bluuebunny/crossref_metadata_2025 huggingface dataset:
A mathematical framework for peristaltic mechanism of non-Newtonian fluid in an elastic heated channel with Hall effect
Authors: Javed Maryiam
Published: July 2020

Purpose

objective of the present investigation is to examine the influence of Hall on the peristaltic mechanism of Johnson-Segalman fluid in a heated channel with elastic walls. The transmission of heat is carried out. Relevant equations are computed for heat transfer coefficient, temperature and velocity. Low Reynolds number assumptions and long wavelength are employed. The interpretation of various parameters is analyzed. The results indicate that the heat transfer coefficient, temperature and velocity are larger for viscous material in comparison with Johnson-Segalman material.

Design/methodology/approach

The transmission of heat is carried out. Relevant equations are computed for heat transfer coefficient, temperature and velocity. Low Reynolds number assumptions and long wavelength are employed. The interpretation of various parameters is analyzed. The results indicate that the heat transfer coefficient, temperature and velocity are larger for viscous material in comparison with Johnson-Segalman material.

Findings

The formulation of paper is executed as follows. Section 2 comprises problem summary and mathematical design. Solution methodology is discussed, and expressions for temperature, velocity and coefficient of heat transfer are derived in Section 3. Graphical outcomes for the parameters are reported in Section 4. Conclusions are outlined in Section 5.

Practical implications

Peristaltic phenomenon of fluids has a definite role in many physiological, industrial and engineering processes. The mechanical devices for instance finger and roller pumps operate via this process, and it is quite significant for vasomotion of blood vessels, consumption of food via esophagus, chyme flow in gastrointestinal zone, toxic liquid flow in nuclear industry and transport of corrosive fluids.

Originality/value

Literature review witnesses that information about peristalsis of conducting fluid in a heated channel with flexible walls and Hall effect is scarce. So, our goal is to discuss the peristaltic activity of non-Newtonian fluids in flexible channel. Johnson-Segalman fluid is taken into account. This model is used to allow non-affine deformations. Experimentalists relate “spurt” with wall slip. That is why the work presented is original.
Is there a marriage or parenthood effect on police income?
Authors: Luo Xiaoshuang Iris , Schleifer Cyrus
Published: July 2020

Purpose

The purpose of this paper is to examine the gendered effects of marriage and parenthood on income inequality among police officers.

Design/methodology/approach

This study uses survey data collected by the Current Population Survey (CPS) from 1976 to 2018. Ordinary least squares (OLS) regression is employed to analyze the effect of gender, marriage and parenthood on the yearly income of police officers, controlling for other demographic variables.

Findings

The analyses reveal that there is a large income difference among men and women police officers and the compensation processes appear strongly gendered based on family composition. Police women experience a large motherhood income penalty, while police men with traditional family structures have significant income advantages.

Research limitations/implications

While the CPS dataset allows us to track national level trends of within-occupational income inequality, these data are unable to provide detailed information on the specifics of each police job, such as rank of police officers or work experience. Despite these limitations, this study uncovers important patterns in how family structure shapes police income.

Originality/value

The present study fills the knowledge gap about marriage and motherhood penalty among police. This study represents one of the first attempts to explore the gendered compensation processes that are shaped by marriage and parenthood status among police officers at a national level.
Low serum levels of bone turnover markers are associated with the presence and severity of diabetic retinopathy in patients with type 2 diabetes mellitus
Authors: An Yaxin , Liu Simo , Wang Wenbo , Dong Huan , Zhao Wenying , Ke Jing , Zhao Dong
Published: July 2020

Background

Accumulating evidence demonstrates an association of type 2 diabetes mellitus (T2DM) and its microvascular complications with increased fracture risk. In this study, we aimed to evaluate the relationships between serum concentrations of bone turnover markers and the presence and/or severity of diabetic retinopathy (DR) among patients with T2DM.

Methods

A total of 285 patients with T2DM comprising 168 patients without DR and 117 patients with DR were enrolled in the cross‐sectional study. In the latter group, patients were further divided into patients of mild and severe DR stages. The biochemical parameters and bone turnover markers were determined in all participants.

Results

This study found that serum levels of procollagen type 1 N‐terminal propeptide (P1NP), a bone formation marker, and the bone resorption marker serum β‐cross‐linked C‐telopeptide of type I collagen (β‐CTX) were more decreased in diabetic patients with DR than in those without DR, with differences remaining significant (P < .05) in multivariate linear regression models after adjustments for multiple confounding factors. Osteocalcin and β‐CTX levels were further reduced along with the severity of DR among participants with DR. Moreover, multivariate logistic regression analysis revealed that lower serum levels of P1NP and β‐CTX were associated with higher odds for the presence of DR, while β‐CTX was associated with the severity of DR.

Conclusion

Our results suggest that the development of DR might be involved in the progression of T2DM‐induced deficits in bone formation and resorption or vice versa. Follow‐up studies and further research are necessary to validate the associations and elucidate the underlying mechanisms.
Forming diagnostic criteria for vulvar lichen planus
Authors: Wu Michelle , Lee Geoffrey , Fischer Gayle
Published: July 2020

Background/Objectives

Vulvar lichen planus is a debilitating skin condition usually complicated by delayed diagnosis due to its highly variable clinical appearance and inconsistent histopathological characteristics. This study aims to devise a clinical diagnostic tool for the disease and to correlate this with histopathology findings.

