bluuebunny/crossref_metadata_2025 huggingface dataset:
Challenges and Alternatives in Dental Education During the COVID-19 pandemic. Integrative Literature Review
Authors: Cazares de León Francisco , Cantú Canales María de Lourdes Juanita , Rodríguez Castillo Víctor Rafael , Gutiérrez Lizardi Pedro , Soto Gámez David Ernesto , Peraldi Sada María Gabriela
Published: May 2021

Background: The current COVID-19 pandemic has become a major health challenge and a public health emergency, so it is important to strengthen preventive measures to control its spread. The transmissibility and routes that characterize this virus make it very high risk during dental procedures. For this reason, different organizations and institutions of dental education worldwide have been forced to implement new teaching modalities for dental students to provide a high academic and safe education in clinical practice. Purpose: To examine and analyze different existing publications in relation to dental education, as well as its challenges and alternatives around the COVID-19 disease. Methods: An integrative review of literature on dental education in times of pandemic was carried out. Results: In all continents, countries agree that three key aspects in terms of education must be reinforced are new educational tools, telemedicine, and biosecurity. Conclusion: It is decisive and crucial that dental students and professionals acquire knowledge in matters of health regulations, biosafety, and general aspects of epidemiology, through new forms of teaching, in order to be better prepared to provide the best possible dental care during and after this pandemic.
Caries dental: de la placa ecológica a las decisiones clínicas
Authors: Moreno Abello Gloria Cristina , Lara Hernández Laura Catalina
Published: May 2021

Antecedentes: la caries dental ha sido estudiada desde múltiples enfoques, sin embargo, a pesar del conocimiento disponible, lograr medidas efectivas para prevenir su aparición en los individuos y las comunidades, aún parece lejano. Objetivo: integrar los cambios conceptuales actualmente aceptados para caries, con escenarios en la práctica clínica, para apoyar a los profesionales en las decisiones terapéuticas. Método:  en esta revisión integrativa se consultaron PubMed, Cochrane, Science Direct, SciELO, EBSCO utilizando como palabras claves: dental caries, model, prevention, ICDAS, risk factors, risk assessment. se verificó que el objetivo de cada fuente permitiera hacer el recorrido histórico del concepto de caries identificando aspectos centrales, relacionándolos con las limitaciones para que la teoría se evidencie en la práctica clínica. Resultados: la síntesis de la literatura se presenta organizada en: evolución de la definición de la caries dental a partir del papel de las bacterias y su impacto en las decisiones clínicas, acciones para abarcar la definición actual de caries dental y acciones ajustadas al modelo ICCMS para llevarlo a la práctica. Conclusión: los cambios conceptuales en caries dental se reflejan en los diagnósticos actuales y abordajes multivariados que aun requieren fortalecer el análisis y un control efectivo de los factores de riesgo, buscando un cuidado centrado en la persona, basado en la relación entre el comportamiento de los individuos a lo largo de la vida y la dinámica de la patología, que invitan al profesional a fortalecer un abordaje preventivo para controlar la enfermedad y evitar sus secuelas discapacitantes.
Cáncer escamocelular orofaríngeo: experiencias y avances en la Facultad de Odontología, Pontificia Universidad Javeriana, Colombia
Authors: García Robayo Dabeiba Adriana , Bustillo Rojas Jairo Alberto , Gamboa Jaimes Fredy Omar , Cid Arregui Angel , Bernal Vélez Camilo Javier , García Quiñones Malory Daniela , Hernández Sánchez Paola
Published: May 2021

Antecedentes: En Colombia, el carcinoma escamocelular orofaríngeo (CEO) puede afectar tanto a hombres como a mujeres. Cerca del 30 % tiene como causa la infección con el virus del papiloma humano (VPH) y el 70 % se debe al consumo excesivo de tabaco y alcohol. La historia natural de la enfermedad del CEO es similar a la del cáncer cervical. Se ha observado una asociación positiva entre Chlamydia trachomatis y VPH. A partir de esa evidencia, se podría hipotetizar que, para el CEO, las bacterias orales tendrían alguna asociación positiva con el VPH. Objetivo: Exponer algunas experiencias y avances sobre el CEO en la Pontificia Universidad Javeriana de Bogotá, Colombia. Hallazgos: En este grupo de investigación se realizó primero una descripción del papel del VPH en CEO (frecuencia, tipos virales de alto riesgo e integración viral) en muestras de pacientes con cáncer en Colombia. Un segundo estudio consistió en una revisión sistemática de la literatura en la que se buscó identificar posibles bacterias asociadas al desarrollo del CEO. En un último estudio se evaluó la frecuencia de bacterias orales asociadas a procesos carcinogénicos y su posible coinfección con VPH en pacientes con CEO e incluyó una comparación con personas sanas. Conclusión: En este manuscrito se presentan los resultados propios más relevantes que permiten comprobar la hipótesis formulada.
Editorial: Dossier microbiología oral y salud pública
Authors: Gamboa Jaimes Fredy Omar , García Robayo Dabeiba Adriana
Published: May 2021

