bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparing Conventional and Machine‐Learning Approaches to Risk Assessment in Domestic Abuse Cases
Authors: Grogger Jeffrey , Gupta Sean , Ivandic Ria , Kirchmaier Tom
Published: March 2021

We compare predictions from a conventional protocol‐based approach to risk assessment with those based on a machine‐learning approach. We first show that the conventional predictions are less accurate than, and have similar rates of negative prediction error as, a simple Bayes classifier that makes use of only the base failure rate. Machine‐learning algorithms based on the underlying risk assessment questionnaire do better under the assumption that negative prediction errors are more costly than positive prediction errors. Machine‐learning models based on two‐year criminal histories do even better. Indeed, adding the protocol‐based features to the criminal histories adds little to the predictive adequacy of the model. We suggest using the predictions based on criminal histories to prioritize incoming calls for service, and devising a more sensitive instrument to distinguish true from false positives that result from this initial screening.
Design‐based stereological study of the guinea‐pig (Cavia porcellus) cerebellum
Authors: De Silva Margherita , Sadeghinezhad Javad , Nyengaard Jens R. , Aghabalazadeh Asl Mahdi , Saeidi Ava , De Sordi Nadia , Chiocchetti Roberto , Grandis Annamaria
Published: March 2021

Guinea pigs have proved useful as experimental animal models in studying cerebellar anatomical and structural alterations in human neurological disease; however, they are also currently acquiring increasing veterinary interest as companion animals. The morphometric features of the normal cerebellum in guinea pigs have not been previously investigated using stereology. The objective of the present work was to establish normal volumetric and quantitative stereological parameters for cerebellar tissues in guinea pigs, by means of unbiased design‐based stereology. Cerebellar total volume, gray and white matter volume fractions, molecular and granular layers volume fractions, cerebellar surface area, Purkinje cellular and nuclear volumes, and the Purkinje cell total count were stereologically estimated. For this purpose, cerebellar hemispheres from six adult male guinea pigs were employed. Isotropic, uniform random sections were obtained by applying the orientator method, and subsequently processed for light microscopy. The cerebellar total volume, the white and grey matter volume fractions, and the molecular and granular layer volumes were estimated using the Cavalieri's principle and the point counting system. The cerebellar surface area was estimated through the use of test lines; Purkinje cellular and nuclear volumes were analysed using the nucleator technique, whereas the Purkinje cell total count was obtained by means of the optical disector technique. The mean ± standard deviation total volume of a guinea‐pig cerebellar hemisphere was 0.11 ± 0.01 cm3. The mean volumetric proportions occupied by the gray and white matters were, respectively, 78.0 ± 2.6% and 22.0 ± 2.6%, whereas their mean absolute volumes were found to be 0.21 ± 0.02 cm3 and 0.059 ± 0.006 cm3. The volumes of the molecular and granular layers were estimated at 112.4 ± 20.6 mm3 and 104.4 ± 7.3 mm3, whereas their mean thicknesses were calculated to be 0.184 ± 0.020 mm and 0.17 ± 0.02 mm. The molecular and granular layers accounted for 40.7 ± 3.9% and 37.4 ± 1.8% of total cerebellar volume respectively. The surface area of the cerebellum measured 611.4 ± 96.8 mm2. Purkinje cells with a cellular volume of 3210.1 µm3 and with a nuclear volume of 470.9 µm3 had a higher incidence of occurrence. The mean total number of Purkinje cells for a cerebellar hemisphere was calculated to be 253,090 ± 34,754. The morphometric data emerging from the present study provide a set of reference data which might prove valuable as basic anatomical contribution for practical applications in veterinary neurology.
The Distinctive Domain of the Sharing Economy: Definitions, Value Creation, and Implications for Research
Authors: Markman Gideon D. , Lieberman Marvin , Leiblein Michael , Wei Li‐Qun , Wang Yonggui
Published: March 2021

The objective of this special issue is to expand our understanding of the sharing economy. To this end, we consider how the sharing economy can be demarcated and provide a definition that distinguishes the sharing economy from other forms of economic organization and resource orchestration. Specifically, the sharing economy entails multisided platforms that facilitate user access to – rather than ownership of – assets that are rivalrous in their use, and that are not owned by said platforms. Using this definition, we identify and show how the sharing economy creates and distributes economic value among participants and we summarize the six articles in the special issue. All in all, this introduction and the six studies clarify how the sharing economy and its three main constituencies – sharing platforms, asset providers, and users – reduce commercial friction by increasing trust, facilitating interaction, easing resource access and orchestration, and maximizing ecosystem‐wide value.
Biopsy‐proven liver cirrhosis in young children: A 10‐year cohort study
Authors: Dong Yi , Li Aiqin , Zhu Shishu , Chen Weibin , Li Meina , Zhao Pan
Published: March 2021