Methods

The retrospective single‐centre chart review was conducted for patients presenting between January 2010 and December 2019. Clinical features were compared between 243 women with clinically suspected vulvar lichen planus with available histopathology, 50 patients with biopsy‐proven vulvar lichen sclerosus and 50 patients with culture‐proven chronic vulvovaginal candidiasis. Features which significantly differentiated between conditions were further studied using multivariate nonlinear regression analyses to formulate a score‐based diagnostic criteria. Criteria was then applied to the remaining patients with inconclusive biopsies (classified as ‘normal’, ‘non‐specific’ or ‘suggestive or lichenoid’) to determine sensitivity and specificity.

Results

The clinical features that significantly differentiated the conditions were the presence of erosions (P < 0.001), glazed erythema (P < 0.001), oral involvement (P < 0.001), pain/burning sensation (P < 0.001) and hyperkeratotic border (P < 0.001). A score ≥2 correlated with a histopathological diagnosis of vulvar lichen planus with a sensitivity of 100%. The specificity was 92% and 88% when compared against vulvar lichen sclerosus and chronic vulvovaginal candidiasis, respectively. Sensitivity was 97%, 97% and 93% in suggestive, nonspecific and normal histopathological subgroups, respectively.

Conclusions and Relevance

The proposed criteria may aid clinicians in diagnosing patients if histopathology is inconclusive. Nonspecific and suggestive findings on biopsy for patients with ≥2 features on diagnostic criteria are comparable to a conclusive biopsy.
Combined effects of life‐history traits and human impact on extinction risk of freshwater megafauna
Authors: He Fengzhi , Langhans Simone D. , Zarfl Christiane , Wanke Roland , Tockner Klement , Jähnig Sonja C.
Published: July 2020

Megafauna species are intrinsically vulnerable to human impact. Freshwater megafauna (i.e., freshwater animals ≥30 kg, including fishes, mammals, reptiles, and amphibians) are subject to intensive and increasing threats. Thirty‐four species are listed as critically endangered on the International Union for Conservation of Nature (IUCN). Red List of Threatened Species, the assessments for which are an important basis for conservation actions but remain incomplete for 49 (24%) freshwater megafauna species. Consequently, the window of opportunity for protecting these species could be missed. Identifying the factors that predispose freshwater megafauna to extinction can help predict their extinction risk and facilitate more effective and proactive conservation actions. Thus, we collated 8 life‐history traits for 206 freshwater megafauna species. We used generalized linear mixed models to examine the relationships between extinction risk based on the IUCN Red List categories and the combined effect of multiple traits, as well as the effect of human impact on these relationships for 157 classified species. The most parsimonious model included human impact and traits related to species’ recovery potential including life span, age at maturity, and fecundity. Applying the most parsimonious model to 49 unclassified species predicted that 17 of them are threatened. Accounting for model predictions together with IUCN Red List assessments, 50% of all freshwater megafauna species are considered threatened. The Amazon and Yangtze basins emerged as global diversity hotspots of threatened freshwater megafauna, in addition to existing hotspots, including the Ganges‐Brahmaputra and Mekong basins and the Caspian Sea region. Assessment and monitoring of those species predicted to be threatened are needed, especially in the Amazon and Yangtze basins. Investigation of life‐history traits and trends in population and distribution, regulation of overexploitation, maintaining river connectivity, implementing protected areas focusing on freshwater ecosystems, and integrated basin management are required to protect threatened freshwater megafauna in diversity hotspots.
CIMT as a risk factor for stroke subtype: A systematic review
Authors: Kumar Pradeep , Sharma Rakhee , Misra Shubham , Kumar Amit , Nath Manabesh , Nair Pallavi , Vibha Deepti , Srivastava Achal Kumar , Prasad Kameshwar
Published: July 2020

Introduction

An increase in the common carotid artery intima‐media thickness (CCA‐IMT) is generally considered an early marker of atherosclerosis and is a well‐established predictor of cardiovascular disease (CVD). An association between changes in CCA‐IMT and risk of stroke has been reported but has conflicting findings.

Objective

The present meta‐analysis was aimed to clarify the association between CCA‐IMT with the risk of stroke and its subtype by estimating pooled analysis of published literature.

Methods

Comprehensive search for all published articles was performed in electronic databases including PubMed, Embase, Cochrane Library, Trip Databases, Worldwide Science, CINAHL and Google Scholar from 01 January 1950 to 30 April 2020.

Results

In our meta‐analysis, a total of 19 studies, of which sixteen studies involving 3475 ischaemic stroke (IS) cases and 11 826 controls; six studies with 902 large vessel disease (LVD) and 548 small vessel disease (SVD) of IS subtypes; five studies with 228 intracerebral haemorrhage (ICH) and 1032 IS cases, were included. Our findings suggest a strong association between increased CCA‐IMT with risk of IS as compared to control subjects [SMD = 1.46, 95% CI = 0.90‐2.02]. However, there is an increased risk of LVD as compared to the SVD subtype of IS [SMD = 0.36, 95% CI = 0.19‐0.52] and more chance of occurrence of IS rather than ICH [SMD = 0.71, 95% CI = 0.28‐1.41].

