bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiac sarcoidosis in the donor heart without extracardiac manifestations
Authors: Al-Ani Mohammad , Taha Mohamad Badie , Stewart Brian D , Graves Gabrielle S , Ahmed Mustafa M , Parker Alex M , Aranda Jr Juan M , Vilaro Juan
Published: April 2021

A middle-aged woman who received heart transplantation for end-stage sarcoid cardiomyopathy developed recurrent cardiac sarcoidosis in the donor heart. She presented 5 years post-transplantation with heart block and systolic dysfunction, without extracardiac involvement. Her disease was unresponsive to corticosteroids. Routine functional imaging may help identify such recurrences.
Computer-aided detection and abnormality score for the outer retinal layer in optical coherence tomography
Authors: Rim Tyler Hyungtaek , Lee Aaron Yuntai , Ting Daniel S , Teo Kelvin Yi Chong , Yang Hee Seung , KIM Hyeonmin , Lee Geunyoung , Teo Zhen Ling , Teo Wei Jun Alvin , Takahashi Kengo , Yoo Tea Keun , Kim Sung Eun , Yanagi Yasuo , Cheng Ching-Yu , Kim Sung Soo , Wong Tien Yin , Cheung Chui Ming Gemmy
Published: April 2021

Background

To develop computer-aided detection (CADe) of ORL abnormalities in the retinal pigmented epithelium, interdigitation zone and ellipsoid zone via optical coherence tomography (OCT).

Methods

In this retrospective study, healthy participants with normal ORL, and patients with abnormality of ORL including choroidal neovascularisation (CNV) or retinitis pigmentosa (RP) were included. First, an automatic segmentation deep learning (DL) algorithm, CADe, was developed for the three outer retinal layers using 120 handcraft masks of ORL. This automatic segmentation algorithm generated 4000 segmentations, which included 2000 images with normal ORL and 2000 (1000 CNV and 1000 RP) images with focal or wide defects in ORL. Second, based on the automatically generated segmentation images, a binary classifier (normal vs abnormal) was developed. Results were evaluated by area under the receiver operating characteristic curve (AUC).

Results

The DL algorithm achieved an AUC of 0.984 (95% CI 0.976 to 0.993) for individual image evaluation in the internal test set of 797 images. In addition, performance analysis of a publicly available external test set (n=968) had an AUC of 0.957 (95% CI 0.944 to 0.970) and a second clinical external test set (n=1124) had an AUC of 0.978 (95% CI 0.970 to 0.986). Moreover, the CADe highlighted well normal parts of ORL and omitted highlights in abnormal ORLs of CNV and RP.

Conclusion

The CADe can use OCT images to segment ORL and differentiate between normal ORL and abnormal ORL. The CADe classifier also performs visualisation and may aid future physician diagnosis and clinical applications.
Extending tubing to place intravenous smart pumps outside of patient rooms during COVID-19: an innovation that increases medication dead volume and risk to patients
Authors: Blake Jeannine W C , Giuliano Karen K , Butterfield Robert D , Vanderveen Tim , Sims Nathaniel M
Published: April 2021

The COVID-19 pandemic has stretched hospitals to capacity with highly contagious patients. Acute care hospitals around the world have needed to develop ways to conserve dwindling supplies of personal protective equipment (PPE) while front-line clinicians struggle to reduce risk of exposure. By placing intravenous smart pumps (IVSP) outside patient rooms, nurses can more quickly attend to alarms, rate adjustments and bag changes with reduced personal risk and without the delay of donning necessary PPE to enter the room. The lengthy tubing required to place IVSP outside of patient rooms comes with important clinical implications which increase the risk to patient safety for the already error-prone intravenous medication administration process. This article focuses on the implications of increasing medication dead volume as intravenous tubing lengths increase. The use of extended intravenous tubing will lead to higher medication volumes held in the tubing which comes with significant safety implications related to unintended alterations in drug delivery. Safe intravenous medication administration is a collaborative responsibility across the team of nurses, pharmacists and ordering providers. This article discusses the importance and safety implications for each role when dead volume is increased due to IVSP placement outside of patient rooms during the COVID-19 pandemic.
Experiences of a non-clinical set of adolescents and young adults living with persistent pain: a qualitative metasynthesis
Authors: Fegran Liv , Johannessen Berit , Ludvigsen Mette Spliid , Westergren Thomas , Høie Magnhild , Slettebø Åshild , Rohde Gudrun , Helseth Sølvi , Haraldstad Kristin
Published: April 2021

Purpose

Around 15%–30% of adolescents and young adults (AYAs) experience persistent or chronic pain. The purpose of this study was to synthesise evidence from qualitative primary studies on how AYAs in a non-clinical population experience living with persistent pain.

Method

A qualitative metasynthesis guided by Sandelowski and Barroso’s guidelines was used. The databases Medline, Embase, Cinahl, PsycINFO, Mednar and ProQuest were searched for studies from 1 January 2005 to 15 February 2021. Inclusion criteria were AYAs aged 13–24 years with first-hand experience of living with persistent, recurrent or episodic non-clinical pain in any body site. Pain associated with a medical diagnosis, malignant diseases, medical procedures or sport activities was excluded.