Young children with liver cirrhosis have a significantly high risk of mortality. However, there are few studies regarding early childhood‐onset cirrhosis. This study aims to explore the causes, clinical findings and prognosis of biopsy‐proven cirrhosis in infants, toddlers and preschoolers. We enroled young children with biopsy‐proven cirrhosis from January 2010. Till January 2020, the study has been going on for 10 years. A total of 139 cirrhotic children were enrolled, including 87 boys and 52 girls. The median age at initially histological diagnosis of cirrhosis was 2 years old (range: 1 month–6 years). Sixty‐two patients reported yellowish discoloration of sclera and/or skin as an initial symptom. Ninety‐three patients had definite aetiologies while 46 had indeterminate causes. Among the confirmed cases, 31 had hepatitis B virus (HBV) infection, accounting for 33.3%. Subsequently, glycogen storage disease was diagnosed in 16 cases and Wilson disease in 14 cases. In these patients with HBV infection, nine finally achieved hepatitis B surface antigen (HBsAg) loss (29.0%) after effective antiviral therapy during the follow‐up. Logistic regression revealed that baseline alanine aminotransferase (odds ratio 1.008, p = 0.028) was the independent predictor of HBsAg loss. Furthermore, one patient who underwent second biopsies showed histological reverse. HBV infection is an important cause of paediatric cirrhosis in our study. The pathogenesis of HBV‐related cirrhosis in early childhood deserves further studies.
Oral and topical extra‐label administration of fipronil to laying hens: Assessment of the egg residue patterns
Authors: Canton Lucila , Canton Candela , Ceballos Laura , Domínguez Paula , Rodríguez José , Lanusse Carlos , Alvarez Luis , Moreno Laura
Published: March 2021

This experimental work reproduces the fipronil extra‐label administration performed by producers in laying hens. The scientific goal was to characterize the residual concentrations in eggs from treated hens and suggest the withdrawal periods that should be respected to avoid risk for consumers. Thirty‐four laying hens were allocated into two groups: Group A was treated with fipronil in feed, two single doses of 1 mg kg−1 day−1; Group B was administered a single dose of 1 mg kg−1 by the topical route. Fipronil egg residues were quantified by HPLC‐MS/MS. Fipronil and its sulphone metabolite (fipronil‐SO2) were measured in egg after both treatments. The highest egg residual profile was always for fipronil‐SO2. Mean maximum egg concentrations (Cmax) of 228.5 ± 79.8 ng/g (fipronil) and 1,849 ± 867 ng/g (fipronil‐SO2) were found after fipronil administration in feed. The lowest residual levels were quantified after the topical treatment with Cmax of 27.1 ± 4.9 and 163 ± 26 ng/g for fipronil and fipronil‐SO2. Mean fipronil marker residues and established MRLs allowed calculating the withdrawal periods, the shortest being 74 days after topical administration. Such a long withdrawal period is difficult to meet in egg production systems. Thus, the extra‐label use of fipronil in laying hens should not be recommended under any circumstances.
Facilitation in plants shifts along a recovery gradient induced by long‐term overgrazing in a temperate steppe community
Authors: Wang Xinting , Jiang Chao , Chi Yanyan , Tai Yang , Liang Cunzhu , Yonghong Li Frank , Hou Yali
Published: March 2021

Questions

Plant facilitation often dominates over competition in stressful environments. However, to our knowledge few studies have examined plant facilitation within the context of herbivore pressure. Herbivory‐induced is a classic example of indirect facilitation. For example, in the temperate steppe region of Inner Mongolia, China, the intensive grazing by domestic animals has induced widespread grassland degradation. Here, we ask whether such long‐term overgrazing leads to facilitation in plants.

Location

Xilingol steppe region, Inner Mongolia, China.

Methods

We examined the spatial structure of three dominant plant species, including two species that are palatable to sheep (Leymus chinensisandAgropyron michnoi) and one that is unpalatable (Stipa grandis). We examined whether the spatial aggregation of these three species provided evidence for facilitation by comparing their spatial patterns along a recovery gradient: high grazing pressure (HG), an eight‐years grazing exclusion (early‐stage recovery from grazing; ER), and a 21‐years grazing exclusion (late‐stage recovery; LR). To accomplish this, we used the bivariate pair‐correlation function,g12(r), to assess the spatial association between unpalatable and palatable species. A positive spatial association indicates that facilitation dominates over competition (or dispersal limitation, habitat heterogeneity). We used a null model to assess the significance of spatial associations. Furthermore, we evaluated intraspecific spatial aggregation with theg11(r) by combining to three null models at fine spatial scales.

Results

The spatial association between palatable and unpalatable species suggests a hump‐shaped relationship along the gradient of the grazing exclusion time. Specifically,Leymus chinensisandStipa grandisshowed a neutral, positive and negative association across the three stages of natural recovery from 21 years of grazing exclusion to current grazing. Similarly,Agropyron michnoiandStipa grandisshowed a negative, very positive and positive spatial association along the same gradient. Moreover, intraspecific spatial aggregation was higher in the current grazing treatment than in the grazing exclusion treatment. This was particularly true at the finest spatial scales (i.e., <0.2 m).

