Gray Zone Research Articles

Hepatocellular carcinoma among patients with chronic hepatitis B in the indeterminate phase.

Hepatitis B virus (HBV) infection is a dynamic disease where patients progress through several stages defined by HBV e-antigen (HBeAg) status, HBV-DNA levels and transaminase elevations, with antiviral therapy indicated only in specific stages. However, some patients cannot be classified into one of the stages and are said to fall into an 'indeterminate phase' or 'grey zone'. Exact definitions of the indeterminate phase vary from guideline to guideline as a result of different cut-off values for biomarker measurements. Data suggest that as many as 50% of HBV patients may be in an indeterminate phase and may not rapidly transition out of this phase. Clinical data that suggest these patients are at increased risk of hepatocellular carcinoma (HCC) are complemented by molecular evidence of integrations of HBV-DNA into the host genome, chromosomal translocations and immune activation despite liver enzymes that may suggest lack of inflammation. Antiviral therapy reduces these hepatocarcinogenic mechanisms and is reflected in a reduction of fibrosis and HCC risk. We review key data on patients in the indeterminate phase, with emphasis on HCC as an outcome. We take a holistic approach and link new biological data with clinical observations as well as examine the potential role of antiviral therapy in reducing HCC risk among patients in the indeterminate phase. With the availability of safe and effective oral antivirals, consideration must be given as to how much residual risk of HCC should be tolerated among patients in the indeterminate phase.

First report of large-berry coffee (Coffea liberica) anthracnose caused by Colletotrichum kahawae in China.

Large-berry coffee (Coffea liberica) is one of the three cultivated coffee species and a precious breeding germplasm in China (Yan et al, 2019). Anthracnose is a damaging epidemic disease on coffee worldwide (Mohammed et al. 2015). Between June and September 2022, anthracnose was observed on coffee plants in Puer area, Yunnan, China and disease incidence (% plants diseased) of 8.5%-28.2% was recorded in the field. The disease symptoms were observed at all growth stages. Lesions on leaves were circular or oval, with a white to gray central zone outlined by a brown margin and surrounded by a chlorotic halo, Φ5.1-18.5 mm; some lesions extended and coalesced later to form large, blighted areas, leading to complete leaf senescence, defoliation and bare blighted branches on heavily infected trees. The spots on coffee berries were oval or fusiform, sunken and brown-black; diseased berries became gray-black and dried-out but remained on the tree. Leaves with typical anthracnose lesions were collected from fields in Simao ( 22.07°E,100.98°N) to isolate the pathogen. Leaf pieces (5×5mm) from the lesion margin were cut, surface-sterilized with 75% ethanol and 2% NaClO, and cultured on PDA at 25°C. Three isolates with the same colony morphology were obtained by hyphal tip purification. Detached and intact leaves of 6-month coffee seedlings were inoculated with Φ5mm mycelial discs of the isolates. Anthracnose lesions developed on the inoculated leaves, with all 3 isolates, 7d after incubation in a growth chamber (25°C, > 90% RH and lighting 8 h/d at 11000 lux). Pathogens with the same colony morphology as those of the original isolates were re-isolated from the infected tissues of inoculated leaves, thus fulfilling Koch's Postulates. The ITS sequence (PP550861) for the isolate was PCR-amplified and Blast-n analyses showed 100 % (554/554bp) identity to Colletotrichum kahawae LWTJ01; so they were the same population and coded as KFTJ02. The actin (ACT), calmodulin(CAL), glyceraldehydes-3-phosphate dehydrogenase (GAPHD) and histone 3 (HIS3) genes (Qiu et al. 2020) were amplified from one of KFTJ02 isolates, sequenced and deposited in NCBI GenBank (OR842543, OR842544, OR842545 & OR842546). A phylogenetic tree was generated based on the concatenated sequences of the four genes and those of related Colletotrichum spp. using MEGA 6.0 and KFTJ02 clustered in the same clade with C. kahawae IMI319418 on the tree (Bootstrap sup.=88%). When cultured at 25°C on PDA for 7 days, its colonies were near round or ovoid, gray-white, contoured, Φ73.2-80.1 (76.2±2.3)mm or growth rate 10.2-11.1(8.1) mm/d (n=10). The hyphae were hyaline, septated, branching at near right angles. Conidial masses formed 14 days after incubation. The conidia were elliptical, hyaline, monocellular, 10.2-15.5 (12.7±1.06)×3.8-5.2 (4.3±0.52) µm (n=50). The appressoria were black-brown, oval or irregular, 7.8-9.3 (8.5±0.81)μm (n= 50). These morphological characteristics were consistent with those of C. kahawae (Bridge et al, 2008). Therefore, KFTJ02 was identified as C. kahawae, which has been found to infect Camellia oleifera, Areca catechu and Ficus microcarpa (Wei et al, 2023; Zhang et al, 2020; Lin 2023). The coffee berry disease pathogen (C. kahawae) is a quarantine species which has not been recorded and so it is first reported on coffee crops in China. Results of the present study provide important references for further studies on this disease.

