bluuebunny/crossref_metadata_2025 huggingface dataset:
Extending ageing nurses' working lives: A mixed‐methods systematic review
Authors: Nurmeksela Anu , Välimäki Tarja , Kvist Tarja , Savolainen Helmiina , Tahiraj Vanesa , Hult Marja
Published: January 2023

Aim(s)

To identify, describe and assess research evidence on factors that promote working until and beyond the official retirement age among nurses.

Design

A mixed‐methods systematic review.

Prospero ID

CRD42022303890.

Data Sources

The CINAHL, PsycINFO, MEDLINE, Scopus, SocINDEX and Web of Science databases were searched in December 2021.

Review Methods

The Preferred Reporting Items for Systematic Reviews and Meta‐Analysis (PRISMA) checklist was followed. Two researchers independently applied eligibility criteria, selected studies and conducted quality appraisals. Data‐based convergent synthesis and thematic analysis were used.

Results

Eighteen studies were included, most of which were survey‐based. Eleven studies were quantitative, six were qualitative and one used mixed methods. Our results reveal that willingness to continue in work increased with age. Six factors promoted working until and beyond the official retirement age among nurses: good health and work ability, the significance of work sufficient income, meaningful relationships and support in the working community, individually tailored work arrangements, and organizational support and recognition.

Conclusion

To sustain experienced nurses in working life and promote their working beyond retirement age organizations urgently need to apply throughout working lives supporting age management schemes. Interventions should target supportive relations and individual and flexible arrangements at the workplace. Scarce studies investigated factors contributing to an extension of working life among nurses. Most published evidence on this topic is based primarily on nurses' subjective opinions and preferences: no intervention studies or objective evaluations of factors affecting retirement were found.

Impact

The available evidence suggests the most critical factors for extending nurses' working lives are support and individual and flexible arrangements in the workplace. There is a need to test interventions and evaluate the effectiveness of measures encouraging nurses to extend their working lives.

No Patient or Public Contribution

Systematic review.
Decomposing clinical practice guidelines panels' deliberation into decision theoretical constructs
Authors: Djulbegovic Benjamin , Hozo Iztok , Lizarraga David , Guyatt Gordon
Published: January 2023

Rationale, Aims and Objectives

The development of clinical practice guidelines (CPG) suffers from the lack of an explicit and transparent framework for synthesising the key elements necessary to formulate practice recommendations. We matched deliberations of the American Society of Haematology (ASH) CPG panel for the management of pulmonary embolism (PE) with the corresponding decision‐theoretical constructs to assess agreement of the panel recommendations with explicit decision modelling.

Methods

Five constructs were identified of which three were used to reformulate the panel's recommendations: (1) standard, expected utility threshold (EUT) decision model; (2) acceptable regret threshold model (ARg) to determine the frequency of tolerable false negative (FN) or false positive (FP) recommendations, and (3) fast‐and‐frugal tree (FFT) decision trees to formulate the entire strategy for management of PE. We compared four management strategies: withhold testing versus d‐dimer → computerized pulmonary angiography (CTPA) (‘ASH‐Low’) versus CTPA→
d‐dimer (‘ASH‐High’) versus treat without testing.

Results

Different models generated different recommendations. For example, according to EUT, testing should be withheld for prior probability PE < 0.13%, a clinically untenable threshold which is up to 15 times (2/0.13) below the ASH guidelines threshold of ruling out PE (at post probability of PE ≤ 2%). Three models only agreed that the ‘ASH low’ strategy should be used for the range of pretest probabilities of PE between 0.13% and 13.27% and that the ‘ASH high’ management should be employed in a narrow range of the prior PE probabilities between 90.85% and 93.07%. For all other prior probabilities of PE, choosing one model did not ensure coherence with other models.

Conclusions

CPG panels rely on various decision‐theoretical strategies to develop its recommendations. Decomposing CPG panels' deliberation can provide insights if the panels' deliberation retains a necessary coherence in developing guidelines. CPG recommendations often do not agree with the EUT decision analysis, widely used in medical decision‐making modelling.
Processing of encapsulated flaxseed oil‐rich banana‐based (Dwarf cavendish) functional fruit leather
Authors: Sarma Onkar , Kundlia Mohit , Chutia Hemanta , Mahanta Charu Lata
Published: January 2023

Banana fruit leather enriched with flaxseed oil in the form of encapsulates was prepared. Initially, the optimized conditions of 836 W power for 4 min for blanching of banana using microwave were obtained by Response Surface Methodology with residual polyphenol oxidase activity and vitamin C retention taken as responses. The addition of maltodextrin, citric acid, and pectin for blending with banana puree to obtain a non sticky puree having low pH was also optimized, while keeping the quantity of sugar constant. The blend was added with 5% encapsulates of flaxseed oil (FSO) in alginate used as wall material. The blend was dried in a tray drier at 40, 50, and 60°C and the drying behavior of the leather was studied. Henderson and Pabis model satisfactorily described the drying kinetics of banana leather. GAB model described well the sorption behavior of the leather. Fat content in the optimized leather increased to 3.27% due to addition of FSO. The ash content in the enriched leather was 5.56 ± 0.03%. Phenolic content increased from 91.84 ± 0.06 mg GAE/100 g to 100.90 ± 0.05 mg GAE/100 g for the enriched leather as compared to the control. The study revealed that the banana leather can be considered as a functional snack food due to the availability of flaxseed oil (rich in ω‐3 fatty) and high phenolic acid content.