Results

Of 2618 screened records, data from nine studies conducted in a Western cultural context including 184 participants (127 female and 57 male aged 11–28 years) were analysed into metasummaries and a metasynthesis. Headaches was the most focused pain condition (n=5), while three of the studies did not specify type of pain. The participants’ experiences were characterised by (1) juggling pain with everyday life; (2) exploring sources of information to manage pain; (3) AYAs’ use of medication to find relief and (4) non-pharmacological strategies for pain relief.

Conclusion

These AYAs experience of how pain influences everyday life, and their striving to find relief from pain by support from family, friends, professionals and the Internet should be strongly respected. Public health nurses and other healthcare professionals encountering AYAs need to respect their pain experiences, and to support them in healthy coping strategies. Further studies on this issue are needed, especially research focusing on AYAs pain in exposed populations and AYAs from non-Western cultures.
Interprofessional teamwork for managing medical deterioration in pregnancy: what contributes to good clinical performance in simulated practice?
Authors: Lavelle Mary , Reedy Gabriel B , Simpson Thomas , Banerjee Anita , Anderson Janet E
Published: April 2021

Objectives

To identify the patterns of teamwork displayed by interprofessional teams during simulated management of medical deterioration in pregnancy and examine whether and how they are related to clinical performance in simulated practice.

Design

Exploratory observational cohort study.

Setting

Interprofessional clinical simulation training with scenarios involving the management of medical deterioration in pregnant women.

Participants

Seventeen simulated scenarios involving 62 qualified healthcare staff working within the National Health Service attending clinical simulation training (midwives (n=18), obstetricians (n=24) and medical physicians (n=20)).

Main outcome measure(s)

Teamwork behaviours over time, obtained through detailed observational analysis of recorded scenarios, using the Temporal Observational Analysis of Teamwork (TOAsT) framework. Clinician rated measures of simulated clinical performance.

Results

Scenarios with better simulated clinical performance were characterised by shared leadership between obstetricians and midwives at the start of the scenario, with obstetricians delegating less and midwives disseminating rationale, while both engaged in more information gathering behaviour. Towards the end of the scenario, better simulated clinical performance was associated with dissemination of rationale to the team. More delegation at the start of a scenario was associated with less spontaneous sharing of information and rationale later in the scenario. Teams that shared their thinking at the start of a scenario continued to do so over time.

Conclusions

Teamwork during the opening moments of a clinical situation is critical for simulated clinical performance in the interprofessional management of medical deterioration in pregnancy. Shared leadership and the early development of the shared mental model are associated with better outcomes.
Indoleamine 2,3 Dioxygenase, Age, and Immune Activation in People Living with Hiv
Authors: Baer Stephanie L , Colombo Rhonda E , Johnson Maribeth H , Wakade Sushama , Pacholczyk Gabriela , Newman-Whitlow Cheryl , Thompson Stuart A , Saag Michael S , Martin Jeffrey N , Floris-Moore Michelle , Huang Lei , Mellor Andrew L
Published: April 2021

Immune activation complicates HIV despite antiretroviral therapy (ART). Indoleamine 2,3 dioxygenase (IDO) catabolizes tryptophan (T) to kynurenine (K), regulating immune activity, and IDO activity increases with age. This study examines the relationship of IDO activity, bacterial translocation, and aging in people living with HIV (PLWH) on ART. Samples and data from PLWH on ART from the Centers for AIDS Research Network of Integrated Clinical Systems and from matched HIV-uninfected patients (controls) from the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study were analyzed. The ratio of K to T (K:T) and neopterin were indicators of inflammation; 16S ribosomal DNA (16S rDNA) and lipopolysaccharide (LPS) were markers of bacterial translocation. Samples and data from 205 PLWH and 99 controls were analyzed. PLWH had higher K:T values across all ages, with a significant relationship between age and K:T for both groups. CD4 count or CD4 nadir had no association with K:T. There was no positive association between level of 16S rDNA or LPS detection and K:T. K:T and neopterin were associated. PLWH had elevated IDO activity, at younger ages, despite ART. This study suggests K:T ratio increases with age in both groups and is elevated in PLWH at all ages compared with age-matched controls.
Hydroxychloroquine availability during COVID-19 crisis and its effect on patient anxiety
Authors: Cornet Alain , Andersen Jeanette , Tani Chiara , Mosca Marta
Published: April 2021

Objective

To report the results of a survey exploring the experience of patients with SLE facing hydroxychloroquine (HCQ) shortage that occurred during the early phases of the COVID-19 pandemic.

Methods

A survey was designed by Lupus Europe’s patient advisory network and distributed through its social media, newsflash and members' network. People with lupus were asked about their last HCQ purchases and their level of anxiety (on a 0–10 scale) with regard to not being able to have access to HCQ, once in April 2020 (first wave) and after 11 August (second wave). The results were compared.

Results

2075 patients responded during the first wave; 1001 (48.2%) could get HCQ from the first place they asked, 230 (11.1%) could get the drug by going to more than one pharmacy, 498 (24.0%) obtained HCQ later from their usual pharmacy and 126 (6.1%) from other sources. 188 (9.1%) could not get any; 32 (1.5%) did not respond to this question. All countries showed significant improvement in HCQ availability during the second wave. 562 (27.4%) patients reported an extremely high level of anxiety in wave 1 and 162 (10.3%) patients in wave 2; 589 (28.7%) and 268 (17.1%) patients reported a high level of anxiety in wave 1 and wave 2, respectively.

