bluuebunny/crossref_metadata_2025 huggingface dataset:
755 Research priorities for prehospital care of older patients with injuries: scoping review
Authors: Harthi Naif , Goodacre Steve , Sampson Fiona , Alharbi Rayan
Published: June 2022

Introduction and purpose

The use of ambulance services by older patients with injuries increases within the impacts of ageing-related changes leading to adverse patient outcomes. There is increasing recognition of the importance of prehospital trauma care for older patients, but little systematic research to guide practice. We aimed to review the published evidence on prehospital trauma care for older patients, determine the scope of existing research and identify research gaps in the literature.

Methods

A systematic scoping review guided by the Arksey and O’Malley framework reported in line with the PRISMA-ScR checklist. A systematic search was conducted of Scopus, CINAHL, MEDLINE, PubMed and Cochrane library databases to identify articles published between (2001–2021) years. Inclusion and exclusion criteria were applied independently by two reviewers. Data were extracted, charted and summarised from eligible articles.

Results

65 studies were identified and reviewed, and 25 included. Five categories were identified: ‘field triage, ‘ageing impacts’, ‘decision-making’, ‘paramedic’ awareness’ and ‘paramedic’s behaviour’. Undertriage & overtriage (sensitivity & specificity) were commonly cited as poorly investigated field-triage subthemes. Ageing-related physiologic changes, comorbidities and polypharmacy were the most widely researched. Inaccurate decision-making and poor early identification of major injuries were identified as potentially influencing patient outcomes. More research is required into paramedic knowledge of geriatric care & ageing changes and the potential impact of paramedic care.

Conclusion

This is the first study reviewing the published evidence on prehospital trauma care for older patients and identifying research priorities for future research. This review has identified the prehospital triage for older trauma victims and studies of paramedic knowledge of older trauma care as key priorities. Investigating and understanding these can improve providing prehospital care of the older patient with injuries for positive patient outcomes.
833 Using the GEMLR as a proxy for global health engagement of emergency care practitioners
Authors: Jafar Anisa , Prager Gabrielle , Jones Pete , Bromley Claire , Kennedy Harriet , Ndiaye Haarith , Ingham Jack
Published: June 2022

Aims/Objectives/Background

There is broad involvement of emergency medicine (EM) practitioners in global EM (GEM) research. However this work is often siloed, reducing efficiency of collaboration and impeding healthy critical appraisal. The purpose of this novel longitudinal study is to identify the GEM research undertaken by those in EM. Quantifying, displaying and understanding the ‘who’, ‘what’ and ‘where’ of such research is a key step to facilitate collaboration and highlight important gaps to ultimately drive quality in GEM research as a whole.

Methods/Design

The Global Emergency Medicine Literature Review (GEMLR) is an annual summary of the top-ranked GEM literature. A spreadsheet of all papers identified by each initial search (before ranking) is freely available. We searched the past six years of GEMLR’s 3,634 initial titles to identify authors with EM affiliations. We also collected data on author institutions, country focus, topic, funding sources and if co-authorship included local collaborators.

Results/Conclusions

From 2014–2019 the GEMLR found over 800 individual papers with at least one EM affiliated author. Authors were from over 600 different institutions (see figure 1) and research focused on over 100 countries.

Abstract 833 Figure 1

Author spread

Approximately 60% had no funding/documented and 5% papers did not include a local author.

There are limitations, including the GEMLR search strategy and EM practitioners omitting their EM affiliations (a take home message, if we wish to strengthen EM’s perceived research presence). However this study serves as a robust start-point to map GEM research engagement. Interestingly, the study demonstrates a modest UK author slice with 20 being identified, contributing to 12 papers over 6 years.

Further analysis will target the sociodemographic association between the most/least researched countries, expanding to include further years of data. Using a data visualisation strategy we will make the work accessible online to provide leverage in areas of much-needed GEM research growth.
791 The EDCO study: screening patients for unintentional carbon monoxide exposure in emergency department patients
Authors: Jarman Heather , Atkinson Richard , Baramova Desislava , Quinn Tom
Published: June 2022

Aims/Objectives/Background

Carbon monoxide (CO) is the most common cause of death by poisoning worldwide. Repeated low-level exposure to CO is significant health concern leading to long-term neurological sequelae but is difficult to diagnose due to non-specific symptoms such as headache. We aimed to establish the prevalence of low-level CO poisoning in patients presenting to the ED with symptoms suggestive of CO exposure.

Methods/Design

This prospective multi-centre observational study recruited from four UK EDs between December 2018 and March 2020. Eligible patients were those with symptoms suggestive of CO poisoning including headache, flu-like symptoms and cardiac chest pain. We collected data using the RCEM endorsed ‘COMA’ questions to detect CO poisoning and measured carboxyhaemoglobin (COHb). An investigation of the home was undertaken to identify sources of CO exposure. The proportion (exact 95% confidence interval) of probable CO poisoning in each symptom group was calculated.

Results/Conclusions

We analysed data from 4190 patients. 159 (3.8%) had suspected CO poisoning based on COHb level and/or COMA questions. Prevalence was highest in patients with flu-like symptoms 14.8% (7.9, 24.4).