Tenemos el gusto de presentar a nuestros lectores el dossier temático Microbiología oral y salud pública. Este dossier es producto de la interacción multidisciplinar de profesores investigadores de la Facultad de Odontología y del Centro de Investigaciones Odontológicas (CIO) de la Pontificia Universidad Javeriana (PUJ) de Bogotá y refleja de manera clara, destacada y pertinente la producción académica que han tenido en los últimos años. El CIO pertenece a la Facultad de Odontología de la PUJ. Está comprometido con la generación de conocimiento en las áreas de ciencias básicas (microbiología, inmunología, genética, bioquímica y física), clínicas y sociales relacionadas con enfermedades orales (infecciosas y no infecciosas) y sistémicas, que contribuyan a solucionar los problemas de salud pública de la población colombiana.
Postgrowth modification of monolayer graphene films by low-pressure diborane-argon plasma
Authors: Vinchon Pierre , Glad Xavier , Robert Bigras Germain , Sarkissian Andranik , Martel Richard , Stafford Luc
Published: May 2021

Polycrystalline monolayer graphene films grown by chemical vapor deposition were exposed to a low-pressure inductively coupled plasma operated in a gaseous mixture of argon and diborane. Optical emission spectroscopy and plasma sampling mass spectrometry reveal high B2H6 fragmentation leading to significant populations of both boron and hydrogen species in the gas phase. X-ray photoelectron spectroscopy indicates the formation of a boron-containing layer at the surface and provides evidence of a substitutional incorporation of boron atoms within the graphene lattice. Graphene doping by graphitic boration is confirmed by hyperspectral Raman imaging of graphene domains. These results demonstrate that diborane-containing plasmas are efficient tools for boron substitutional incorporation in graphene with minimal domain hydrogenation.
Stadium Giveaway Promotions: How Many Items to Give and the Impact on Ticket Sales in Live Sports
Authors: Cisyk Jeffrey , Courty Pascal
Published: May 2021

Although stadium giveaways are the most common type of promotion used in Major League Baseball to increase demand, most teams supply fewer giveaway items than there are tickets sold. This study argues that giveaway availability is a major component of teams’ promotion strategies and has been largely overlooked in the literature. The authors document the choice of giveaway availability across all Major League Baseball teams over an 8-year period and demonstrate that attendance increases with giveaway availability up to the point where there are enough giveaway items to serve 40% of a stadium’s capacity. Roughly two thirds of teams set giveaway availability in a fashion that is consistent with the standard price discrimination rationale for promotions found in the economic and marketing literatures. The remaining teams exhibit levels of high availability, indicating an additional investment into fan lifetime value, which is corroborated by these teams’ unique fan relationships.
Severity of Overuse Injury Impacts Self-Efficacy and Quality of Life in Runners: A 2-Year Prospective Cohort Study
Authors: Mihalko Shannon L. , Cox Phillip , Ip Edward , Martin David F. , DeVita Paul , Love Monica , Saldana Santiago , Cannon D. Wayne , Fellin Rebecca E. , Seay Joseph F. , Messier Stephen P.
Published: May 2021

