bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term efficacy and safety during open‐label erenumab treatment in Japanese patients with episodic migraine
Authors: Sakai Fumihiko , Takeshima Takao , Tatsuoka Yoshihisa , Hirata Koichi , Cheng Sunfa , Numachi Yotaro , Peng Cheng , Xue Fei , Mikol Daniel D.
Published: March 2021

Objective

To assess long‐term (up to 2 years) efficacy, tolerability, and safety of erenumab for the prevention of episodic migraine (EM) in Japanese patients.

Background

Previously published results from the double‐blind treatment phase (DBTP) of a phase 2 clinical study have demonstrated the efficacy and safety of erenumab in Japanese patients with EM.

Methods

Patients completing the 24‐week placebo‐controlled DBTP could continue into the 76‐week open‐label treatment phase (OLTP), receiving erenumab 70 mg or 140 mg subcutaneously once monthly. The initial dose in the OLTP was erenumab 70 mg monthly, which was later changed to 140 mg. After study completion, the following were assessed: change from baseline in monthly migraine days (MMD), change from baseline in monthly acute migraine‐specific medication days (MSMD), percentage of patients achieving ≥50% and ≥75% reduction in MMD, change from baseline in the 6‐item Headache Impact Test (HIT‐6™) score, and safety (exposure‐adjusted patient‐incidence of adverse events [AEs], calculated as number of patients per 100 patient‐years).

Results

Of 475 patients enrolled in the DBTP, 459 (96.6%) continued in the OLTP. The mean (SD) MMD was 7.9 (2.3) at baseline with the overall change from baseline at week 100 of –2.9 (4.1) days. The monthly acute MSMD was 5.7 (2.8) at baseline with change from baseline at week 100 of −1.7 (3.7) days. The proportion of patients who achieved ≥50% and ≥75% reduction in MMD from baseline at week 100 was 177/398 (44.5%) and 94/398 (23.6%), respectively. The HIT‐6™ score was 58.4 (5.4) at baseline with a change of −6.4 (8.2) at week 100. The exposure‐adjusted patient‐incidence of AEs during the OLTP was 207.1/100 patient‐years for the combined erenumab group, similar to that observed for either erenumab (271.0/100 patient‐years) or placebo (257.3/100 patient‐years) during the DBTP, and no new safety signals were detected during the OLTP.

Conclusion

Long‐term erenumab treatment in Japanese patients with EM demonstrated sustained efficacy for up to 2 years, with a safety profile similar to previous studies, supporting erenumab as a potential new therapy for EM prevention in Japan.
Failure to eradicate Helicobacter pylori infection is more frequent among HIV‐positive patients
Authors: Nkuize M , Vanderpas J , Buset M , Delforge M , Cadière G‐B , De Wit S
Published: March 2021

Objectives

Helicobacter pylori is a worldwide infection, but little is known about the efficacy of treatment for H. pylori infection in HIV‐positive patients. The goal of this work was to evaluate outcomes after first‐line H. pylori treatment and identify risk factors for failure in HIV‐positive patients.

Methods

This registry study of unmatched H. pylori‐infected HIV‐positive patients and HIV‐negative obese pre‐bariatric surgery controls was performed in a tertiary university hospital. Cases were enrolled from 2006 to 2017, controls from 2007 to 2014, and both received standard of care. An additional ‘optimal’ subgroup of cases was enrolled prospectively from 2017 to 2019 which was treated only on the basis of antibiogram, drug interaction search and additional support by one referent physician. Helicobacter pylori eradication failure rates were compared according to clinical, microbiological and pathological parameters and treatment.

Results

We analysed 258 HIV‐positive patients and 204 HIV‐negative control patients. Helicobacter pylori eradication failure rates were markedly greater in cases (24.1%) than in controls (8.8%). The proportions of levofloxacin and metronidazole resistance were greater in cases than in controls (P < 0.05). Among cases treated with H. pylori triple therapy (S3T), the ‘optimal’ subgroup experienced a 9.5% failure rate vs. 28.6% with other strategies (P = 0.01). Risk factors for failure were H. pylori treatment strategy, exposure to antiretroviral treatment, and alcohol status. Overall, positive HIV status was a risk factor for S3T eradication failure.

Conclusions

Patients co‐infected with H. pylori and HIV frequently failed to eradicate H. pylori and this was related to treatment strategy, antiretroviral exposure and lifestyle.
The presence of smear layer affects the antimicrobial action of root canal sealers
Authors: Zancan R. F. , Di Maio A. , Tomson P. L. , Duarte M. A. H. , Camilleri J.
Published: March 2021

Aim

To assess the chemical and microstructural characteristics of dentine after the use of two irrigation protocols and correlate this with the antimicrobial properties of hydraulic calcium silicate cement (HCSC) sealers and changes to the dentine structure/chemistry after sealer placement.