Conclusions

The HCQ shortage had a significant impact on patients with SLE and has been responsible for psychological consequences including anxiety. Indeed, despite an objective improvement in drug availability, the event is leaving significant traces in patients’ mind and behaviours.
Evaluation of a blended care programme for caregivers and working pregnant women to prevent adverse pregnancy outcomes: an intervention study
Authors: van Beukering Monique , Velu Adeline , Schonewille Lydia Henrike Nicole , Duijnhoven Ruben , Mol Ben Willem , Brand Teus , Frings-Dresen Monique , Kok Marjolein
Published: April 2021

Objective

Work-related activities can be a risk factor for pregnancy complications such as preterm birth. This study evaluates the effectiveness of a blended care programme, Pregnancy and Work, that provides pregnant workers and their obstetrical caregivers with advice on work adjustment.

Methods

Women less than 20 weeks of gestation, in paid employment or self-employed, in the care of four participating hospitals and their referring midwifery practices in the Netherlands received either the blended care programme (n=119), consisting of a training for professionals and a mobile health application, or care as usual (n=122) in a controlled intervention study with a follow-up in intervention and control populations. All participants completed three questionnaires concerning health and working conditions at 16, 24 and 32 weeks of pregnancy. Primary outcome was the percentage of women who received advice from their obstetrical caregiver about work adjustment. Secondary outcomes were work status, realised work adjustment and working conditions. Groups were compared using univariate and multivariate regression analyses.

Results

A total of 188 (78%) completed all three questionnaires. In the blended care group, women received more advice from obstetrical caregivers to adjust their work than in the control group, 41 (39%) vs 21 (18%) (adjusted relative risk (aRR) 2.2, 95% CI 1.4 to 3.4), but less from their employer 8 (8%) vs 31 (28%) (aRR 0.29, 95% CI 0.14 to 0.61). There were no significant differences in realised work adjustments. At 24 weeks, 30% of the pregnant women in both groups continued to work in hazardous workplaces.

Conclusion

Among working pregnant women, the blended care intervention increases advice on work adjustment given by midwives and obstetricians, but does not lead to more work adjustments.
The effects of alcohol consumption and its associations with disease activity among 979 patients with inflammatory arthritis
Authors: Turk Matthew , Murray Kieran , Alammari Yousef , Gorman Aine , Young Francis , Gallagher Phil , Saber Tajvur , Freeman Lorna , Maguire Sinead , O’Shea Finbar , Fearon Ursula , Veale Douglas
Published: April 2021

Objective

The role of alcohol in inflammatory disease remains debated. This study explores the relationship between alcohol and disease activity in patients with inflammatory arthritis.

Methods

Patients attending a rheumatology clinic between 2010 and 2020 were prospectively followed. Information on demographics, alcohol use, smoking habits and disease outcome measures were collected from these patients. Statistical analysis included univariate and multivariate linear and binary logistic regressions, Mann-Whitney U tests and one-way analysis of variance with Tukey’s honest significant difference (HSD) test.

Results

Of the 979 analysed patients, 62% had rheumatoid arthritis (RA), 26.7% had psoriatic arthritis (PsA) and 11.2% had ankylosing spondylitis. Mean DAS28-CRP (Disease Activity Score 28 - C-reactive protein) in RA and PsA at 1 year was 2.96±1.39, and 64.2% of patients were in remission (DAS28-CRP ≤2.6 or BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) ≤4). Both male gender and risky drinking (>15 units of weekly alcohol) were significantly associated with remission. Compared with women, men had an OR of 1.8 (1.1, 2.5) (p=0.034) for any alcohol consumption and 6.9 (4.7, 9.1) (p=0.001) for drinking at least 15 weekly drinks. When adjusted for gender, there was no association between alcohol and disease activity. Yet, when adjusted for alcohol consumption, gender still significantly influenced disease activity.

Conclusion

While it may appear that alcohol is linked to remission in inflammatory arthritis, when adjusted for gender, it is not. Men with inflammatory arthritis drink significantly more than women and have less severe disease activity.
ANCA-associated renal vasculitis is associated with rurality but not seasonality or deprivation in a complete national cohort study
Authors: Aiyegbusi Oshorenua , Frleta-Gilchrist Marina , Traynor Jamie P , Mackinnon Bruce , Bell Samira , Hunter Robert W , Dhaun Neeraj , Kidder Dana , Stewart Graham , Joss Nicola , Kelly Michael , Shah Shahzad , Dey Vishal , Buck Kate , Stevens Kathryn I , Geddes Colin C , McQuarrie Emily P
Published: April 2021

Background

Small studies suggest an association between ANCA-associated vasculitis (AAV) incidence and rurality, seasonality and socioeconomic deprivation. We examined the incidence of kidney biopsy-proven AAV and its relationship with these factors in the adult Scottish population.