Context: While 55 million Americans incorporate running into their exercise routines, up to 65% of runners sustain an overuse injury annually. It has been consistently shown that regular physical activity positively impacts quality of life (QOL), an essential public health indicator; however, the impact of running-related injuries on QOL is unknown. This study seeks to determine whether overuse injury severity impacts QOL in recreational runners, and if self-efficacy mediates this relationship. Design: Community-based prospective cohort study of 300 runners who had been running injury free for at least 5 miles/wk in the past 6 months. Methods: Self-efficacy for running and QOL measures (Short Form-12 Physical Component and Mental Component, Satisfaction with Life, Positive Affect and Negative Affect) were assessed at baseline, time of injury, and follow-up visits. Over 2 years of observation, overuse injuries were diagnosed by an orthopedic surgeon and injured runners were referred to a physical therapist. Results: Injury severity was significantly (P < .01) related with 2 indices of QOL, such that the effect of injury severity was −2.28 units on the Short Form-12 physical component and −0.73 units on positive affect. Self-efficacy accounted for 19% and 48% of the indirect effects on Short Form-12 physical component and positive affect, respectively. Conclusions: Since self-efficacy is a modifiable factor related to decreased QOL, these findings have important clinical implications for rehabilitation interventions.
SARS-CoV-2 variants of concern partially escape humoral but not T cell responses in COVID-19 convalescent donors and vaccine recipients
Authors: Geers Daryl , Shamier Marc C. , Bogers Susanne , den Hartog Gerco , Gommers Lennert , Nieuwkoop Nella N. , Schmitz Katharina S. , Rijsbergen Laurine C. , van Osch Jolieke A. T. , Dijkhuizen Emma , Smits Gaby , Comvalius Anouskha , van Mourik Djenolan , Caniels Tom G. , van Gils Marit J. , Sanders Rogier W. , Oude Munnink Bas B. , Molenkamp Richard , de Jager Herbert J. , Haagmans Bart L. , de Swart Rik L. , Koopmans Marion P. G. , van Binnendijk Robert S. , de Vries Rory D. , GeurtsvanKessel Corine H.
Published: May 2021

Infection- or vaccination-induced SARS-CoV-2 S–specific CD4
+
T cells are indifferent to the S mutations of variants of concern.
NK cells integrate signals over large areas when building immune synapses but require local stimuli for degranulation
Authors: Verron Quentin , Forslund Elin , Brandt Ludwig , Leino Mattias , Frisk Thomas W. , Olofsson Per E. , Önfelt Björn
Published: May 2021

The spatial distribution of activating ligands dictates NK cell synapse formation, stability, and function.
Forced into glucose metabolism
Authors: Wong Wei
Published: May 2021

Glucose uptake through GLUT1 enables actin cytoskeletal reinforcement in response to mechanical strain.
Supplemental Material: Quantifying structural controls on submarine channel architecture and kinematics
Authors: Mitchell W. Hamish , al. et
Published: May 2021

Figure S1: Location of cross sections through Channel Complex Five; Figure S2: Location of cross-sections taken through Channel Complex Six; Figure S3: (a) The final channel elements of channel complex five (ChC 5) and six (ChC 6) overlain on interval strain rates presented in Pizzi et al. (2020); Table S1: KS test values for channel complex five and six. Critical values based on the two sample sizes (structured (m) and unstructured (n) measurements) and Dmax values for channel complex width, thickness, aspect ratio, and complex-averaged stratigraphic mobility.
Impact of an anticipatory care planning intervention on unscheduled acute hospital care using difference-in-difference analysis
Authors: Leckcivilize Attakrit , McNamee Paul , Cooper Christopher , Steel Robby
Published: May 2021

Unscheduled admissions to hospital place great demands on the use of limited healthcare resources in health systems worldwide. A range of approaches exist to manage demand; however, interventions within hospitals have received less attention, and the evidence base on effectiveness is limited. This study aimed to assess the effectiveness of a novel intervention, implemented in National Health Service Lothian, to reduce the number of unscheduled attendances, and to estimate the impact on hospital admissions, length of hospital stay and overall total acute hospital costs.

Methods

Before and after observational study of an anticipatory care planning intervention targeted among people identified by a prediction algorithm (Scottish Patients at Risk of Readmission and Admission) as being at high risk of future unscheduled hospital admissions. The statistical significance of the difference in outcomes observed before and after implementation of the intervention between August 2014 and July 2015 was tested using difference-in-difference analysis.

Results

The intervention was estimated to reduce the number of unscheduled hospital admissions and emergency department (ED) visits by approximately 0.36 (95% CI −0.905 to 0.191) per patient per year (based on 954 and 450 patients in the intervention and control groups, respectively). There was also non-significant reductions in length of hospital stay for unscheduled admissions and hospital costs for ED visits and inpatient care. The overall predicted effect of the intervention for the average participant was a saving of around £2912 (95% CI −7347.0 to 1523.9) per patient per year.