Conclusions

Carotid intima thickness measurements are found to be associated with the risk of stroke along with its subtypes and may be used as a diagnostic marker for predicting the risk of stroke events.
Measuring the effect of environmental stress on inbreeding depression alone obscures the relative importance of inbreeding–stress interactions on overall fitness in Callosobruchus maculatus
Authors: Springer Amy L. , Messina Frank J. , Gompert Zachariah
Published: July 2020

Environmental stress can have a profound effect on inbreeding depression. Quantifying this effect is of particular importance in threatened populations, which are often simultaneously subject to both inbreeding and environmental stress. But while the prevalence of inbreeding–stress interactions is well known, the importance and broader applicability of such interactions in conservation are not clearly understood. We used seed beetles, Callosobruchus maculatus, as a model system to quantify how environmental stressors (here host quality and temperature stress) interact with inbreeding as measured by changes in the magnitude of inbreeding depression, δ, as well as the relative importance of inbreeding–stress interactions to overall fitness. We found that while both environmental stressors caused substantial inbreeding–stress interactions as measured by change in δ, the relative importance of these interactions to overall survival was modest. This suggests that assessing inbreeding–stress interactions within the framework of δ alone may give an inaccurate representation of the relevance of interactions to population persistence. Furthermore, we found that the effect of environmental stress on fitness, but not inbreeding depression, varied strongly among populations. These results suggest that the outcomes of inbreeding–stress interactions are not easily generalized, an important consideration in conservation settings.
A systematic review and meta‐analysis comparing second‐generation cryoballoon and contact force radiofrequency ablation for initial ablation of paroxysmal and persistent atrial fibrillation
Authors: Ravi Venkatesh , Poudyal Abhushan , Pulipati Priyanjali , Larsen Timothy , Krishnan Kousik , Trohman Richard G. , Sharma Parikshit S. , Huang Henry D.
Published: July 2020

Introduction

Cryoballoon ablation (CBA) and radiofrequency ablation (RFA) are the preferred modalities for catheter ablation of atrial fibrillation (AF). Technological advances have improved procedural outcomes, warranting an updated comparison. We sought to evaluate the efficacy and safety of CBA–2nd generation (CBA‐2G) in comparison to RFA‐contact force (RFA‐CF) in patients with AF.

Methods

MEDLINE, Cochrane, and ClinicalTrials.gov databases were searched until 03/01/2020 for relevant studies comparing CBA‐2G versus RFA‐CF in patients undergoing initial catheter ablation for AF.

Results

A total of 17 studies, involving 11 793 patients were included. There was no difference between the two groups in the outcomes of freedom from atrial arrhythmia (p = .67) and total procedural complications (p = .65). There was a higher incidence of phrenic nerve palsy in CBA‐2G (odds ratio: 10.7; 95% confidence interval [CI]: 5.85 to 19.55; p < .001). Procedure duration was shorter (mean difference: −31.32 min; 95% CI: −40.73 to −21.92; p < .001) and fluoroscopy duration was longer (+3.21 min; 95% CI: 1.09 to 5.33; p = .003) in CBA‐2G compared to RFA‐CF. In the subgroup analyses of patients with persistent AF and >1 freeze lesion delivered per vein, there was no difference in freedom from atrial arrhythmia.

Conclusions

In AF patients undergoing initial ablation, CBA‐2G and RFA‐CF were equally efficacious. The procedure duration was shorter, but with a higher incidence of phrenic nerve palsy in CBA‐2G. In patients with persistent AF, there was no difference in the efficacy between CBA‐2G or RFA‐CF techniques.
SNP rs2243828 in MPO associated with myeloperoxidase level and atrial fibrillation risk in Chinese Han population
Authors: Wang Pengyun , Cheng Mian , Wang Pengxia , Xiong Liang , Zeng Yali , Tu Xin , Zhang Rongfeng , Xia Yunlong , Wu Gang , Wang Qing , Cheng Xiang , Xu Chengqi
Published: July 2020

Previous studies shown that myeloperoxidase (MPO) level is higher in patients with atrial fibrillation (AF); however, no genetic evidence between MPO and AF risk in human population was observed. Therefore, the present study was aimed to investigate the association between rs2243828, a variant in promoter region of MPO and the risk of AF in Chinese GeneID population. The results demonstrated that the minor G allele of rs2243828 showed a significant association with AF in two independent population (GeneID‐north population with 694 AF cases and 710 controls, adjusted P‐adj = 6.25 × 10−3 with an odds ratio was 0.77, GeneID‐central population with 1106 cases and 1501 controls, P‐adj = 9.88 × 10−5 with an odds ratio was 0.75). The results also showed G allele was significantly associated with lower plasma concentration of myeloperoxidase in general population. We also observed a significant difference of odds ratio between subgroups of hypertension and non‐hypertension. Therefore, our findings identified variant in MPO associated with risk of AF and it may give strong evidence to link the inflammation with the incidence of AF.
Counts of coral reef fishes by an experienced observer are not biased by the number of target species
Authors: Cheal Alistair J. , Emslie Michael J.
Published: July 2020