Methods

Using the Scottish Renal Biopsy Registry, all adult native kidney biopsies performed between 2014 and 2018 with a diagnosis of granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) were identified. The Scottish Government Urban Rural Classification was used for rurality analysis. Seasons were defined as autumn (September–November), winter (December–February), spring (March–May) and summer (June–August). Patients were separated into quintiles of socioeconomic deprivation using the validated Scottish Index of Multiple Deprivation and incidence standardised to age. Estimated glomerular filtration rate and urine protein:creatinine ratio at time of biopsy were used to assess disease severity.

Results

339 cases of renal AAV were identified, of which 62% had MPA and 38% had GPA diagnosis. AAV incidence was 15.1 per million population per year (pmp/year). Mean age was 66 years and 54% were female. Incidence of GPA (but not MPA) was positively associated with rurality (5.2, 8.4 and 9.1 pmp/year in ‘urban’, ‘accessible remote’ and ‘rural remote’ areas, respectively; p=0.04). The age-standardised incidence ratio was similar across all quintiles of deprivation (p=ns).

Conclusions

Seasonality and disease severity did not vary across AAV study groups. In this complete national cohort study, we observed a positive association between kidney biopsy-proven GPA and rurality.
HIV and STI positivity rates among transgender people attending two large STI clinics in the Netherlands
Authors: Drückler Susanne , Daans Ceranza , Hoornenborg Elske , De Vries Henry , den Heijer Martin , Prins Maria , Kuizenga Wessel Sophie , van Rooijen Martijn
Published: April 2021

Background

Global data show that transgender people (TGP) are disproportionally affected by HIV and sexually transmitted infections (STIs); however, data are scarce for Western European countries. We assessed gender identities, sexual behaviour, HIV prevalence and STI positivity rates, and compared these outcomes between TGP who reported sex work and those who did not.

Methods

We retrospectively retrieved data from all TGP who were tested at the STI clinics of Amsterdam and The Hague, the Netherlands in 2017–2018. To identify one’s gender identity, a ‘two-step’ methodology was used assessing, first, the assigned gender at birth (assigned male at birth (AMAB)) or assigned female at birth), and second, clients were asked to select one gender identity that currently applies: (1) transgender man/transgender woman, (2) man and woman, (3) neither man nor woman, (4) other and (5) not known yet. HIV prevalence, bacterial STI (chlamydia, gonorrhoea and/or infectious syphilis) positivity rates and sexual behaviour were studied using descriptive statistics.

Results

TGP reported all five categories of gender identities. In total 273 transgender people assigned male at birth (TGP-AMAB) (83.0%) and 56 transgender people assigned female at birth (TGP-AFAB) (17.0%) attended the STI clinics. Of TGP-AMAB, 14,6% (39/267, 95% CI 10.6% to 19.4%) were HIV-positive, including two new diagnoses and bacterial STI positivity was 15.0% (40/267, 95% CI 10.9% to 19.8%). Among TGP-AFAB, bacterial STI positivity was 5.6% (3/54, 95% CI 1.2% to 15.4%) and none were HIV-positive. Sex work in the past 6 months was reported by 53.3% (137/257, 95% CI 47.0% to 59.5%) of TGP-AMAB and 6.1% (3/49, 95% CI 1.3% to 16.9%) of TGP-AFAB. HIV prevalence did not differ between sex workers and non-sex workers.

Conclusion

Of all TGP, the majority were TGP-AMAB of whom more than half engaged in sex work. HIV prevalence and STI positivity rates were substantial among TGP-AMAB and much lower among TGP-AFAB. Studies should be performed to provide insight into whether the larger population of TGP-AMAB and TGP-AFAB are at risk of HIV and STI.
Spectral and scattering theory of one-dimensional coupled photonic crystals
Authors: De Nittis G. , Moscolari M. , Richard S. , Tiedra de Aldecoa R.
Published: April 2021

We study the spectral and scattering theory of light transmission in a system consisting of two asymptotically periodic waveguides, also known as one-dimensional photonic crystals, coupled by a junction. Using analyticity techniques and commutator methods in a two-Hilbert spaces setting, we determine the nature of the spectrum and prove the existence and completeness of the wave operators of the system.
What is the potential for a second peak in the evolution of SARS-CoV-2 in emerging and developing economies? Insights from a SIRASD model considering the informal economy
Authors: Pires Marcelo A. , Crokidakis Nuno , Cajueiro Daniel O. , Argollo de Menezes Marcio , Duarte Queirós Silvio M.
Published: April 2021

We study the potential scenarios from a Susceptible-Infected-Recovered-Asymptomatic-Symptomatic-Dead (SIRASD) model. As a novelty, we consider populations that differ in their degree of compliance with social distancing policies following socioeconomic attributes that are observed in emerging and developing countries. Considering epidemiological parameters estimated from data of the propagation of SARS-CoV-2 in Brazil — where there is a significant stake of the population making their living in the informal economy and thus prone to not follow self-isolation — we assert that if the confinement measures are lifted too soon, namely as much as one week of consecutive declining numbers of new cases, it is very likely the appearance of a second peak. Our approach should be valid for any country where the number of people involved in the informal economy is a large proportion of the total labor force. In summary, our results point out the crucial relevance of target policies for supporting people in the informal economy to properly comply with preventive measures during the pandemic.
A Novel Adaptive Differential Privacy Algorithm for Empirical Risk Minimization
Authors: Zhang Kaili , Zhang Haibin , Zhao Pengfei , Chen Haibin
Published: April 2021

