % of the studied area experiences moderate to very high pollution levels during peak hours. Secondly, an investigation into pollution sources within a leisure park identifies heavy-duty and light-duty vehicles as the primary NOx polluters. This modelling approach provides a valuable decision-making tool for policymakers and local authorities. It enables the assessment of urban design changes, strategic placement of sensitive structures, and future traffic fleet composition choices to mitigate pollution exposure. As air quality regulations tighten, this study offers a robust method for guiding impactful mitigation strategies.

Evaluating GreenFeed and respiration chambers for daily and intraday measurements of enteric gaseous exchange in dairy cows housed in tiestalls

The objective of this study was to evaluate the GreenFeed (GF) and respiration chambers (RC) for daily and intraday measurements of the enteric gaseous exchange, as well as the metabolic heat production, lying behavior, and feed intake (FI) rate of dairy cows at these 2 respective housing conditions [tie-stall barn (TS) vs. RC] during the summer periods. Sixteen multiparous lactating dairy cows were recruited and arranged in a randomized complete block design with a baseline period established for each cow. Cows were given a basal diet (CON) for a baseline period of 7 d and were then fed a 3-nitrooxypropanol (3-NOP)-containing feed for the subsequent 26 d as experimental period. During both the baseline and the last 7 d of treatment period, gaseous exchanges of each animal were measured in the TS using GF for 8 6-hourly staggered measurements over 3 d, immediately followed by the measurement in RC for 2 d. Corresponding DMI, milk yield, and behavior parameters (e.g., lying behavior and FI rate) in TS and RC were recorded. The correlation coefficients of CH4 and H2 using raw data were 0.84 and 0.85, respectively. For all gases, correlation coefficients between GF and RC on individual cow level decreased when the marginal fixed effects (e.g., inhibitor and breed) were corrected by a mixed model. There were no differences in daily CH4 production or intensity between GF and RC (442 vs. 443 g CH4/d or 16.6 vs. 16.2 g CH4 /kg MY). However, greater CH4 yield was measured by GF than RC (19.0 vs. 17.8 g CH4/kg DMI), driven by a lower DMI (23.3 vs. 24.6 kg/d) when cows were housed in TS sampled by GF compared with cows being housed and sampled in RC. The correlations for CO2 production and O2 consumption were moderate and expected due to the variation associated with the mild heat stress condition during GF measurements in the TS (Thermal humidity index (THI) 56 vs. 68), as indicated by the reduced lying time (-2.1 h/d). At the intraday level, there was an interaction between techniques and hour-of-day for CH4 production, as indicated by the discrepancies in post-prandial CH4 emissions between techniques. In summary, this set of results showed that there were strong positive correlations for CH4 and H2 emissions between GF and RC based on individual cow data. However, such relationship should be interpreted with caution, given the data clustering resulting from the use of inhibitor 3-NOP. On treatment level, these 2 techniques detected similar inhibitor effect on the estimated daily CH4 emissions. The intraday patterns of CH4 and H2 production captured by GF provided a close approximation for those measured by RC. Nevertheless, potential underestimation may occur, especially following fresh feed delivery. For measuring CO2 production and O2 consumption, the GF captured similar intraday variations to those in the RC. However, the estimated daily production and consumption were not directly comparable, which was expected due to the variable thermal conditions during the summer. Further evaluations under the same weather conditions are warranted.

Field assessments on the impact of CO2 concentration fluctuations along with complex-terrain flows on the estimation of the net ecosystem exchange of temperate forests

Abstract. CO2 storage (Fs) is the cumulation or depletion in CO2 amount over a period in an ecosystem. Along with the eddy covariance flux and wind-stream advection of CO2, it is a major term in the net ecosystem CO2 exchange (NEE) equation. The CO2 storage dominates the NEE equation under a stable atmospheric stratification when the equation is used for forest ecosystems over complex terrains. However, estimating Fs remains challenging due to the frequent gusts and random fluctuations in boundary-layer flows that lead to tremendous difficulties in capturing the true trend of CO2 changes for use in storage estimation from eddy covariance along with atmospheric profile techniques. Using measurements from Qingyuan Ker Towers equipped with NEE instrument systems separately covering mixed broad-leaved, oak, and larch forest towers in a mountain watershed, this study investigates gust periods and CO2 fluctuation magnitudes and examines their impact on Fs estimation in relation to the terrain complexity index (TCI). The gusts induce CO2 fluctuations for numerous periods of 1 to 10 min over 2 h. Diurnal, seasonal, and spatial differences (P &lt; 0.01) in the maximum amplitude of CO2 fluctuations (Am) range from 1.6 to 136.7 ppm, and these differences range from 140 to 170 s in a period (Pm) at the same significance level. Am and Pm are significantly correlated to the magnitude of and random error in Fs with diurnal and seasonal differences. These correlations decrease as CO2 averaging time windows become longer. To minimize the uncertainties in Fs, a constant [CO2] averaging time window for the Fs estimates is not ideal. Dynamic averaging time windows and a decision-level fusion model can reduce the potential underestimation of Fs by 29 %–33 % for temperate forests in complex terrain. In our study, the relative contribution of Fs to the 30 min NEE observations ranged from 17 % to 82 % depending on turbulent mixing and the TCI. The study's approach is notable as it incorporates the TCI and utilizes three flux towers for replication, making the findings relevant to similar regions with a single tower.