Fishes are commercially, recreationally and functionally important inhabitants of coral reefs. Accordingly, accurate assessments of fish abundance and diversity are necessary for effective reef management. While some reef fish monitoring programmes target all fishes, many survey a subset of common and visually obvious species. Changing to counts of all species, while desirable, risks new and unwelcome biases from altered observer swimming speeds and search patterns. Here we test whether substantially increasing the number of target species in an established fish monitoring programme biases counts of the original subset, so precluding ongoing comparisons with historical data. A subset of 141 fish species have been visually surveyed along 50 × 5 m transects over 27 years throughout Australia's Great Barrier Reef. We experimentally compared counts of the subset from standard subset‐only surveys and from surveys of all species (excluding small site‐attached fishes that are surveyed separately) at three diverse reefs. Subset species richness and abundance, in total and of major families, and assemblage structure did not differ due to survey method. The high‐level experience of the one observer appeared to overcome new biases from counting more species and the extra 2 min/transect was not logistically excessive. Surveys of all fishes recorded almost 80% more species than subset‐only surveys and >130% higher total abundance on average from >150% more genera that included abundant and functionally important taxa. Overall, fish counts by an experienced observer were not biased by the number of species surveyed and counts of all species markedly improved assessments of reef fish diversity and function.
Self‐management programmes for cirrhosis: A systematic review
Authors: Boudreault Samuel , Chen Junqiao , Wu Kevin Y. , Plüddemann Annette , Heneghan Carl
Published: July 2020

Background and aims

Liver cirrhosis severely decreases patients' quality of life. Since self‐management programmes have improved quality of life and reduce hospital admissions in other chronic diseases, they have been suggested to decrease liver cirrhosis burden.

Methods

We performed a systematic review and meta‐analysis to evaluate the clinical impact of self‐management programmes in patients with liver cirrhosis, which followed the Preferred Reporting for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. Primary outcomes include health‐related quality of life (HRQOL) and hospitalisation. We searched MEDLINE, CENTRAL, Embase, CINAHL, PsycINFO and two trial registers to July 2017.

Results

We identified four randomised trials (299 patients) all rated at a high risk of bias. No difference was demonstrated for HRQOL (standardised mean difference −0.01, 95% CI: −0.48 to 0.46) and hospitalisation days (incidence rate ratio 1.6, 95% CI: 0.5–4.8). For secondary outcomes, one study found a statistically significant improvement in patient knowledge (mean difference (MD) 3.68, 95% CI: 2.11–5.25) while another study found an increase in model for end‐stage liver disease scores (MD 2.8, 95% CI: 0.6–4.9) in the self‐management group. No statistical difference was found for the other secondary outcomes (self‐efficacy, psychological health outcomes, healthcare utilisation, mortality). Overall, the quality of the evidence was low. The content of self‐management programmes varied across studies with little overlap.

Conclusions

The current literature indicates that there is no evidence of a benefit of self‐management programmes for people with cirrhosis.

Relevance to clinical practice

Practitioners should use self‐management programmes with caution when delivering care to patients living with cirrhosis. Further research is required to determine what are the key features in a complex intervention like self‐management. This review offers a preliminary framework for clinicians to develop a new self‐management programme with key features of effective self‐management interventions from established models.
Sharing the cure: Building primary care and public health infrastructure to improve the hepatitis C care continuum in Maryland
Authors: Irvin Risha , Ntiri‐Reid Boatemaa , Kleinman Mary , Agee Tracy , Hitt Jeffrey , Anaedozie Onyeka , Arowolo Tolu , Cassidy‐Stewart Hope , Bush CaSaundra , Wilson Lucy E. , Millman Alexander J. , Nelson Noele P. , Canary Lauren , Brinkley Sherilyn , Moon Juhi , Falade‐Nwulia Oluwaseun , Sulkowski Mark S. , Thomas David L. , Melia Michael T.
Published: July 2020

In 2014, trained healthcare provider capacity was insufficient to deliver care to an estimated 70 000 persons in Maryland with chronic hepatitis C virus (HCV) infection. The goal of Maryland Community Based Programs to Test and Cure Hepatitis C, a public health implementation project, was to improve HCV treatment access by expanding the workforce. Sharing the Cure (STC) was a package of services deployed 10/1/14‐9/30/18 that included enhanced information technology and public health infrastructure, primary care provider training and practice transformation. Nine primary care sites enrolled. HCV clinical outcomes were documented among individuals who presented for care at sites and met criteria for HCV testing including risk factor or birth cohort (born between 1945 and 1965) based testing. Fifty‐three providers completed the STC training. STC providers identified 3237 HCV antibody‐positive patients of which 2624 (81%) were RNA+. Of those HCV RNA+, 1739 (66%) were staged, 932 (36%) were prescribed treatment, 838 (32%) started treatment, 721 (27%) completed treatment and 543 (21%) achieved cure. Among 1739 patients staged, 693 (40%) patients had a liver fibrosis assessment score < F2, rendering them ineligible for treatment under Maryland Medicaid guidelines. HCV RNA testing among HCV antibody‐positive people increased from 40% (baseline) to 95% among STC providers. Of 554 patients with virologic data reported, 543 (98%) achieved cure. Primary care practices can effectively serve as HCV treatment centers to expand treatment access. However, criteria by insurance providers in Maryland were a major barrier to treatment.
Improving the safety and quality of the intra‐hospital transport of critically ill patients
Authors: Alizadeh Sharafi Rahimeh , Ghahramanian Akram , Sheikhalipour Zahra , Ghafourifard Mansour , Ghasempour Mostafa
Published: July 2020

Background

Adverse events during patient transport are common and may threaten critically ill patients' lives.