Methodology

Two irrigation protocols – Protocol A using 2% NaOCl used 5 mL/5 min and Protocol B with 2% NaOCl (5 mL/5 min) followed by 17% EDTA (5 mL/3 min) – were used to prepare dentine. The chemical and microstructural changes following irrigation were assessed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared (FT‐IR) spectroscopy (n = 5) on dentine obtained from the mid‐root and coronal parts of extracted human teeth. Four sealers (AH Plus, BioRoot, MTA Fillapex, TotalFill) were characterized by SEM/EDS (n = 3). The ability of the sealers to eradicate intratubular Enterococcus faecalis biofilms was assessed by live/dead dye and confocal laser scanning microscopy to measure the percentage of living cells. The effect of combined irrigation and root filling on dentine was assessed by SEM and EDS analysis (n = 5). Statistical analysis was undertaken using one‐way anova and a number of post hoc tests to detect intergroup differences. The F‐test was used for comparison of variances in the microbiology testing.

Results

The use of NaOCl alone left the smear layer intact, with traces of chlorine remaining on dentine. The use of BioRoot sealer restored the calcium levels of dentine which had been depleted by the irrigation with EDTA. BioRoot exhibited antimicrobial properties against intratubular bacteria even in the presence of smear layer (Protocol A). Smear layer removal improved the bactericidal effect of all sealers and Ca2+ leaching. The use of a chelating agent was important for the intratubular sealer penetration for AH Plus but not the other sealers.

Conclusion

The removal of smear layer was necessary for penetration of AH Plus into the dentinal tubules. BioRoot was a more effective sealer in reducing the bacterial load in the dentinal tubules than the other materials tested and the presence of smear layer did not affect its activity.
LmjF.36.3850, a novel hypothetical Leishmania major protein, contributes to the infection
Authors: Zutshi Shubhranshu , Sarode Aditya Yashwant , Ghosh Soumya Kanti , Jha Mukesh Kumar , Sudan Raki , Kumar Sunil , Sadhale Late Parag , Roy Somenath , Saha Bhaskar
Published: March 2021

Leishmania is a protozoan parasite that resides in mammalian macrophages and inflicts the disease known as leishmaniasis. Although prevalent in 88 countries, an anti‐leishmanial vaccine remains elusive. While comparing the virulent and avirulent L. major transcriptomes by microarray, PCR and functional analyses for identifying a novel virulence‐associated gene, we identified LmjF.36.3850, a hypothetical protein significantly less expressed in the avirulent parasite and without any known function. Motif search revealed that LmjF.36.3850 protein shared phosphorylation sites and other structural features with sucrose non‐fermenting protein (Snf7) that shuttles virulence factors. LmjF.36.3850 was predicted to bind diacylglycerol (DAG) with energy value similar to PKCα and PKCβ, to which DAG is a cofactor. Indeed, 1‐oleoyl‐2‐acetyl‐sn‐glycerol (OAG), a DAG analogue, enhanced the phosphorylation of PKCα and PKCβI. We cloned LmjF.36.3850 gene in a mammalian expression vector and primed susceptible BALB/c mice followed by challenge infection. We observed a higher parasite load, comparable antibody response and higher anti‐inflammatory cytokines such as IL‐4 and IL‐10, while expression of major anti‐leishmanial cytokine, IFN‐γ, remained unchanged in LmjF.36.3850‐vaccinated mice. CSA restimulated LN cells from vaccinated mice after challenge infection secreted comparable IL‐4 and IL‐10 but reduced IFN‐γ, as compared to controls. These observations suggest a skewed Th2 response, diminished IFN‐γ secreting Th1‐TEM cells and increased central and effector memory subtype of Th2, Th17 and Treg cells in the vaccinated mice. These data indicate that LmjF.36.3850 is a plausible virulence factor that enhances disease‐promoting response, possibly by interfering with PKC activation and by eliciting disease‐promoting T cells.
Evaluating working memory outcome measures for children with Down syndrome
Authors: Schworer E. K. , Esbensen A. J. , Fidler D. J. , Beebe D. W. , Carle A. , Wiley S.
Published: March 2021

Background

There is a critical need for the psychometric evaluation of outcome measures to be used in clinical trials targeting cognition in Down syndrome (DS). This study examines a specific cognitive skill that is of particular importance in DS, working memory, and the psychometric properties of a set of standardised measurements to assess working memory in individuals with DS.

Methods

Ninety children and adolescents ages 6 to 18 years old with DS were assessed on a selection of verbal and visuospatial working memory subtests of standardised clinical assessments at two time points to examine feasibility, distributional qualities, test–retest reliability and convergent validity against a priori criteria. Caregivers also completed an adaptive behaviour questionnaire to address working memory subtests' associations with broader developmental functioning.

Results

The Stanford Binet‐5 Verbal Working Memory, Differential Ability Scales‐2 Recognition of Pictures, Stanford Binet‐5 Nonverbal Working Memory and Wechsler Intelligence Scale for Children‐5 Picture Span measures met the most psychometric criteria overall across the full age and IQ range of the study. Although Differential Ability Scales‐2 Recall of Sequential Order and Differential Ability Scales‐2 Recall of Digits Backward met the fewest a priori criteria, follow‐up analyses suggested greater feasibility in specific age and IQ ranges.