Data linked to CO testing in the home confirmed 1 case of CO presence and 21 probable cases based on a possible CO source from gas appliances. 62% of probable cases had normal COHb level in ED and were identified using only the COMA questions. Only 7.5% of patients with raised COHb level were considered by ED clinicians to have been exposed to CO as a cause for their symptoms.

This study provides evidence that ED patients with non-specific symptoms and no clear history of CO exposure are at risk from CO poisoning from faulty appliances in the home. We advocate that the COMA tool is used in conjunction with testing of COHb levels at the earliest opportunity to ensure that patients with potential CO exposure are not missed.
871 Virtual platforms for learning: balancing pandemic needs springboards future educational success
Authors: Mossad Tim
Published: June 2022

Aims/Objectives/Background

The current Covid-19 pandemic poses many unprecedented educational challenges. Virtual learning is a recognised and increasingly validated modality that has been strategically adapted to facilitate pandemic educational delivery. Balancing platform usage with fewer available face to face sessions could facilitate clinical competency development and progression for all workforce colleagues and beyond.

Methods/Design

This prospective cross-site large DGH survey, powered at an 8% margin of error with 95% confidence intervals, aimed to identify colleague perceptions of virtual learning platforms.

80 colleagues (41 males, 39 females) participated in survey monkey questionnaire completion over a designated three-week period following governance approval.

Demographic data was collated on job title/grade, sex, age bracket and whether the respondent currently worked in ED. Likert scale referenced statements on knowledge, confidence, utility and enjoyability were transcribed into metric data for analysis (1- strongly disagree, 2- partially disagree, 3- neither agree or disagree, 4- partially agree, 5- strongly agree).

Results/Conclusions

Survey participants at undergraduate and postgraduate levels believed virtual platforms are useful (3.80, p<0.002) and had confidence in them (3.90, p<0.001) despite face to face preferences (4.23, p<0.001). Respondents believed virtual mapping facilitated competency development and portfolio completion with high utility and system knowledge (3.68–4.08, p<0.001). Whilst preferring platform variety and pre-determined guidance, subgroup analyses showed Foundation and Core EM Trainees had highest enjoyment levels (3.85–4.88, p<0.001). Trainees preferred receiving virtual learning on one platform (4.78, p<0.001). Perceptions on needing traditional classroom teaching were neutral (3.2, p<0.01).

Overall, themes relating to respondent’s perception of virtual platforms were positive. This survey provides a valid, transferable platform for developing and exploring future balanced use of virtual platforms as resources for educational progression and development.
892 Treatment variables associated with outcome in emergency department suspected sepsis
Authors: Sivayoham Narani , Blake Lesley , Tharimoopantavida Shafi , Chughtai Saad , Hussain Adil , Rhodes Andrew
Published: June 2022

Aims/Objectives/Background

Early treatment is advocated in the management of patients with suspected sepsis. We sought to understand the association between the emergency department (ED) treatments and outcome in these patients. The treatments studied were: (i) the time to antibiotics, (ii) the volume of intravenous fluid (IVF), (iii) mean arterial pressure (MAP) after 2,000 ml of IVF and (iv) the final MAP in the ED.

Methods/Design

A retrospective analysis of the ED database of adult patients who met two SIRS criteria or one red flag sepsis criteria on arrival, received intravenous antibiotics for a suspected infection and admitted between February 2016 and August 2017, was performed. The primary outcome measure was all-cause in-hospital mortality. The four treatments stated above were controlled for severity of illness and subject to multivariate logistic regression and Cox proportional-hazard regression to identify independent predictors of mortality.

Results/Conclusions

Of the 2,066 patients studied 272 (13.2%) died in hospital. The median time to antibiotics was 48 (Interquartile range 30–82) minutes. The time to antibiotics was an independent predictor of mortality only in those who developed refractory hypotension (RH); antibiotics administered more than 55 mins after arrival was associated with an odd-ratio (OR) for mortality of 2.75 [95% confidence interval (CI) 1.22–6.14]. The number-needed-to-treat was 4. IVF >2,000 ml (95%CI >500->2,100), except in RH, and a MAP≤66 mmHg after 2,000 mls of IVF were also independent predictors of mortality. The OR for mortality of IVF>2,000 ml in non-RH was 1.80 (95%CI 1.15–2.82); Number-needed-to-harm was 14. The OR for morality for a MAP≤66 mmHg after 2,000 ml of IVF was 3.42 (95%CI 2.10–5.57). A final MAP<75 mmHg in the ED was associated with, but not an independent predictor of mortality.

Antibiotics were time-critical only in refractory hypotension. Intravenous fluids >2,000 mls in non-RH and a MAP≤66 mmHg after 2,000 ml of IVF were also independent predictors of mortality.
834 Comparative analysis of major incident triage tools in children – a UK population-based analysis
Authors: Vassallo James , Chernbumroong Saisakul , Malik Nabeela , Xu Yuanwei , Keene Damian , Gkoutos George , Lyttle Mark , Smith Jason
Published: June 2022

Aims/Objectives/Background

Triage is a key principle in the effective management of major incidents. There is currently a paucity of evidence to guide the triage of children. The aim of this study was to perform a comparative analysis of nine adult and paediatric triage tools, including the novel ‘Sheffield Paediatric Triage Tool’ (SPTT), assessing their ability in identifying patients needing life-saving interventions (LSI).