Conclusion

An anticipatory care planning intervention focused among people judged to be at higher risk of future unscheduled hospital admissions can be effective in reducing the number of unscheduled admissions to hospital and ED visits, and may lead to an overall saving in use of hospital resources.
Guidelines to inform the generation of clinically relevant and realistic blast loading conditions for primary blast injury research
Authors: Denny J W , Dickinson A S , Langdon G S
Published: May 2021

‘Primary’ blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. With continued experimental focus on PBI mechanisms, recently on blast traumatic brain injury, meaningful test outcomes rely on appropriate simulated conditions. Selected PBI predictive criteria (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) are combined and plotted to provide rationale for generating clinically relevant loading conditions. Using blast engineering theory, explosion characteristics including blast wave parameters and fireball dimensions were calculated for a range of charge masses assuming hemispherical surface detonations and compared with PBI criteria. While many experimental loading conditions are achievable, this analysis demonstrated limits that should be observed to ensure loading is clinically relevant, realistic and practical. For PBI outcomes sensitive only to blast overpressure, blast scaled distance was demonstrated to be a useful parameter for guiding experimental design as it permits flexibility for different experimental set-ups. This analysis revealed that blast waves should correspond to blast scaled distances of 1.75<Z<6.0 to generate loading conditions found outside the fireball and of clinical relevance to a range of PBIs. Blast waves with positive phase durations (2–10 ms) are more practical to achieve through experimental approaches, while representing realistic threats such as improvised explosive devices (ie, 1–50 kg trinitrotoluene equivalent). These guidelines can be used by researchers to inform the design of appropriate blast loading conditions in PBI experimental investigations.
Quality indicators development and prioritisation for emergency medical call centres: a stakeholder consensus
Authors: Alem Lucie , Bacqué Julie , Guihenneuc Jérémy , Delelis-Fanien Henri , Mimoz Olivier , Migeot Virginie
Published: May 2021

Introduction

Emergency medical regulation is a risky activity. In France, emergency medical societies have proposed activity and performance indicators, but their lists are non-exhaustive, unstructured and used heterogeneously among emergency medical call centres (Centres de Réception et de Régulation des Appels, CRRA). Our objective was to build by means of regional stakeholder consensus an operational quality dashboard for CRRAs.

Methods

We conducted an observational step in a French CRRA from June to September 2018 and at the same time listed existing activity and quality indicators through a rapid international literature review. We adapted and classified all indicators identified in a structured table. We prioritised them from April to September 2019 by seeking consensus with one regulator physician and one medical regulation assistant from the 13 CRRAs of the largest French region. We used an adapted Delphi method with a prioritisation scale from 1 to 9.

Results

The rapid review of literature included 33 studies among the 414 identified and, with the first observational step, resulted in a list of 360 quality indicators covering the following areas: material resources, human resources, quality approach, call handling and postcall support. 15 of the 26 members participated in the entire process. Seventy indicators were considered as priorities with strong agreement among participants. We built an operational dashboard of quality indicators deemed high priority and provided 70 descriptive indicator sheets.

Conclusion

Our study allowed to build an operational quality dashboard for CRRAs as a ready-to-use support for an internal audit, for prioritisation of quality approach actions and for national and international benchmarking.
Building the barricade—DIY slit lamp breath shield
Authors: Wu Clara Hoi Ka , Jarrar Zakariya , Harsum Steven
Published: May 2021

Ophthalmologists were concerned about the risk of SARS-COV-2 transmission via droplets given the close proximity to the patient during slit lamp examination. There is a need to design a simple, low-cost, waterproof breath shield to minimise risk of infection.

Dimensions of the Haag-Streit slit lamp (model BM 900) were recorded to guide accurate design of the breath shield. A questionnaire was circulated among slit lamp users on their perceived risk and concern about SARS-CoV-2 transmission and their perception of how effective different designs of breath shields would be at protecting them from an infection. A number of breath shield prototypes were designed and trialled. Plan, Do, Study, Act (PDSA) cycles were used to improve the design. Materials used to create the breath shields included transparent A3 laminating pouches and laminator, two sheets of A4 paper, scissors, hole punch and a ruler. The breath shield was designed to fit over the objective lens on the slit lamp after temporarily removing the standard, manufacturer-provided breath shield, before replacing it. The breath shields were cleaned after every patient with alcohol wipes and removed for deep cleaning with hand soap and water after each session. We used a proof of concept experiment using fluorescein instilled spray to test the effectiveness of each breath shield at preventing droplet transmission to the slit lamp user.