Aim

This study aimed to determine the incidence of adverse events during intra‐hospital transport and to obtain suggestions from critical care nurses for improving the transportation process.

Design

This was a cross‐sectional study.

Methods

This study was carried out with 160 critical care nurses between September 2018 and January 2019. Data were collected through a semi‐structured interview using a 53‐item questionnaire developed by Brunsveld‐Reinders et al. It assesses nurses' experiences of adverse events during the three phases of intra‐hospital transport related to equipment, patient physiology, monitoring, medications, and fluid management. The data were analysed using descriptive statistics in SPSS software, and the responses of open‐ended questions were analysed using a conventional qualitative content analysis.

Results

On scales from 0 to 10, the mean (and SD) values of fear, confidence, and skill to carry out a safe intra‐hospital transport were 2.66 (2.73), 6.45 (3.16), and 7.75 (1.55), respectively. The most important causes of feeling afraid or unconfident about the transport among the nurses were unstable patient condition, cardiac arrest, extubation, and oxygen desaturation. In all three phases, oxygen desaturation, haemodynamic instability, and agitation were reported as the most frequent events. The most important suggestions by nurses for improving the transport process were related to paying attention to the patient's clinical condition and connections before, during, and after the transfer.

Conclusions

Along with the acquisition and improvement of technical and tactical skills, adequate human resources and appropriate equipment can improve the quality of intra‐hospital transport.

Relevance to clinical practice

Nurses are key members of the transport team and lead the team. They are responsible for keeping patients safe during transport. By identifying adverse events and trying to modify risk factors, nurses can improve patients' safety.
Bulking as a Mechanism in the Failure of Advanced Ceramics
Authors: Koch Brendan M. L. , Lo Calvin , Sano Tomoko , Hogan James David
Published: July 2020

Failure in brittle materials is characterized by crack growth and fracture, processes which involve an increase in the volume of a sample to accommodate these cracks. This process is called bulking and it is known to be an important factor in the failure of materials such as ceramics, stone, and concrete. While volumetric strains are obtainable under quasi-static conditions, under dynamic conditions technical challenges have stood in the way of obtaining multi-dimensional strain data that would allow for assessment of bulking under the sort loading conditions that would simulate a high velocity impact. Advances in digital-image-correlation and ultra-high-speed-photography have however opened up the capacity to obtain this higher dimensional data. This data in turn has prompted an assessment of prior theory to produce a framework through which stress-strain behavior can be expressed in terms of changes to multiple elastic constants simultaneously. This presentation offers initial results in quasi-static and dynamic experiments and discusses the implications for brittle material behavior and crack evolution phenomenon under a variety of conditions.
Deformation and Acceleration of Zn and Cu Liners under Explosive Shock Loading
Authors: Sutipanya Puwadet , Saito Fumikazu , Nakashita Mitsuyori , Ogino Takashi , Takizawa Yutaka , Okada Yohsuke , Natsubori Masahiko
Published: July 2020

Shaped charge jets (SCJs) are of interest in the field of ballistics because of their excellent penetration ability. The various characteristics of an SCJ, such as density, temperature and length of the jet, are important when estimating the expected penetration depth. Therefore, these characteristics have been widely researched [1-5]. Zernow studied the density deficit associated with an in-flight jet using densitometry [1]. This prior work determined that the 15-20% density deficit of a Cu jet (as reported by Jamet [2]) includes a temperature contribution of 3.5%, an experimental error of 5% and a so-called “vacancy avalanche” contribution of 6.5%. Uhlig and Hummer measured the conductivity and temperature of in-flight Cu SCJs by employing a novel magnetic diffusion technique and five color radiometry. The resulting conductivity values indicated that the tip of the SCJ had a bulk temperature on the order of 1200 K, which is in the vicinity of the melting point of Cu (1350 K) [3]. Hertel et al. developed an analytical model for the SCJ formation process. CTH calculations utilizing their analytical model accurately predicted the thermodynamic characteristics of the SCJ [4, 5]. Huang quantified the density of an SCJ and reported the density distribution based on evaluating the x-ray absorption coefficient of a metal jet [6], and found that the density of a powder metal jet decreases toward the jet tip as the jet elongates. These prior reports indicate that observations of various jet features under high temperature conditions (close to the melting point) can be a useful means of assessing the density deficit of an SCJ.
Modelling the deformation of a high-hardness armour steel in Taylor rod-on-anvil experiments
Authors: Ryan Shannon , McDonald Brodie , Scott Nikki , Bigger Rory , Chocron Sidney
Published: July 2020