Conclusions

Our results suggest that facilitation between and within species along the recovery gradient in steppe communities is related to herbivore pressure induced by long‐term overgrazing. First, we observed no evidence of indirect facilitation between species in current grazing treatment, while direct facilitation between plant species appears strongest at early stages of natural recovery along the gradient of the grazing exclusion time. Moreover, we observed indirect intraspecific facilitation dominated in the current grazing treatment, especially at small scales across the same gradient.
Amino acid abundances and compositions in iron and stony‐iron meteorites
Authors: Elsila Jamie E. , Johnson Natasha M. , Glavin Daniel P. , Aponte José C. , Dworkin Jason P.
Published: March 2021

The organic compositions of carbonaceous chondrite meteorites have been extensively studied; however, there have been fewer reports of other meteorite classes, and almost none from iron meteorites, which contain much less carbon than carbonaceous chondrites but make up ~4% of observed meteorite falls. Here, we report the bulk amino acid content of three iron meteorites (Campo del Cielo, IAB; Canyon Diablo, IAB; and Cape York, IIIAB) and both the metal and silicate portions of a pallasite (Imilac). We developed a novel method to prepare the samples for analysis, followed by hot water extraction and analysis via liquid chromatography‐mass spectrometry. Free amino acid abundances ranging from 301 to 1216 pmol g−1 were observed in the meteorites, with the highest abundance in the silicate portion of the pallasite. Although some of the amino acid content could be attributed to terrestrial contamination, evidence suggests that some compounds are indigenous. A suite of C5 amino acids was observed with a distinct distribution favoring a straight chain (n‐pentanoic acid) structure; this straight chain dominance is suggestive of that observed in thermally altered stony meteorites. Amino acids were also observed in terrestrial iron granules that were milled and analyzed in the same way as the meteorites, although the distribution of detected amino acids was different. It is possible that similar formation mechanisms existed in both the meteorites and the terrestrial iron, or that observed amino acids resulted from reactions of precursors during sample preparation. This work suggests that iron meteorites should not be overlooked for contributions of amino acids and likely other soluble organic molecules to the early Earth. Future studies of iron–nickel meteorites and asteroids, such as Psyche, may provide further insights into their potential organic inventory.
Long‐term passive acoustics to assess spatial and temporal vocalization patterns of Atlantic common bottlenose dolphins (Tursiops truncatus) in the May River estuary, South Carolina
Authors: Marian Alyssa D. , Monczak Agnieszka , Balmer Brian C. , Hart Leslie B. , Soueidan Jamileh , Montie Eric W.
Published: March 2021

Passive acoustics has been used extensively to study bottlenose dolphins; yet very few studies have examined the spatial, temporal, and environmental influences on vocalization types (echolocation, burst pulse sounds, and whistles), and few are long‐term and provide high temporal resolution over multiple years. We used data from 2013 to 2018 to establish baseline acoustic patterns for bottlenose dolphins in the May River estuary, South Carolina. We deployed acoustic recorders at six stations during 2013–2014 and three stations during 2015–2018, with locations spanning the entire estuary (headwaters to the mouth). We discovered that acoustic detection of dolphins varied not only spatially, but also yearly, monthly, and tidally. Higher numbers of echolocation bouts, burst pulse sounds, and whistles were detected at the mouth as compared to the headwaters. At the mouth, vocalization detections were greatest in fall and winter for multiple years, and echolocation detection was greatest during falling and low tides. This study provides an example of another tool, long‐term passive acoustics monitoring, to better understand spatial and temporal distribution of dolphins in a typical salt marsh estuary, that can be applied to other ecosystems throughout the southeastern United States and globally.
Grit, Grind, and Praxis: The Memphis Model of Applying Anthropology
Authors: Feldman Lindsey Raisa , Brondo Keri Vacanti , Hyland Stanley , Maclin Edward
Published: March 2021

In this paper we define “The Memphis Model,” or the type of praxis‐oriented, critically engaged anthropology developed and used by the Department of Anthropology at the University of Memphis. This model draws inspiration from the Grit and Grind ethos of the city of Memphis, along with its deep cultural and political traditions of grassroots activism for social justice. Here, we define how this is done in practice. The Department of Anthropology continually brings together current students, faculty, alumni, and community partners in coalition to develop approaches to address emerging social justice issues throughout the city, country, and world. This paper draws on one specific example, the Welcome Home Memphis Initiative, a long‐term partnership with community housing agencies, alumni, faculty, and students to counter exploitative housing practices, to explain the process of the Memphis Model.
“Applying” Education: A Focused Review of the 2019 American Anthropology Master's Career Survey Data
Authors: Cronin Shannon , Hawvermale Erica M.
Published: March 2021