Following four PDSA cycles, a breath shield that is user-friendly, easy to clean was produced. The percentage of confidence that the final design would be effective at preventing droplet transmission increased from 5.6% to 80%.

Implementation of a low cost, simple to make, transparent, waterproof breath shield together with other forms of person protective equipment (PPE) creates a safe working environment for clinicians and patients. This intervention can be readily replicated and modified for other slit lamp models.
Impact of lockdown and school closure on children’s health and well-being during the first wave of COVID-19: a narrative review
Authors: Rajmil Luis , Hjern Anders , Boran Perran , Gunnlaugsson Geir , Kraus de Camargo Olaf , Raman Shanti
Published: May 2021

Background

In the context of containment measures against the COVID-19 pandemic, the aims were to examine the impact of lockdown and school closures on childs’ and adolescents’ health and well-being and social inequalities in health.

Methods

Literature review by searching five databases until November 2020. We included quantitative peer-reviewed studies reporting health and well-being outcomes in children (0–18 years) related to closure measures" impact due to COVID-19. A pair of authors assessed the risk of bias of included studies. A descriptive and narrative synthesis was carried out.

Findings

Twenty-two studies, including high-income, middle-income and low-income countries, fulfilled our search criteria and were judged not to have an increased risk of bias. Studies from Australia, Spain and China showed an increase in depressive symptoms and decrease in life satisfaction. A decrease in physical activity and increase in unhealthy food consumption were shown in studies from two countries. There was a decrease in the number of visits to the emergency department in four countries, an increase in child mortality in Cameroon and a decrease by over 50% of immunisations administered in Pakistan. A significant drop of 39% in child protection medical examination referrals during 2020 compared with the previous years was found in the UK, a decrease in allegations of child abuse and neglect by almost one-third due to school closures in Florida, and an increase in the number of children with physical child abuse trauma was found in one centre in the USA.

Interpretation

From available reports, pandemic school closure and lockdown have adverse effects on child health and well-being in the short and probably long term. We urge governments to take the negative public health consequences into account before adopting restrictive measures in childhood.
Impact of mobile stroke units
Authors: Fassbender Klaus , Merzou Fatma , Lesmeister Martin , Walter Silke , Grunwald Iris Quasar , Ragoschke-Schumm Andreas , Bertsch Thomas , Grotta James
Published: May 2021

Since its first introduction in clinical practice in 2008, the concept of mobile stroke unit enabling prehospital stroke treatment has rapidly expanded worldwide. This review summarises current knowledge in this young field of stroke research, discussing topics such as benefits in reduction of delay before treatment, vascular imaging-based triage of patients with large-vessel occlusion in the field, differential blood pressure management or prehospital antagonisation of anticoagulants. However, before mobile stroke units can become routine, several questions remain to be answered. Current research, therefore, focuses on safety, long-term medical benefit, best setting and cost-efficiency as crucial determinants for the sustainability of this novel strategy of acute stroke management.
Women’s voices, emotion and empathy: engaging different publics with ‘everyday’ health histories
Authors: Loughran Tracey , Mahoney Kate , Payling Daisy
Published: May 2021

This article explores our experiences on a Wellcome Trust-funded project on women’s experiences of ‘everyday health’ in Britain between the 1960s and the 1990s. We explore issues around researching ‘everyday health’, including the generation and interpretation of source materials, and the role of empathy and emotion in interactions with different audiences as we share these materials in public engagement activities. We discuss three case studies of engagement activities to draw out potential uses of source materials and the responses of different audiences to these materials, and reflect on what we have learnt since embarking on these public engagement activities. We took into our interactions with different audiences the belief that fully historicised understandings of ‘health’ enrich individual lives and create new capacities for meaningful action now. The public engagement activities we carried out reinforced this belief, but also caused us to question some of our assumptions. In particular, an activity with trainee healthcare professionals designed to demonstrate how active and empathetic listening can prevent the unintentional infliction of harm in healthcare settings achieved this end—but did so in a way that was itself unintentionally insensitive to the pressures healthcare professionals face. Medical humanities can help to contextualise, nuance and improve healthcare practice—but only through active listening and dialogue across medicine and the humanities. We conclude by considering how these activities, which currently rely on the interpersonal relations of the team with audiences, might be adapted and preserved in digital form beyond the span of the project.
Higgs-mass predictions in the MSSM and beyond
Authors: Slavich P. , Heinemeyer S. , Bagnaschi E. , Bahl H. , Goodsell M. , Haber H. E. , Hahn T. , Harlander R. , Hollik W. , Lee G. , Mühlleitner M. , Paßehr S. , Rzehak H. , Stöckinger D. , Voigt A. , Wagner C. E. M. , Weiglein G. , Allanach B. C. , Biekötter T. , Borowka S. , Braathen J. , Carena M. , Dao T. N. , Degrassi G. , Domingo F. , Drechsel P. , Ellwanger U. , Gabelmann M. , Gröber R. , Klappert J. , Kwasnitza T. , Meuser D. , Mihaila L. , Murphy N. , Nickel K. , Porod W. , Rojas E. A. Reyes , Sobolev I. , Staub F.
Published: May 2021

