bluuebunny/crossref_metadata_2025 huggingface dataset:
Topographic heterogeneity lengthens the duration of pollinator resources
Authors: Olliff‐Yang Rachael L. , Ackerly David D.
Published: August 2020

The availability of sufficient and diverse resources across time is important for maintenance of biodiversity and ecosystem functioning. In this study, we examine the potential for variation in environmental conditions across topographic gradients to extend floral resource timing. Flowering time on a landscape may vary across topography due to differences in abiotic factors, species turnover, or genotypic differences. However, the extent to which this variation in phenology affects overall flowering duration on a landscape, and the components of diversity that influence flowering duration, are unexplored. We investigate whether differences in flowering time due to topography yield an overall extension in duration of flowering resources in a northern California grassland. We recorded flowering time of pollinator resource species across four successive spring growing seasons (2015–2018) on paired north and south aspects. Flowering time differences were evaluated both at the community level and within species present on both paired aspects. The role of plasticity was examined in an experimental case study using genotypes of Lasthenia gracilis. We found that aspect is a strong determinant of phenology, with earlier flowering on warmer south‐facing slopes. Aspect differences resulted in complementarity in timing of flowering resources across sites, as aspects that started flowering earlier also ended earlier. Complementarity between north and south aspects served to extend the flowering time of pollinator resources by an average of 4–8 days (8%–15%), depending on the year. This extension can be attributed to both within‐species responses to aspect differences and species turnover. Flowering of L. gracilis genotypes was distinct across aspects, demonstrating that plasticity can drive the extension of flowering duration. Our findings indicate that heterogeneous topography can extend overall flowering time of pollinator resources, which may support pollinator biodiversity. Extension was most pronounced at the community level, which incorporates species turnover as well as plastic and genotypic differences within species.
Sodium Transition Metal Vanadates from Hydrothermal Brines: Synthesis and Characterization of NaMn4(VO4)3, Na2Mn3(VO4)3, and Na2Co3(VO4)2(OH)2
Authors: Smith Pellizzeri Tiffany M. , Morrison Gregory , McMillen Colin D. , zur Loye Hans‐Conrad , Kolis Joseph W.
Published: August 2020

Three new examples of transition metal vanadates have all been synthesized by a related hydrothermal synthetic route using variations of sodium hydroxide/sodium chloride brines as mineralizers. Compound 1, NaMn4(VO4)3, is built from equivalent interlocking chains of Mn2+ edge shared octahedra, further coordinated to one another by (VO4)3– vanadate groups to form a three‐dimensional structure. Compound 2, Na2Mn3(VO4)3, forms a complex three‐dimensional structure of mixed‐valence 2+/3+ manganese edge‐sharing octahedra forming chains, with (VO4)3– tetrahedra acting as space‐fillers in the structure. Structure 3, Na2Co3(VO4)2(OH)2, is built of a two‐dimensional distorted honeycomb of edge shared Co2+ layers decorated by, but not connected by, vanadate groups. The layers bear a relationship to Kagome nets but the structure contains no ideal trigonal symmetry. All compounds were characterized by single‐crystal X‐ray diffraction. Compounds 1 and 3 were characterized by magnetic susceptibility. The magnetic susceptibility of 1 displays the moment characteristic of Mn2+ and a transition at 46 K to a spin canted antiferromagnet. Compound 3 shows evidence of spin–orbit coupling in the Co2+ ions with antiferromagnetic ordering at 4.4.K and highly anisotropic field‐dependent behavior with multiple metamagnetic transitions.
Multidentate N‐Heterocyclic Carbene Complexes of Nickel and Palladium: Structural Analysis and Catalytic Application in Mizoroki–Heck Coupling Reaction
Authors: Liu Li‐Cheng , Tzeng Yan‐Hsiang , Hung Cheng‐Hau , Lee Hon Man
Published: August 2020

Two series of electron‐rich metal (Ni and Pd) complexes, namely a pyridine‐coordinated tridentate NHC/amidate/phenoxy metal complex and a tetradentate complex bearing an extra pyridyl group, were synthesized. Two carbene moieties, imidazole‐based and benzimidazole‐based NHCs, were also incorporated into the ligand backbones. Seven of the new complexes were structurally characterized and comparative structural analysis revealed that the tetradentate complex with a flanking pyridyl side‐arm was less distorted, leading to chelation‐assisted stronger NHC coordination and hence a shorter metal–carbene bond. The catalytic activities of the two sets of palladium complexes for the Mizoroki–Heck coupling reaction were investigated. The comparative data showed that despite the higher thermal stability and the presence of the flanking hemilabile pyridyl side‐arm which provided unsaturation to the metal center, the catalytic performance was slightly inferior to that of the tridentate palladium complex with a “throw‐away” pyridine ligand. The tridentate palladium complex with the benzimidazole‐based NHC moiety was the most effective catalyst, allowing the utilization of a range of aryl chlorides including deactivated substrates with a low 0.2 mol‐% Pd loading in molten n‐tetrabutylammonium bromide.
Synthesis and Biological Evaluation of a Library of AGE‐Related Amino Acid Triazole Crosslinkers
Authors: Icik Esra , Jolly Anthony , Löffler Paul , Agelidis Nektarios , Bugdayci Bakiye , Altevogt Luca , Bilitewski Ursula , Baro Angelika , Laschat Sabine
Published: August 2020