This paper reports the results of the National Association for the Practice of Anthropology‐sponsored 2019 American Anthropology Master's Career Survey. Aimed at replicating the 2009 American Anthropological Association/Committee on Practicing, Applied, and Public Interest Anthropology MA Career Survey, the purpose of this new survey was to understand 1) how master's degree anthropology alumni have crafted careers, 2) what retrospective advice they have for departmental programs, and 3) whether they continue to identify with the profession. A total of 850 participants completed the survey. Parallel to the 2009 survey, applied anthropologists indicated overall satisfaction with their master's degree programs and reflected high variability in types of employment respondents hold. However, the lack of practical skills development and career preparation within master's programs were critiqued. We conclude with recommendations for anthropology programs to help better inform them of what their students need to learn in order to lead successful careers after graduation.
Cropping systems alter hydraulic traits of barley but not pea grown in mixture
Authors: Sun Qing , Gilgen Anna K. , Signarbieux Constant , Klaus Valentin H. , Buchmann Nina
Published: March 2021

Extreme events such as drought and heatwaves are among the biggest challenges to agricultural production and food security. However, the effects of cropping systems on drought resistance of arable crops via their hydraulic behaviour remain unclear. We investigated how hydraulic traits of a field‐grown pea‐barley (Pisum sativum L. and Hordeum vulgare L.) mixture were affected by different cropping systems, that is, organic and conventional farming with intensive or conservation tillage. Xylem vulnerability to cavitation of both species was estimated by measuring the pressure inducing 50% loss of hydraulic conductivity (P50), while the water stress plants experienced in the field were assessed using native percentage loss of hydraulic conductivity (nPLC). Pea and barley showed contrasting hydraulic behaviours: pea was less vulnerable to xylem cavitation and less stressed than barley; cropping systems affected the xylem vulnerability of barley, but not of pea. Barley grown under conventional farming with no tillage was more vulnerable and stressed than under organic farming with intensive tillage. nPLC proved to be a valuable indicator for plant water stress. Our results highlight the impact of cropping systems on crop xylem vulnerability and drought resistance, thus plant hydraulic traits, for protecting food security under future climate.
The cell wall of green microalgae and its role in heavy metal removal
Authors: Spain Olivia , Plöhn Martin , Funk Christiane
Published: March 2021

Heavy metals in industrial wastewaters are posing a serious threat to the environment and to human health. Microalgae are increasingly being seen as potential solutions to this problem as they can remove pollutants through biosorption. This process offers certain advantages over other more traditional metal removal techniques as it is simple, inexpensive, eco‐friendly, and can be performed over a wide range of experimental conditions. Biosorption is possible due to the unique and complex structure of the microalgal cell wall. The variety of functional groups on the surface of the cell wall (such as carboxyl or amino groups) can act as binding sites for the heavy metals, thus removing them from the environment. This review focuses on the cell wall composition and structure of the most commonly used microalgae in heavy metal removal and shows the role of their cell wall in the biosorption process. This review also aims to report the most commonly used models to predict the velocity of microalgal biosorption and the removal capacities.
Is there local adaptation in plant species to soil reaction? A lesson from a multispecies experiment
Authors: Rupprecht Denise , Hölzel Norbert , Bucharova Anna
Published: March 2021

Seed sourcing for restoration measures is a currently highly debated issue in conservation ecology. Where to take the seeds from, if reintroduction of plant species is necessary? In many countries, seed transfer zones have been defined to preserve genetic variability and to provide locally adapted plants. However, delineation of seed transfer zones mostly relies on climatic gradients, ignoring other abiotic factors, such as bedrock and soil conditions. One of the main soil properties is soil reaction (pH), yet it is still unclear whether pH is an important driver for local adaptation in plants. In this study, we tested whether plants are adapted to soil reaction across five common grassland species. For each species, we sampled seeds from two provenances, and within each provenance from two populations—one coming from basic and one from acidic soil. We grew the plants in a common garden in an artificial substrate with manipulated pH, which allowed us to test for the effect of soil reaction, isolated from other soil properties. All species produced more biomass on acidic substrate, in most cases independently of their original soil and provenance. Only one out of five species showed weak local adaptation to soil reaction. The experimental substrate by far explained most of the biomass production in all species. This suggests that adaptation to soil reaction is rare and of low importance in common species of temperate grasslands.
Rapid colonization of aquatic communities in an urban stream after daylighting
Authors: Baho Didier L. , Arnott David , Myrstad Karoline D. , Schneider Susanne C. , Moe Therese F.
Published: March 2021

Restoring aquatic ecosystems is still at an early stage and the outcomes of the remediation techniques used are often not reported, which limit opportunities to learn and further improve these methods. One common remediation technique in urban areas is daylighting, which involves the re‐opening of once buried streams with the aim of restoring ecosystem functions and services. In this study, we monitored the colonization of two important aquatic communities, benthic algae and macroinvertebrates, and assessed the nutrient retention capacity of a recently daylighted urban stream in the city of Oslo, Norway. The approach used involved transforming a buried channel into an open stream consisting of interconnected riffles and ponds seeded with aquatic and terrestrial plants. Benthic algal and macroinvertebrate communities begun to colonize the restored stretch within a relatively short time, 9 months following daylighting. The dynamics of the two aquatic communities differed, indicating that spatial processes are influential in determining the establishment of benthic algae, whereas time is more important for macroinvertebrate communities. The observed net nutrient retention from the daylighted stretch for phosphate, total nitrogen, total phosphorus, and calcium were 226, 128, 38 and 14%, respectively. However, the efficiency of the daylighted stretch to sequester nutrients was limited by the lack of controlling nutrient inputs from diffuse sources. This highlights the importance of addressing the influence of broader‐scale processes, extending beyond the boundaries of the restored reach, which can otherwise demise the success of daylighting.
Estimation of the Size of Informal Employment Based on Administrative Records With Non-Ignorable Selection Mechanism
Authors: Berȩsewicz Maciej , Nikulin Dagmara
Published: March 2021