Machine learning parameterization of the multi-scale Kain–Fritsch (MSKF) convection scheme and stable simulation coupled in the Weather Research and Forecasting (WRF) model using WRF–ML v1.0

Abstract. Warm-sector heavy rainfall along the south China coast poses significant forecasting challenges due to its localized nature and prolonged duration. To improve the prediction of such high-impact weather events, high-resolution numerical weather prediction (NWP) models are increasingly used to more accurately represent topographic effects. However, as these models' grid spacing approaches the scale of convective processes, they enter a “gray zone”, where the models struggle to fully resolve the turbulent eddies within the atmospheric boundary layer, necessitating partial parameterization. The appropriateness of applying convection parameterization (CP) schemes within this gray zone remains controversial. To address this, scale-aware CP schemes have been developed to improve the representation of convective transport. Among these, the multi-scale Kain–Fritsch (MSKF) scheme enhances the traditional Kain–Fritsch (KF) scheme, incorporating modifications that facilitate its effective application at spatial resolutions as high as 2 km. In recent years, there has been an increase in the application of machine learning (ML) models across various domains of atmospheric sciences, including efforts to replace conventional physical parameterizations with ML models. This work introduces a multi-output bidirectional long short-term memory (Bi-LSTM) model intended to replace the scale-aware MSKF CP scheme. This multi-output Bi-LSTM model is capable of simultaneously predicting the convection trigger while also modeling the associated convective tendencies and precipitation rates with a high performance. Data for training and testing the model are generated using the Weather Research and Forecast (WRF) model over south China at a horizontal resolution of 5 km. Furthermore, this work evaluates the performance of the WRF model coupled with the ML-based CP scheme against simulations with the traditional MSKF scheme. The results demonstrate that the Bi-LSTM model can achieve high accuracy, indicating the promising potential of ML models to substitute the MSKF scheme in the gray zone.

Robustness and classification capabilities of MRI radiomic features in identifying carotid plaque vulnerability.

To assess how radiomic features may be combined with plaque morphological and compositional features identified by multi-contrast magnetic resonance imaging (MRI) to improve upon conventional risk assessment models in determining culprit lesions. Fifty-five patients (mean age: 62.6; 35 males) with bilateral carotid stenosis who experienced transient ischaemic attack (TIA) or stroke were included from the CARE-II multi-centre carotid imaging trial (ClinicalTrials.gov Identifier: NCT02017756). They underwent MRI within 2 weeks of the event. Classification capability in distinguishing culprit lesions was assessed by machine learning. Repeatability and reproducibility of the results were investigated by assessing the robustness of the radiomic features. Radiomics combined with a relatively conventional plaque morphological and compositional metric-based model provided incremental value over a conventional model alone [area under curve (AUC), 0.819 ± 0.002 vs. 0.689 ± 0.019 respectively, p = 0.014]. The radiomic model alone also provided value over the conventional model [AUC, 0.805 ± 0.003 vs. 0.689 ± 0.019 respectively, p = 0.031]. T2-weighted imaging-based radiomic features had consistently higher robustness and classification capabilities compared with T1-weighted images. Higher-dimensional radiomic features outperformed first-order features. Grey Level Co-occurrence Matrix (GLCM), Grey Level Dependence Matrix (GLDM) and Grey Level Size Zone Matrix (GLSZM) sub-types were particularly useful in identifying textures which could detect vulnerable lesions. The combination of MRI-based radiomic features and lesion morphological and compositional parameters provided added value to the reference-standard risk assessment for carotid atherosclerosis. This may improve future risk stratification for individuals at risk of major adverse ischemic cerebrovascular events.