Conclusions

Several working memory measures appear to be psychometrically sound and appropriate for use in clinical trials for children with DS, especially when focusing on raw scores. However, floor effects on standard scores and feasibility of some measures were problematic. Guidelines for use of the working memory subtests with this population are provided.
Taking into account patient preferences in personalised care: Blending types of nursing knowledge in evidence‐based practice
Authors: den Hertog Ria , Niessen Theo
Published: March 2021

Aims and objectives

To explore how excellent nurses in hospitals take into account patient preferences in nursing decision‐making in the evidence‐based practice towards personalised care.

Background

In evidence‐based practice, nursing decision‐making is based on scientific evidence, evidence of best practice and individual patient preferences. Little is known about how nurses in hospitals take into account patient preferences in nursing decision‐making.

Design

Qualitative grounded theory.

Methods

Data collection entailed 27 semi‐structured interviews with nurses designated by their colleagues as excellent caregivers, followed by 57 hours of participant observation. Data analysis was conducted using three‐level coding with constant comparison and theoretical sampling. The COREQ checklist for qualitative research was followed.

Results

A main finding was that participants used three implicit tools to discover patient preferences: establishing a connection, using antennae and asking empathic questions, thus instantly reassuring patients from the very first contact. Their starting point in care was the patient's perception of quality of life wherein they shifted towards their patient's perspective: “Teach me to provide the best care for you in this situation.” During the observations, it was confirmed that the excellent nurses behaved as they had described before.

Conclusion

Excellent nurses actively turn towards patients’ expectations and experienced quality of life by carefully blending individual sensitive and situation specific patient preferences with scientific evidence and evidence of best practice. In doing so, they are able to balancing more equally patient preferences in to the equation called evidence‐based practice, thus leading to wise decision‐making in personalised nursing care.

Relevance to clinical practice

Patient preferences become a fully fledged part of nursing decision‐making in EBP when in education and practice, the implicit knowledge of excellent nurses about how to take into account patient preferences to provide personalised care is more valued and taught.
The Emotion of Fear: Its Experience in Situations Involving Animals, Accidents, and Violence and Its Regulation by the Cognitive Reappraisal Strategy
Authors: Prosen Simona , Poljšak Škraban Olga , Slana Ozimič Anka , Repovš Grega , Smrtnik Vitulić Helena
Published: March 2021

In the present study, the experience of fear in various stimulus situations (involving animals, accidents, and violence) and its regulation by the cognitive reappraisal strategy in 46 psychology students was analyzed. The students self‐assessed their experience of fear via questionnaires and a computerized task. In the questionnaires, the intensity of the experience of fear in everyday situations and the frequency of cognitive reappraisal strategy use were measured. In the computer application, photos eliciting fear were presented under two conditions: the first involved experiencing the photos and the continuation of this experience, while the second involved experiencing the photos followed by the use of the cognitive reappraisal strategy. The results confirm differences between the various stimulus situations. When measured with the questionnaires, the most intense fear was reported in situations involving accidents, whereas violence triggered the most intense fear while experiencing the photos. When the students continued to experience a photo, their experience of fear intensified significantly, but when they regulated their experience using cognitive reappraisal, their fear decreased. However, the intensity of the regulated fear was not connected to the frequency of the everyday use of cognitive reappraisal, as reported in the questionnaire. The study confirms the importance of contextual factors when experiencing and regulating fear.
Periodic autoregressive conditional duration
Authors: Aknouche Abdelhakim , Almohaimeed Bader , Dimitrakopoulos Stefanos
Published: March 2021

We propose an autoregressive conditional duration (ACD) model with periodic time‐varying parameters and multiplicative error form. We name this model periodic autoregressive conditional duration (PACD). First, we study the stability properties and the moment structures of it. Second, we estimate the model parameters, using (profile and two‐stage) Gamma quasi‐maximum likelihood estimates (QMLEs), the asymptotic properties of which are examined under general regularity conditions. Our estimation method encompasses the exponential QMLE, as a particular case. The proposed methodology is illustrated with simulated data and two empirical applications on forecasting Bitcoin trading volume and realized volatility. We found that the PACD produces better in‐sample and out‐of‐sample forecasts than the standard ACD.
Natural history of hepatitis C virus infection in a large national seroconversion cohort in the direct‐acting antiviral agent era: Results from ERCHIVES
Authors: Butt Adeel A. , Yan Peng ,   the ERCHIVES study team
Published: March 2021