Methods/Design

A ten-year retrospective database review of TARN data for paediatric patients (<16years) was performed. Primary outcome was identification of patients receiving one or more LSIs from a previously defined list. Secondary outcomes included mortality and prediction of ISS>15. Primary analysis was conducted on patients with complete pre-hospital physiological data with planned secondary analyses using first recorded physiological data. Performance characteristics were evaluated using sensitivity, specificity, under and over-triage.

Results

15133 patients met TARN inclusion criteria. 4962 (32.8%) had complete pre-hospital physiological data and 8255 (54.5%) had complete first recorded data. Male patients predominated (69.5%), sustaining blunt trauma (95.4%) with a median ISS of 9. 875 patients (17.6%) received at least one LSI.

The SPTT demonstrated the greatest sensitivity of all triage tools at identifying need for LSI (92.2%) but was associated with the highest rate of over-triage (75.0%). Both the PTT (sensitivity 34.1%) and JumpSTART (sensitivity 45.0%) performed less well at identifying LSI. By contrast, the adult MPTT-24 triage tool had the second highest sensitivity (80.8%) with tolerable rates of over-triage (70.2%).

Conclusion

The SPTT and MPTT-24 outperform existing paediatric triage tools at identifying those patients requiring LSIs. This may necessitate a change in recommended practice. Further work is needed to determine the optimum method of paediatric major incident triage, but consideration should be given to simplifying major incident triage by the use of one generic tool (the MPTT-24) for adults and children.
Unfavourable intrauterine environment contributes to abnormal gut microbiome and metabolome in twins
Authors: Yang Jing , Hou Lingling , Wang Jinfeng , Xiao Liwen , Zhang Jinyang , Yin Nanlin , Yao Su , Cheng Kun , Zhang Wen , Shi Zhonghua , Wang Jing , Jiang Hai , Huang Nana , You Yanxia , Lin Mingmei , Shang Ruiyan , Wei Yuan , Zhao Yangyu , Zhao Fangqing
Published: June 2022

Objective

Fetal growth restriction (FGR) is a devastating pregnancy complication that increases the risk of perinatal mortality and morbidity. This study aims to determine the combined and relative effects of genetic and intrauterine environments on neonatal microbial communities and to explore selective FGR-induced gut microbiota disruption, metabolic profile disturbances and possible outcomes.

Design

We profiled and compared the gut microbial colonisation of 150 pairs of twin neonates who were classified into four groups based on their chorionicity and discordance of fetal birth weight. Gut microbiota dysbiosis and faecal metabolic alterations were determined by 16S ribosomal RNA and metagenomic sequencing and metabolomics, and the long-term effects were explored by surveys of physical and neurocognitive development conducted after 2~3 years of follow-up.

Results

Adverse intrauterine environmental factors related to selective FGR dominate genetics in their effects of elevating bacterial diversity and altering the composition of early-life gut microbiota, and this effect is positively related to the severity of selective FGR in twins. The influence of genetic factors on gut microbes diminishes in the context of selective FGR. Gut microbiota dysbiosis in twin neonates with selective FGR and faecal metabolic alterations features decreased abundances ofEnterococcusandAcinetobacterand downregulated methionine and cysteine levels. Correlation analysis indicates that the faecal cysteine level in early life is positively correlated with the physical and neurocognitive development of infants.

Conclusion

Dysbiotic microbiota profiles and pronounced metabolic alterations are associated with selective FGR affected by adverse intrauterine environments, emphasising the possible effects of dysbiosis on long-term neurobehavioural development.
Patient autonomy in an East-Asian cultural milieu: a critique of the individualism-collectivism model
Authors: Lim Max Ying Hao
Published: June 2022

The practice of medicine—and especially the patient-doctor relationship—has seen exceptional shifts in ethical standards of care over the past few years, which by and large originate in occidental countries and are then extrapolated worldwide. However, this phenomenon is blind to the fact that an ethical practice of medicine remains hugely dependent on prevailing cultural and societal expectations of the community in which it serves. One model aiming to conceptualise the dichotomous efforts for global standardisation of medical care against differing sociocultural expectations is the individualism-collectivism model, with the ‘West’ being seen as individualistic and the ‘East’ being seen as collectivistic. This has been used by many academics to explain differences in approach towards ethical practice on key concepts such as informed consent and patient autonomy. However, I argue that this characterisation is incomplete and lacks nuance into the complexities surrounding cross-cultural ethics in practice, and I propose an alternative model based on the ethics of clinical care in Hong Kong, China. Core ethical principles need not be culture-bound—indeed, their very existence mandates for them to be universal and non-derogable—but instead cultural alignment occurs in the particular implementation of these principles, insofar as they respect the general spirit of contemporary ethical standards.
Prospective comparison of two methods for assessing sarcopenia and interobserver agreement on retrospective CT images
Authors: Dale MacLaine Thomas , Baker Oliver , Omura Miyuki , Clarke Christopher , Howell Simon J , Burke Dermot
Published: June 2022

Purpose of the study

To compare the relationships between two CT derived sarcopenia assessment methods, and compare their relationship with inter-rater and intrarater validations and colorectal surgical outcomes.