Integrity games: an online teaching tool on academic integrity for undergraduate students

In this paper, we introduce Integrity Games (https://integgame.eu/) – a freely available, gamified online teaching tool on academic integrity. In addition, we present results from a randomized controlled experiment measuring the learning outcomes from playing Integrity Games.Integrity Games engages students in reflections on realistic and relevant academic integrity issues that lie in the grey zone between good practice and misconduct. Thereby, it aims to 1) motivate students to learn more about academic integrity, 2) increase their awareness of the grey-zone issues, and 3) increase their awareness of misconduct. To achieve these aims, the tool presents four gamified cases that lead students through an engaging narrative.The experiment to measure learning outcomes was conducted in three European countries, and included N = 257 participants from across natural science, social science and the humanities. We show that the participants enjoyed playing Integrity Games, and that it increased their sensitivity to grey-zone issues and misconduct. However, the increases identified were similar to those achieved by the participants in the control group reading a non-gamified text.We end by discussing the value of gamification in online academic integrity training in light of these results.

Translation and Memory from the Cremation Ovens in Poland to Freedom in Greece and the US: The Journey and the Manuscripts of Marcel Nadjary

In a timeframe of 35 years, from 1945 to 1980, some manuscripts left by 5 Jewish members of the Sonderkommando were found buried near the crematories in Auschwitz-Birkenau. These prisoners were forced to do activities directly connected to the genocide, and because of that they were considered as bearers of secrets. Known as The Scrolls of Auschwitz, these manuscripts have been held as sources of high historical-social-psychological value. The narrative found in 1980 was written by a Greek Jew called Marcel Nadjary (1917-1971), the only amongst the authors to survive the Lager. The degradation of the papers demanded a long recovery work that recently produced two books: Μαρσελ Νατζαρή Χειρόγραφα 1944-1947 (2018) and Marcel Nadjari’s Manuscript November 3, 1944 (2020). The work of translation from Greek to Portuguese has allowed us to examine the paths in which a survivor of the Gray Zone builds his memories, in two different moments: at the time of the event, and a posteriori. Therefore, it is possible to identify what is kept and what changes in the subjective assumption of History itself, and in the way the author uses the words to narrate his memories and transmit the secrets he carried. Keywords: Marcel Nadjary, translation, testimony, Auschwitz-Birkenau, Sonderkommando.

NEC versus NET G3—is there a grey zone? Case report of pancreatic NET G3 with rapid disease progression

Summary Introduction Patients with well-differentiated neuroendocrine tumors of grade 3 (NET G3) exhibit a significantly better survival than patients with poorly differentiated neuroendocrine carcinomas (NEC). However, some cases of NET G3 with high Ki-67 index present with highly aggressive clinical behavior, prompting the question whether there are selected tumors representing a biological continuum between NET G3 and NEC. Case presentation Here we report the case of a 49-year-old man with pancreatic NET G3 metastasized to the liver. Surgery was not indicated, and the patient was initially treated with cisplatin/etoposide on account of the high proliferation rate (Ki-67 index of 50%). Restaging showed immediate disease progression with new liver metastases, so therapy with capecitabine/temozolomide was initiated and continued until progressive disease after 7 cycles. Comprehensive diagnostic evaluation, including functional imaging and genetic analyses, revealed no potential therapeutic targets, and further treatment options were limited. The patient died shortly after a therapeutic attempt with streptozotocin/5-fluorouracil. Conclusion This case exemplifies the unfortunate course of a rapidly progressive NET G3 and highlights the limited number of effective therapies for some tumors within the relatively new cohort of NET G3 with a yet unsatisfactory understanding of its underlying tumor biology and behavioral spectrum.

On the Interplay Between Duration of Employment, Relational Quality and Wages—Results About Non-Family Farm Workers in Switzerland

Our knowledge on non-family farm workers has been hampered by a lack of reliable and relevant data. This study tackled this problem by asking Swiss managers of fruit, wine and vegetable farms about their employees. Using a dataset of 921 employees, we explain the duration of the labour contract, the level of wages and the relational quality between employers and workers. The level of wages and other resources like shelter are linked to employment duration but also to social factors like joint social events or the perception of relational quality by employers. Workers with the liberty to allocate their labour time have better relationships with their employers. The best wages are paid to full-time male employees with agricultural education residing in Switzerland. The fact that Swiss citizens receive a significant reduction in their payment compared to foreigners may point to a grey zone between unpaid family labour and market-based employment relations.