Practical Applications

Banana can be processed into functional fruit leather with the addition of flaxseed oil encapsulated beads to complement the fast moving consumer goods market. Developing the banana leather by drying enhances its shelf life while encapsulation increases the stability of flaxseed oil for a prolonged storage of the product. Flaxseed oil is rich in ω‐3 fatty acid, an important bioactive compound required for good human health. Moreover, modeling of the drying behavior allows optimization of the process, which is necessary for designing of energy efficient industrial flow dryers. Therefore, this study on development of a novel functional product and drying kinetics will give a new edge to the industrial processing of similar snack products with a potential alternative to reduce the waste of banana as a raw material.
Frailty predicts referral for elder abuse evaluation in a nationwide healthcare system—Results from a case–control study
Authors: Makaroun Lena K. , Rosland Ann‐Marie , Mor Maria K. , Zhang Hongwei , Lovelace Elijah , Rosen Tony , Dichter Melissa E. , Thorpe Carolyn T.
Published: January 2023

Background

Elder abuse (EA) is common and has devastating health impacts. Frailty may increase susceptibility to and consequences of EA for older adults, making healthcare system detection more likely, but this relationship has been difficult to study. We examined the association between a recently validated frailty index and referral to social work (SW) for EA evaluation in the Veterans Administration (VA) healthcare system.

Methods

We conducted a case–control study of veterans aged ≥60 years evaluated by SW for suspected EA between 2010 and 2018 (n = 14,723) and controls receiving VA primary care services in the same 60‐day window (n = 58,369). We used VA and Medicare claims data to measure frailty (VA Frailty Index) and comorbidity burden (the Elixhauser Comorbidity Index) in the 2 years prior to the index. We used adjusted logistic regression models to examine the association of frailty or comorbidity burden with referral to SW for EA evaluation. We used Akaike Information Criterion (AIC) values to evaluate model fit and likelihood ratio (LR) tests to assess the statistical significance of including frailty and comorbidity in the same model.

Results

The sample (n = 73,092) had a mean age 72 years; 14% were Black, and 6% were Hispanic. More cases (67%) than controls (36%) were frail. LR tests comparing the nested models were highly significant (p < 0.001), and AIC values indicated superior model fit when including both frailty and comorbidity in the same model. In a model adjusting for comorbidity and all covariates, pre‐frailty (aOR vs. robust 1.7; 95% CI 1.5–1.8) and frailty (aOR vs. robust 3.6; 95% CI 3.3–3.9) were independently associated with referral for EA evaluation.

Conclusions

A claims‐based measure of frailty predicted referral to SW for EA evaluation in a national healthcare system, independent of comorbidity burden. Electronic health record measures of frailty may facilitate EA risk assessment and detection for this important but under‐recognized phenomenon.
Negative Interest Rate Policy and the Influence of Macro‐Economic News on Yields
Authors: FATUM RASMUS , HARA NAOKO , YAMAMOTO YOHEI
Published: January 2023

We consider the influence of domestic and U.S. macro‐economic news surprises on daily bond yields over the January 1999 to January 2018 period for four advanced negative interest rate policy (NIRP) economies—Germany, Japan, Sweden, and Switzerland. Our results suggest that the influence of macro‐economic news surprises is for all four countries under study during the NIRP period nonexistent or noticeably weaker than during the preceding zero interest rate policy (ZIRP) period. Our results are consistent with the suggestion that NIRP is characterized by a lower bound that is no less constraining than the zero‐lower bound that characterizes ZIRP.
The possible impact of DNA‐binding chromodomain‐helicase 5 polymorphisms on male infertility: A case–control study
Authors: Moudi Bita , Asemi‐Rad Azam , Sheibak Nadia , Heidari Zahra , Mahmoudzadeh‐Sagheb Hamidreza
Published: January 2023

Background

Chromodomain‐helicase 5 (CHD5) is a conventional tumor‐suppressing gene in many tumors. The CHD5 gene, as a key factor in the chromatin density process during sperm maturation, can affect the risk of infertility. This study aimed to determine whether CHD5 variants contribute to the risk of male infertility.

Methods

Gene variants were identified using tetra primer‐ARMS‐PCR method on nonobstructive azoospermia and severe oligozoospermia in a case–control study. SPSS software 20 (SPSS Inc. Chicago, IL, USA) was used for data recording and statistical analysis.