In this study, we used company level administrative data from the National Labour Inspectorate and The Polish Social Insurance Institution in order to estimate the prevalence of informal employment in Poland in 2016. Since the selection mechanism is non-ignorable, we employed a generalization of Heckman’s sample selection model assuming non-Gaussian correlation of errors and clustering by incorporation of random effects. We found that 5.7% (4.6%, 7.1%; 95% CI ) of registered enterprises in Poland, to some extent, take advantage of the informal labour force. Our study exemplifies a new approach to measuring informal employment, which can be implemented in other countries. It also contributes to the existing literature by providing, to the best of our knowledge, the first estimates of informal employment at the level of companies based solely on administrative data.
Multidimensional parameter estimation of heavy‐tailed moving averages
Authors: Ljungdahl Mathias Mørck , Podolskij Mark
Published: March 2021

In this article we present a parametric estimation method for certain multiparameter heavy‐tailed Lévy‐driven moving averages. The theory relies on recent multivariate central limit theorems obtained via Malliavin calculus on Poisson spaces. Our minimal contrast approach is related to previous papers, which propose to use the marginal empirical characteristic function to estimate the one‐dimensional parameter of the kernel function and the stability index of the driving Lévy motion. We extend their work to allow for a multiparametric framework that in particular includes the important examples of the linear fractional stable motion, the stable Ornstein–Uhlenbeck process, certain CARMA(2, 1) models, and Ornstein–Uhlenbeck processes with a periodic component among other models. We present both the consistency and the associated central limit theorem of the minimal contrast estimator. Furthermore, we demonstrate numerical analysis to uncover the finite sample performance of our method.
Are School Reopening Decisions Related to Union Influence?
Authors: DeAngelis Corey A. , Makridis Christos
Published: March 2021

Objective

The COVID‐19 pandemic led to widespread school closures affecting millions of K‐12 students in the United States in the spring of 2020. Groups representing teachers have pushed to reopen public schools virtually in the fall because of concerns about the health risks associated with reopening in person. In theory, stronger teachers’ unions may more successfully influence public school districts to reopen without in‐person instruction.

Methods

We examine the relationship between teachers’ union strength and the reopening decisions of 835 public school districts in the United States using regression analyses.

Results

We find that school districts in locations with stronger teachers’ unions are less likely to reopen in person even after we control semiparametrically for differences in local demographic characteristics. These results are robust to four measures of union strength, various potential confounding characteristics, a further disaggregation to the county level, and various analytic techniques and datasets. We do not find evidence that measures of COVID‐19 risk are correlated with school reopening decisions.

Conclusion

Our findings that school closures are uncorrelated with the actual incidence of the virus, but are rather strongly associated with unionization, implies that the decision to close schools has been a political—not scientific—decision.
Reanalysis of the apoid wasp phylogeny with additional taxa and sequence data confirms the placement of Ammoplanidae as sister to bees
Authors: Sann Manuela , Meusemann Karen , Niehuis Oliver , Escalona Hermes E. , Mokrousov Mikhail , Ohl Michael , Pauli Thomas , Schmid‐Egger Christian
Published: March 2021

Apoid wasps and bees (Apoidea) are an ecologically and morphologically diverse group of aculeate Hymenoptera (ants, bees and wasps). During the last decades, significant progress has been made in illuminating the phylogenetic relationships of the major Apoidea lineages. However, some uncertainties have remained. In this study, we present results from re‐investigating the phylogeny of Apoidea by including genome skimming data of key taxa that were missing in previous investigations: a representative of Entomosericini (tribe of the former Pemphredoninae) and a representative of Eremiaspheciinae (subfamily of the former ‘Crabronidae’). We additionally skimmed the genomes of two Heterogyna species (Heterogynaidae). Our results from applying concatenation and coalescence‐based phylogenetic approaches confirm the previously suggested sister group relationship of Ammoplanidae and bees. They also corroborate most taxonomic changes published in 2018 granting eight lineages of the former family ‘Crabronidae’ family status. However, some of our analyses indicate that the families Pemphredonidae and Psenidae could be para‐ or polyphyletic. After carefully assessing topological discordance and data quality, the exact placements of Heterogyna and of the genera Eremiasphecium and Entomosericus in the apoid wasp phylogeny remain ambiguous. However, our analyses indicate that inclusion of Entomosericus and Eremiasphecium in any of the currently accepted apoid wasp families cannot be well justified, and we consequently suggest raising Entomosericinae and Eremiaspheciini to family rank, respectively, to acknowledge this situation in the apoid classification: Entomosericidae Dalla Torre, 1897 (stat. n.) and Eremiaspheciidae Menke, 1967 (stat. n.).
Turbulence Anisotropy Investigations in an Internal Combustion Engine
Authors: MacDonald James R. , Fajardo Claudia M.
Published: March 2021