Privacy-preserving empirical risk minimization model is crucial for the increasingly frequent setting of analyzing personal data, such as medical records, financial records, etc. Due to its advantage of a rigorous mathematical definition, differential privacy has been widely used in privacy protection and has received much attention in recent years of privacy protection. With the advantages of iterative algorithms in solving a variety of problems, like empirical risk minimization, there have been various works in the literature that target differentially private iteration algorithms, especially the adaptive iterative algorithm. However, the solution of the final model parameters is imprecise because of the vast privacy budget spending on the step size search. In this paper, we first proposed a novel adaptive differential privacy algorithm that does not require the privacy budget for step size determination. Then, through the theoretical analyses, we prove that our proposed algorithm satisfies differential privacy, and their solutions achieve sufficient accuracy by infinite steps. Furthermore, numerical analysis is performed based on real-world databases. The results indicate that our proposed algorithm outperforms existing algorithms for model fitting in terms of accuracy.
Optimization of the Sino-Europe Transport Networks Under Uncertain Demand
Authors: Nie Qing , Liu Songyun , Qian Qiyuan , Tan Zheyi , Wang Huiwen
Published: April 2021

This paper studies a consolidation center selection and cargo transportation optimization problem of the Sino-Europe railway express. It takes account of demand uncertainty and multiple cost factors, such as transportation cost, time cost, waiting cost before consolidation, penalty cost of not full load after distribution, track changing cost, and customs clearance fee. A complicated mixed-integer programming (MIP) model is presented to describe the problem. Then a solution method based on binary particle swarm optimization (BPSO) is designed to solve the model of different scales of cases. Extensive numerical experiments generated from real-world data are conducted to validate the effectiveness of the proposed model. Moreover, we compare the efficiency of the solution method with a commercial solver and a heuristic algorithm based on variable neighborhood search (VNS). Results show that our solution method can optimally solve the problem in small-scale cases and get near-optimal solutions for large-scale problem instances. The proposed mathematical model and the calculation results may provide valuable insights for both business owners and government.
Fractional-order derivatives in cosmological models of accelerated expansion
Authors: Shchigolev V. K.
Published: April 2021

In this brief review, we present the results of the fractional differential approach in cosmology in the context of the exact models of cosmological accelerated expansion obtained by several authors to date. Most of these studies are devoted to the problem of introducing fractional derivatives or fractional integrals into the classical General Relativity (GR). There are several observational and theoretical motivations to investigate the modified or alternative theories of GR. Among other things, we cover General Relativity modified by a phenomenological approach dealing with fractional calculus. At the same time, a sufficiently large number of exact solutions of the cosmological equations modified by this approach were obtained. Some of these models may be especially relevant in the light of solving the problem of late accelerated expansion of the Universe. These studies are largely motivated by rapid progress in the field of observational cosmology that now allows, for the first time, precision tests of fundamental physics on the scale of the observable Universe. The purpose of this review is to provide a reference tool for researchers and students in cosmology and gravitational physics, as well as a self-contained, comprehensive and up-to-date introduction to the subject as a whole.
Design and Implementation of Single-Input Multiple-Output DC–DC Buck Converter for Electric Vehicles
Authors: Aden Ilyass Abdillahi , Kahveci Hakan , Şahin Mustafa Ergin
Published: April 2021

The transportation sector uses a big portion of the world’s petroleum products thus increasing the greenhouse gas (GHG) emissions. Electric vehicles (EVs) have the potential to solve GHG emissions. The requirements for EVs have brought many different problems such as the conversion of voltage level from the battery to other parts of the EV using DC–DC converters. The design and implementation of a nonisolated DC–DC buck converter with single input and dual output are presented, which is also called the single-input multiple-output (SIMO) converter. The converter is designed especially for electric cars. The battery (48[Formula: see text]V) of the electric vehicle is used as an input to the SIMO. Small-signal analysis and effective control strategy for the converter are presented in this paper. The simulation of the system is performed and compared with the experimental results.
New CMOS Realizable All-Pass Frequency Selective Structures
Authors: Mohan Jitendra , Chaturvedi Bhartendu , Kumar Atul
Published: April 2021

This paper deals with the realization of two first-order all-pass filter (APF) structures. First structure provides both inverting and non-inverting voltage-mode APF functions. This structure utilizes one differential difference dual-[Formula: see text] second generation current conveyor (DD-DXCCII) without [Formula: see text] terminals, one active resistor and one capacitor only. The use of active resistor makes the proposed structure electronically tunable. Therefore, the attributes such as use of single DD-DXCCII without [Formula: see text] terminals and electronic tunability make the proposed structure simple and attractive. Conversely, second proposed circuit structure of first-order APF enriches the quality of this paper as both inverting and non-inverting APF functions in both voltage and current forms are available simultaneously within the same circuit structure. This circuit is realized with the help of one DD-DXCCII, three active resistors and one capacitor. The second circuit structure also enjoys gain controllability feature along with electronically tunable pole frequency that proves to be very essential in many of the applications. Additionally, the proposed APF structures provide the demanding feature of cascadability along with chip fabrication support. Furthermore, the performance of proposed circuits is less affected by the non-idealities and parasitic of DD-DXCCII. PSPICE simulations are provided to validate the theoretical presumptions.
Close stellar encounters kicking planets out of habitable zone in various stellar environments
Authors: Arbab Behzad Bojnordi , Rahvar Sohrab
Published: April 2021