Results

In the codominant pattern, the rs12067480 TT variant versus CC significantly increased the risk of disease, and also, in the recessive pattern, TT variant versus CC + CT and T allele versus C. The rs2273032 variant was associated with the risk of infertility in codominant pattern AA versus GG and recessive pattern AA versus GG + GA and allele. We discovered that the rs12067480 T and rs2273032 A alleles increase the risk of male infertility. Also, the interaction of the CT/GA, CT/AA, TT/GA genotypes and rs12067480T/rs2273032A and rs12067480T/rs2273032G haplotypes significantly increased the risk of infertility.

Conclusions

Our results suggest that the CHD5 gene polymorphisms contribute to the risk of male infertility. Our findings can be valuable in improving the diagnosis and treatment of infertility.
Empowering the youth to choose non‐traditional careers in research and academia
Authors: Castilho Rogerio M. , Castilho Matthew S. , Simmons Zoë , Squarize Cristiane H.
Published: January 2023

Backgroud

The United States is facing a dramatic shortage of clinician‐scientists within the domains of medicine and dentistry.

Point of view

In this perspective article, we stressed the problem involving the continuous shortage of specialized professionals capable of addressing complex basic sciences questions, while maintaining clinical relevance. Here we present a different perspective regarding the early engagement of young students to clinical sciences by teaming up with high schools across the United States, and to energize the debate on our current shortage of clinician‐scientists.
Improved selection strategy for multi‐objective evolutionary algorithms with application to water distribution optimization problems
Authors: Wang Peng , Zecchin Aaron C. , Maier Holger R.
Published: January 2023

Multi‐objective evolutionary algorithms (MOEAs) have been applied to water distribution system (WDS) optimization problems for over two decades. The selection strategy is a key component of an MOEA that determines the composition of a population, and thereby the evolutionary search process, which imitates natural selection by granting fitter individuals an increasing opportunity to reproduce. This paper proposes the convex hull contribution (CHC) selection strategy for generational MOEAs (CHCGen) as a novel selection strategy that is based on the CHC of solutions to the Pareto front in the objective space. Numerical experiments using a general MOEA framework demonstrate that the CHCGenselection strategy is able to outperform existing popular selection strategies (e.g., crowding distance, hypervolume contribution, and hybrid replacement selection). Moreover, it is illustrated that the CHCGenselection strategy is able to improve the performance of existing MOEAs such as NSGA‐II and GALAXY. The conclusions are based on the results of six bi‐objective WDS problems.
A single region of the Phytophthora infestans avirulence effector Avr3b functions in both cell death induction and plant immunity suppression
Authors: Gu Biao , Gao Wenxin , Liu Zeqi , Shao Guangda , Peng Qin , Mu Yinyu , Wang Qinhu , Zhao Hua , Miao Jianqiang , Liu Xili
Published: January 2023

As a destructive plant pathogen, Phytophthora infestans secretes diverse host‐entering RxLR effectors to facilitate infection. One critical RxLR effector, PiAvr3b, not only induces effector‐triggered immunity (ETI), which is associated with the potato resistance protein StR3b, but also suppresses pathogen‐associated molecular pattern (PAMP)‐triggered immunity (PTI). To date, the molecular basis underlying such dual activities remains unknown. Based on phylogenetic analysis of global P. infestans isolates, we found two PiAvr3b isoforms that differ by three amino acids. Despite this sequence variation, the two isoforms retain the same properties in activating the StR3b‐mediated hypersensitive response (HR) and inhibiting necrosis induced by three PAMPs (PiNpp, PiINF1, and PsXeg1) and an RxLR effector (Pi10232). Using a combined mutagenesis approach, we found that the dual activities of PiAvr3b were tightly linked and determined by 88 amino acids at the C‐terminus. We further determined that either the W60 or the E134 residue of PiAvr3b was essential for triggering StR3b‐associated HR and inhibiting PiNpp‐ and Pi10232‐associated necrosis, while the S99 residue partially contributed to PTI suppression. Additionally, nuclear localization of PiAvr3b was required to stimulate HR and suppress PTI, but not to inhibit Pi10232‐associated cell death. Our study revealed that PiAvr3b suppresses the plant immune response at different subcellular locations and provides an example in which a single amino acid of an RxLR effector links ETI induction and cell death suppression.
An ecological and epidemiological single‐season survey of Anaplasma and Ehrlichia positive ticks in Victoria Falls National Park, Zimbabwe
Authors: Day C. A. , Butler R. A. , Durick H. E. , Chandler J. G. , Paulsen David J. , Mordoh S. L. , Foggin C. , Parry R. , Moyo I. , Russo L. , Kennedy M. A. , Trout Fryxell R. T.
Published: January 2023