A high hardness armour steel (HHA) has been subjected to mechanical characterization under tension, compression, and shear loading at quasi-static and dynamic rates incorporating ambient and elevated temperatures. The resulting data has been used to derive constants for four plasticity constitutive models: Johnson-Cook (JC), Zerilli-Armstrong (ZA), modified Johnson-Cook (MJC), and a generalized J2-J3 yield surface (GYS). The resulting models have been used to predict the response of the HHA material during Taylor rod-on-anvil experiments. High speed photography and digital image correlation was used during the rod-on-anvil experiments to capture both transient deformation profiles and maximum principal strain along the surface of the rod (i.e. compression along the length of the rod). The JC, MJC, and GYS models were found to provide the best prediction of the shape of the rod (nose diameter and length), within 2% of the experimental measurement in all four rod-on-anvil experiments which did not result in fracture. The JC and GYS models, furthermore, were found to provide the best agreement with the measured transient surface strain profiles, predicting the experimental measurement to within 10% at all measurement locations and time steps for the experiment resulting in maximum deformation (impact velocity = 208 m/s). The results suggest that the added complexity of models such as the MJC and GYS, which incorporate strain hardening saturation, two-part strain rate dependency, and J3 plasticity effects, are unnecessary for HHA under the loading conditions experienced during rod-on-anvil experiments.
Modelling the Fracture of High-Hardness Armour Steel in Taylor Rod-on-Anvil Experiments
Authors: McDonald Brodie , Ryan Shannon , Cimpoeru Stephen J. , Edwards Nathan , Orifici Adrian
Published: July 2020

A series of Taylor rod-on-anvil experiments have been performed to validate the predicted impact velocity fracture threshold and fracture mode of a high hardness armour steel (HHA) obtained through explicit finite element simulations. Experimentally, the rods exhibited principal shear failure, a condition that can be closely linked to adiabatic shear band (ASB) formation in high strength steel. Using a stress triaxiality and Lode angle dependent failure strain criterion (Basaran 3D fracture locus), calibrated from quasi-static mechanical characterisation tests, the simulations were unable to predict the onset of fracture observed in experiments. As such, a strength-fading criterion is proposed using a phenomenological description to capture the loss of load-carrying capacity resulting from ASB formation. The ASB criterion is based on an exponential fit to experimentally-observed instability strains measured at different average stress triaxialities in a series of tests on inclined cylindrical and modified flat-hat specimens. With the prediction of ASB formation the material strength is reduced to model the thermal softening experienced in the shear band, and fracture of the material (in the form of element erosion) remains controlled by the Basaran fracture model. Incorporating the ASB-based criterion, the numerical models were found to accurately predict both the impact velocity fracture threshold, as well as the general appearance of the observed principal shear fracture. The proposed criterion enables the effects of ASB formation to be captured in an impact simulation with little increase in computational cost.
Simulation study of non-spherical, graphite-epoxy projectiles
Authors: Miller Joshua E.
Published: July 2020

The DebriSat hypervelocity impact experiment, performed at the Arnold Engineering Development Center, is intended to update the catastrophic break-up models for modern satellites. To this end, the DebrisSat was built with many modern materials including structural panels of carbon-fiber, reinforced-polymer (CFRP). Subsequent to the experiment, fragments of the DebrisSat have been extracted from porous, catcher panels used to gather the debris from the impact event. Thus far, one of the key observations from the collected fragments is that CFRP represents a large fraction of the fragments and that these fragments tend to be thin, flake-like structures or long, needle-like structures; whereas, debris with nearly equal dimensions is less prevalent. As current ballistic limit models are all developed based upon spherical impacting particles, the experiment has pointed to a missing component in the current approach that must be considered. To begin to understand the implications of this observation, simulations have been performed using cylindrical structures at a representative orbital speed into an externally-insulated, double-wall shield that is representative of shielding on the current International Space Station crew transport vehicle, the Soyuz. These simulations have been performed for normal impacts to the surface with three different impact angles-of-attack to capture the effect on the shield performance. This paper documents the simulated shield and the models developed to study the effect of fragments and derives the critical characteristics of CFRP impacting particles for the selected shield. This work gives a deployable form of a critical, non-spherical projectile ballistic limit equation for evaluating non-spherical space debris for orbital debris environment modeling.
Automatic Mesh-Generation (FEM/SPH) for HVI-Simulations of Arbitrary Rotational Symmetric Impactors
Authors: Becker Marvin , Seidl Marina , Mehl Miriam , Souli Mhamed
Published: July 2020

For the numerical description of high velocity impact, Smooth-Particle-Hydrodynamics (SPH) has gained more and more interest. The standard Lagrangian Finite-Element (FE) approach has difficulties in describing large deformations and fracture. However, a simulation based on SPH only is very expensive due to the small size of the particles. A well adopted solution to this is to couple both methods, using SPH only where it is necessary, and capturing the outer boundary conditions with a bias FE-mesh correctly - without considerable extra computational cost.