Continuous habitability of a planet is a critical condition for advanced forms of life to appear, but it can be endangered by astronomical events such as stellar encounters. The purpose of this study is to analyze close stellar encounters able to change planetary orbits initially in circumstellar habitable zones and to investigate the expected encounter rates in a variety of stellar environments. Using gravitational simulations for three-body systems, this study analyzed the dependencies of encounter impact-parameters with kinematic, geometric, and habitability parameters of the system. We also used kinematic properties of various stellar regions and estimated encounter rates of the events. The expected number of threatening stellar encounters in the Solar neighborhood is [Formula: see text] in 4 billion years, while for the Galactic bulge environment, we expect approximately 5.5 times the value. The encounter rates for other stellar environments are calculated and spheroidal dwarf galaxies and globular clusters encounter rates are estimated. The results show that in contrast with the solar neighborhood, close stellar encounters can play a significant role in the expected number of planets with continuous habitability in dense stellar environments. Another notable result shows that threatening stellar encounter rate follows the number density of stars, and is not strongly dependent of the region’s velocity dispersion. Further investigations are needed to study long-term multiple planetary systems and how they can change the overall expected value of continuously habitable planets.
The Nature of Equilibria Under Noncollusive Product Design and Collusive Pricing
Authors: Rath Kali P. , Zhao Gongyun
Published: April 2021

The basic framework is Hotelling’s model of product choice with quadratic transportation cost. Duopolists choose locations in the initial period and compete in prices in subsequent infinite periods. The firms share profits on the profit possibility frontier. It is shown that under very general conditions, both the firms locating at the center is an equilibrium. It is not necessarily unique and multiple symmetric equilibria can exist. Thus, the products are not necessarily minimally differentiated. How the profits are shared when the firms are located together off the center has a critical bearing on the nature of equilibria. If the firms share profits equally at those locations, then all the equilibria are symmetric. Otherwise, asymmetric equilibria can appear. The equilibria can be classified into three types: a unique equilibrium at the center of the market, multiple symmetric equilibria and multiple asymmetric agglomerated equilibria. The second case entails nonminimal product differentiation. Sufficient conditions for each of these equilibria are given. Necessary conditions for multiple symmetric equilibria off the center are also obtained.
An Efficient Weighted Residual Time Integration Family
Authors: Rezaiee-Pajand Mohammad , Esfehani S. A. H. , Ehsanmanesh H.
Published: April 2021

A new family of time integration methods is formulated. The recommended technique is useful and robust for the loads with large variations and the systems with nonlinear damping behavior. It is also applicable for the structures with lots of degrees of freedom, and can handle general nonlinear dynamic systems. By comparing the presented scheme with the fourth-order Runge–Kutta and the Newmark algorithms, it is concluded that the new strategy is more stable. The authors’ formulations have good results on amplitude decay and dispersion error analyses. Moreover, the family orders of accuracy are [Formula: see text] and [Formula: see text] for even and odd values of [Formula: see text], respectively. Findings demonstrate the superiority of the new family compared to explicit and implicit methods and dissipative and non-dissipative algorithms.
Enhancement of MRI Brain Images Using Notch Filter Based on Discrete Wavelet Transform
Authors: Ravikumar M. , Shivaprasad B. J. , Guru D. S.
Published: April 2021

In this work, we have proposed Notch filter method to enhance MRI brain images. The proposed method performs better when compared with the existing methods from the literature. The performance is evaluated using quantitative measures like Michelon Contrast (MC), entropy, Peak Signal-to-Noise Ratio (PSNR), Structure Similarity Index Measurement (SSIM) and Absolute Mean Brightness Error (AMBE), as a parameter on publically available BRATS-2018 & 2019 dataset. Overall, the proposed method performs well in comparison to the other existing methods.
Effect of the Length of TiO2 Nanotube Arrays on Responsivity of Photoelectrochemical-Based Ultraviolet Photodetectors
Authors: Ravan Bahram Abedi , Saadati Ali Akbar , Cheraghi Akbar
Published: April 2021

In this study, one-dimensional titanium dioxide (TiO[Formula: see text] nanotube arrays (NTAs) with different tube lengths are synthesized via anodic oxidation of Ti foils and their ultraviolet (UV) light detection properties are investigated to determine their optimum growth conditions. A TiO2 nanotube ultraviolet photodetector based on photoelectrochemical cell is fabricated using the optimum TiO2 nanotubes and its characteristics in the ultraviolet region are determined. The photodetector is examined under a UV illumination intensity of 10[Formula: see text]mW/cm2and at a wavelength of 368[Formula: see text]nm. Its responsivity is measured to be about 96[Formula: see text][Formula: see text]A/cm2 and its response time is less than 0.2[Formula: see text]s under an applied bias of 0.5[Formula: see text]V.
Extending ARAS with Integration of Objective Attribute Weighting under Spherical Fuzzy Environment
Authors: Gül Sait
Published: April 2021