There is an urgent need for continued research on the ecology of tick‐borne diseases in Africa. Our objective was to provide a preliminary description of the ecology and epidemiology of tick species, tick‐borne pathogens, and animal hosts in Zimbabwe, focusing efforts at Victoria Falls National Park, for a single season. We tested the hypothesis that tick surveillance and pathogen screening data can be used to model associations among ticks, hosts, and pathogens. We collected ticks from domesticated animals and wildlife in Zimbabwe and screened the ticks for the presence of Anaplasma and Ehrlichia bacteria. Nearly 30% of the screened ticks were PCR‐positive; 89% of tick species were PCR‐positive, and 88% of animal species carried at least one PCR‐positive tick. We sequenced a subset of amplicons that were similar to three Anaplasma species and three Ehrlichia species. The odds of a tick being PCR‐positive increased when many ticks were collected from the host or the tick was collected from a cow (domesticated animal). Tick species shared host species more often than expected. We demonstrate that ticks in northwestern Zimbabwe present a One Health problem for nearby wildlife and humans.
Selective Mortality and the Long‐Term Effects of Early‐Life Exposure to Natural Disasters
Authors: Triyana Margaret , Xia Xing
Published: January 2023

We analyze the effects of early‐life shocks in the Philippines and find that in utero exposure to severe typhoons is associated with adverse outcomes. We exploit variations in typhoon exposure and sharp increases in short‐term disaster relief efforts in the 1960s. Before the increase in disaster relief efforts, in utero exposure to severe typhoons was associated with higher mortality (a 9% reduction in cohort size); survivors exhibited similar levels of human capital as the unaffected. After the increase in disaster relief, the mortality effects were mitigated; however, survivors exhibited lower human capital in the long term. We offer suggestive evidence that the observed changes in adverse long‐term effects are due to the relief efforts' effectiveness in increasing survival probability.
Intraoperative blood product transfusion in pediatric cardiac surgery patients: A retrospective review of adverse outcomes
Authors: Busack Christopher , Rana Md Sohel , Beidas Yousef , Almirante Juan Miguel , Deutsch Nina , Matisoff Andrew
Published: January 2023

Background

Resuscitation with blood products is often required for pediatric cardiac surgery patients following cardiopulmonary bypass. However, data suggest that blood product transfusion is an independent predictor of adverse outcomes. Most studies have specifically found detrimental effects of overall transfusion of red blood cells in particular, but few have analyzed outcomes by the other specific blood product components.

Aims

The objective of this study is to analyze adverse outcomes associated with intraoperative transfusion of specific blood product components.

Methods

A retrospective review was performed on 643 pediatric patients who underwent cardiac surgery requiring cardiopulmonary bypass to evaluate the risk of selected adverse outcomes associated with intraoperative blood product transfusion. Adverse outcomes included thrombotic complications, stroke, acute kidney injury, prolonged mechanical ventilation, and death. Univariate logistic and linear regression analyses were performed to explore the association between various blood products and the occurrence of postoperative complications. Multiple logistic and linear regression analyses were performed adjusting for age, cyanotic status, The Society of Thoracic Surgeons‐European Association for Cardio‐Thoracic Surgery Score (STAT score), and cardiopulmonary bypass time.

Results

Unadjusted analysis using univariate logistic and linear regressions showed statistically significant associations of almost all blood components (per 10 mL/kg dose increments) with multiple postoperative complications, including mortality, thrombotic complications, stroke, and days of mechanical ventilation. After adjusting for patient age, cyanotic status, STAT score, and cardiopulmonary bypass time, multivariable logistic and linear regression analyses revealed no association between transfusion of blood products with acute kidney injury and stroke. Administration of red blood cells was the only category significantly correlated with increased days of mechanical ventilation (0.5 days increase in mechanical ventilation per 10 mL/kg transfusion of red blood cells). The only blood product to show complete lack of a statistically significant association with any of the studied outcomes was cryoprecipitate.

Conclusions

Transfusion of blood products following cardiopulmonary bypass is associated with postoperative adverse outcomes. Future studies aimed at strategies to reduce intraoperative bleeding and decrease the amount of blood products administered are warranted.
Late airway complications following pediatric liver transplantation: A case series
Authors: Rajasekaran Vivek , McCaffer Craig , Bishop Jonathan , Van Der Meer Graeme , Toll Edward C. , Evans Helen
Published: January 2023

Background

Late airway complications, as consequence of immunosuppression following pediatric liver transplantation are uncommonly reported.

Methods

In this retrospective case series, we describe two young children presenting with symptoms of airway obstruction, secondary to differing pathologies in the supraglottic airway, as a result of immunosuppression following liver transplantation.

Results

Case 1, a 2‐year‐old girl who presented with stridor 12‐months following liver transplantation, was found to have a proliferative soft tissue mass involving the supraglottic larynx. Biopsies were consistent with infiltrative eosinophilic laryngitis and associated eosinophilic esophagitis. Case 2, a 12‐month‐old female who presented with stridor 5‐months following liver transplantation, was found to have an exophytic soft tissue mass involving the supraglottis and hypopharynx. Biopsies revealed polymorphic Epstein–Barr virus (EBV) driven post‐transplant lymphoproliferative disease (PTLD). Case 1 was managed with local resection and high dose oral corticosteroids. Case 2 responded to debulking of the necrotic supraglottic mass, reduction of immunosuppression and rituximab.