Study design

157 CT scans were identified across Leeds Teaching Hospitals National Health Service Trust for patients undergoing colorectal cancer surgery. 107 had body mass index data available, required to determine sarcopenia status. This work explores the relationship between sarcopenia, as measured by both total cross sectional-area (TCSA) and psoas-area (PA) and surgical outcomes. All images were assessed for inter-rater and intrarater variability for both TCSA and PA methods of sarcopenia identification. The raters included a radiologist, an anatomist and two medical students.

Results

Prevalence of sarcopenia was different when measured by PA (12.2%–22.4%) in comparison to TCSA (60.8%–70.1%). Strong correlation exists between muscle areas in both TCSA and PA measures, however, there were significant differences between methods after the application of method-specific cut-offs. There was substantial agreement for both intrarater and inter-rater comparisons for both TCSA and PA sarcopenia measures. Outcome data were available for 99/107 patients. Both TCSA and PA have poor association with adverse outcomes following colorectal surgery.

Conclusions

CT-determined sarcopenia can be identified by junior clinicians, those with anatomical understanding and radiologists. Our study identified sarcopenia to have a poor association with adverse surgical outcomes in a colorectal population. Published methods of identifying sarcopenia are not translatable to all clinical populations. Currently available cut-offs require refinement for potential confounding factors, to provide more valuable clinical information.

What is already known on this topic?

What does this study add?

How might this study affect research, practice or policy?
Cisternostomy for malignant middle cerebral artery infarction: proposed pathophysiological mechanisms and preliminary results
Authors: Cardali Salvatore Massimiliano , Caffo Maria , Caruso Gerardo , Scalia Gianluca , Gorgoglione Nicola , Conti Alfredo , Vinci Sergio Lucio , Barresi Valeria , Granata Francesca , Ricciardo Giuseppe , Garufi Giada , Raffa Giovanni , Germanò Antonino
Published: June 2022

Background

The ischaemic stroke of the territory of the middle cerebral artery represents an event burdened by high mortality and severe morbidity. The proposed medical treatments do not always prove effective. Decompressive craniectomy allows the ischaemic tissue to shift through the surgical defect rather than to the unaffected regions of the brain, thus avoiding secondary damage due to increased intracranial pressure. In this study, we propose a novel treatment for these patients characterised by surgical fenestration of the cisterns of the skull base.

Methods

We have treated 16 patients affected by malignant middle cerebral artery ischaemia and treated with cisternostomy between August 2018 and December 2019. The clinical history, neurological examination findings and neuroradiological studies (brain CT, CT angiography, MRI) were performed to diagnose stroke. Clinical examination was recorded on admission and preoperatively using the Glasgow Coma Scale and the National Institutes of Health Stroke Scale.

Results

The study included 16 patients, 10 males and 6 females. The mean age at surgery was 60.1 years (range 19–73). Surgical procedure was performed in all patients. The patients underwent immediate postoperative CT scan and were in the early hours evaluated in sedation window. In total, we recorded two deaths (12.5%). A functional outcome between mRS 0–3, defined as favourable, was observed in 9 (64.2%) patients 9 months after discharge. A functional outcome between mRS 4–6, defined as poor, was observed in 5 (35.7%) patients 9 months after discharge.

Conclusions

The obtained clinical results appear, however, substantially overlapping to decompressive craniectomy. Cisternostomy results in a favourable functional outcome after 9 months. This proposed technique permits that the patient no longer should be undergone cranioplasty thus avoiding the possible complications related to this procedure. The results are certainly interesting but higher case numbers are needed to reach definitive conclusions.
Force probes for development and testing of different electric propulsion systems
Authors: Spethmann Alexander , Trottenberg Thomas , Kersten Holger , Hey Franz Georg , Grimaud Lou , Mazouffre Stéphane , Bock Daniel , Tajmar Martin
Published: June 2022

Diagnostics with force probes in plumes of electric propulsion systems for spacecraft (thrusters) are presented. This contribution focuses on showing example measurements with force probes for the most common gridless ion thruster types. The gridless thrusters are investigated at typical operation modes with a force probe at fixed or variable positions in the plume. The probe measures the force on a tiny plate that is attached to a sensitive cantilever in the plume. The elastic deflection of the cantilever is measured interferometrically and translated into a proportional force. Several variants of the instrument have been developed. A HEMP thruster is investigated with a variant of the force probe that simultaneously measures two components of the force vector. With this vectorial probe, it is possible to determine the force vector acting on the probe target while moving the probe through the thruster plume. A Hall thruster is investigated with a simplified variant of the probe, which measures the force along one axis and is equipped with an additional shutter in front of the target. This allows monitoring over long periods of operation. Finally, a force probe is used as an indirect thrust balance for a FEEP thruster. In this case, the force probe can collect the entire plume.
Lupeol Alleviates Myocardial Ischemia-Reperfusion Injury in Rats by Regulating NF-κB and Nrf2 Pathways
Authors: Li Jing , Ma Xuming , Yang Jun , Wang Luzhen , Huang Yan , Zhu Yan
Published: June 2022