Three N‐Boc‐protected amino acids, l‐serine, l‐aspartic, and l‐glutamic acid, were either converted into their methyl azidoalkanoates or various alkynes via Bestmann‐Ohira strategy or via reaction with propargylamine and propargyl bromide, respectively. The Cu‐catalyzed click reaction provided a library of amino acid based triazoles, which were further N‐methylated to triazolium iodides or deprotected and precipitated as free amino acid triazole dihydrochlorides. The biological properties of all derivatives were investigated by cytotoxicity assay (against L929 mouse fibroblasts) and broth microdilution method (E. coli ΔTolC and S. aureus). First results reveal complete inactivity for triazolium iodides with cell viabilities and microbial growths nearly 100 %, indicating them as possible analogs of advanced glycation endproducts (AGEs).
Synthetic Strategy Studies for a Concise Access to Functionalized Pyrano[4,3‐b]pyridin‐7‐ones: An Entry to Semi‐Rigid Analogs of Antihistamines
Authors: Beghennou Anissa , Passador Kevin , Passador Anthony , Corcé Vincent , Thorimbert Serge , Botuha Candice
Published: August 2020

We report short and efficient syntheses of polyfunctionalized 5,8‐dihydro‐7H‐pyrano[4,3‐b]pyridin‐7‐ones and 1,4‐dihydro‐3H‐pyrano[4,3‐c]pyridin‐3‐ones which can be considered as new aza analogs of 3‐isochromanones and as promising scaffolds for medicinal chemistry. Depending on the nature of the substituent, three different and complementary synthetic methodologies were used allowing the introduction of significant diversity in the substituent on the lactone ring of the pyranopyridinones. The selective α‐arylation of nitrile (SNAr) and tert‐butyl ester enolate (Pd catalyzed) followed by an acidic mediated lactonisation gives access to original C8‐functionalized pyrano[4,3‐b]pyridin‐7‐ones and a seleno‐mediated cyclization to C1‐functionalized pyrano[4,3‐c]pyridin‐3‐ones. We have also applied the outlined synthetic methodologies to the preparation of potential semi‐rigid analogs of antihistamines.
An assessment of the breastfeeding practices in Momo division, North West region of Cameroon
Authors: Nwachan Mirabelle Boh , Ejoh Richard Aba
Published: August 2020

The aim of this study was to assess maternal breastfeeding practices of children aged 0 to 24 months in Momo Division. It was also to identify the maternal sources of breastfeeding information and determine their impact on maternal breastfeeding decision in this division. Structured interviewer questionnaires were administered to 540 mothers. Among the 540 children included in the study, 77% of them received no prelacteal foods. Despite the fact that 47% of mothers initiated breastfeeding early, only 38% exclusively breastfed their infants for 6 months. Complementary feeding was introduced before the age of 6 months (59.5%). Few infants (2.4%) received complementary feeding later than 6 months. Only 3.1% of the children were breastfed up to two years or beyond. The most common source of breastfeeding information for the mothers is from the family, friends, and neighbors but information from healthcare professionals had the most influential effect on maternal breastfeeding decision. Although a few mothers in Momo Division followed the recommended breastfeeding practices, the breastfeeding practices in this division are generally suboptimal.
17‐Beta Hydroxysteroid Dehydrogenase 13 Deficiency Does Not Protect Mice From Obesogenic Diet Injury
Authors: Ma Yanling , Brown Philip M. , Lin Dennis D. , Ma Jing , Feng Dechun , Belyaeva Olga V. , Podszun Maren C. , Roszik Jason , Allen Joselyn N. , Umarova Regina , Kleiner David E. , Kedishvili Natalia Y. , Gavrilova Oksana , Gao Bin , Rotman Yaron
Published: August 2020

Background and Aims

17‐Beta hydroxysteroid dehydrogenase 13 (HSD17B13) is genetically associated with human nonalcoholic fatty liver disease (NAFLD). Inactivating mutations in HSD17B13 protect humans from NAFLD‐associated and alcohol‐associated liver injury, fibrosis, cirrhosis, and hepatocellular carcinoma, leading to clinical trials of anti‐HSD17B13 therapeutic agents in humans. We aimed to study the in vivo function of HSD17B13 using a mouse model.

Approach and Results

Single‐cell RNA‐sequencing and quantitative RT‐PCR data revealed that hepatocytes are the main HSD17B13‐expressing cells in mice and humans. We compared Hsd17b13 whole‐body knockout (KO) mice and wild‐type (WT) littermate controls fed regular chow (RC), a high‐fat diet (HFD), a Western diet (WD), or the National Institute on Alcohol Abuse and Alcoholism model of alcohol exposure. HFD and WD induced significant weight gain, hepatic steatosis, and inflammation. However, there was no difference between genotypes with regard to body weight, liver weight, hepatic triglycerides (TG), histological inflammatory scores, expression of inflammation‐related and fibrosis‐related genes, and hepatic retinoid levels. Compared to WT, KO mice on the HFD had hepatic enrichment of most cholesterol esters, monoglycerides, and certain sphingolipid species. Extended feeding with the WD for 10 months led to extensive liver injury, fibrosis, and hepatocellular carcinoma, with no difference between genotypes. Under alcohol exposure, KO and WT mice showed similar hepatic TG and liver enzyme levels. Interestingly, chow‐fed KO mice showed significantly higher body and liver weights compared to WT mice, while KO mice on obesogenic diets had a shift toward larger lipid droplets.