Conclusion

A high index of suspicion needs to be maintained for complications of immunosuppression for appropriate diagnosis of airway presentations following pediatric liver transplantation. Further research is necessary to improve early detection and consolidate management strategies for these airway lesions.
Demand uncertainty reduction among competing retailers
Authors: Li Meng
Published: January 2023

While the existing literature has studied the impact of demand uncertainty extensively within various monopoly settings, there is little research on its impact among competitive retailers. In this paper, we study the effects of demand uncertainty reduction in a setting with two newsvendor retailers competing on product availability. We parameterize the uncertainty level via a mean‐preserving spread and investigate the behavior of both retailers' equilibrium stocks and their expected profits in response to demand uncertainty reduction. We find that as one retailer's demand uncertainty decreases, it might move its order quantity away from the demand mean, which contrasts with the “pull‐to‐center” effect in the monopoly setting. Moreover, we show that as a retailer's demand uncertainty decreases, its own equilibrium profit increases while that of its competitor decreases.
Empirical investigation of the agriculture–malnutrition nexus in Africa: Spatial clustering and spillover effects
Authors: Okunlola Oluyemi Adewole , Kassouri Yacouba
Published: January 2023

Many studies have been conducted to examine the direct effect of agriculture on the prevalence of malnutrition; however, there is little solid evidence on spatial spillover effects and much less on the heterogeneous effects stemming from spatial differences in nutritional conditions. We make up this gap by using a dynamic spatial Durbin model to characterize the impact of agricultural productivity on malnutrition in Africa. Our results show that countries in Eastern Africa are more likely to suffer from severe malnutrition than other regions. We find evidence for convergence in agricultural productivity across countries with moderate and high prevalence of malnutrition as disparities in their agricultural productivity narrow down over the sample period. It appears that the negative effect of agriculture on malnutrition is more evident in countries where the prevalence of malnutrition is lower. This implies that agricultural development does not play a substantial role in reducing malnutrition in the worst affected areas. We also report that poor agricultural development can deteriorate the nutritional status among neighboring countries in the short term, consistent with the spatial‐locking effect of agriculture.
Phylogeny of the Poritiinae (Lepidoptera: Lycaenidae), butterflies with ant associations and unusual lichenivorous diets
Authors: Boyle John H. , Espeland Marianne , Sáfián Szabolcs , Ducarme Robert , Gardiner Alan J. , Coleman James W. , Heath Alan , Fisher Stewart , Collins Steve C. , Martins Dino J. , Aduse‐Poku Kwaku , Libert Michel , Dankowicz Even , Kawahara Akito Y. , Lohman David J. , Pierce Naomi E.
Published: January 2023

The Poritiinae are a diverse subfamily of lycaenid butterflies with about 700 species divided into two major groups: the Asian endemic tribe Poritiini, and the African endemic tribe Liptenini. Among these, the Liptenini are notable for their lichenivorous diet and the strong but apparently non‐mutualistic ant associations of many species. We present the first molecular phylogeny for this subfamily, based on data from 14 gene regions, and including 218 representatives from 177 taxa (approximately 25% of species) in 50 of the 58 (86%) recognized genera. From this analysis, we confirm the division of the subfamily into two tribes, and we rearrange the Liptenini tribe into six subtribes, Durbaniina, Pentilina, Liptenina, Iridanina and Epitolina, plus a new tribe, Cooksoniina subtrib. n., to fill a gap in the nomenclature revealed by the phylogenetic analysis. We also point to several genera in need of further taxonomic revision. Ancestral range reconstruction could not infer the range of the common ancestor of the Poritiinae; however, the common ancestor of the Poritiini was likely Asian, while that of the Liptenini was likely African, with subsequent narrowing of ranges in several lineages.
Everyday materialities, territorial bordering, and place-identity defined by recent administrative reform: reactions from Estonian dispersed ruralities
Authors: Kasemets Kadri , Nugin Raili
Published: January 2023

Population decline in rural areas has been a concern for many European countries for decades. To deal with shrinking, several measures have been taken in different countries. The study focuses on one of such measures – the administrative reform passed in Estonia in 2017, which merged smaller municipalities into regional municipality centres. This article examines the impact of this reform on rural transformation, concentrating on shifts in everyday mobilities, governance, and territorial identity at the village level. The research data is contextualised with the new mobilities paradigm, examining the relational everyday materialities that include interviews reflecting on changes at the regional, structural, and ideological levels. The analysis is based on in-depth interviews (N=60) with local activists and inhabitants in three study areas in sparsely populated parts of Estonia. The creation of municipality districts with representative bodies within larger municipalities have influenced these rural villages in various ways. In some cases, it has caused shifts in the mechanisms of civil governance that shape community activism. In others, strengthened awareness of representations of the rural appeared, offering a meaningful territorial identity and self-realisation to local people. However, the study also indicates that the distribution of rural municipalities into municipality districts can jeopardise local coherence and socio-cultural sustainability.
Young people as agents in regional shrinkage – commentary to Syssner
Authors: Kettunen Marika , Prokkola Eeva-Kaisa
Published: January 2023