Cardiovascular disease is a global health problem. Previous studies revealed that it involves acute myocardial infarction and ischemia-reperfusion (I/R) injury. The mechanism of myocardial I/R injury is complex. But recognizing its mechanisms will bring important clinical significance. Lupeol is widely found in Chinese medicinal herbs and has been shown to have a variety of bio-activities. However, the pharmacological action of lupeol in the progress of myocardial ischemia-reperfusion injury (MIRI) is unclear. This study used a rat myocardial I/R model and the morphological changes in myocardium were determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining. The expression levels of IL-10, IL-1[Formula: see text], TNF-[Formula: see text], and IL-6 were assessed by quantitative real-time PCR (qRT-PCR) and ELISA. The expression levels of MB isoenzyme of creatine kinase (CK-MB), lactate dehydrogenase (LDH) level and inflammatory cytokines were quantified using ELISA. The cellular apoptotic rate was determined by TUNEL staining. The findings showed that lupeol significantly decreased myocardial infarction after I/R and ameliorated I/R-induced myocardial inflammation, apoptosis, and oxidative stress. Furthermore, our results suggested that lupeol protected against MIRI-induced myocardial infarction through modulation of NF-[Formula: see text]B and Nrf2 signaling pathways. In summary, this study first clarified the cardioprotective effects of lupeol against I/R-induced myocardial infarction in rats, which could be due to its anti-oxidant, anti-inflammatory, and anti-apoptotic activities. Our study also highlighted a mechanism of NF-[Formula: see text]B and Nrf2 signaling, through which lupeol could be a promising agent in protecting against I/R-induced myocardial infarction.
Quercetin Mitigates Cisplatin-Induced Oxidative Damage and Apoptosis in Cardiomyocytes through Nrf2/HO-1 Signaling Pathway
Authors: Wang Shih-Hao , Tsai Kun-Ling , Chou Wan-Ching , Cheng Hui-Ching , Huang Yu-Ting , Ou Hsiu-Chung , Chang Yun-Ching
Published: June 2022

Cisplatin is massively used to treat solid tumors. However, several severe adverse effects, such as cardiotoxicity, are obstacles to its clinical application. Cardiotoxicity may lead to congestive heart failure and even sudden cardiac death in patients receiving cisplatin. Therefore, finding a novel therapeutic strategy for the prevention of cisplatin-induced cardiotoxicity is urgent. Quercetin is a flavonol compound that can be found in dietary fruits and vegetables. The antioxidant function and anti-inflammatory capacity of quercetin have been reported. However, whether quercetin could protect against cisplatin-caused apoptosis and cellular damage in cardiomyocytes is still unclear. H9c2 cardiomyocytes were treated with cisplatin (40 μM) for 24 h to induce cellular damage with or without quercetin pretreatment. We found that quercetin activates Nrf2 and HO-1 expression, thereby mitigating cisplatin-caused cytotoxicity in H9c2 cells. Quercetin also increases SOD levels, maintains mitochondrial function, and reduces oxidative stress under cisplatin stimulation. Quercetin attenuates cisplatin-induced apoptosis and inflammation in H9c2 cardiomyocytes; however, these cytoprotective effects were diminished by silencing Nrf2 and HO-1. In conclusion, this study reports that quercetin has the potential to antagonize cisplatin-caused cardiotoxicity by reducing ROS-mediated mitochondrial damage and inflammation via the Nrf2/HO-1 and p38MAPK/NF-[Formula: see text]Bp65/IL-8 signaling pathway. This study provided the theoretical basis and experimental proof for the clinical application of quercetin as a new effective strategy to relieve chemotherapy-induced cardiotoxicity.
The string little algebra
Authors: Glennon Keith , West Peter
Published: June 2022

We consider the string, like point particles and branes, to be an irreducible representation of the semi-direct product of the Cartan involution invariant subalgebra of [Formula: see text] and its vector representation. We show that the subalgebra that preserves the string charges, the string little algebra, is essentially the Borel subalgebra of [Formula: see text]. We also show that the known string physical states carry a representation of parts of this algebra.
Probing neutrino sector via a statistical approach
Authors: Qiu Yu-Cheng , Zhu Hui-Yu
Published: June 2022

In this paper, we apply the idea of landscape (motivated by string theory) to study the statistical nature of parameters/couplings in the standard model of strong and electroweak interactions. Following the success of this approach on the fermion masses, we discuss the divergent behavior of the probability distributions of other physical parameters/couplings to obtain some insights on the quantities that cannot be measured by current experiments but can be relevant in cosmology, in particular those in the neutrino sector. From a relatively strongly mixed PMNS matrix, we argue that the probability distribution of heavy neutrino mass [Formula: see text] does not diverge at [Formula: see text]. This analysis favors the degenerate heavy neutrino scenarios.
New asymptotic techniques for the partial-wave-cutoff method for calculating the QED one-loop effective action
Authors: Huet Adolfo , Huet Idrish , Cornejo-Pérez Octavio
Published: June 2022