Conclusions

Extensive evaluation of Hsd17b13 deficiency in mice under several fatty liver–inducing dietary conditions did not reproduce the protective role of HSD17B13 loss‐of‐function mutants in human NAFLD. Moreover, mouse Hsd17b13 deficiency induces weight gain under RC. It is crucial to understand interspecies differences prior to leveraging HSD17B13 therapies.
Asymmetric interdependence between currency markets' volatilities across frequencies and time scales
Authors: Shahzad Syed Jawad Hussain , Arreola‐Hernandez Jose , Rahman Md Lutfur , Uddin Gazi Salah , Yahya Muhammad
Published: August 2020

We investigate the dynamics of interdependence between realized variances and realized semivariances of six major currencies across frequencies and time scales. The empirical results are derived, first, through constructing daily measures of realized variance and semivariance from a high frequency 5‐min interval data, and second, by fitting wavelet squared coherence and wavelet cohesion measure with time‐varying weights. The realized volatilities of the currencies and their cross‐currency influences are found to increase during the global financial crisis. The realized volatilities of the Euro, Swiss Franc, and British Pound are closely synchronized over the short‐term horizon. However, over the long‐run, the Euro, Swiss Franc, and Japanese Yen lead the realized volatilities of the British Pound, Australian Dollar, and Canadian Dollar. The synchronization structure of positive and negative realized volatilities indicates asymmetric dependence among the currencies across time horizons. We further observe strong positive (negative) cohesion among the realized volatilities over the medium‐ and long‐term horizons. Finally, significant counter cyclical comovements among the currencies are observed over the medium‐ and long‐term horizons. These findings have important implications for foreign exchange portfolio managers.
A two‐stage Bayesian network model for corporate bankruptcy prediction
Authors: Cao Yi , Liu Xiaoquan , Zhai Jia , Hua Shan
Published: August 2020

We develop a Bayesian network (LASSO‐BN) model for firm bankruptcy prediction. We select financial ratios via the Least Absolute Shrinkage Selection Operator (LASSO), establish the BN topology, and estimate model parameters. Our empirical results, based on 32,344 US firms from 1961–2018, show that the LASSO‐BN model outperforms most alternative methods except the deep neural network. Crucially, the model provides a clear interpretation of its internal functionality by describing the logic of how conditional default probabilities are obtained from selected variables. Thus our model represents a major step towards interpretable machine learning models with strong performance and is relevant to investors and policymakers.
A survey of cariology education in U.S. dental hygiene programs: The need for a core curriculum framework
Authors: McComas Martha J , Hurlbutt Michelle , Fontana Margherita
Published: August 2020

Objective

Dental hygienists play a key role in dental caries prevention and management. As the evidence of dental caries risk, prevention, and management becomes more complex, it is essential that dental hygiene (DH) programs have a strong cariology curriculum. This project aimed to assess current cariology content in U.S. DH programs, how content is taught, and interest in development/implementation of a common/core cariology curriculum framework.

Methods

Directors of 336 U.S. DH programs were invited to participate in a voluntary online survey using Qualtrics. The survey consisted of 41 items including demographics, details about the program's cariology content, and how it was delivered, and items related to a core cariology curriculum.

Results

The overall response rate used for analyses was 27.3%. Some findings include: 61.6% stated their program had a defined cariology curriculum, 35.2% did not have an individual cariology course, 61.5% had preclinical hands‐on experiences in cariology, 79.7% are teaching management strategies related to salivary gland hypofunction, 68.3% are teaching use of silver diamine fluoride (SDF), and 64.2% felt cariology was adequately being taught. Only 17.7% are teaching the International Caries Detection and Assessment System (ICDAS) system. 87.3% indicated support for developing a core curriculum framework for teaching cariology in DH programs.

Conclusions

This study indicated that, although DH programs reported that cariology concepts are being taught both didactically and clinically, discrepancies between concepts taught and the literature exist. Therefore, there is a need to create a more standardized curriculum framework for all U.S. DH programs.
Studies on the cross‐interaction between hIAPP and Aβ25–35 and the aggregation process in binary mixture by electrospray ionization‐ion mobility‐mass spectrometry
Authors: Pang Bo , Zhuang Xiaoyu , Bian Xinyu , Liu Shu , Liu Zhiqiang , Song Fengrui
Published: August 2020