Predictions for the Higgs masses are a distinctive feature of supersymmetric extensions of the Standard Model, where they play a crucial role in constraining the parameter space. The discovery of a Higgs boson and the remarkably precise measurement of its mass at the LHC have spurred new efforts aimed at improving the accuracy of the theoretical predictions for the Higgs masses in supersymmetric models. The “Precision SUSY Higgs Mass Calculation Initiative” (KUTS) was launched in 2014 to provide a forum for discussions between the different groups involved in these efforts. This report aims to present a comprehensive overview of the current status of Higgs-mass calculations in supersymmetric models, to document the many advances that were achieved in recent years and were discussed during the KUTS meetings, and to outline the prospects for future improvements in these calculations.
Quark, pion and axial condensates in three-flavor finite isospin chiral perturbation theory
Authors: Adhikari Prabal , Andersen Jens O. , Mojahed Martin A.
Published: May 2021

We calculate the light-quark condensate, the strange-quark condensate, the pion condensate, and the axial condensate in three-flavor chiral perturbation theory ($$\chi $$χPT) in the presence of an isospin chemical potential at next-to-leading order at zero temperature. It is shown that the three-flavor$$\chi $$χPT effective potential and condensates can be mapped onto two-flavor$$\chi $$χPT ones by integrating out mesons with strange-quark content (kaons and eta), with renormalized couplings. We compare the results for the light-quark and pion condensates at finite pseudoscalar source with ($$2+1$$2+1)-flavor lattice QCD, and we also compare the axial condensate at zero pseudoscalar and axial sources with lattice QCD data. We find that the light-quark, pion, and axial condensates are in very good agreement with lattice data. There is an overall improvement by including NLO effects.
Bifurcations, symmetries and the notion of fixed subspace
Authors: Cicogna Giampaolo
Published: May 2021

In the context of stationary bifurcation problems admitting a symmetry, this paper is focused on the key notion of Fixed Subspace (FS), and provides a review of some applications aimed at detecting bifurcating solutions in various situations. We start recalling, in its commonly used simplified version, the old Equivariant Bifurcation Lemma (EBL), where the FS is one-dimensional; then we provide a first generalization in a typical case of non-semisimple critical eigenvalues, where the presence of the symmetry produces a non-trivial situation. Next, we consider the case of FSs of dimension [Formula: see text] in very different contexts. First, relying on the topological index theory and in particular on the Krasnosel’skii theorem, we provide a largely applicable statement of an extension of the EBL. Second, we propose a completely different and new application which combines symmetry properties with the notion of stability of bifurcating solutions. We also provide some simple examples, constructed ad hoc to illustrate the various situations.
Heuristic determination of the cosmological constant
Authors: Palomo Manuel Urueña , Lara Fernando Pérez
Published: May 2021

The vacuum catastrophe results from the disagreement between the theoretical value of the energy density of the vacuum in quantum field theory and the estimated one observed in cosmology. In a similar attempt in which the ultraviolet catastrophe was solved, we search for the value of the cosmological constant by brute-force through computation. We explore combinations of the fundamental constants in physics performing a dimensional analysis, in search of an equation resulting in the measured energy density of the vacuum or cosmological constant that is assumed to cause the accelerated expansion of the universe.
Thin-shell wormhole from ABGB–de Sitter black holes
Authors: Rahman Nilofar , Murshid Masum , Kalam Mehedi
Published: May 2021