Hepatitis C virus (HCV) natural history studies are limited by not knowing the time of infection, small numbers and non‐representative populations. No studies are available from the direct‐acting antiviral agents (DAA) era. We created the largest known cohort of persons with HCV with a known window of seroconversion in the DAA era. We compared the annual cumulative incident events and incidence rate/1000 person‐years of follow‐up for liver cirrhosis, hepatic decompensation, hepatocellular carcinoma (HCC) and mortality from the time of seroconversion among untreated and those treated and attaining a sustained virologic response (SVR). Among 12,881 persons in the final analyses, 10,417 had never been treated for HCV, 2464 (23.6%) were treated with a DAA regimen and 1836 (74.5%) attained SVR. After 9 years of follow‐up, cirrhosis was diagnosed in 17.4% of untreated and 13.6% of the SVR group. Overall, 29.5% in the untreated versus 3.5% in the SVR group died. Incidence rates/1000 person‐years of follow‐up (95% CI) for untreated versus SVR group were 22.7 (21.6, 23.9) versus 19.5 (17.0, 21.9) for cirrhosis (p = 0.03), 0.1 (0.03, 0.2) versus 0.07 (−0.07, 0.2) for HCC (p = 0.74) and 35.4 (34.0, 36.8) versus 4.53 (3.4, 5.7) for mortality (p < 0.0001). After excluding those with alcohol‐related diagnoses at baseline, the difference in cirrhosis was not statistically significant. Cirrhosis and mortality occur early and steadily increase over the first decade after acquiring HCV infection, while HCC is rarely observed. Those treated with a DAA regimen have sharply lower cirrhosis and mortality rates, particularly among those without alcohol abuse or dependence.
Mixotrophic growth of the extremophile Galdieria sulphuraria reveals the flexibility of its carbon assimilation metabolism
Authors: Curien Gilles , Lyska Dagmar , Guglielmino Erika , Westhoff Phillip , Janetzko Janina , Tardif Marianne , Hallopeau Clément , Brugière Sabine , Dal Bo Davide , Decelle Johan , Gallet Benoit , Falconet Denis , Carone Michele , Remacle Claire , Ferro Myriam , Weber Andreas P.M. , Finazzi Giovanni
Published: March 2021

Galdieria sulphuraria is a cosmopolitan microalga found in volcanic hot springs and calderas. It grows at low pH in photoautotrophic (use of light as a source of energy) or heterotrophic (respiration as a source of energy) conditions, using an unusually broad range of organic carbon sources. Previous data suggested that G. sulphuraria cannot grow mixotrophically (simultaneously exploiting light and organic carbon as energy sources), its photosynthetic machinery being repressed by organic carbon.

Here, we show that G. sulphuraria SAG21.92 thrives in photoautotrophy, heterotrophy and mixotrophy. By comparing growth, biomass production, photosynthetic and respiratory performances in these three trophic modes, we show that addition of organic carbon to cultures (mixotrophy) relieves inorganic carbon limitation of photosynthesis thanks to increased CO2 supply through respiration. This synergistic effect is lost when inorganic carbon limitation is artificially overcome by saturating photosynthesis with added external CO2.

Proteomic and metabolic profiling corroborates this conclusion suggesting that mixotrophy is an opportunistic mechanism to increase intracellular CO2 concentration under physiological conditions, boosting photosynthesis by enhancing the carboxylation activity of Ribulose‐1,5‐bisphosphate carboxylase‐oxygenase (Rubisco) and decreasing photorespiration.

We discuss possible implications of these findings for the ecological success of Galdieria in extreme environments and for biotechnological applications.
Influence of Cage Design on Radiological and Clinical Outcomes in Dorsal Lumbar Spinal Fusions: A Comparison of Lordotic and Non‐Lordotic Cages
Authors: Walter Christian , Baumgärtner Tobias , Trappe Dominik , Frantz Sandra , Exner Lisanne , Mederake Moritz
Published: March 2021

Objectives

To evaluate the comparison between lordotic and non‐lordotic transforaminal lumbar interbody fusion (TLIF) cages in degenerative lumbar spine surgery and analyze radiological as well as clinical outcome parameters in long‐term follow up.

Methods

In a retrospective study design, we compared 37 patients with non‐lordotic cage (NL‐group) and 40 with a 5° lordotic cage (L‐group) implanted mono‐ or bi‐segmental in TLIF‐technique from 2013 to 2016 and analyzed radiological parameters of pre‐ and postoperative (Lumbar lordosis (LL), segmental lordosis (SL), and pelvic tilt (PT), as well as clinical parameters in a follow‐up physical examination using the Oswestry disability index (ODI), Roland–Morris Score (RMS), and visual analog scale (VAS).

Results

Surgery was mainly performed in lower lumbar spine with a peak in L4/5 (mono‐segmental) and L4 to S1 (bi‐segmental), long‐term follow‐up was on average 4 years postoperative. According to the literature, we found significantly better results in radiological outcome in the L‐group compared to the NL‐group: LL increased 6° in L‐group (51° preoperative to 57° postoperative) and decreased 1° in NL‐group (50° to 49° (P < 0.001). Regarding SL, we found an increase of 5° in L‐group (13° to 18°) and no difference in NL‐group (15°)(P < 0.001). In PT, we found a clear benefit with a decrease of 2° in L‐group (21° to 19°) and no difference in NL‐group (P = 0.008).

In direct group comparison, ODI in NL‐group was 23% vs 28% in L‐group (P = 0.25), RMS in NL‐group was 8 points vs 9 points in L‐group (P = 0.48), and VAS was in NL‐group 2.7 vs 3.2 in L‐group (P = 0.27) without significant differences.

However, the clinical outcome in multivariate analysis indicated a significant multivariate influence across ODI and RMS of BMI (Wilks λ = 0.57, F [4, 44] = 3.61, P = 0.012) and preoperative SS (Wilks λ = 0.66, F [4, 44] = 2.54, P = 0.048). Age, gender, cage type and postoperative PT had no significant influence (P > 0.05). Intraoperatively, we saw three dura injuries that could be sutured without problems and had no consequences for the patient. In the follow‐up, we did not find any material‐related problems, such as broken screws or cage loosening, also no pseudarthrosis.