A wealth of epidemiological evidence indicates a strong link between type 2 diabetes (T2D) and Alzheimer's disease (AD). The fiber deposition with cross‐β‐sheet structure formed by self‐aggregation and misfolding of amyloidogenic peptides is a common hallmark of both diseases. For the patients with T2D, the fibrils are mainly found in the islets of Langerhans that results from the accumulation of human islet amyloid polypeptide (hIAPP). The major component of aggregates located in the brain of AD patients is amyloid‐β (Aβ). Many biophysical and physiological properties are shared by hIAPP and Aβ, and both peptides show similar cytotoxic mechanisms. Therefore, it is meaningful to investigate the possible cross‐interactions of hIAPP and Aβ in both diseases. In this article, the segment 25–35 of Aβ was selected because Aβ25–35 was a core region in the process of amyloid formation and showed similar aggregation tendency and toxicity with full‐length Aβ. The electrospray ionization‐ion mobility‐mass spectrometry analysis and thioflavin T fluorescence kinetic analysis combined with transmission electron microscopy were used to explore the effects of the coexistence of Aβ25–35 and hIAPP on the self‐aggregation of both peptides and whether there was co‐assembly in fibrillation. The results indicated that the aggregation of hIAPP and Aβ25–35 had two nucleation stages in the binary mixtures. hIAPP and Aβ25–35 had a high binding affinity and a series of hetero‐oligomers formed in the mixtures of hIAPP and Aβ25–35 in the early stage. The cross‐reaction between hIAPP monomers and Aβ25–35 monomers as well as a little of oligomers during primary nucleation stage could accelerate the aggregation of Aβ25–35. However, owing to the obvious difference in aggregation ability between hIAPP and Aβ25–35, this cross‐interaction had no significant impact on the self‐assembly of hIAPP. Our study may offer a better understanding for exploring the molecular mechanism of the association between AD and T2D observed in clinical and epidemiological studies and developing therapeutic strategies against amyloid diseases.
Sequential Protocol Biopsies Post–Liver Transplant From Donors With Moderate Macrosteatosis: What Happens to the Fat?
Authors: Croome Kristopher P. , Livingston David , Croome Sarah , Keaveny Andrew P. , Taner C. Burcin , Nakhleh Raouf
Published: August 2020

The number of steatotic deceased donor livers encountered has continued to rise as a result of the obesity epidemic. Little is known about the histological characteristics of moderately macrosteatotic livers over time in the recipient following liver transplantation (LT). All recipients undergoing LT at Mayo Clinic Florida with donor livers with moderate macrosteatosis (30%‐60%) from 2000‐2017 were identified (n = 96). Routine protocol liver biopsies were performed 1‐week and 6‐months following LT. All liver donor and protocol biopsies were read by an experienced liver pathologist. Of the 96 moderate macrosteatosis LTs, 70 recipients had post‐LT protocol liver biopsies available and comprised the study cohort. Median donor allograft macrosteatosis at the time of transplant was 33% (IQR, 30%‐40%) compared with 0% (IQR, 0%‐2%) at 1‐week (P < 0.001) and 0% (IQR, 0%‐0%) at 6‐months (P < 0.001) following LT. Biopsies at 1‐week post‐LT displayed pericentral necrosis in 57.1% of recipients and lipopeliosis in 34.3% of recipients. In the 6‐month post‐LT biopsies, cholestasis was seen in 3 (4.3%) of the recipients, whereas grade 2 fibrosis was seen in 6 recipients (8.6%). Graft survival at 5 years in the present cohort was 74.0%. Moderate macrosteatosis (30%‐60%) in the donor allograft demonstrates complete reversal on liver biopsies performed as early as 7 days following LT and remains absent at 6‐months following LT. Both pericentral necrosis and lipopeliosis are common features on day 7 biopsies. Despite these encouraging findings, the perioperative risks of using these livers (postreperfusion cardiac arrest and primary nonfunction) should not be understated. Long‐term graft survival is acceptable in patients who are able to overcome the immediate perioperative risk of using moderately steatotic donor livers.
Vitamin A Corrects Tissue Deficits in Diet‐Induced Obese Mice and Reduces Influenza Infection After Vaccination and Challenge
Authors: Penkert Rhiannon R. , Cortez Valerie , Karlsson Erik A. , Livingston Brandi , Surman Sherri L. , Li Yaqi , Catharine Ross A. , Schultz‐Cherry Stacey , Hurwitz Julia L.
Published: August 2020

Objective

Individuals with obesity suffer from an increased susceptibility to severe respiratory viral infections and respond poorly to vaccinations, making it imperative to identify interventions. Recent evidence suggesting that obesity leads to tissue‐specific vitamin A deficiency led to an investigation of whether high‐dose oral vitamin A, a treatment used for remediating vitamin A deficiency in developing countries, could correct obesity‐associated tissue deficits.

Methods

Adult C57BL/6 diet‐induced obese mice were supplemented with vitamin A for 4 weeks. A subset of mice were then vaccinated with inactivated influenza virus and challenged. Following supplementation, tissue vitamin A levels, lung immune cell composition, blood inflammatory cytokines, antibody responses, and viral clearance were evaluated.

Results

Supplementation significantly improved vitamin A levels in lung and adipose tissues in diet‐induced obese mice. Additionally, supplementation decreased inflammatory cytokines in the blood and altered the lung immune environment. Importantly, vaccinated, vitamin A–treated diet‐induced obese mice exhibited improved antibody responses and significantly reduced viral loads post challenge compared with PBS‐treated mice.

Conclusions

Results demonstrate a low‐cost intervention that may correct vitamin A tissue deficits and help control respiratory viral infections in individuals with obesity.
Public Affairs: A field's maturation from 2000+ to 2030
Authors: Fleisher Craig , McGrath Conor
Published: August 2020

This paper explores the development of the field of public affairs (PA) through the observations, research and experiences of two of its most cited scholars, deputy editors, and longtime contributors to the Journal of Public Affairs. We examine how PA and its practitioners have moved non‐linearly from 2000+ PA, to Public Affairs 2.0, toward a still evolving model of practice. Three areas of practice are explored in depth, including (a) how the function is managed, (b) its communication activity, and (c) how it supports organizations in interacting and engaging with stakeholders and issues. Finally, four alternative futures are laid out as possible paths along which the function may evolve as it moves forward to its next decade's end in 2030.
The effects of participants’ sex and the facial trustworthiness of proposers on third‐party decision‐making in a dictator game
Authors: Shang Junchen , Li Yutong
Published: August 2020