This paper reflects on Josefina Syssner’s Fennia lecture “What could geographers do for shrinking geographies”. In this commentary, we extend upon and complement Syssner’s inquiry by suggesting that to gain a better understanding of regional shrinkage and shrinking geographies it is important to ask the who question as well. Shrinkage and the policies used to deal with it impact different people in different ways, and people have different abilities to react to these changes or to take part in shaping the policies. In this reflection paper, we focus on a specific age group that is often considered important in regional development and policy discussions but that has been ignored in the debates on shrinking geographies – young people. In the end, we ask what geographers could do to increase the understanding of and possibilities for young people to live a good life in shrinking regions in times of environmental crises.
Assessment of Using Software for the Acquisition of Problem-solving Skills in Mechanical Engineering Students
Authors: Góngora Nicolás , Malagón Dionisio Humberto , Velasco Marco Antonio
Published: January 2023

Objective: To investigate the effect of using mathematical software as a tool to develop problem-solving competence in mechanical engineering students. Methods: A group of 59 students were evaluated using a test consisting of four technological problems related to Bloom´s taxonomy levels of understanding and application. Interpretation and explanation questions were used for the understanding level, and execution and implementation questions were used for the application level. First, the students tried to solve the problems by manual calculations; then, after brief instruction, they tried to solve them by coding using mathematical software. Results: Successful problem solutions increased from 72 to 93%, 15 to 62% and 13 to 26% of the students’ totals in interpreting, explaining, and implementing situations, respectively, but there was a 55 to 44% regression in regard to execution. Better results in understanding questions with respect to applying questions could be due to the increase in difficulty at the taxonomy level. Conclusion: The current study demonstrates the convenience of using computational tools to facilitate the application of mathematical techniques in problem solving and to improve the learning of engineering students.
Fatigue behavior of ultrahigh-performance fiber-reinforced concrete as an alternative for flexible pavement rehabilitation
Authors: Torres Giovanni , Romano Juan , Vacca Hermes , Alvarado Yezid , Reyes Fredy
Published: January 2023

The fatigue behavior of ultrahigh-performance fiber-reinforced concrete for use as an overlay in the typical rehabilitation of a flexible pavement structure was analyzed in this study. Compression and four-point bending tests were carried out to characterize the concrete mechanical properties. Fatigue tests were performed using the four-point method, and test beams were evaluated without precracking. The specimens were subjected to constant-amplitude sinusoidal loading with a loading frequency of 10 Hz. The magnitude of each stress level was calculated as a percentage of the initial crack stress. The following results were obtained for the concrete: a compressive strength of 127.1 MPa, bending yield strength of 6.23 MPa, maximum bending stress of 9.89 MPa, Young's modulus of 38.1 GPa, and dynamic modulus of 28.6 GPa. The stress and strain at one million cycles were 6.0 MPa and 166 μm/m, respectively. The fatigue test results indicated superior properties of the ultrahigh-performance concrete to those of similar materials.
A Geographical Method for Assessing Social Distancing as a Preliminary Tool for Implementation Planning. A Case Study: Chapinero, Bogota
Authors: Sánchez Gómez Juan Sebastián , Gutiérrez Aguilar Laura Alejandra
Published: January 2023

Given the pandemic situation generated by Covid-19, it’s necessary to rethink the lifestyle of society and its quality of life around public and urban spaces, researching in 2019 mobility Bogotá survey’s; on average, they record trips is 14,069 of foot trips, between 10 and 20 minutes according to the travel patterns in the distinctive transport analysis areas at the zonal planning unit Chapinero Centro in the city of Bogotá. In spite of having great social and economic dynamics, this UPZ has very small platforms that make it difficult to comply with social distancing, necessary to mitigate the Coronavirus pandemic. For this reason, this article carried out a geographical analysis of this area, using the data provided by the vulnerability map of the Coronavirus website in Colombia of the Departamento Nacional de Planeación, the Instituto de Evaluación Tecnológica en Salud and the Departamento Administrativo Nacional de Estadística. This geographical analysis allowed calculating the variables of the population indicator per block, the maximum population per platform and the criterion of compliance with social distance. These variables allowed designing the vulnerability and social distancing maps. It was evident that 37% of the platforms do not comply the 2-meter distance between people, so it was
Due to the COVID-19 pandemic, rethinking lifestyle and quality of life through the appropriate use of public space is necessary. This study aims to verify the measures of social distancing in Chapinero Centro, which, according to the mobility survey 2019 of Bogota, has an average of 4,633 trips on foot between 10 and 20 minutes according to the travel patterns in the areas of transportation analysis studied. Despite having great social and economic dynamics, this area has small sidewalks that hinder compliance with social distancing, which is necessary to mitigate the coronavirus pandemic. Therefore, geographic analysis of this area was performed using data provided by the vulnerability map of the Coronavirus web in Colombia by the National Planning Department, the Institute for Health Technology Assessment, and the National Administrative Department of Statistics. This geographic analysis made it possible to calculate the variables of population indicator per block, maximum population per sidewalk, and the criterion of compliance with social distancing. When developing the vulnerability and social distancing maps, it became evident that 37% of the sidewalks do not comply with the 2 meters of social distancing between people, so we propose extending them to 3.5 meters and reducing this same value in the vehicular space to design an effective social distancing map. We concluded that the widening of the sidewalks allows flexible use of the streets oriented to a healthy distance, which could be complemented with an accessibility study and a study of vehicular traffic to measure the impact of this intervention.
Combustion Variability Monitoring in Engines Using High-Speed Exhaust Temperature and Pressure Measurements
Authors: Bajwa Abdullah U. , Patterson Mark A. , Jacobs Timothy J.
Published: January 2023