The Gel’fand–Yaglom theorem has been used to calculate the one-loop effective action in quantum field theory (QFT) by means of the “partial-wave-cutoff method.” This method works well for a class of radially symmetric background fields, allowing the inclusion of an arbitrary profile function in the background and does not require approximations. However, its implementation has been semi-analytical so far since it involves solving a nonlinear ordinary differential equation (ODE) for which solutions are in general only available in numerical form. Within the context of quantum electrodynamics (QED) and [Formula: see text] symmetric backgrounds, we present two complementary asymptotic methods that provide approximate analytical solutions to this equation. We test these approximations for different background field configurations and mass regimes, and demonstrate that the effective action can indeed be calculated using these asymptotic expressions. To further probe one of these methods, we analyze the massless limit of the effective action and obtain its divergence structure with respect to the radial suppression parameter of the background field, comparing our findings with previously reported results.
iVenture: A Process-Driven Tool for Business Model Creation and Presentation
Authors: Shanbhag Narendranath , Pardede Eric
Published: June 2022

Despite a rise in interest in software start-ups, most entrepreneurs struggle to find their footing and eventually fail. Novice entrepreneurs could benefit from a tailored process-driven experience for business model (BM) development, which would take the end user from conception to realisation. This research uncovers if a process-based experience could help entrepreneurs develop BMs and aid in documenting and presenting the outcome. This work discusses the efficacy of the Blitz Canvas model for BM generation using an application called iVenture, which is designed as a digital realisation of the said model. The model is shown to students at a university who have expressed interest in building their own start-ups. Qualitative data was collected in the form of feedback around their BM development experience, when using iVenture. Analysis of data showed potential for process-based models in BM development and a future for BM dashboards as online tools for planning and presentation.
A Novel Moving Load Integration Method for Real-Time Hybrid Shaking Table Test of High-Speed Maglev Vehicle–Bridge Interaction System
Authors: Gu Quan , Yuan Bin , Ozcelik Ozgur , Chang Ruijie , Guo Wei , Zhou Huimeng , Lin Jian-Yuan , Wang Tao , Zhang Jianguo
Published: June 2022

Real-time hybrid shaking table test for high-speed maglev vehicle–bridge interaction (VBI) system is an important method to study dynamic response of the system. Numerical experiments are usually conducted in advance to guarantee the test performed smoothly. This paper presents a novel moving load integration method combined with a truncated bridge model for fast calculation of bridge responses, and presents a framework for performing numerical experiment of a real-time hybrid test of VBI system. A realistic numerical experiment is conducted on a real-time simulator, i.e. xPC Target, integrating three commercial software, i.e. SIMPACK, ANSYS, and MATLAB-Simulink[Formula: see text], to model a real TR08 single-carriage maglev train, a 5-spans bridge and 28 shaking tables, respectively. The driving speed is 400–600[Formula: see text]km/h and the time step size in the test is 1/256[Formula: see text]s. The accuracy of moving load integration method with truncated bridge model is verified, the effects of speed on the dynamic responses of VBI systems are studied, the time delay of shaking tables and compensation algorithm is investigated, and the effects of local nonlinearity of the bridge on system responses are studied. This paper provides a practical method and valuable reference for the real-time hybrid shaking table test of vehicle–bridge coupled systems.
An Optimal H∞ Approach for Local Stability Analysis of Non Linear Digital Systems with Saturation Non Linearity and External Interference
Authors: Jogi Srinivasulu , Kokil Priyanka
Published: June 2022

An optimal [Formula: see text] criterion for the stability investigation of non linear digital filters with saturation non linearity and external interference is proposed in this paper. The proposed criterion can be used for overflow oscillation-free realization of the non linear digital system implemented with fixed wordlength machines like digital computers or special purpose embedded systems. The proposed approach ascertains the local asymptotic stability of non linear digital filtering schemes without external interference. Further, by employing [Formula: see text] performance criterion the conditions for local stability and performance measurement are proposed with external interference. In the proposed work, the stability conditions are proposed in linear matrix inequality (LMI) by exploiting energy-based Lyapunov theory, Lipschitz inequality, and saturation arithmetic. The proposed criterion is shown to be less conservative which will improve the operating region and obtain a better estimate of [Formula: see text] performance index compared to the existing local criterion. Moreover, the proposed criterion can be used in selecting the appropriate wordlength of a digital system for tolerable values of interference energy, [Formula: see text] performance level, and fixed-point resolution. This will be an additional advantage of this work compared with existing global criteria. Sufficient examples to show the efficacy of the proposed technique are also provided.
Enabling Intelligent Services at the Network Edge
Authors: Tassiulas Leandros
Published: June 2022

The proliferation of novel mobile applications and the associated AI services necessitates a fresh view on the architecture, algorithms and services at the network edge in order to meet stringent performance requirements. Some recent work addressing these challenges is presented. In order to meet the requirement for low-latency, the execution of computing tasks moves form the cloud to the network edge, closer to the end-users. The joint optimization of service placement and request routing in dense mobile edge computing networks is considered. Multidimensional constraints are introduced to capture the storage requirements of the vast amounts of data needed. An algorithm that achieves close-to-optimal performance using a randomized rounding technique is presented. Recent advances in network virtualization and programmability enable realization of services as chains, where flows can be steered through a pre-defined sequence of functions deployed at different network locations. The optimal deployment of such service chains where storage is a stringent constraint in addition to computation and bandwidth is considered and an approximation algorithm with provable performance guarantees is proposed and evaluated. Finally the problem of traffic flow classification as it arises in firewalls and intrusion detection applications is presented. An approach for realizing such functions based on a novel two-stage deep learning method for attack detection is presented. Leveraging the high level of data plane programmability in modern network hardware, the realization of these mechanisms at the network edge is demonstrated.
Zero Queueing for Multi-Server Jobs
Authors: Wang Weina , Xie Qiaomin , Harchol-Balter Mor
Published: June 2022

Cloud computing today is dominated by multi-server jobs. These are jobs that request multiple servers simultaneously and hold onto all of these servers for the duration of the job. Multi-server jobs add a lot of complexity to the traditional one-server-per-job model: an arrival might not "fit" into the available servers and might have to queue, blocking later arrivals and leaving servers idle. From a queueing perspective, almost nothing is understood about multi-server job queueing systems; even understanding the exact stability region is a very hard problem.