This study investigated the effects of participants’ sex and the facial trustworthiness of proposers on third‐party decision‐making. Sixty‐three participants participated in this study. The participant's task was to act as an interest‐free third party who observed a dictator game in which proposers with either trustworthy or untrustworthy faces made offers to recipients, to evaluate the reasonableness of the offers, and to express their intentions to punish the proposers. The results showed that offers from trustworthy proposers were rated as more reasonable than offers from untrustworthy proposers. Similarly, the participants were more likely to punish untrustworthy proposers than trustworthy proposers. In addition, there was a trend that male participants punished proposers more severely than female participants when proposers made unfair offers. These results demonstrate that an individual's facial trustworthiness affects other people's judgment and decisions.
Psychological aspects of gestational cancer: A systematic review
Authors: Leung Vivien , Bryant Christina , Stafford Lesley
Published: August 2020

Objective

Gestational cancer is defined as any type of cancer diagnosed during pregnancy or within 12 months of delivery. To date, existing studies on the psychological aspects of this type of cancer have not been evaluated for methodological quality. The aim of this systematic review was to identify the psychological aspects of gestational cancer.

Methods

Five journal databases were searched to identify peer‐reviewed articles reporting upon the psychological aspects of women with gestational cancer. Studies published from journal inception to December 2019 were included, and Preferred Reporting Items for Systematic Reviews and Meta‐analyses (PRISMA) guidelines were followed. The Mixed‐Method Appraisal Bias Tool was used, to assess the methodological quality of the studies. A narrative description was developed for the psychological outcomes reported in quantitative studies. Qualitative data was synthesized using thematic analysis.

Results

Five papers were eligible for inclusion (two qualitative and three quantitative studies). Factors that contributed to women's psychological distress during gestational cancer included disease characteristics, sociodemographic factors, the baby's health, pregnancy‐related factors and cognitive emotion regulation. Four main themes emerged from the qualitative studies; concerns about the baby's health, lost opportunities, “not fitting in,” and healthcare decision‐making.

Conclusions

These findings suggest that (a) women with gestational cancer experience psychological distress that is associated with concerns about their babies' health, and (b) their healthcare experiences are affected by communication within multidisciplinary care teams.
Carnosic acid ameliorates depressive‐like symptoms along with the modulation of FGF9 in the hippocampus of middle carotid artery occlusion‐induced Sprague Dawley rats
Authors: Azhar Mudassar , Zeng Guirong , Ahmed Ayaz , Dar Farooq Ahsana , Choudhary Muhammad I. , De‐Jiang Jiang , Liu Xinmin
Published: August 2020

The increased survival rate of stroke patients has led to the higher incidences of post‐stroke depression. Carnosic acid has the ability to cross blood brain barrier with good neuro‐modulatory actions. Recently, inclined level of fibroblast growth factor 9 (FGF9) in the postmortem brain of the depressed patients was noted. Therefore, in the present study, the effect of carnosic acid on post‐stroke depression‐like behavior, and the expression of FGF9 were evaluated. After 3 weeks of middle carotid artery occlusion in Sprague Dawley rats, carnosic acid (20 and 40 mg/kg) was administered for 2 weeks. Sucrose preference test, forced swimming test, and open field test were performed and hippocampi were analyzed for FGF9 and FGFR‐3. In comparison to post‐stroke depressed rats, carnosic acid increased the sucrose preference, and reduced the immobility time of the rats by ~2×. The speed and distance‐covered were also increased. At 40 mg/kg, FGF9 was reduced by ~3× while FGFR‐3/Actin was increased by ~1.5×. Altogether results suggest anti‐depressant‐like activity of carnosic acid in post‐stroke depressed rats with decreased expression of hippocampal FGF9.
Forward and backward risk assessment throughout a system life cycle using dynamic Bayesian networks: A case in a petroleum refinery
Authors: Ashrafi Maryam
Published: August 2020

In this paper, risk modeling was conducted based on the defined risk elements of a conceptual risk framework. This model allows for the estimation of a variety of risks, including human error probability, operational risk, financial risk, technological risk, commercial risk, health risk, and social and environmental risks. Bayesian network (BN) structure learning techniques were used to determine the relationships among the model variables. By solving a bi‐objective optimization problem applying the genetic algorithm (GA) with the Pareto ranking approach, the network structure was learned. Then, risk modeling was performed for a petroleum refinery focusing on HydroDeSulfurization (HDS) technology throughout its life cycle. To extend the model horizontally and make it possible to evaluate the risk trend throughout the technology life cycle, we developed a dynamic Bayesian network (DBN) with three‐time slices. A two‐way forward and backward approach was used to analyze the model. The model validation was performed by applying the leave‐one‐out cross‐validation method.
Performance optimization of an ion funnel driven by novel radiofrequency waveforms
Authors: Zhou Shao , Tang Keqi , Wu Huanming , Xie Zhijun , Wu Yong , Yu Jiancheng
Published: August 2020

Rationale

In mass spectrometry, ion transmission is usually achieved by driving an ion funnel with a reversed sine wave radiofrequency. However, the mass range of this conventional ion funnel is limited. In order to overcome this limitation, and to improve the transmission efficiency of the ion funnel, we explore the use of different radiofrequency waveforms for different m/z ranges.