The diagnostic merits of high-speed (HS) exhaust gas temperature and pressure measurements for indexing engine stability and identifying abnormal combustion cycles are explored through experimental investigations on a low speed, single-cylinder engine. Exhaust temperature and pressure are measured using a fine wire 50 μm thermocouple and a piezoresistive pressure transducer, respectively. Synchronously recorded cylinder pressure data is used to continuously index combustion variations, and then anomalous combustion event detection and engine stability monitoring are attempted using HS exhaust temperature and pressure measurements. Two types of abnormal combustion cycles, namely, misfiring and overload cycles are used to typify low and high intensity anomalous combustion cycles, respectively. The results demonstrate that if suitable cyclic exhaust pressure and temperature metrics are used, anomalous combustion cycles can be identified, and overall combustion variability levels can be indexed. The comparative diagnostic performance of HS measured exhaust pressure and temperature and slow speed measured exhaust temperature are also discussed. A thermodynamic simulation of the engine and the HS thermocouple is used to provide theoretical support for the discussion by comparing measured and simulated “actual” exhaust temperature and identifying the flow, heat transfer, and thermodynamic influences that act as limits to the thermocouple's dynamic performance.
Single Accelerometer to Recognize Human Activities Using Neural Networks
Authors: Vakacherla Sai Siddarth , Kantharaju Prakyath , Mevada Meet , Kim Myunghee
Published: January 2023

Exoskeletons have decreased physical effort and increased comfort in activities of daily living (ADL) such as walking, squatting, and running. However, this assistance is often activity specific and does not accommodate a wide variety of different activities. To overcome this limitation and increase the scope of exoskeleton application, an automatic human activity recognition (HAR) system is necessary. We developed two deep-learning models for HAR using one-dimensional-convolutional neural network (CNN) and a hybrid model using CNNs and long-short term memory (LSTM). We trained both models using the data collected from a single three-axis accelerometer placed on the chest of ten subjects. We were able to classify five different activities, standing, walking on level ground, walking on an incline, running, and squatting, with an accuracy of 98.1% and 97.8%, respectively. A two subject real-time validation trial was also conducted to validate the real-time applicability of the system. The real-time accuracy was measured at 96.6% and 97.2% for the CNN and the hybrid model, respectively. The high classification accuracy in the test and real-time evaluation suggests that a single sensor could distinguish human activities using machine-learning-based models.
Biomechanical Evaluation of Rigid Interspinous Process Fixation Combined With Lumbar Interbody Fusion Using Hybrid Testing Protocol
Authors: Fan Wei , Zhang Chi , Zhang Dong-Xiang , Guo Li-Xin , Zhang Ming , Wang Qing-Dong
Published: January 2023

Rigid interspinous process fixation (RIPF) has been recently discussed as an alternative to pedicle screw fixation (PSF) for reducing trauma in lumbar interbody fusion (LIF) surgery. This study aimed to investigate biomechanics of the lumbar spine with RIPF, and also to compare biomechanical differences between two postoperative stages (before and after bony fusion). Based on an intact finite-element model of lumbosacral spine, the models of single-level LIF with RIPF or conventional PSF were developed and were computed for biomechanical responses to the moments of four physiological motions using hybrid testing protocol. It was found that compared with PSF, range of motion (ROM), intradiscal pressure (IDP), and facet joint forces (FJF) at adjacent segments of the surgical level for RIPF were decreased by up to 8.4%, 2.3%, and 16.8%, respectively, but ROM and endplate stress at the surgical segment were increased by up to 285.3% and 174.3%, respectively. The results of comparison between lumbar spine with RIPF before and after bony fusion showed that ROM and endplate stress at the surgical segment were decreased by up to 62.6% and 40.4%, respectively, when achieved to bony fusion. These findings suggest that lumbar spine with RIPF as compared to PSF has potential to decrease the risk of adjacent segment degeneration but might have lower stability of surgical segment and an increased risk of cage subsidence; When achieved bony fusion, it might be helpful for the lumbar spine with RIPF in increasing stability of surgical segment and reducing failure of bone contact with cage.
Damage Localization in 3D-Printed Plates with Different Infill Densities
Authors: Fakih Mohammad Ali , Singh Shishir Kumar , Mustapha Samir , Malinowski Paweł
Published: January 2023