In this paper, we investigate a multi-server job queueing model under scaling regimes where the number of servers in the system grows. Specifically, we consider a system with multiple classes of jobs, where jobs from different classes can request different numbers of servers and have different service time distributions, and jobs are served in first-come-first-served order. The multi-server job model opens up new scaling regimes where both the number of servers that a job needs and the system load scale with the total number of servers. Within these scaling regimes, we derive the first results on stability, queueing probability, and the transient analysis of the number of jobs in the system for each class. In particular we derive sufficient conditions for zero queueing. Our analysis introduces a novel way of extracting information from the Lyapunov drift, which can be applicable to a broader scope of problems in queueing systems.
Improving the Performance of Heterogeneous Data Centers through Redundancy
Authors: Anton Elene , Ayesta Urtzi , Jonckheere Matthieu , Verloop Ina Maria
Published: June 2022

We analyze the performance of redundancy in a multi-type job and multi-type server system where PS is implemented. We characterize the stability condition, which coincides with that of a system where each job type only dispatches copies into its least-loaded servers, and those copies need to be fully served. We then investigate the impact of redundancy in the stability condition by comparing that to the stability condition of a non-redundant system in which a job arrival is routed to only one randomly selected compatible server. We observe that if server loads are sufficiently heterogeneous redundancy can considerably improve the stability region of the system.
Online Virtual Machine Allocation with Lifetime and Load Predictions
Authors: Buchbinder Niv , Fairstein Yaron , Mellou Konstantina , Menache Ishai , Naor Joseph (Seffi)
Published: June 2022

The cloud computing industry has grown rapidly over the last decade, and with this growth there is a significant increase in demand for compute resources. Demand is manifested in the form of Virtual Machine (VM) requests, which need to be assigned to physical machines in a way that minimizes resource fragmentation and efficiently utilizes the available machines. This problem can be modeled as a dynamic version of the bin packing problem with the objective of minimizing the total usage time of the bins (physical machines). Motivated by advances in Machine Learning that provide good estimates of workload characteristics, this paper studies the effect of having extra information about future (total) demand. We show that the competitive factor can be dramatically improved with this additional information; in some cases, we achieve constant competitiveness, or even a competitive factor that approaches 1. Along the way, we design new offline algorithms with improved approximation ratios for the dynamic bin-packing problem.
A Systematic Framework to Identify Violations of Scenario-dependent Driving Rules in Autonomous Vehicle Software
Authors: Zhang Qingzhao , Hong David Ke , Zhang Ze , Chen Qi Alfred , Mahlke Scott , Mao Z. Morley
Published: June 2022

Safety compliance is paramount to the safe deployment of autonomous vehicle (AV) technologies in real-world transportation systems. As AVs will share road infrastructures with human drivers and pedestrians, it is an important requirement for AVs to obey standard driving rules. Existing AV software testing methods, including simulation and road testing, only check fundamental safety rules such as collision avoidance and safety distance. Scenario-dependent driving rules, including crosswalk and intersection rules, are more complicated because the expected driving behavior heavily depends on the surrounding circumstances. However, a testing framework is missing for checking scenario-dependent driving rules on various AV software.

In this paper, we design and implement a systematic framework AVChecker for identifying violations of scenario-dependent driving rules in AV software using formal methods. AVChecker represents both the code logic of AV software and driving rules in proposed formal specifications and leverages satisfiability modulo theory (SMT) solvers to identify driving rule violations. To improve the automation of systematic rule-based checking, AVChecker provides a powerful user interface for writing driving rule specifications and applies static code analysis to extract rule-related code logic from the AV software codebase. Evaluations on two open-source AV software platforms, Baidu Apollo and Autoware, uncover 19 true violations out of 28 real-world driving rules covering crosswalks, traffic lights, stop signs, and intersections. Seven of the violations can lead to severe risks of a collision with pedestrians or blocking traffic.
The Making of a Heterocyst in Cyanobacteria
Authors: Zeng Xiaoli , Zhang Cheng-Cai
Published: June 2022