Methods

Right triangle, sawtooth, and variable phase sine (VPS) waves are used in different m/z ranges to improve ion transmission efficiency. We use SIMION‐based numerics to simulate their potential field distributions and ion flight trajectories. We compare transmission and focusing performances with those of a conventional ion funnel.

Results

Ions with high m/z values require a larger potential gradient to limit their flight trajectory. Right triangle waves can quickly adjust electrode potential through a step change. The equipotential line distribution of VPS waves is wider than that of a sine wave which improves focusing performance. At the same time, the local ion trap effect at the outlet of the ion funnel is improved because of the “snake potential”. The maximum effective potential of the sawtooth wave is smaller than that of the sine wave, which is suitable for low m/z ion transmission.

Conclusions

Sawtooth and VPS waves may improve the transmission performance of the ion funnel in the low m/z regime whereas right triangle waves may improve the transmission performance in the high m/z regime.
Automatic three‐dimensional mapping for tree diameter measurements in inventory operations
Authors: Tremblay Jean‐François , Béland Martin , Gagnon Richard , Pomerleau François , Giguère Philippe
Published: August 2020

Forestry is a major industry in many parts of the world, yet this potential domain of application area has been overlooked by the robotics community. For instance, forest inventory, a cornerstone of efficient and sustainable forestry, is still traditionally performed manually by qualified professionals. The lack of automation in this particular task, consisting chiefly of measuring tree attributes, limits its speed, and, therefore, the area that can be economically covered. To this effect, we propose to use recent advancements in three‐dimensional mapping approaches in forests to automatically measure tree diameters from mobile robot observations. While previous studies showed the potential for such technology, they lacked a rigorous analysis of diameter estimation methods in challenging and large‐scale forest environments. Here, we validated multiple diameter estimation methods, including two novel ones, in a new publicly‐available dataset which includes four different forest sites, 11 trajectories, totaling 1458 tree observations, and 14,000 m2. From our extensive validation, we concluded that our mapping method is usable in the context of automated forest inventory, with our best diameter estimation method yielding a root mean square error of 3.45 cm for our whole dataset and 2.04 cm in ideal conditions consisting of mature forest with well‐spaced trees. Furthermore, we release this dataset to the public (https://norlab.ulaval.ca/research/montmorencydataset), to spur further research in robotic forest inventories. Finally, stemming from this large‐scale experiment, we provide recommendations for future deployments of mobile robots in a forestry context.
Directing Group Assisted Unsymmetrical Multiple Functionalization of Arene C−H Bonds
Authors: Ghosh Koushik , Rit Raja K. , Shankar Majji , Mukherjee Kallol , Sahoo Akhila K.
Published: August 2020

Multiple C−H bond functionalizations promptly install diverse groups on the molecular framework and consequently fabricate complex molecular entities. This review briefly surveys the conceptual development of directing group assisted unsymmetrical multiple functionalization of arene C(sp2)−H bonds, which is exceedingly appealing and highly important.
Polarized U.S. publics, Pope Francis, and climate change: Reviewing the studies and data collected around the 2015 Papal Encyclical
Authors: Landrum Asheley R. , Vasquez Rosalynn
Published: August 2020

As soon as it was clear that Pope Francis's 2015 Encyclical, Laudato Si’: On Care for Our Common Home, would discuss, among other issues, the moral imperative to address global climate change, U.S. scholars and research institutions rushed to collect data surrounding its release. These groups aimed to determine whether there would be a “Francis Effect,” in which U.S. Conservatives (and Conservative Catholics in particular) would show greater concern about the negative effects of global climate change. Here, we first provide context by discussing the history of political polarization in the U.S. over global climate change. Then, we review the published literature and publicly available data that aimed to examine potential influences of Laudato Si’ on people's climate change attitudes. Taken together, the available scholarship provides strong evidence that U.S. publics were differentially responsive to the Pope's messaging (with political Conservatives expressing less climate change concern and viewing Pope Francis as less credible), but there is correlational evidence of an overall “Francis Effect.” U.S. population data collected following the encyclical's release show small, potentially temporary, increases in perceptions of papal credibility, climate change concern, and the perspective that global climate change is a moral issue.

This article is categorized under:

Trans‐Disciplinary Perspectives > Humanities and the Creative Arts

Perceptions, Behavior, and Communication of Climate Change > Communication
HPS Accelerated Spectral Solvers for Time Dependent Problems: Part II, Numerical Experiments
Authors: Babb Tracy , Martinsson Per-Gunnar , Appelö Daniel
Published: August 2020

This is the second of a two part series describing a spectrally accurate “Hierarchial Poincaré–Steklov (HPS)” solver for time-dependent problems with a leading order elliptic spatial operator. In this second part we provide numerical experiments and in the first part we provide a detailed description of the method.
Discrete Equivalence of Adjoint Neumann–Dirichlet div-grad and grad-div Equations in Curvilinear 3D Domains
Authors: Zhang Yi , Jain Varun , Palha Artur , Gerritsma Marc
Published: August 2020

In this paper, we will show that the equivalence of a div-grad Neumann problem and a grad-div Dirichlet problem can be preserved at the discrete level in 3-dimensional curvilinear domains if algebraic dual polynomial representations are employed. These representations will be introduced. Proof of the equivalence at the discrete level follows from the construction of the algebraic dual representations. A 3-dimensional test problem in curvilinear coordinates will illustrate this approach.
Spectral Analysis of Isogeometric Discretizations of 2D Curl-Div Problems with General Geometry
Authors: Mazza Mariarosa , Manni Carla , Speleers Hendrik
Published: August 2020