Conclusion

In conclusion, we think it's not cage design but other influenceable factors such as correct indication and adequate decompression that lead to surgical success and the minimal difference in the LL therefore seemed to be of subordinate importance.
The negative binomial process: A tractable model with composite likelihood‐based inference
Authors: Barreto‐Souza Wagner , Ombao Hernando
Published: March 2021

We propose a log‐linear Poisson regression model driven by a stationary latent gamma autoregression. This process has negative binomial (NB) marginals to analyze overdispersed count time series data. Estimation and statistical inference are performed using a composite (CL) likelihood function. We establish theoretical properties of the proposed count model, in particular, the strong consistency and asymptotic normality of the maximum CL estimator. A procedure for calculating the standard error of the parameter estimator and confidence intervals is derived based on the parametric bootstrap. Monte Carlo experiments were conducted to study and compare the finite‐sample properties of the proposed estimators. The simulations demonstrate that, compared with the approach that combines generalized linear models with the ordinary least squares method, the proposed composite likelihood approach provides satisfactory results for estimating the parameters related to the correlation structure of the process, even under model misspecification. An empirical illustration of the NB process is presented for the monthly number of viral hepatitis cases in Goiânia (capital and largest city of the Brazilian state of Goiás) from January 2001 to December 2018.
Optimism: Enduring resource or miscalibrated perception?
Authors: Purol Mariah F. , Chopik William J.
Published: March 2021

There is a general, widely‐held belief that optimism is always a good thing. While there is much previous research suggesting that optimists enjoy several health and wellness benefits, there is also a large body of research suggesting that optimism is not always advantageous. Perhaps examining how optimism develops and changes across the lifespan may give us insight into how people use optimism and allow us to determine if and when optimism is helpful or maladaptive for them. In the current review, we review evidence debating the benefits and costs of optimism, as well as examine how optimism develops across the lifespan. We discuss how life events may or may not impact the developmental trajectory of optimism. Lastly, we address currently unanswered questions and emphasize the contextual nature of optimism's advantages.
Unloaded Organ Culturing Has a Detrimental Effect on the Axial Mechanical Properties of the Intervertebral Disc
Authors: Zwambag Derek P. , Laird Brigitte N. , DeWitte-Orr Stephanie J. , Gregory Diane E.
Published: March 2021

Healthy function of intervertebral discs (IVDs) depends on their tissue mechanical properties. Native cells embedded within IVD tissues are responsible for building, maintaining, and repairing IVD structures in response to genetic, biochemical, and mechanical signals. Organ culturing provides a method for investigating how cells respond to these stimuli in their natural architectural environment. The purpose of this study was to determine how organ culturing affects the mechanical characteristics of functional spine units (FSUs) across the entire range of axial loading, including the neutral zone (NZ), using a rat tail model. Rat tail FSUs were organ cultured at 37 °C in an unloaded state in standard culture media for either 1-day (n = 8) or 6-days (n = 12). Noncultured FSUs (n = 12) were included as fresh control specimens. Axial mechanical properties were tested by applying cyclical compression and tension. A novel mathematical approach was developed to fully characterize the relationship between load, stiffness, and deformation through the entire range of loading. Culturing FSUs for 1-day did not affect any of the axial mechanical outcome measures compared to noncultured IVDs; however, culturing for 6 days increased the size of NZ by 112% and decreased the stiffness in NZ, compressive, and tensile regions by 53%, 19%, and 15%, respectively, compared to noncultured FSUs. These results highlight the importance of considering how the mechanical integrity of IVD tissues may affect the transmission of mechanical signals to cells in unloaded organ culturing experiments.
A Concurrent Design Framework for the Ergonomics of Production Processes
Authors: Brown Don R. , Budnick Peter M. , Bloswick Donald S.
Published: March 2021

Ergonomics is a term derived from the Greek words ergon meaning “work” and nomos, meaning “natural laws of” or “study of.” Ergonomics is therefore defined as the study of the natural laws of work, in particular, the relationship between the worker and the work environment. The work environment includes the workplace, tools, parts, materials and work processes required to combine these elements. The work environment may be as simple as a hammer or as complex as the cockpit of a sophisticated aircraft.
Spatial Reasoning on Form Feature Interactions for Manufacturability Assessment
Authors: Chen Yuh-Min , Miller R. Allen , Lu Shao-Chiung
Published: March 2021

This paper presents the definition, reasoning and representation of part geometry characteristics to support manufacturability assessment. The scope is limited to the extraction of significant items formed from feature interactions for castability and moldability assessment. Reasoning for part geometry characteristics is performed as a refinement procedure. High-level spatial relationships between features - “Is_In” and “Adjacent_To” are first derived to support the specialization of the characteristics of individual features as well as other detailed relationships. The significant items formed from feature interactions are then extracted based on the detailed spatial relationships and geometric details.
Design Representation for Manufacturability Evaluation in CAD: Beyond Feature-Based Design
Authors: Ishii Kos , Miller R. A.
Published: March 2021