A thin shell wormhole is constructed utilizing the cut and paste technique from ABGB–de Sitter black hole derived by Matyjasek et al. The surface stress localized at the wormhole throat is determined using Darmois–Israel formalism. We examine the attractive and repulsive nature of the thin shell wormhole on which cosmological constant [Formula: see text] has a significant effect. For the fixed values of charge [Formula: see text] and mass [Formula: see text], the attractiveness of the wormhole decreases with increasing [Formula: see text]. We calculate the total amount of exotic matter in the shell, which is not much affected by [Formula: see text]. For the construction of the wormhole in de Sitter universe, the regular black holes have to be heavily charged with a light mass to minimize the amount of required exotic matter. The stability of the wormhole solution is explored by considering a general equation of state in the form of linear perturbation. The stability regions are shown in the figures.
Entanglement entropy from TFD entropy operator
Authors: Dias M. , Nedel Daniel L. , Senise C. R.
Published: May 2021

In this work, a canonical method to compute entanglement entropy is proposed. We show that for two-dimensional conformal theories defined in a torus, a choice of moduli space allows the typical entropy operator of the TFD to provide the entanglement entropy of the degrees of freedom defined in a segment and their complement. In this procedure, it is not necessary to make an analytic continuation from the Rényi entropy and the von Neumann entanglement entropy is calculated directly from the expected value of an entanglement entropy operator. We also propose a model for the evolution of the entanglement entropy and show that it grows linearly with time.
Unsteady characteristics of pressure on wind turbine blade surface in the field
Authors: Li Yinran , Guo Xingduo , Li Rennian , Li Deshun , Dong Yanbin , Zhao Li
Published: May 2021

Field experiments are carried out to investigate the fluctuation characteristics of pressure on wind turbine blade surface in real operating environments. The tested wind turbine positioned pressure tapes along the blade span to obtain the dynamic pressure of seven airfoil sections over six rotation periods, and analyzed its time-domain, frequency domain, and standard deviation. The results show that the pressure on blade surface presents highly unsteady characteristics, and rotation of the wind turbine is one of the main factors that causes pressure fluctuations on the blade surface. The standard deviation of pressure near the leading edge of each airfoil section is relatively larger, indicating that the leading edge is the most sensitive to field wind conditions. Compared with the pressure surface, the blade suction surface contributes more to wind turbine power fluctuation and is more sensitive to various unsteady sources. Moreover, the standard deviation of the pressure on the blade pressure surface is largest at the tip, and the standard deviation of the pressure on the blade suction surface is clearly divided into two regions along the chord direction with different scales at different spanwise sections.
Polarons and molecules in a mixed-dimensional Fermi gas
Authors: Gong Baihua , Zhang Xin-Hui
Published: May 2021

We address the problem of a single impurity atom moving in a two-dimensional (2D) layer immersed in a 3D Fermi gas. Using a variational approach, we show that in this mixed-dimensional (MD) system, there is a transition between polaron and molecule ground states, similar to the case of pure 3D. Moreover, we find that the attractive polaron energy in MD is higher than that in 3D, while molecular energy in MD is lower than that in 3D, which leads to a shift of the critical interaction strength of transition. Further analysis shows that the energy difference between 3D and MD systems is attributed to the increment of the effective mass of the impurity, which is induced by the spatial constraint on the impurity.
Adaptive Layered Segregated Fit Scheme for Dynamic Memory Allocation
Authors: Guan Yuqian , Guo Jian
Published: May 2021

Embedded applications are becoming more complex and are required to utilize computing platform resources more efficiently. Existing dynamic memory allocation (DSA) schemes cannot adaptively perform memory management according to the environment in which they are located or integrate various memory allocation strategies, making it impossible to guarantee a constant execution time. Efficient memory utilization is a crucial challenge for developers, especially in embedded OSs (operating systems). In this paper, we propose an adaptive layered segregated fit (ALSF) scheme for DSA. The ALSF scheme combines dynamic two-dimensional arrays and bitmaps, completes the allocation and freeing of memory blocks within constant execution time, and uses memory splitting technology to reduce internal fragmentation. The proposed scheme also adjusts the number of segregated lists by analyzing the system’s allocation of different memory sizes, which improves the matching accuracy of memory blocks. We conducted a comparative experimental analysis and investigation of the ALSF and two-level segregated fit (TLSF) schemes in the Zephyr OS. Experiments show that the average memory utilization of the proposed ALSF scheme reaches 94.95%. Compared with the TLSF scheme, our scheme has a 12.99% higher allocation success rate in the memory-scarce environment, and the execution speeds of the two are similar.
Impact of doping concentration, thickness, and band-gap on individual layer efficiency of CIGS solar cell
Authors: Ngoy Kitalu Ricin , Singh Abhay Kumar , Jen Tien-Chien
Published: May 2021