We study the spectral distribution of matrices arising in Galerkin isogeometric methods for weighted curl-div operators defined on a general planar domain. It can be compactly described by means of a spectral symbol which depends on the characteristic parameters of the problem: the weight parameters, the basic curl and div operators, the degree of the B-spline approximation, and the geometry map used to represent the computational domain.
Performance of Preconditioners for Large-Scale Simulations Using Nek5000
Authors: Offermans N. , Peplinski A. , Marin O. , Merzari E. , Schlatter P.
Published: August 2020

BoomerAMG, the algebraic multigrid solver from the hypre library, is used to solve a coarse grid problem which is part of the preconditioning strategy for the pressure equation arising from the numerical resolution of the Navier–Stokes equations. A set of optimal parameters for the setup phase is determined and used for selected strong scaling tests on two different supercomputers, namely Mira and Hazel Hen, on up to 131, 072 compute cores. The results are compared to an existing algebraic multigrid solver, designed specifically for the coarse grid problem at hand. It is shown that the BoomerAMG solver is fast and scalable, and that performance depends on the computer architecture. The test cases considered are the turbulent flow past a NACA4412 airfoil and the turbulent flow inside wire-tapped pin bundles.
High-Order Propagation of Jet Noise on a Tetrahedral Mesh Using Large Eddy Simulation Sources
Authors: Moratilla-Vega M. A. , Saini V. , Xia H. , Page G. J.
Published: August 2020

Jet noise is an important area of research in commercial aviation due to its high contribution to the overall noise generated by an aircraft. Conventionally, CFD combined with surface integral methods is used to study jet noise because of its low cost. However, it is not always trivial to define integration surfaces around complex geometries. This study employs a different two-step approach that can handle complex geometries. It combines a large-eddy simulation (LES) to obtain the acoustic sources from the flow field, and an acoustic perturbation equations (APE) solver to propagate the sound to the far field. The LES is performed with an industrial 2nd-order finite volume solver. The APE code is a high-order discontinuous Galerkin (DG) spectral/hp solver of the Nektar+ + framework. The APE solver is validated on a canonical test case. A study on different polynomial expansion orders and meshes is further performed to estimate the mesh size for noise propagation in the high-order spectral/hp DG context. Finally, a three-dimensional jet noise case (Re = 10, 000 and Mach =  0.9) is simulated using unstructured tetrahedral mesh for the APE solver and improved noise results for high frequencies are obtained. The results demonstrate that the present approach is capable of predicting noise in complex geometry scenarios, such as installed jets under the aircraft wings.
Dynamical Degree Adaptivity for DG-LES Models
Authors: Tugnoli M. , Abbà A. , Bonaventura L.
Published: August 2020

We present a first dynamically adaptive test of a physically based p-refinement criterion for DG-LES approaches recently proposed by the authors and applied so far to static adaptation only. The results, albeit preliminary, are encouraging and show that, also in the dynamically adaptive case, the proposed criterion allows to reduce significantly the number of degrees of freedom employed in a LES simulation without a major loss of accuracy.
A Novel Eighth-Order Diffusive Scheme for Unstructured Polyhedral Grids Using the Weighted Least-Squares Method
Authors: Albuquerque Duarte M.  S. , Vasconcelos Artur G.  R. , Pereira Jose C.  F.
Published: August 2020

A new very high-order scheme for elliptic operators in unstructured polyhedral grids is proposed, based on the weighted least-squares technique. It can go up to eighth-order accuracy and uses face centred reconstructions for the integration of the diffusive fluxes. In order to maintain the local high-order, a new stencil extension algorithm is applied near the boundaries of the computational domain. The algorithm maintains the intended accuracy order independently of the grid type or the perturbation imposed to the grid. Concerning Neumann boundary conditions, a new approach is proposed that is better than the classic one used in schemes based in weighted least-squares.
Explicit Polynomial Trefftz-DG Method for Space-Time Elasto-Acoustics
Authors: Barucq H. , Calandra H. , Diaz J. , Shishenina E.
Published: August 2020

The popularity of Discontinuous Galerkin (DG) methods has increased during the last years in particular with easy access to high performance computers. DG approximations gather different interesting features such as high-order accuracy, hp-adaptivity, easy parallelization but have the disadvantage of requiring a high number of degrees of freedom. DG methods are thus known to use higher computational burden and herein, we investigate the possibility of reducing it by employing an appropriate set of basis functions. We then solve the first-order elasto-acoustic wave problem in a space-time Trefftz-DG space. We use a space-time mesh with space-time polynomial basis functions. The space-time variational formulation reduces then to surface integrals set only on the skeleton of the mesh. However, the solution of the problem requires inverting a sparse matrix whose size could be very large when addressing realistic geophysical problems. A direct implementation of the Trefftz-DG formulation creates thus extra cost as compared to that of standard DG formulation where the space and time integrations are performed one by one after another. We then propose an approximate formulation which amounts to inverting the block-diagonal component of the Trefftz-DG matrix. We then end up with an explicit representation of the wavefield which is stable provided a CFL condition is satisfied.
New Preconditioners for Semi-linear PDE-Constrained Optimal Control in Annular Geometries
Authors: Christiansen Lasse Hjuler , Jørgensen John Bagterp
Published: August 2020