Various fuzzy sets have been developed in the recent years to model the uncertainty in judgments. Spherical fuzzy set (SFS) concept is one of these developments. It can provide an extensive preference domain for decision-makers by allowing them to state their hesitancy more explicitly. The peculiarity of SFS is that the squared sum of membership, nonmembership, and hesitancy degrees should be between 0 and 1 while each is independently defined in [0, 1]. In this study, ARAS as one of the most applied multiple attribute decision-making approaches is extended into a spherical fuzzy environment. Entropy-based and OWA operator-based objective attribute weights are also integrated with the newly proposed spherical fuzzy ARAS for coping with the drawbacks of subjective weighting such as longer data collection time and manipulation risk. The applicability of the proposition is shown in a hypothetical example of a product design problem and its robustness is shown by a comparative analysis.
Rec-CFSVD++: Implementing Recommendation System Using Collaborative Filtering and Singular Value Decomposition (SVD)++
Authors: Anwar Taushif , Uma V. , Srivastava Gautam
Published: April 2021

In recommender systems, Collaborative Filtering (CF) plays an essential role in promoting recommendation services. The conventional CF approach has limitations, namely data sparsity and cold-start. The matrix decomposition approach is demonstrated to be one of the effective approaches used in developing recommendation systems. This paper presents a new approach that uses CF and Singular Value Decomposition (SVD)[Formula: see text] for implementing a recommendation system. Therefore, this work is an attempt to extend the existing recommendation systems by (i) finding similarity between user and item from rating matrices using cosine similarity; (ii) predicting missing ratings using a matrix decomposition approach, and (iii) recommending top-N user-preferred items. The recommender system’s performance is evaluated considering Root Mean Square Error (RMSE) and Mean Absolute Error (MAE). Performance evaluation is accomplished by comparing the systems developed using CF in combination with six different algorithms, namely SVD, SVD[Formula: see text], Co-Clustering, KNNBasic, KNNBaseline, and KNNWithMeans. We have experimented using MovieLens 100[Formula: see text]K, MovieLens 1[Formula: see text]M, and BookCrossing datasets. The results prove that the proposed approach gives a lesser error rate when cross-validation ([Formula: see text]) is performed. The experimental results show that the lowest error rate is achieved with MovieLens 100[Formula: see text]K dataset ([Formula: see text], [Formula: see text]). The proposed approach also alleviates the sparsity and cold-start problems and recommends the relevant items.
Two-Dimensional Boundary Element Method Using Interval B-Spine Wavelet
Authors: Wei Qi , Xiang Jiawei
Published: April 2021

A two-dimensional (2D) boundary element method (BEM) is proposed by replacing traditional polynomial interpolation with one-dimensional (1D) scaling functions of B-spine wavelet on the interval (BSWI). Potential problem and elasticity problem are investigated by BSWI BEM. For these two problems, the boundary variables represented by coefficients of wavelets expansions are transformed from wavelet space to physical space through the nonsingular transformation matrices. To make the curve boundary able to be compatible well, the second-order scaling functions are applied to approximate geometric boundary. In addition, singular integral problems appearing in BSWI BEM are solved. Numerical examples verify that BSWI BEM has a desirable performance by comparing with conventional 2D BEM.
Synthesis, properties and reactivity of an ortho-phenylene-cyclopentene-bridged tetrapyrrole
Authors: Morimoto Yuki , Osuka Atsuhiro , Tanaka Takayuki
Published: April 2021

Increasing the number of meso-methine carbons of porphyrin has led to a creation of a series of vinylogous expanded porphyrins, while the introduction of an ortho-phenylene-unit as a pyrrole-connecting two-carbon bridge usually leads to prevention of effective macrocyclic conjugation. Cyclopentene can serve as a conjugative bridge to increase the macrocyclic conjugation owing to its cis-geometry. In this work, ortho-phenylene-cyclopentene-bridged tetrapyrrole 5 was prepared on the basis of a coupling strategy. The tetrapyrrole 5 exhibited slightly more conjugative features as compared to ortho-phenylene-bridged tetrapyrrole 4. Oxidation of 5 with [bis(trifluoroacetoxy)iodo]benzene (PIFA) at low temperature afforded a partly fused tetrapyrrolic compound 9 having a spiro-connected pyrrolo[2,1-[Formula: see text]]isoindole moiety.
Natural selection between two games with environmental feedback
Authors: Yuan Hairui , Meng Xinzhu , Li Zhenqing
Published: April 2021

Evolutionary game theory has extensively investigated situations in which several games are competing against each other at the same time, but the model only assumes symmetric interactions in homogeneous environments. Now, the population is considered in heterogeneous environments, individuals in the population occupy a different quality of patches, and individual fitness depends not only on the interaction between individuals, but also on the quality of the environment. Here, by establishing a mathematical framework, we analyze the natural selection between two strategies and two games in heterogeneous environments. Furthermore, we analyze the natural selection of Prisoner’s Dilemma and Hawk–Dove games theoretically to demonstrate the dynamics of cooperators and defectors in their choice of environment and their respective games. As expected, the distribution of games and strategies changes with time. Based on different initial population compositions, we also discuss the invasion problem of games from different perspectives. To one’s surprise, we can find that good quality patches attract all individuals; the long-term dynamics in invariant rich environments is the same as the dynamics of symmetric interactions in homogeneous environments.
Mathematical analysis of multi-target cells and multi-strain age-structured model with two HIV infection routes
Authors: Wu Peng , Zhao Hongyong
Published: April 2021