The assumption of isotropic turbulence is commonly incorporated into models of the internal combustion engine (ICE) in-cylinder flows. While preliminary analysis with two-dimensional (2D) velocity data indicates that the turbulence may tend to isotropy as the piston approaches top-dead-center (TDC), the validity of this assumption has not been fully investigated, partially due to the lack of three-component velocity data in ICEs. In this work, the velocity was measured using two-dimensional, three-component (2D-3C) particle image velocimetry in a single-cylinder, motored, research engine to investigate the evolution of turbulence anisotropy throughout the compression stroke. Invariants of the Reynolds stress anisotropy tensor were calculated and visualized, through the Lumley triangle, to investigate turbulence states. Results showed the turbulence to be mostly anisotropic, with preferential tendency toward 2D axisymmetry at the beginning of the compression stroke and approaching-isotropy near top-dead-center. Findings provide new insights into turbulence in dynamic, bounded flows to assist with the development of physics-based, quantitative models.
Thermal Analysis of Paraffin-Embedded Tissue Blocks for Anatomic Pathology Processes
Authors: Ciancia Sabrina , Lucantonio Alessandro , Vannozzi Lorenzo , Pedrazzini Gian Andrea , Ricotti Leonardo
Published: March 2021

We analyze temperature dynamics in anatomic pathology samples to identify the most efficient refrigeration method and to predict the time available for optimal sectioning before sample heating, thus getting appropriate information for a correct diagnosis by anatomopathologists. A thermal finite element (FE) analysis was carried out with comsolmultiphysics to evaluate temperature variations in paraffin-embedded tissues, i.e., muscle, bone and fat, and the corresponding thermal stresses. Experiments with different tissues and thermocouple-based measurements allowed validating the FE simulations. Simulations allowed to estimate the time needed to bring the sample at the optimal temperature for sectioning (−8 to −4 °C) in different conditions: refrigeration on a cold plate, refrigeration in a cooled environment, and refrigeration in an environment with forced convection. Among the three cooling methods tested, the forced convection at −20 °C and with an air-flow speed of 5 m/s resulted in the shortest cooling time. As compared to the other methods, thermal stresses can be modulated by varying the air-flow speed. For the different conditions, the time needed for the surface of the tissue block to exit from a temperature corresponding to an optimal cutting, when leaving the sample exposed to room temperature after refrigeration, ranged from 12 to 310 s. We quantify the time needed to adequately refrigerate paraffin-embedded tissue samples and the time available before they leave the optimal temperature window for sectioning. We also evaluate the maximum stress attained in the paraffin block during the cooling and the heating transients. This information will help optimize anatomic pathology processes.
Blood Flow Velocimetry in a Microchannel During Coagulation Using Particle Image Velocimetry and Wavelet-Based Optical Flow Velocimetry
Authors: Kucukal E. , Man Y. , Gurkan Umut A. , Schmidt B. E.
Published: March 2021

This article describes novel measurements of the velocity of whole blood flow in a microchannel during coagulation. The blood is imaged volumetrically using a simple optical setup involving a white light source and a microscope camera. The images are processed using particle image velocimetry (PIV) and wavelet-based optical flow velocimetry (wOFV), both of which use images of individual blood cells as flow tracers. Measurements of several clinically relevant parameters such as the clotting time, decay rate, and blockage ratio are computed. The high-resolution wOFV results yield highly detailed information regarding thrombus formation and corresponding flow evolution that is the first of its kind.
In Silico Finite Element Analysis of the Foot Ankle Complex Biomechanics: A Literature Review
Authors: Phan P. K. , Vo A. T. N. , Bakhtiarydavijani A. , Burch R. , Smith B. , Ball J. E. , Chander H. , Knight A. , Prabhu R. K.
Published: March 2021

Computational approaches, especially finite element analysis (FEA), have been rapidly growing in both academia and industry during the last few decades. FEA serves as a powerful and efficient approach for simulating real-life experiments, including industrial product development, machine design, and biomedical research, particularly in biomechanics and biomaterials. Accordingly, FEA has been a “go-to” high biofidelic software tool to simulate and quantify the biomechanics of the foot–ankle complex, as well as to predict the risk of foot and ankle injuries, which are one of the most common musculoskeletal injuries among physically active individuals. This paper provides a review of the in silico FEA of the foot–ankle complex. First, a brief history of computational modeling methods and finite element (FE) simulations for foot–ankle models is introduced. Second, a general approach to build an FE foot and ankle model is presented, including a detailed procedure to accurately construct, calibrate, verify, and validate an FE model in its appropriate simulation environment. Third, current applications, as well as future improvements of the foot and ankle FE models, especially in the biomedical field, are discussed. Finally, a conclusion is made on the efficiency and development of FEA as a computational approach in investigating the biomechanics of the foot–ankle complex. Overall, this review integrates insightful information for biomedical engineers, medical professionals, and researchers to conduct more accurate research on the foot–ankle FE models in the future.
Two-Segment Flexible Macintosh Laryngoscope to Improve Glottic Visualization During Endotracheal Intubation
Authors: Sand Yashovardhan , Erdman Arthur G. , Konia Mojca R.
Published: March 2021