The growth in the use of additive manufacturing techniques for prototypes and industrial components implies the need to find robust and reliable tools for damage detection, localization, size estimation, and identification. This study focuses on guided-wave propagation in 3D-printed components and their sensitivity to damage. The material under investigation is 3D-printed poly(lactic acid) (PLA), which was used to manufacture flat plates. Several plates were prepared with varying infill densities. Lower infill density allows to save printing material, but it influences the guided-wave propagation behavior. To study the damage localization capability, plates with and without internal artificial defects were prepared. For each infill density, a healthy and a damaged plate were prepared. The guided waves were excited in the plates using surface-mounted piezoelectric transducers, while the sensing was realized by a scanning laser Doppler vibrometer. Five-cycle-long tone-burst excitation signals of different central frequencies were used, for comparison, where it was demonstrated that lowering the plate's infill density results in the appearance of higher-order modes at lower cut-off frequencies. Additionally, it was shown that guided-wave-based imaging can reveal hidden flaws and even the inner structure of 3D-printed polymers. This shows the good potential of guided-wave-based techniques for the structural health monitoring of 3D-printed structures.
Crawler-Based Automated Non-Contact Ultrasonic Inspection of Large Structural Assets
Authors: McMillan Ross , Tabatabaeipour Morteza , Tzaferis Konstantinos , Jackson William , Edwards Rachel S. , Trushkevych Oksana , Macleod Charles , Dobie Gordon , Gachagan Anthony
Published: January 2023

This paper presents an update on the progress of developing a crawler-based automated non-contact ultrasonic inspection system for the evaluation of large structural assets. The system presented is a significant improvement on current robotic NDT crawlers and aims to greatly reduce the time of inspection by creating an internal feature map of the subject in a Simultaneous Localisation And Mapping (SLAM) style method instead of using a lawnmower scanning style where all areas are scanned regardless if they contain features or are featureless. This map will be generated through rapid automated path planning and scanning and will show the location of potential areas of interest, where then, the appropriate method of inspection can be used for a high detailed evaluation. Current and ongoing work presented is as follows; the use of guided waves as the sensory input of an occupancy grid map; evaluating guided wave modes to find the mode most appropriate for this system; minimum thickness estimation using machine learning; improving the transducer setup using a unidirectional transmitter.
A Non-Linear Ultrasonic Approach Using a Fine-Tuned Experimentally Defined Frequency for Structural Health Monitoring of Composite Plates
Authors: Alnuaimi Hamad , Amjad Umar , Russo Pietro , Lopresto Valentina , Kundu Tribikram
Published: January 2023

The Sideband Peak Count – Index (SPC-I) technique, which is a newly developed non-linear ultrasonic (NLU) technique has been established as a reliable technique for detecting and monitoring non-linear detects in various materials such as metals, composites, and concrete. In prior investigations the SPC-I technique is performed by exciting a wideband sweep signal through the material. Although this is a good general approach, the SPC-I technique can be fine-tuned for specific specimens under investigation. In this investigation, a single frequency is selected as an excitation signal that is propagated through the composite plate specimens. This single frequency is experimentally defined using a pristine composite plate as a control specimen. Multiple signals are propagated through the pristine specimen at a range of frequencies in order to find the sensitive frequency. By applying the SPC-I technique on the range of signals obtained for the pristine specimen, a single fine-tuned frequency can be identified that can be used to detect and monitor impact damage in composite plates. In this investigation glass fiber composite plates that are impacted with increasing impact energy (0J, 5J, 10J, 20J, 30J, 40J and 50J) are examined using the fine-tuned excitation frequency coupled with the NLU SPC-I technique. The SPC-I technique is capable of detecting and monitoring the impact induced damage in the composite plate specimens.
Validation of Numerical Wavefield Modelling and Damage Interaction in Complex Composite Structures Using Data from Open Guided Waves
Authors: Savli Enes , Tschöke Kilian , Schubert Lars
Published: January 2023

Ultrasonic Guided waves (UGW) are one of the most promising tools for SHM especially for thin-walled structures like composites by allowing fast inspection of a large area in-service conditions. However, for practical applications a quality assessment is necessary to estimate damage detection capacity and probability of the designed SHM system. Such evaluation of a general overview for an arbitrary structure is limited with experiments due to repetitive wavefield measurements. Validated numerical analysis tools must be used. In this work, validation study for a complex composite structure with Elastodynamic Finite Integration Technique (EFIT) will be presented. As reference model the measurement data coming from the Open Guided Waves Project (OGW) was selected. The dataset consists of measurements for two different cases called local and large stringer debond with additional baseline measurements. Within this contribution this experiment is reproduced by simulation using EFIT. Results show a good match between the experimental and simulated datasets, as the input parameters are fully determined prior to the simulations. The paper motivates further research, for example related to probability of detection analysis and numerical performance of the results.