This paper addresses CAD representation suitable for intelligent programs that evaluate life-cycle concerns. Design for net shape manufacturing serves as a vehicle for our discussion. We argue that feature-based design alone could lead to an unmanageable number of predefined features and tagged data in order to accommodate the different perspectives of the design engineer, tooling engineer, and process engineer. The paper proposes a compromise between full scope feature-based design and pure geometry as the recommended form of design representation. This mode requires methods or formulae to infer information needed for evaluation. There are two types of methods important in manufacturability evaluation: 1) macroscopic search of problems in the entire design, and 2) microscopic evaluation of a local form feature. We illustrate our ideas with two working systems.
A Hybrid Computational Model for Mechanical Design
Authors: Rangaraj B. S. , Thompson J. G. , Krishnaswami P.
Published: March 2021

Engineering design is a complex activity which involves knowledge application and creativity to generate and explore the space of possible designs. Since engineering knowledge is heterogeneous in terms of the kinds of problems it encompasses and the methods used to solve them, an hybrid computational model for design, in particular for mechanical design, is proposed in this paper.

The proposed model called the Design Frame (DF) is based on the iterative application of a generalized solution strategy. A given design problem is recursively decomposed into smaller subproblems until the subproblems can be directly solved. Repeated application of decomposition produces a natural design hierarchy. A Rule-based Controller (RBC) can call one or more decision modules and a subproblem DF during the iterative process. The RBC along with the decision modules gives the model the capability to handle both qualitative and quantitative knowledge and data. The DF’s for all subproblems have the same structure as the top-level and apply the same solution strategy. Domain dependent knowledge can be added by the user to the existing modules or new modules can be supplied by the user.

A brief discussion on a prototype implementation of the DF model has been included.
Quality Improvement of the Product Development Process Using Performance Metrics
Authors: Johnson Timothy L. , Dooley Kevin J.
Published: March 2021

As the international marketplace has opened up, companies are finding that both their competition and customer bases have expanded greatly. In addition, the rate of technological growth continues to accelerate, leaving many products out-dated in a relatively short time. Companies must meet both of these challenges in order to remain competitive. This requires an efficient product development process, one that is flexible and able to meet its customers’ diverse requirements in a timely manner. This paper examines product development and, in particular, looks at the use of metrics in evaluation, control, and improvement of the product development process. Specifically, it is shown how metrics can be used to evaluate the progress, performance, and quality of development activities. Issues involving data collection are described, and the paper concludes with a discussion of organizational issues and a case study.
Experiment and Computer Modelling of the Filling Flows in Pressure Die Casting
Authors: Hu J. , Ramlingam S. , Meyerson G. , Eckert E. R. G. , Goldstein R. J.
Published: March 2021

Until recently, computer simulation of filling flows in die casting have been focused on the determination of the free surfaces of injected liquid and has had difficulties to relate the flows with the formation of casting porosity. Flow visualization in scaled experiments indicates that the liquid has very complicated surfaces and that, in many cases, the surfaces break up and create a mixture zone with liquid droplets and air. This is especially true in pressure die casting where liquid metal is injected at a speed in order of 100 m/s and at a pressure up to 100 atm. The Reynolds number in the process could be above 105 and the Weber number above 102. Surface tension is far from sufficiently strong to sustain disturbance growth due to various instabilities. It is hard to keep the liquid as a separate continuous phase.

Based on flow visualization experiments, a mathematical model is proposed as an alternative and effective simplification to the traditional tracing methods. Instead of determining the continuous free surfaces, the model tries to predict distributions of mass fraction of the injected liquid by solving a partial differential equation of mass transport together with the Navier-Stokes equations. Appropriate unsteady schemes of a finite difference analysis have been developed and are described in the paper. Results with an uniform straight injection into a die cavity are presented, which have re-created the filling patterns of the flows in experiments.
Particle Transport in CVD and Diffusion Processes
Authors: Busnaina Ahmed , Zhu Xiaoying , Zheng Xiaowei
Published: March 2021

Particle transport and deposition in a CVD chamber and a horizontal diffusion furnace are studied. Mean flow and thermal fields are simulated using GENFLOW, which is a general computer code for fluid flow and heat transfer computations. Trajectories of aerosol particles in the chamber and the furnace are evaluated by solving the corresponding Lagrangian equation of motion that includes effects of temperature, drag, gravity, Brownian motion and turbulence fluctuations generated during pumping or venting. Aerosol particles are released at the gas inlet and are carried towards the wafers with sizes of 0.05–1.0 micron in the CVD chamber and 1.0 micron in the diffusion furnace. Depositions of particles on the wafer, wafer temperature and inlet turbulence intensity are evaluated.
Optimization of Noise Level Reduction by Truncated Model Coupled Structural-Acoustic Sensitivity Analysis
Authors: Kozukue Wakae , Pal Chinmoy , Hagiwara Ichiro
Published: March 2021