We apply such a hybrid approach in LS-DYNA® for the characterization of threats in terminal ballistics. Different meshing approaches for the projectile and target were implemented to guarantee an optimal initial condition. The particle size and the required size of the SPH-region were studied to exclude discretization effects. Exemplarily, a projectile surrogate with simplified geometry is investigated for a fixed impact velocity and two different angles of obliquity. A qualitative comparison between experiments, observed with X-ray cinematography, reveals a good potential of this approach towards predicting fracture and ricochet during high velocity impact events.
Effect of Liquid Parameters on Protective Performance of a Liquid Composite Target Subjected to Jet Impact
Authors: Yaping Tan , Xin Jia , Zhengxiang Huang , Youer Cai , Xudong Zu
Published: July 2020

In order to study the influence of liquid parameters on the protective performance of liquid composite targets (LCT), based on the theory of interaction between the jet and the LCT, three dimensionless numbers - C, G, and V - are obtained by dimensional analysis in this paper. These 3 dimensionless parameters represent the compressibility, inertia, and viscosity of the liquid, respectively. The empirical formula, P/H = 0.346C1.251G−0.7120V0.036, was obtained by fitting experimental data of the static depth of penetration (DOP) experiment which can predict the residual depth of penetration (RDOP) of the jet penetrating the LCT. It turns out that the 2 dimensionless parameters - C and G - which characterize the compressibility and inertia of the liquid, plays a decisive role in the protection performance of the LCT, while the influence of liquid viscosity is small. In addition, according to the research results of this paper, the protective performance of the LCT can be improved by selecting a liquid with high sound velocity, high viscosity, and low density.
High Velocity Impact Testing for Evaluation of Intermetallic Projectiles
Authors: Cagle Colton B. , Hill Kevin J. , Woodruff Connor , Pantoya Michelle L. , Abraham Joseph , Meakin Casey
Published: July 2020

Experiments were performed to study penetration through multiple aluminum plates followed by impact into an inert steel anvil using a High-velocity Impact-ignition Testing System (HITS). The projectiles are intermetallic pellets launched from a propellant driven gun into a catch chamber equipped with view ports and imaging diagnostics. Penetration, impact and reaction are monitored using high-speed cameras that provide local and macroscopic perspectives of projectile and target interaction as well as overall reactivity. Results demonstrate the range of visual data that can be captured by a non-gas generating intermetallic projectile that fragments and reacts upon penetration and impact. Results show that higher velocity projectiles (~ 1300 and 800 m/s) produce smaller fragments upon target penetration that result in flame spreading through the chamber upon impact while lower velocity projectiles (~ 500 m/s) negligibly fragment upon target penetration and produce no flames even upon anvil impact.
Optimized Impact Mitigation Barriers for Insensitive Munitions Compliance of a 120mm Warhead
Authors: Miers Kevin T. , Prillaman Daniel L. , Al-Shehab Nausheen M.
Published: July 2020

The U.S. Army Combat Capabilities Development Command (CCDC) Armaments Center at Picatinny Arsenal, NJ is working to develop technologies to mitigate the violent reaction of a 120 mm warhead, loaded with an aluminized HMX-based enhanced blast explosive, when subjected to the NATO Insensitive Munitions (IM) Fragment Impact (FI) test. As per NATO STANAG 4496, FI testing is conducted at 8300±300 ft/s with a 0.563” diameter, L/D~1, 160˚ conical nosed mild steel fragment. Reaction violence resulting from FI can be mitigated by the use of liners or barriers applied to the munition itself or its packaging, commonly referred to as a Particle Impact Mitigation Sleeves (PIMS). Previous development efforts for this item focused on a lightweight plastic warhead support which was able to reduce the severity of the input shock sufficiently to prevent high order detonation. However, violent sub-detonative responses were still observed which occurred over several hundred microseconds, consumed part of the explosive charge, and ejected hazardous debris over large distances. These responses are driven by rapid combustion coupled with damage to the explosive as well as mechanical confinement. Quantitative modeling of these scenarios is a challenging active research area. Prior experimental results and modeling guidance have shown that mitigation of these reactions requires a more substantial reduction in the overall mechanical insult to the explosive. In particular, steel and aluminum PIMS have been able to efficiently provide the necessary fragment velocity reduction, breakup and dispersion in typical packaging applications. Packaged warheads were tested at the GD-OTS Rock Hill facility with several PIMS designs incorporated into the ammunition containers. Several designs were demonstrated to provide benign reactions with minimal added weight. Future iterations will attempt to further improve the design using advanced lightweight barrier materials.
Laser-Driven High-Velocity Microparticle Launcher In Atmosphere And Under Vacuum
Authors: Veysset David , Sun Yuchen , Kooi Steven E. , Nelson Keith A.
Published: July 2020

The study of high-velocity microparticles is important to a wide range of both space and terrestrial applications. In space, high- and hyper-velocity micro-debris and micrometeorites, while also a subject of study, pose a threat to equipment and personnel integrity [1–4]. On earth, high-velocity microparticle impact can be, for instance, utilized for therapeutic purposes in the field of biolistics [5] or to build metallic coatings via the cold spray method [6]. While macroscale projectile impacts have been studied using well established experimental tools, such as light-gas guns, optical methods are gaining interest in the field of micro-particle impacts.
Reducing Anxiety and Anxiety Sensitivity With High-Intensity Interval Training in Adults With Asthma
Authors: O’Neill Carley , Dogra Shilpa
Published: July 2020