Optimization problems that are constrained by partial differential equations (PDEs) often pose significant computational challenges to black-box optimization algorithms. This is particular the case for non-linear problems that typically rely on multi-query solution of large-scale linearized subsystems. In this regard, this paper proposes a customized solution strategy for a class of semi-linear PDE-constrained optimization problems in annular domains. At its core, the strategy relies on a collection of new Poisson-like preconditioners that are based on boundary-adapted spectral Galerkin methods. The preconditioners are matrix-free and scale linearly with the problem size. To establish proof-of-concept, a case study solves a benchmark control problem for various model parameters. The results show that the preconditioners lead to fast solution strategies that outperform conventional direct approaches.
Model Reduction by Separation of Variables: A Comparison Between Hierarchical Model Reduction and Proper Generalized Decomposition
Authors: Perotto Simona , Carlino Michele Giuliano , Ballarin Francesco
Published: August 2020

Hierarchical Model reduction and Proper Generalized Decomposition both exploit separation of variables to perform a model reduction. After setting the basics, we exemplify these techniques on some standard elliptic problems to highlight pros and cons of the two procedures, both from a methodological and a numerical viewpoint.
A First Meshless Approach to Simulation of the Elastic Behaviour of the Diaphragm
Authors: Cacciani Nicola , Larsson Elisabeth , Lauro Alberto , Meggiolaro Marco , Scatto Alessio , Tominec Igor , Villard Pierre-Frédéric
Published: August 2020

The diaphragm is the main muscle that regulates the human respiration. When a patient is put under controlled mechanical ventilation, the diaphragm is exposed to forces that damage the muscle function. The long-term aim of this work is to study this process through numerical simulation. Here, we take the first steps in developing a meshless numerical simulation method for the diaphragm. We describe how the diaphragm geometry can be extracted from medical images, and then be used in the meshless method. We show that for a thin volume like the diaphragm, the resolution of the thin dimension is highly relevant for the accuracy of the approximation, and we also show that the method converges for a test case, where realistic displacements are used as boundary conditions.
Multiwavelet Troubled-Cell Indication: A Comparison of Utilizing Theory Versus Outlier Detection
Authors: Vuik Mathea J.
Published: August 2020

This article discusses the effectiveness of the theoretical detection of troubled cells using multiwavelet approaches for the discontinuous Galerkin method and compares them with a statistical approach that uses boxplots. This is an important study in order to understand in which regime these tools are valid. Troubled cells are regions in the domain where a shock or discontinuity has developed, leading to spurious oscillations in the numerical approximation. One option for improving the numerical treatment near these artifacts is through the application of a limiter. The elements where such treatment is necessary are referred to as troubled cells. In this article, a new multiwavelet troubled-cell indicator is formed using the cancelation property (Dahmen, J Comput Appl Math 128:133–185, 2001) and the derived thresholding technique (Gerhard et al., J Sci Comput 62:25–52, 2015). We show that the new detector based on the cancelation property is very accurate in asymptotic regimes (very fine meshes). For coarser meshes, it might be better to use a different indicator, such as the ones that were designed by Vuik and Ryan (J Comput Phys 270:138–160, 2014; SIAM J Sci Comput 38:A84–A104, 2016).
An Anisotropic p-Adaptation Multigrid Scheme for Discontinuous Galerkin Methods
Authors: Rueda-Ramírez Andrés M. , Rubio Gonzalo , Ferrer Esteban , Valero Eusebio
Published: August 2020

In this work, we present an anisotropic p-adaptation multigrid algorithm for discontinuous Galerkin methods for steady-state problems that uses a p-multigrid scheme both as a solver and as an anisotropic error estimator. To achieve this, we develop a new anisotropic truncation error estimator based on the tau-estimation method, that can be evaluated inside the multigrid cycle with a negligible extra cost. The new error estimator is cheaper to evaluate and more accurate than previous versions of the tau-estimation procedure. In our technique, a non-converged solution in a reference mesh is used to estimate the truncation error with the multigrid scheme for different combinations of polynomial orders in different directions inside every element, and the mesh is adapted accordingly to target a desired truncation error threshold. The accuracy and computational cost of the proposed p-anisotropic adaptation algorithm is tested for the steady viscous flow past a NACA0012 airfoil. A speed-up of 16 can be achieved in the proposed numerical example compared with the uniformly refined simulation without multigrid.
Non-conforming Elements in Nek5000: Pressure Preconditioning and Parallel Performance
Authors: Peplinski A. , Offermans N. , Fischer P. F. , Schlatter P.
Published: August 2020

Adaptive mesh refinement (AMR) is an important component of modern numerical solvers, as it allows to control the computational error during the simulation, increasing the reliability of the numerical modelling and giving the possibility to study a broad range of different phenomena even without knowing the physics a priori. In this work we present selected aspects of the implementation and parallel performance of a newh-type AMR framework developed for the high-order CFD solverNek5000; the development was done within the ExaFLOW EU project. We utilise in this case the natural domain decomposition inherent to the spectral element method (SEM), which constitutes the main source of parallelism and provides meshing flexibility that can be exploited in AMR. We use standard libraries for parallel mesh management (p4est) and partitioning (ParMetis) and focus on developing efficient preconditioners for the pressure problem solved on non-conforming meshes. Two different approaches are considered: an additive overlapping Schwarz and a hybrid Schwarz-multigrid method. The strong scaling is shown on the example of the simulation of the turbulent flow around a NACA4412 wing section atRe = 200, 000.