Endotracheal intubation is a frequently performed life-saving procedure in medicine. Obtaining view of glottic structures is essential for successful completion of endotracheal intubation. Most frequently used devices called laryngoscopes sometimes fail to obtain view, which would allow for a successful completion of endotracheal intubation. To improve visualization of glottic structures, practitioners can use high-tech video-laryngoscopes, but these are not available to everyone, especially not in the third world countries. Alternatively, practitioners can use two-segment laryngoscopes. We developed a prototype of a two-segment flexible laryngoscope and tested it in a simulated environment. The glottic visualization statistically significantly (p = 0.000038) improved with the use of flexible laryngoscope. Our study strengthens available evidence that multisegment laryngoscope blades can improve glottic visualization and decrease forces exerted on soft tissues of larynx.
A Computer-Aided Fixture Design System With Process Planning Integration for Prismatic Parts Manufactured on CNC Machining Centers
Authors: Prombanpong S. , Lewis R. L. , Bishop A. B.
Published: March 2021

Jigs and fixtures are indispensable tools in various manufacturing processes. These processes include metal removal, assembly, welding, and inspection processes. Not only do jigs and fixtures facilitate the operations, but also provide quick loading/unloading, proper and consistent supporting and locating of a workpiece. As a result, the workpiece can be manufactured economically in proportion to the volume of production.

With the advent of computer aided design and computer aided manufacturing together with an increasing power of both computer hardware and software, computerized fixture design systems become feasible and more sophisticated. The current computerized fixture design systems are developed utilizing several approaches ranging from simple interactive placement of fixture components to sophisticated generative systems. However, one of the common drawbacks of these systems is a lack of process planning integration in the fixture design considerations. As a result, the contradiction between fixture design generated by the computerized fixture design system and a process plan generated by a process planner or by computer aided process planning software always occurs. In other words, the fixture set-ups and workpiece orientation are not congruent to the process plan.

This paper serves to discuss a solution to the problem mentioned above. A mathematical model was developed to integrate process planning in fixture design considerations. An optimized fixture design system will be presented and discussed. Examples of tested cases are also presented.
Automated Gating Plan Synthesis for Injection Molds
Authors: Saxena Mukul , Irani Rohinton K.
Published: March 2021

The task of design synthesis can be accomplished by human beings because of their ability to take into account the physics of the problem, past experience, and to evaluate a number of alternatives to determine the best compromise design. This paper illustrates a system that automates this procedure for injection mold design, and more specifically, gating design. The gating plan synthesis system described in this paper, automatically determines an initial gating configuration based on a features representation of the part and a knowledge-base that captures some of the design rules used in practice. A Feature Modeling Utility (FMU), a Topology and Geometry Utility System (TAGUS), and an automatic mesh generator, OCTREE, are used to identify and query features and to perform geometric reasoning about the part. The methodology used, implementation details, and examples of test cases are presented.
Minkowski Sums: A Simulation Tool for CAD/CAM
Authors: Kaul Anil
Published: March 2021

In this paper we provide a survey of Minkowski sums, their applications as a simulation tool in Computer Aided Design and some simple algorithms to compute them. The intent of the paper is to exhibit the relevance of morphological operations, like Minkowski sums, in practical aspects of CAD/CAM and to provide enough motivation to stimulate research in finding efficient algorithms for their computation. Except for cases where the two initial objects are convex, there are no known algorithms which guarantee efficient performance in the polyhedral domain. Some initial work has been done for finding algorithms where the boundaries of the objects are composed of algebraic curves, but again very little is known on how to actually compute the Minkowski sum for objects bounded by general curves. Some of the applications that we describe in this paper include Robot path planning, interference detection, NC cutter path planning, rounding and filleting, shape design, etching and deposition processes in semiconductor process simulation and polyhedral interpolation.
A Computer Model for Thermofluid Analysis of Vehicle Cooling Systems
Authors: Veshagh Alireza , Chen Changyou , Moffatt Richard
Published: March 2021

This paper describes a computer model developed for analysing the thermofluid performance of vehicle cooling systems. The model has a modular structure which links various system submodels. The individual component submodels can be extended and modified in order to conduct parametric studies to examine the effects of various design and operating parameters on performance. The model can predict the overall thermal performance of the vehicle heating and cooling systems, providing useful information at the early stages of the design and development. In this paper, details of each submodel are described together with the overall structure of the vehicle model. The model predictions are compared with measured data and the application of the model is illustrated by several test cases.
Parallel Substructure Approach for Massively Parallel Computers
Authors: Fulton Robert E. , Su Philip S.
Published: March 2021