Cold-water octocoral interactions with microplastics under laboratory conditions

Microplastic pollution is ubiquitous in the oceans, threatening the health of marine ecosystems. The deep sea is recognized as a sink for microplastics, but there is a paucity of information on how deep-sea organisms are being affected by this stressor. Considering their vulnerability to disturbance, this information is crucial to fully understand the need for conservation actions. Here, we develop a novel methodology to provide a detailed characterisation of the behavioural responses of the cold-water octocoral Viminella flagellum to microplastic exposure under laboratory conditions. Coral fragments were individually exposed to a concentration of 1500 items/L of fluorescent green polyethylene microspheres biofouled for three weeks, for a period of 24 h, and carefully monitored for the entire exposure period using high resolution time-lapse video. After exposure, each fragment was transferred to another tank, free of microplastics, and monitored for further 24 h. The coral fragments were dissected at the end of the experimental period to assess the number of microplastics that remained in the digestive tract of each polyp. Our results showed that during this short-term exposure period, V. flagellum was ingesting microspheres, but most importantly it demonstrated the capacity of egesting all particles within 24 h. These results are especially important when quantifying microplastic contamination in cold-water corals in their natural habitat, as only recently ingested microplastics may be detected, leading to potential underestimations of their exposure. Additionally, our results indicated that microplastics adhered to the coral tissue surface could be discarded through periodic shedding of the mucus. These observations suggest that cold-water octocorals can handle microplastics as they do with other foreign particles, although the cleaning mechanisms may require significant energy expenditures.

Ethical considerations of use of hold-out sets in clinical prediction model management

AbstractClinical prediction models are statistical or machine learning models used to quantify the risk of a certain health outcome using patient data. These can then inform potential interventions on patients, causing an effect called performative prediction: predictions inform interventions which influence the outcome they were trying to predict, leading to a potential underestimation of risk in some patients if a model is updated on this data. One suggested resolution to this is the use of hold-out sets, in which a set of patients do not receive model derived risk scores, such that a model can be safely retrained. We present an overview of clinical and research ethics regarding potential implementation of hold-out sets for clinical prediction models in health settings. We focus on the ethical principles of beneficence, non-maleficence, autonomy and justice. We also discuss informed consent, clinical equipoise, and truth-telling. We present illustrative cases of potential hold-out set implementations and discuss statistical issues arising from different hold-out set sampling methods. We also discuss differences between hold-out sets and randomised control trials, in terms of ethics and statistical issues. Finally, we give practical recommendations for researchers interested in the use hold-out sets for clinical prediction models.

Evaluation of greenhouse gas emission and reduction potential of high-food-waste-content municipal solid waste landfills: A case study of a landfill in the east of China

This study proposes a comprehensive evaluation method based on a two-stage model to assess greenhouse gas (GHG) emissions and reductions in high-food-waste-content (HFWC) municipal solid waste (MSW) landfills. The proposed method considers typical processes such as fugitive landfill gas (LFG), LFG collection, flaring, power generation, and leachate treatment. A case study of an HFWC MSW landfill in eastern China is considered to illustrate the evaluation. The findings revealed that the GHG emissions equivalent of the case landfill amounted to 21.23 million tons from 2007 to 2022, averaging 1.03 tons CO2-eq per ton of MSW. There was a potential underestimation of LFG generation at the landfill site during the initial stages, which led to delayed LFG collection and substantial fugitive LFG emissions. Additionally, the time distribution of GHG emissions from HFWC MSW was significantly different from that of low-food-waste-content (LFWC) MSW landfills, with peak emissions occurring much earlier. Owing to the rapid degradation characteristics of HFWC MSW, the cumulative LFG production of the landfill by 2022 (2 years after the final cover) was projected to reach 77 % of the total LFG potential. In contrast, it would take until 2030 for LFWC MSW landfills to reach this level. Furthermore, various scenarios were analyzed, in which if the rapid LFG generation characteristics of HFWC MSW are known in advance, and relevant facilities are constructed ahead of time, the collection efficiency can be improved from 31 % to over 78 %, resulting in less GHG emissions.