Scandinavian perspectives on life support at the border of viability.

Advances in neonatal medicine have allowed us to rescue extremely preterm infants. However, both long-term vulnerability and the burden of treatment in the neonatal period increase with decreasing gestational age. This raises questions about the justification of life support when a baby is born at the border of viability, and has led to a so-called "grey zone", where many professionals are unsure whether provision of life support is in the child's best interest. Despite cultural, political and economic similarities, the Scandinavian countries differ in their approach to periviable infants, as seen in their respective national guidelines and practices. In Sweden, guidelines and practice are more rescue-focused at the lower end of the border of viability, Danish guidelines emphasizes the need to involve parental views in the decision-making process, whereas Norway appears to be somewhere in between. In this paper, I will give an overview of national consensus documents and practices in Norway, Sweden and Denmark, and reflect on the ethical justification for the different approaches.

Navigating a grey zone: Neuromonitoring in the management of temporary internal carotid artery occlusion techniques - A case series and literature review

There is a dearth of clearly defined thresholds to guide the application of neuromonitoring modalities in temporary vessel occlusion techniques. We report a case series exploring the utility of various neuromonitoring techniques during temporary vessel occlusion procedures. We conducted a retrospective chart review of patients, who underwent temporary vessel occlusion procedures over a two-year period and examined the neuromonitors employed in temporary vessel occlusion procedures including balloon occlusion test (BOT). We found complete details of nine patients, who were managed with the use of the following neuromonitors: cerebral oximetry, electrical activity monitors, evoked potential monitors, and transcranial Doppler. A literature search identified other studies reporting utilization of adjuvant neuromonitoring in these procedures. Although multiple sensors could be concurrently attached to patients without impeding image acquisition in patients undergoing BOT, our review of the literature and our own findings revealed a lack of consistent correlation with outcome, particularly concerning near-infrared spectroscopy values.

The military-strategic rationality of hybrid warfare: Everyday total defence under strategic non-peace in the case of Sweden

Abstract This article explores the emergence of new military-strategic rationalities in relation to conceptions of hybrid warfare in the grey zone through a case study of Sweden’s reinstatement of total defence since 2015. Through a governmentality-inspired approach, I analyse what it means for the organisation of a new total defence when one of the main threats to be dealt with is daily antagonistic but highly ambiguous hybrid attacks. I illustrate how conceptions of an ambiguous strategic non-peace entails a move beyond war preparedness into urgent demands for an everyday active total defence that hinges on a ‘martialisation’ of civilian life. This in turn run the risk of challenging fundamental democratic principles and civil liberties. The analysis contributes to an increased understanding and uncovering of the politics made possible by a military-strategic rationality geared towards hybrid threats in the grey zone – which in the Swedish case has resulted in a historically specific version of total defence that builds on a highly diffused and rather extreme form of decentralised defence.

Transrectal versus transperineal prostate biopsy for cancer detection in patients with gray-zone prostate-specific antigen: a multicenter, real-world study.

Knowledge about the effect of different prostate biopsy approaches on the prostate cancer detection rate (CDR) in patients with gray-zone prostate-specific antigen (PSA) is limited. We performed this study to compare the CDR among patients who underwent different biopsy approaches and had rising PSA levels in the gray zone. Two hundred and twenty-two patients who underwent transrectal prostate biopsy (TRB) and 216 patients who underwent transperineal prostate biopsy (TPB) between June 2016 and September 2022 were reviewed in this study. In addition, 110 patients who received additional targeted biopsies following the systematic TPB were identified. Clinical parameters, including age, PSA derivative, prostate volume (PV), and needle core count, were recorded. The data were fitted via propensity score matching (PSM), adjusting for potential confounders. TPB outperformed TRB in terms of the CDR (49.6% vs 28.3%, P = 0.001). The clinically significant prostate cancer (csPCa) detection rate was not significantly different between TPB and TRB (78.6% vs 68.8%, P = 0.306). In stratified analysis, TPB outperformed TRB in CDR when the age of patients was 65-75 years (59.0% vs 22.0%, P < 0.001), when PV was 25.00-50.00 ml (63.2% vs 28.3%, P < 0.001), and when needle core count was no more than 12 (58.5% vs 31.5%, P = 0.005). The CDR (P = 0.712) and detection rate of csPCa (P = 0.993) did not significantly differ among the systematic, targeted, and combined biopsies. TPB outperformed TRB in CDR for patients with gray-zone PSA. Moreover, performing target biopsy after systematic TPB provided no additional benefits in CDR.