New massively parallel computer architectures have revolutionized the design of computer algorithms, and promise to have significant influence on algorithms for engineering computations. The traditional global model parallel method has a limited benefit for massively parallel computers. An alternative method is to use the substructure approach. This paper is to explore the potential for substructure strategy through actual examples. Each substructure is mapped on to some processors of a MIMD parallel computer. The internal nodes variables will be condensed into boundary nodes variables in each substructure. All substructures computations can be performed in parallel until the global boundary system equation is formed. A direct solution strategy for the global boundary displacements is performed. The final internal nodes displacements solution in each substructure can be performed in parallel. Examples for two-dimensional static analysis are presented on a BBN Butterfly GP1000 parallel computer.
Belt Vibration Consideration Moving Contact and Parametric Excitation
Authors: Yue M. G.
Published: March 2021

The contacting point between belt and pulley is not fixed but moves along the pulley during vibration and that influences the free span length of the belt. The concept vibrating length is introduced and that will affect the dynamic behavior of the belt.

Parametric excitation can occur through periodic variations in belt tension and speed arising from loading of the pulleys by belt-driven accessories and from engine in automotive applications. The most violent oscillations develop and resonance will occur when the frequency of excitation is close to twice or three times the natural frequency for varying tension and speed case, respectively.
Computer Simulation Program of Dynamic Analysis for Planetary Transmission
Authors: Ming Mao , Ruiting Cheng
Published: March 2021

Based on the angular velocity transformation matrix, the paper develops the differential motion equation BKTJBKdωIK/dt=BKTM for a planetary transmission, which is a linearly constrained system. Although the degrees-of-freedom of the system is varying during shift process, the angular velocity transformation matrix BK, whose entries are constans, is only related to engaged clutches and BK can be easily derived from a constant matrix BF by linear transformation. Based on this theory, a computer simulation program of dynamic analysis of a planetary transmission is written, which provides a perfect means for analysis of dynamic behaviour of a transmission at any shifting transients. As an illustration, that of an Allison-WT transmission from 3rd speed to 4th speed is simulated.
Size Effect in Bending Strength of Carburized Gear Teeth
Authors: Kato M. , Inoue Katsumi , Deng G. , Jeong B. S.
Published: March 2021

This paper deals with the bending strength and the size effect of carburized fine module gears. The fine module gears (m = 1.0–1.5) are made of a low-carbon alloy steel, and they are carburized to have various effective case depths. The bending fatigue tests are performed for these gears. The test results show the validity of the AGMA recommendation for the effective case depth. The experimental formulas of bending strength are estimated from the comparison with the strength of the gears of m = 5. In order to make clear the size effect, a method of fracture mechanics based strength evaluation is introduced and applied to the fatigue test results. The fatigue life is assumed to be the crack propagation process, and the maximum initial length of crack is calculated from the fatigue strength. The relation between this crack length and the thickness of non-martensitic layer at the fillet is obtained, and the size effect is discussed with the relation to the thickness of the non-martensitic layer.
Mechanics of Roller Chain-Sprocket Contact: Observations About the Contact Phenomena and Load Distribution
Authors: Kim Mahn Shik , Johnson Glen E.
Published: March 2021

In a companion paper (“Mechanics of Roller Chain - Sprocket Contact: A General Modelling Strategy” submitted for presentation at this conference), a new theoretical model to describe the quasi-static contact phenomenon between a roller and sprocket is developed from first principles. The new model includes the external loading conditions, the curvature difference between die roller and the seating curve, the net error in the chain pitch (defined as the error in the chain pitch minus the error in the sprocket pitch), and Coulomb friction between the tooth and roller, the roller and bushing, and the bushing and pin. No assumption regarding the pressure angle at each contact point is made — rather the pressure angle at each contact point is calculated during the solution.

In this paper we present results generated by a computer simulation based on the new model. A comparison with experimental data taken from the literature (Naji and Marshek. 1983) indicates that excellent quantitative prediction of load distribution is possible. The simulation results suggest several practical observations about chain performance (including effects of friction, manufacturing tolerances, wear, and the incorporation of idler sprockets) and these are presented and discussed.
Optimal Design of Structural Shape: Minimal Weight Shapes Designed Corresponding to Displacement Restraining Planes
Authors: Itou Motomichi , Ohkouchi Teiichi
Published: March 2021

The designs of the elastic two-dimensional plate structure are optimized for the minimal weight structures of the characteristic shapes. Structures composed of finite elements are modified discretely by attaching and detaching of elements at external boundary of shapes. In the modifications, the steepest descent method is actualized using the sensitivity function that is evaluated from the strain energy of the structure by Finite Element Method. The sensitivity value of each element is calculated by the element stiffness matrix and the nodal displacements. The two structures “A” and “B” are modified by the above mention technique. The structure “A” with vertical and horizontal displacement restraining planes is converged into a hanging bar with a uniform cross-sectional area of the minimal weight shape. The structure “B” with only vertical displacement restraining plane is converged into a V-shaped structure supported by two forked ends.