A method for evaluating simultaneous optimization of a number of strucural/acoustic responses of a coupled strutural-acoustic problem is presented in this paper. Different and mutually conflicting criteria, the strucural response and sound pressure level etc., are taken as objective functions. The general inverse problem is solved to find out the required minimum change of plate thickness which is taken as design variable to satisfy/achieve the target values of the objective functions.
Thermal Residual Stress Analysis for In-Situ and Post-Consolidated Composite Rings
Authors: Tzeng Jerome T. , Pipes R. Byron
Published: March 2021

The thermoelastic response of a thick multilayered composite ring subjected to the sequential addition of layers which undergo instantaneous temperature change and corresponding thermal deformation is modeled. The analysis considers ply-by-ply variations of material properties and fiber orientations. The resulting residual stress field is examined as a function of important physical parameters such as ring geometry, layer material properties, fiber orientation, and layer sequence.
Penetration by Long Rods
Authors: Gillis Peter P. , House Joel W. , Jones S. E.
Published: March 2021

This paper relates to the penetration of large, massive targets by long rods where target penetration is accompanied by rod erosion. A principal criticism of previous analyses of this problem by the present authors was the use of post test measurements to furnish input information for calculations. Thus, the analyses had no truly predictive capability. In particular, the profile hole diameter of the experimental target crater was previously employed as a measure of mushroom strain at the penetrator tip. Because this strain value has a significant effect on calculated penetration depths, it is very important to be able to predict it rather than measure it. In this paper a recent result from the analysis of the initial transient penetration phase is used to estimate mushroom strain. This result is incorporated into the previous steady-state analysis to make it predictive. This new theory is the basis for calculations that are compared with previously published experimental results. The degree of agreement is really quite good for a procedure in which there are no adjustable parameters. In any case, the new computational method is certainly a substantial improvement over the previous reliance on post impact information.
Applications of Electronic Spreadsheets in Mechanical Engineering
Authors: Khosrowjerdi Mohammad
Published: March 2021

Electronic spreadsheet packages which were originally developed to create budget and do financial computations can now be used to perform innovative computer-based analyses. As these packages make increasing inroads into engineering profession, variety of new and innovative professional and instructional applications are being emerged. No longer confined to accountants and business people — electronic spreadsheet utilizations in engineering ranging from sensitivity (parametric) analysis to optimization are becoming more popular. Recently, those engineers who have recognized the usefulness and power of newly added features to these programs have started exploring the possibility of using these packages as a decision-making tool in the area of computer-aided engineering. This growing use of spreadsheets stems from their ability to perform repetitive sophisticated calculations on real time and the availability of built in procedures desirable for technical presentation.

To enhance their teaching and expose students to the applications of electronic spreadsheets, some engineering educators have started integrating these productivity tools into their courses. The computational power of new generation of personal computers in conjunction with ever increasing graphics and advanced mathematics capabilities of spreadsheets can now be employed to perform parametric or what-if analyses.

It is the intent of this paper to demonstrate the use of spreadsheet packages to solve a wide spectrum of problems in mechanical engineering. The case studies used in this paper are taken directly or in some cases with slight modifications from undergraduate text books. The Borland Quattro Pro spreadsheet package version 3 has been utilized to perform spreadsheet-based engineering analyses.
Laser Holographic Measurement of Tooth Flank Form of Cylindrical Involute Gear: Part 2 — For Helical Gear Tooth
Authors: Fujio H. , Kubo A. , Tochimoto S. , Hanaki H. , Saitoh S. , Suzuki M.
Published: March 2021

The interferometry using laser holography is applied to measure the form deviation of tooth flank of involute helical gears. One problem of this method is that the increase of helix angle reduces the region of the flank to which the laser beam can irradiate at a same time. To solve this problem, following method is developed: The objective tooth flank is divided into some regions, and the interferometry measurement is worked out for each region. The measured values for the form deviation of each region of the tooth flank are transformed to the values on the plane of action of this gear. These values for each region of the tooth flank are then concatenated successively until they result the curved surface for the form deviation of the whole tooth flank of the helical gear. The error surface of the tooth flank of helical gear obtained by this procedure is compared with that of conventional measuring method using contacting stylus.
A Research on Bevel Gear Hobbing
Authors: Nagata Shigeyoshi , Komori Tsutomu
Published: March 2021

At present, hob cutters have mainly been used for the tooth cutting of gears. The each blades of the hob cutter have generally been designed with the same module size, therefore, it is not possible to cut gears of another module size using the aforementioned hob cutter. In our research, from the above viewpoint we have through theoretical analysis of a new hob cutter, tried to design a module hob cutter which is able to cut gears of several module sizes during rough cutting. Hereinafter, we are to call this new hob cutter “Variable Module Hob Cutter (= VMHC)”.

This “VMHC” is not uniform in the whole length of hob cutter. It is designed so that the module size is made to vary in accordance with axial direction. With this “VMHC”, not only is it possible for us to cut the tooth profile of gear in any variety of module sizes, but also it is expected to be very suitable for cutting bevel gears by using general type hobbing machine. Most of bevel gears are manufactured by a unipurpose machine tool. Bevel gears, however, are able to be manufactured easily even by using the general type hobbing machine by applying the conventional method of tooth cutting and this hob cutter. The bevel gears have been difficult to manufacture by the conventional hob cutter.