Heterocyst differentiation that occurs in some filamentous cyanobacteria, such as Anabaena sp. PCC 7120, provides a unique model for prokaryotic developmental biology. Heterocyst cells are formed in response to combined-nitrogen deprivation and possess a microoxic environment suitable for nitrogen fixation following extensive morphological and physiological reorganization. A filament of Anabaena is a true multicellular organism, as nitrogen and carbon sources are exchanged among different cells and cell types through septal junctions to ensure filament growth. Because heterocysts are terminally differentiated cells and unable to divide, their activity is an altruistic behavior dedicated to providing fixed nitrogen for neighboring vegetative cells. Heterocyst development is also a process of one-dimensional pattern formation, as heterocysts are semiregularly intercalated among vegetative cells. Morphogens form gradients along the filament and interact with each other in a fashion that fits well into the Turing model, a mathematical framework to explain biological pattern formation.
Morphological and Electrical Properties of Polythiophene Nanostructured Film Synthesized Using Atmospheric Pressure-Plasma Reactor with Double V-Shaped Bare Electrode
Authors: Suleiman Habeeb Olaitan , Kim Jae Young , Jang Hyo Jun , Jung Eun Young , Choi Muhan , Tae Heung-Sik
Published: June 2022

To synthesize a wide-area conducting polymer with improved morphology and electrical properties, we proposed a new atmospheric pressure (AP) plasma reactor with double V-shaped bare wire electrode operating at a low driven voltage to expand the plasma area for nanostructure synthesis. The two wires form a V-shape making a 60° angle at the edges and are joined together forming a cross, creating a canopy-like plasma medium in the plasma reactor center. Using the AP-plasma reactor, the polythiophene (PTh) nanostructured films are successfully synthesized with and without iodine doping. Moreover, the molecular structures and chemical properties of nascent and iodine-doped PTh films are compared, and the electrical resistivities of ex situ and in situ iodine-doped PTh nanostructures are also analyzed.
Extraction of Bias-dependent Source and Drain Resistances in AlGaN/GaN MIS-HEMTs Using Pulsed Measurement Method
Authors: Chen Kun-Ming , Lin Chuang-Ju , Chen Bo-Yuan , Huang Guo-Wei , Chang Edward Yi
Published: June 2022

A new method for extraction of bias-dependent source and drain resistances in AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) is reported. The total source/drain access resistances are extracted by measuring the pulsed transfer characteristics of test devices with various quiescent biases. With short pulse width, the charge trapping and thermal effects will not be affected by the magnitude of pulse voltages, and thus the extracted resistances correspond to the quiescent bias condition. As a result, the dependences of total access resistances on the gate and drain voltages are obtained. While employing the dual-sweep combinational transconductance technique, the source and drain resistances are separated further. To investigate the variation of access resistances with applied voltages, AlGaN/GaN HEMTs are also illuminated with a 365-nm ultraviolet (UV) source during pulsed measurements. Under UV illumination, the resistance will be less dependent on the drain voltage, indicating the charge trapping in GaN buffer layer has a large impact on the access resistance.
Vertical AlGaN Deep Ultraviolet Light Emitting Diodes with Polarization Enhanced p-AlGaN Epilayer on Si Substrate
Authors: Zhang Qihua , Parimoo Heemal , Martel Eli , Yin Xue , Zhao Songrui
Published: June 2022

Despite of the technological importance of developing AlGaN deep UV LEDs on Si, there are only a few reports about AlGaN deep UV LEDs on Si based on AlGaN epilayers. Herein, we show vertical AlGaN deep UV LEDs on Si with polarization enhanced p-AlGaN epilayer. The devices emit at 278 nm, with uniform current injection. Compared to devices using standard p-AlGaN epilayer, the series resistance of devices with polarization enhanced p-AlGaN epilayer is reduced by a factor of 5. This work represents the first report of AlGaN deep UV LEDs on Si with polarization enhanced p-AlGaN epilayers.
Sensitive physiological readouts to evaluate countermeasures for lipopolysaccharide-induced lung alterations in mice
Authors: Khadangi Fatemeh , Tremblay-Pitre Sophie , Dufour-Mailhot Alexis , Rojas-Ruiz Andrés , Boucher Magali , Henry Cyndi , Fereydoonzad Liah , Brunet David , Robichaud Annette , Bossé Ynuk
Published: June 2022

Despite decades of research, studies investigating the physiological alterations caused by an acute bout of inflammation induced by exposing the lung to lipopolysaccharide have yielded inconsistent results. This can be attributed to small effects and/or a lack of fitted physiological testing. Herein, a comprehensive investigation of lung mechanics was conducted on 270 male C57BL/6 mice at 24, 48, or 96 h after an intranasal exposure to saline or lipopolysaccharide at either 1 or 3 mg/kg (30 mice per group). Traditional techniques that probe the lung using small-amplitude perturbations (i.e., oscillometry) were used, together with less conventional and new techniques that probe the lung using maneuvers of large amplitudes. The latter include a partial and a full-range pressure-volume maneuvers to measure quasi-static elastance, compliance, total lung volume, vital capacity, and residual volume. The results demonstrate that lung mechanics assessed by oscillometry was only slightly affected by lipopolysaccharide, confirming previous findings. In contradistinction, lipopolysaccharide markedly altered mechanics when the lung was probed with maneuvers of large amplitudes. With the dose of 3 mg/kg at the peak of inflammation (48 h postexposure), lipopolysaccharide increased quasi-static elastance by 26.7% ( P < 0.0001) and decreased compliance by 34.5% ( P < 0.0001). It also decreased lung volumes, including total lung capacity, vital capacity, and residual volume by 33.3%, 30.5%, and 43.3%, respectively (all P < 0.0001). These newly reported physiological alterations represent sensitive outcomes to efficiently evaluate countermeasures (e.g., drugs) in the context of several lung diseases.