The comprehensive checklist of myxomycetes of Ukraine, based on extended occurrence and reference datasets.

A significant body of valuable data about the myxomycetes of Ukraine lies in a "grey zone". This encompasses undigitised historical books and articles published in languages such as Polish, French or German, as well as proceedings from local conferences, articles featured in local scientific journals and annual reports submitted to public authorities by employees of protected areas, published in Ukrainian or Russian. Yet, due to their exclusive existence in print and often the Cyrillic alphabet, these publications remain neither findable nor accessible to a wider audience. The datasets presented here aim to summarise over 150 years of myxomycetes research in Ukraine. The majority of the data has been extracted from published literature sources spanning the years 1842 to 2023, with a minor supplement from unpublished herbarium specimens. The datasets include 5036 georeferenced occurrences, 339 taxa and 91 literature sources. Seventy-one of the used literature sources, mostly published before 2010, were uploaded to Zenodo and are available in open access.

Changes in the cardiovascular profile in patients 3 and 12 months after COVID-19 pneumonia: parameters of arterial stiffness, global longitudinal strain, and diastolic function of the left ventricle

Aim. To study changes in the brachial – ankle pulse wave velocity (baPWV), ankle – brachial index (ABI), diastolic function, and global longitudinal strain of the left ventricle (LV) 3 and 12 months after COVID-19 pneumonia.Materials and methods. The dynamics of vascular age and LV global longitudinal strain was studied in 154 patients 3 and 12 months after COVID-19 pneumonia (51 ± 12 years, 48% were women). The control group consisted of 55 sexand age-matched individuals.Results. During the follow-up, the average baPWV decreased (13.2 [11.8; 15.1] cm / sec vs. 13.0 [11.8; 14.1] cm/ s; p &lt; 0.001), and the frequency of its elevated values declined (45.4 vs. 35.1%; p = 0.008). The average ABI increased (1.09 [1.04; 1.14] vs. 1.11 [1.06; 1.17]; p = 0.012), but remained within the normal range. LV global longitudinal strain (LV GLS) (–19.6 ± 2.2 and –19.7 ± 2.5%; p = 0.854) and the frequency of reduced LV GLS (21.4 and 26.6%; p = 0.268) did not change significantly and did not differ from values in the control group. Global longitudinal strain in the LV basal inferoseptal segment improved (–19.2 ± 3.6% vs. –20.1 ± 4.0%; p = 0.032). The early diastolic mitral annular velocity decreased (8.4 ± 3.0 cm / s vs. 8.0 ± 2.5 cm / s; p = 0.023). The LV isovolumic relaxation time was greater than in the control group (101.8 ± 22.3 ms at the 1st visit vs. 92.9 ± 21.5 ms; p = 0.012; 105.9 ± 21.9 ms vs. 92.9 ± 21.5 ms at the 2nd visit; p &lt; 0.001). A positive correlation was found between baPWV (r = 0.209; p = 0.009) and ABI (r = 0.190; p = 0.021) and strain parameters of the LV basal segments 12 months after discharge.Conclusion. Patients with optimal visualization on echocardiography at 12 months after COVID-19 pneumonia, compared to the results of the examination 3 months after the disease, had deteriorated parameters of LV diastolic function. LV GLS was within the grey zone and did not change significantly. An improvement in arterial stiffness was noted, associated with an improvement in the strain of basal LV segments.

Navigating the ‘grey zone’: academic collaboration and research on/in Russia during geopolitical crisis

Russia’s illegal annexation of Crimea in 2014 and attack on Ukraine in 2022 have led to widespread sanctions being placed on Russia by the European Union, including sanctions related to academic cooperation. National governments, supranational bodies, science academies and research institutions as well as publishers have likewise formed policies suspending and restricting collaboration regarding Russia-related research. These policies are, however, not straight forward and there are many practical and ethical questions that individual researchers must ask themselves. At Finnish Geography Days 2023 in Joensuu, a panel was dedicated to discussing some of these questions. This article summarizes main themes discussed during the panel and sheds light on the multiple ways researchers experience and navigate the ‘grey zone’ of academic collaboration and research on/in Russia in the current geopolitical context. The article emphasizes the necessity of further discussing the effectiveness and impact of the sanctions and restrictions: Are they reasonable? Who benefits from them, and who suffers?