However, we will be able to expect to get “VMHC” easily through use of CNC technology.
Dynamic Analysis of a Multi-Mesh Helical Gear Train
Authors: Kahraman Ahmet
Published: March 2021

In this paper, the dynamic behavior of a multi-mesh helical gear train is studied. The gear train consists of three helical gears, with one of the gears in mesh with the other two. An 18-degree-of-freedom dynamic model which includes transverse, torsional, axial and rotational (rocking) motions of the flexibly mounted gears is developed. Two different loading conditions are identified. For case I, the system is driven by the gear in the middle, and for case II, the system is driven by one of the gears at either end of the gear train. Gear mesh phases under each loading condition are determined. The natural modes are predicted, and effects of the helix angle and the loading condition on the natural modes are explained. The forced response, which includes dynamic mesh and bearing forces, due to the static transmission error excitation is found. Effects of loading conditions and asymmetric positioning on the response are also explored. The results suggest that the dynamic forces are lower if the number of teeth of the gear in the middle is (i) an odd number for case I type loading, and (ii) an even number for case II type loading.
Fuzzy Optimization Design on Worm Drive
Authors: Qun Lin , Wenhui Zhong , Meijuan Wu
Published: March 2021

A mathematical model of multi-objective fuzzy optimization design is described in this paper, where the volume of corona dentis and the efficiency of transmission were chosen as objective functions. The optimal confidence level λ* and the augmentation coefficient β were specified by using two-level fuzzy synthetic evaluation method. As a consequence, the fuzzy optimization design problem was converted into non-fuzzy optimization design problem which could be solved with the mixed discrete optimization technique. The numerical result would be of some reference value to the design of worm drive.
Transmission Error Characteristics of a Stepping Motor Drive Timing Belt System for a Fixed and an Automatic Tensioner
Authors: Kim Hyunsoo , Wee Hyuk
Published: March 2021

The transmission error characteristics of a stepping motor drive timing belt system are investigated theoretically and experimentally for the fixed and the automatic tensioner. It is found that the amplitude of the transmission error θe due to the pulley eccentricity and θm due to the stepping motor torque variation decrease as the belt tension increases and the applied torque load increases. Also, θe can be reduced by using the automatic tensioner, while θm shows almost same magnitude for both tensioners. The theoretical results based on the bondgraph model are in good accordance with the experimental results.
An Efficient Method for Seeking Minimum in Random Directions
Authors: Yifang Zhou
Published: March 2021

In this paper a new method for seeking minimum in random directions is presented. Mathematical statistical methods are used to seek usable point. So the computation efficiency is enhanced considerably. In examples, the method is placed in context of other widely used methods.
Automated Optimal Shape Design System of Planar Link Mechanisms Using an Object-Oriented Modeling Method
Authors: Fujita Kikuo , Akagi Shinsuke , Tsujimoto Kazunori
Published: March 2021

An optimal shape design system for planar link mechanisms is developed using an object-oriented modeling technique. In the formulation of the shape design problem, the driving forces required for the motion of the follower are considered as objective functions to be minimized, and relationships on kinematics and statics are investigated as constraints. The process of mathematically formulating the problem is so complicated that the usual optimization techniques are not effective enough to support the shape design. In our system, link mechanisms are represented using an object-oriented modeling technique based on their graph representation. Based on the representation, the formulation for optimal design is automatically carried out. The system has effective user-interface functions for setting initial shapes of mechanisms and showing results of optimization calculation. Finally, it is applied to the optimal shape design of a power shovel in order to check its validity and effectiveness.
An Introduction to Mechanical Advantage in Compliant Mechanisms
Authors: Salamon B. A. , Midha A.
Published: March 2021

An energy approach is utilized to determine mechanical advantage in compliant mechanisms by duly accounting for lost work due to deformation. Three mechanical advantage types are then defined which examine the isolated influences of various parameters. Finally, a case study is investigated to exemplify these definitions and demonstrate resulting trends in mechanical advantage.
B-Rep Feature Extraction via Primitive Tracking
Authors: Ganter M. A.
Published: March 2021

A modification of the B-Rep data structure is proposed which would allow tracking of both a given face’s geometric type and primitive generating object during the solid modeling process. A technique termed primitive object tracking is presented which would allow object decomposition (feature extraction) based on this additional data. Existing feature extraction techniques are augmented by the application of the object decomposition technique for the recognition and extraction of various feature types; internal voids, single and multi-surfaced holes, and boundary perturbations. Lastly, a brief discussion is presented of required modification and their implications to B-Rep solid modeling to implement and use primitive object tacking techniques.
CATI: A Computer Aided Tolerancing Interface
Authors: Söderberg Rikard
Published: March 2021

This work presents an interface for tolerance analysis in a CAD system. A method for picking up necessary information from a 2D drawing is developed and implemented as an interface in a commercial CAD system. The interface communicates with an external calculation program which determines unknown tolerance limits using the normal distribution model. Results from the calculation program is in the end used by the interface to present measures with tolerances on the drawing.

The advantage of using CATI in preliminary design is discussed, and a strategy for treating interrelated tolerance chains is presented.