In this paper, we propose detailed and reasonable viral dynamics by using a multi-compartment model that incorporating the age since the infection of multiple infected cells, multiple target cells (Langerhans-cells and CD4[Formula: see text] T-cells), multiple viral strains (CCR5 and CXR4 HIV) and multiple infection routes (cell-to-cell and cell-to-virus). The basic reproduction number, [Formula: see text], of the whole model is derived from two transmission mechanisms: one is the potential trigger from the infection routes for a single target cell and other is the joint effect of multiple viral infections for multi-target cells. Accordingly, we study the global stability of the steady states for the single target model. For the whole model, we prove that the infection-free steady state is globally asymptotically stable if [Formula: see text], whereas viruses persist uniformly if [Formula: see text]. Numerical simulations are carried out to illustrate the theoretical results. Sensitive analyses expound the effect of model parameters on the comprehensive reproduction number. It is remarkable to find that simultaneous control of HIV infection for two target cells can effectively reduce the viral loads within-host. Finally, our work suggests that the synergetic mechanism of multi-target cells and multi-strain cannot be ignored during treatment.
Efficient numerical algorithms for the phase field crystal equation
Authors: Zhuang Qingqu , Zhai Shuying , Weng Zhifeng
Published: April 2021

In this paper, based on the Lagrange Multiplier approach in time and the Fourier-spectral scheme for space, we propose efficient numerical algorithms to solve the phase field crystal equation. The numerical schemes are unconditionally energy stable based on the original energy and do not need the lower bound hypothesis of the nonlinear free energy potential. The unconditional energy stability of the three semi-discrete schemes is proven. Several numerical simulations in 2D and 3D are demonstrated to verify the accuracy and efficiency of our proposed schemes.
Formation temperature and ages of the True North ‘orogenic’ gold deposit in Manitoba, Canada
Authors: Alexandre Paul , Fayek Mostafa
Published: April 2021

The True North orogenic gold deposit is situated in the 2.99–2.70 Ga Rice Lake greenstone belt near Bissett (Manitoba, Canada). This belt is the western equivalent of northern Ontario's Abitibi gold-producing region. The lithology and alteration, structural control, geochronological framework, and ore geology of the True North orogenic gold deposit have been addressed, but its formation temperature and age are poorly constrained.

The deposit's gold-bearing veins are composed mostly of quartz (40 to 80%), ankerite (20 to 30%), and albite (5 to 25%), with minor muscovite, sericite, chlorite, and calcite. Sulfide minerals are dominated by pyrite and chalcopyrite and with minor pyrrhotite; native gold appears as inclusions in sulfides or as free gold. In general, most of the major minerals, the sulfides, and gold all precipitated during the main ore stage.

The oxygen isotopic composition of co-existing quartz–albite and quartz–ankerite couples were used to calculate a formation temperature of approximately 230°C for these minerals, which is comparable to the nearby 007 gold deposit. These temperatures are on the low end of the temperature range reported for orogenic gold deposits.
40
Ar/
39
Ar geochronology (single grain laser fusion of muscovite and sericite) revealed the presence of two age groups, at 2441.2 ± 8.8 Ma and 2483.1 ± 10.2 Ma, approximately 200 myr lower than the age of the main collision-related deformation within the Rice Lake belt. These ages indicate that the True North deposit was clearly post-orogenic, similar to vein gold deposits elsewhere, and was likely produced by the emplacement of the Huronian Supergroup and the thermal effects of the Matachewan large igneous province, which has the same ages. It is suggested that the True North deposit may belong to a descriptive category of post-orogenic low-temperature quartz–carbonate–albite vein gold deposit, more in line with recent developments in classification schemes.
Multi-method 2D and 3D reconstruction of gold grain morphology in alluvial deposits: a review and application to the Rivière du Moulin (Québec, Canada)
Authors: Masson François-Xavier , Beaudoin Georges , Laurendeau Denis
Published: April 2021

The aim of this paper is to document and compare the 2D qualitative and semi-quantitative methods currently used to describe the shape of gold grains in fluvial environments with the 3D quantitative methods using X-ray microtomography and SEM photogrammetry. These 3D methods are used to compute flatness, roundness, convexity, sphericity and ellipticity shape descriptors of 13 gold grains from the Rivière du Moulin (Québec, Canada) in order to quantify the morphological change along 9 km of fluvial transport. Gold grains have moderate to high values of flatness, compactness, sphericity and ellipticity indices that do not change significantly with distance of transport, whereas the roundness increases during transport. Gold grains are used to compare 2D and 3D methods, and the results show small differences (<8%) when shape descriptors are computed using image analysis software, whereas the difference (up to 70%) is more important for 2D measurements performed by a human operator. For application and characterization on a large set of gold grains, the 2D methods offer the advantage of speed, whereas, for a more detailed study on a limited number of gold grains, 3D methods enable estimation of the volume and yield more detailed shape descriptor changes during fluvial transport.