Grey Zone Healers and the COVID-19 Pandemic in Chechnya, Russia.

The Chechen authorities' focus upon population health is enacted both through the principles of Islamic medicine and approved biomedical practices. Any healing practices beyond these domains are met with deep suspicion. Practitioners of unofficial complementary and alternative medicine healers may abruptly find themselves regarded as enemies of the state. In light of this precarious circumstance, it becomes pertinent to inquire: How do these healers employ their daily tactics to negotiate the intricate power dynamics between the formidable state apparatus and the established biomedical order? Drawing from our meticulous fieldwork conducted in the year 2021, we investigated the intricate tactics employed by unofficial healers in the Chechen medical landscape during COVID-19. Our research centred on discerning the nuanced tactics aimed at mitigating potential risks. We conclude that healers, having embodied tactics to creatively manoeuvre within the confines of the authoritarian state, perceived the challenges posed by COVID-19 as merely another, often inconsequential, obstacle in their enduring struggle.

On the Sensitivity of Large-Eddy Simulations of the Atmospheric Boundary Layer Coupled with Realistic Large-Scale Dynamics

Abstract We present a new ensemble of 36 numerical experiments aimed at comprehensively gauging the sensitivity of nested large-eddy simulations (LES) driven by large-scale dynamics. Specifically, we explore 36 multiscale configurations of the Weather Research and Forecasting (WRF) Model to simulate the boundary layer flow over the complex topography at the Perdigão field site, with five nested domains discretized at horizontal resolutions ranging from 11.25 km to 30 m. Each ensemble member has a unique combination of the following input factors: (i) large-scale initial and boundary conditions, (ii) subgrid turbulence modeling in the gray zone of turbulence, (iii) subgrid-scale (SGS) models in LES, and (iv) topography and land-cover datasets. We probe their relative importance for LES calculations of velocity, temperature, and moisture fields. Variance decomposition analysis unravels large sensitivities to topography and land-use datasets and very weak sensitivity to the LES SGS model. Discrepancies within ensemble members can be as large as 2.5 m s−1 for the time-averaged near-surface wind speed on the ridge and as large as 10 m s−1 without time averaging. At specific time points, a large fraction of this sensitivity can be explained by the different turbulence models in the gray zone domains. We implement a horizontal momentum and moisture budget routine in WRF to further elucidate the mechanisms behind the observed sensitivity, paving the way for an increased understanding of the tangible effects of the gray zone of turbulence problem. Significance Statement Several science and engineering applications, including wind turbine siting and operations, weather prediction, and downscaling of climate projections, call for high-resolution numerical simulations of the lowest part of the atmosphere. Recent studies have highlighted that such high-resolution simulations, coupled with large-scale models, are challenging and require several important assumptions. With a new set of numerical experiments, we evaluate and compare the significance of different assumptions and outstanding challenges in multiscale modeling (i.e., coupling large-scale models and high-resolution atmospheric simulations). The ultimate goal of this analysis is to put each individual assumption into the wider perspective of a realistic problem and quantify its relative importance compared to other important modeling choices.

Generalized eddy‐diffusivity mass‐flux formulation for the parametrization of atmospheric convection and turbulence

AbstractThe atmospheric convection is a phenomenon that has a length scale smaller than the resolution at which the state‐of‐the‐art general circulation numerical models are running, and thus the convection needs to be parametrized. In this work, a theoretical formulation for the parametrization of subgrid‐scale convection based on subgrid averaging that represents a generalized eddy‐diffusivity mass‐flux formulation is presented. The subgrid fluxes are derived by considering a decomposition of subgrid variables into convective and turbulent variables, and by assuming that the convection is modeled by round convective plumes with generic radial profiles. The main difference between our formulation and the mass‐flux formulations is that the condition of a very small fractional area occupied by the convection is replaced with the condition that the convective vertical velocity goes to the mean state far from the updraft region of the plume. The plume model can also be generalized by considering that the convective elements are energy‐consistent plumes, governed by the conservation of mass, momentum, kinetic energy, and buoyancy, which provides a physical‐based closure for the entrainment. Therefore, the closing problem of our formulation consists of the specification of the convective radial profiles and the boundary conditions at the initial vertical level. Furthermore, our formulation allows one to consider more realistic profiles for the convective variables, making the formulation suitable for the parametrization of atmospheric convection at the convective gray zone. This aspect is discussed in the last part of this work, where it is showed how the formulation can be implemented at any resolution. Moreover, in the present framework, no distinct assumptions are required for each convective type, thus facilitating the parametrization of convection in a unified way.