Background: Low- and moderate-intensity exercise training has been shown to be effective for reducing general anxiety and anxiety sensitivity among adults with asthma. Exercise frequency and intensity have been shown to play an integral role in reducing anxiety sensitivity; however, less is known about the impact of high-intensity interval training (HIIT) on anxiety in adults with asthma. Methods: A 6-week HIIT intervention was conducted with adults with asthma. Participants completed HIIT (10% peak power output for 1 min, 90% peak power output for 1 min, repeated 10 times) 3 times per week on a cycle ergometer. Preintervention and postintervention assessments included the Anxiety Sensitivity Index-3 and the Body Sensations Questionnaire. Results: Total Anxiety Sensitivity Index-3 (PRE: 17.9 [11.8]; POST 12.4 [13], P = .002, Cohen d = 0.4, n = 20) and Body Sensations Questionnaire (PRE: 2.4 [1.0]; POST: 2.0 [0.8], P = .007, Cohen d = 0.3) improved from preintervention to postintervention. Conclusion: A 6-week HIIT intervention leads to improved anxiety among adults with asthma. Future research should determine the impact of HIIT among adults with asthma with clinical anxiety.
Association of Physical Activity and Cardiometabolic Risk in Children 3–12 Years
Authors: Vanderloo Leigh M. , Maguire Jonathan L. , Dai David W. H. , Parkin Patricia C. , Borkhoff Cornelia M. , Tremblay Mark S. , Anderson Laura N. , Birken Catherine S. , _ _
Published: July 2020

Background: This study aimed to examine the association between physical activity (PA) and a total cardio metabolic risk (CMR) score in children aged 3–12 years. Secondary objectives were to examine the association between PA and individual CMR factors.Methods: A longitudinal study with repeated measures was conducted with participants from a large primary care practice-based research network in Toronto, Canada. Mixed effects models were used to examine the relationship between parent-reported physical activity and outcome variables (total CMR score, triglycerides, glucose, high-density lipoprotein cholesterol, systolic blood pressure, waist circumference, weight-to-height ratio, and non-high-density lipoprotein cholesterol).Results: Data from 1885 children (6.06 y, 54.4% male) with multiple visits (n = 2670) were included in the analyses. For every unit increase of 60 minutes of PA, there was no evidence of an association with total CMR score (adjusted: −0.02 [−0.014 to 0.004],P = .11]. For the individual CMR components, there was evidence of a weak association between PA and systolic blood pressure (−0.01 [−0.03 to −0.01],P < .001) and waist-to-height ratio (−0.81 [−1.62 to −0.003],P < .001).Conclusion: Parent-reported PA among children aged 3–12 years was not statistically associated with total CMR, but was weakly associated with systolic blood pressure and waist-to-height ratio.
The Chief Joseph dike swarm of the Columbia River flood basalts, and the legacy data set of William H. Taubeneck
Authors: Morriss Matthew C. , Karlstrom Leif , Nasholds Morgan W.M. , Wolff John A.
Published: July 2020

The Miocene Columbia River Basalt Group (CRBG) is the youngest and best studied continental flood basalt province on Earth. The 210,000 km3 of basaltic lava flows in this province were fed by a series of dike swarms, the largest of which is the Chief Joseph dike swarm (CJDS) exposed in northeastern Oregon and southwestern Washington. We present and augment an extensive data set of field observations, collected by Dr. William H. Taubeneck (1923–2016; Oregon State University, 1955–1983); this data set elucidates the structure of the CJDS in new detail.

The large-scale structure of the CJDS, represented by 4279 mapped segments mostly cropping out over an area of 100 × 350 km2, is defined by regions of high dike density, up to ∼5 segments/km−2 with an average width of 8 m and lengths of ∼100–1000 m. The dikes in the CJDS are exposed across a range of paleodepths, from visibly feeding surface flows to ∼2 km in depth at the time of intrusion. Based on extrapolation of outcrops, we estimate the volume of the CJDS dikes to be 2.5 × 102–6 × 104 km3, or between 0.1% and 34% of the known volume of the magma represented by the surface flows fed by these dikes. A dominant NNW dike segment orientation characterizes the swarm. However, prominent sub-trends often crosscut NNW-oriented dikes, suggesting a change in dike orientations that may correspond to magmatically driven stress changes over the duration of swarm emplacement. Near-surface crustal dilation across the swarm is ∼0.5–2.7 km to the E-W and ∼0.2–1.3 km to the N-S across the 100 × 350 km region, resulting in strain across this region of 0.4%–13.0% E-W and 0.04%–0.3% N-S. Host-rock partial melt is rare in the CJDS, suggesting that only a small fraction of dikes were long-lived.
Population health, economics and ethics in the age of COVID-19
Authors: Reddy Sanjay G
Published: July 2020

Are the steps that have been taken to arrest the spread of COVID-19 justifiable? Specifically, are they likely to have improved public health understood according to widely used aggregate population health measures, such as Quality Adjusted Life Years (QALYs) and Disability Adjusted Life Years (DALYs) as much or more than alternatives? This is a reasonable question, since such measures have been promoted extensively in global and national health policy by influential actors, and they have become almost synonymous with quantification of public health. If the steps taken against COVID-19 did not meet this test, then either the measures or the policies must be re-evaluated. There are indications that policies against COVID-19 may have been unbalanced and therefore not optimal. A balanced approach to protecting population health should be proportionate in its effects across distinct health concerns at a moment, across populations over time and across populations over space. These criteria provide a guide to designing and implementing policies that diminish harm from COVID-19 while also providing due attention to other threats to aggregate population health. They should shape future policies in response to this pandemic and others.