Robustness of radiomic features in healthy abdominal parenchyma of patients with repeated examinations on dual-layer dual-energy CT

ObjectivesRobustness of radiomic features in physiological tissue is an important prerequisite for quantitative analysis of tumor biology and response assessment. In contrast to previous studies which focused on different tumors with mostly short scan-re-scan intervals, this study aimed to evaluate the robustness of radiomic features in cancer-free patients and over a clinically encountered inter-scan interval. Materials and methodsPatients without visible tumor burden who underwent at least two portal-venous phase dual energy CT examinations of the abdomen between May 2016 and January 2020 were included, while macroscopic tumor burden was excluded based upon follow-up imaging for all patients (≥3 months). Further, patients were excluded if no follow-up imaging was available, or if the CT protocol showed deviations between repeated examinations. Circular regions of interest were placed and proofread by two board-certified radiologists (4 years and 5 years experience) within the liver (segments 3 and 6), the psoas muscle (left and right), the pancreatic head, and the spleen to obtain radiomic features from normal-appearing organ parenchyma using PyRadiomics. Radiomic feature robustness was tested using the concordance correlation coefficient with a threshold of 0.75 considered indicative for deeming a feature robust. ResultsIn total, 160 patients with 480 repeated abdominal CT examinations (range: 2–4 per patient) were retrospectively included in this single-center, IRB-approved study. Considering all organs and feature categories, only 4.58 % (25/546) of all features were robust with the highest rate being found in the first order feature category (20.37 %, 22/108). Other feature categories (grey level co-occurrence matrix, grey level dependence matrix, grey level run length matrix, grey level size zone matrix, and neighborhood gray-tone difference matrix) yielded an overall low percentage of robust features (range: 0.00 %-1.19 %). A subgroup analysis revealed the reconstructed field of view and the X-ray tube current as determinants of feature robustness (significant differences in subgroups for all organs, p < 0.001) as well as the size of the region of interest (no significant difference for the pancreatic head with p = 0.135, significant difference with p < 0.001 for all other organs). ConclusionRadiomic feature robustness obtained from cancer-free subjects with repeated examinations using a consistent protocol and CT scanner was limited, with first order features yielding the highest proportion of robust features.

Modulation of Tropical Convection‐Circulation Interaction by Aerosol Indirect Effects in Convective Self‐Aggregation Simulations of a Gray Zone Global Model

AbstractDisentangling the response of tropical convective updrafts to enhanced aerosol concentrations has been challenging. Leading theories for explaining the influence of aerosol concentrations on tropical convection are based on the dynamical response of convection to changes in cloud microphysics, neglecting possible changes in the environment. In recent years, global convection‐permitting models (GCPM) have been developed to circumvent problems arising from imposing artificial scale separation on physical processes associated with deep convection. Here, we use a global model in the convective gray zone that partially simulates deep convection to investigate how enhanced concentrations of aerosols that act as cloud condensate nuclei (CCN) impact tropical convection features by modulating the convection‐circulation interaction. Results from a pair of idealized non‐rotating radiative‐convective equilibrium simulations show that the enhanced CCN concentration leads to weaker large‐scale circulation, the closeness of deep convective systems to the moist cluster edges, and more mid‐level cloud water at an equilibrium state in which convective self‐aggregation occurred. Correspondingly, the enhanced CCN concentration modulates how the physical processes that support or oppose convective aggregation maintain the aggregated state at equilibrium. Overall, the enhanced CCN concentration facilitates the development of deep convection in a drier environment but reduces mean precipitation. Our results emphasize the importance of allowing atmospheric phenomena to evolve continuously across spatial and temporal scales in simulations when investigating the response of tropical convection to changes in cloud microphysics.