An investigation with the individual layer physical property of the CIGS solar cells is a significant parameter to design and fabricate highly efficient devices. Therefore, this work demonstrates the thickness and carrier concentrations doping dependence simulations using SCAPS 1D software. The optimized CIGS solar cells different layer properties such as short-circuit current density ([Formula: see text], open-circuit voltage ([Formula: see text], Fill Factor (FF) and conversion efficiency ([Formula: see text] with varying thickness and doped concentration are presented. This optimized layer by layer simulation work would be useful to build a suitable CIGS solar cell structure. This simulation investigation showed that an optimal CIGS device structure can be fabricated possessing the configuration of a window layer ZnO : Al thickness 0.02 [Formula: see text]m, ZnO layer thickness 0.01 [Formula: see text] m with [Formula: see text] = 10[Formula: see text] cm[Formula: see text] and [Formula: see text] = 10[Formula: see text] cm[Formula: see text], a CdS buffer layer thickness 0.01 [Formula: see text]m with [Formula: see text] = 10[Formula: see text] cm[Formula: see text] and absorber layer CIGS in the thickness range of 1–4 [Formula: see text]m with the doping level range [Formula: see text] = 10[Formula: see text]–10[Formula: see text] cm[Formula: see text], along with the optimal CIGS energy bandgap range of 1.3–1.45 eV. According to optimized simulation results, a CIGS solar cell device can possess electric efficiency 26.61%, FF 82.96%, current density of 38.21 mA/cm2with the open circuit voltage 0.7977 eV. Hence, these optimized simulation findings could be helpful to provide a path to design and fabricate highly efficient CIGS solar cells devices.
A Survey of Field-based Testing Techniques
Authors: Bertolino Antonia , Braione Pietro , Angelis Guglielmo De , Gazzola Luca , Kifetew Fitsum , Mariani Leonardo , Orrù Matteo , Pezzè Mauro , Pietrantuono Roberto , Russo Stefano , Tonella Paolo
Published: May 2021

Field testing refers to testing techniques that operate in the field to reveal those faults that escape in-house testing. Field testing techniques are becoming increasingly popular with the growing complexity of contemporary software systems. In this article, we present the first systematic survey of field testing approaches over a body of 80 collected studies, and propose their categorization based on the environment and the system on which field testing is performed. We discuss four research questions addressing
how
software is tested in the field,
what
is tested in the field, which are the
requirements
, and how field tests are
managed
, and identify many challenging research directions.
Fork and Join Queueing Networks with Heavy Tails: Scaling Dimension and Throughput Limit
Authors: Zeng Yun , Tan Jian , Xia Cathy H.
Published: May 2021

Parallel and distributed computing systems are foundational to the success of cloud computing and big data analytics. These systems process computational workflows in a way that can be mathematically modeled by a fork-and-join queueing network with blocking (FJQN/B). While engineering solutions have long been made to build and scale such systems, it is challenging to rigorously characterize their throughput performance at scale theoretically. What further complicates the study is the presence of heavy-tailed delays that have been widely documented therein. In this article, we utilize an infinite sequence of FJQN/Bs to study the throughput limit and focus on an important class of heavy-tailed service times that are regularly varying with index

. The throughput is said to be scalable if the throughput limit infimum of the sequence is strictly positive as the network size grows to infinity. We introduce two novel geometric concepts—scaling dimension and extended metric dimension—and show that an infinite sequence of FJQN/Bs is throughput scalable if the extended metric dimension

and only if the scaling dimension

. We also show that for the cases where buffer sizes are scaling in an order of

, the scalability conditions are relaxed by a factor of 

. The results provide new insights on the scalability of a rich class of FJQN/Bs with various structures, including tandem, lattice, hexagon, pyramid, tree, and fractals.
Event Prediction in the Big Data Era
Authors: Zhao Liang
Published: May 2021

Events are occurrences in specific locations, time, and semantics that nontrivially impact either our society or the nature, such as earthquakes, civil unrest, system failures, pandemics, and crimes. It is highly desirable to be able to anticipate the occurrence of such events in advance to reduce the potential social upheaval and damage caused. Event prediction, which has traditionally been prohibitively challenging, is now becoming a viable option in the big data era and is thus experiencing rapid growth, also thanks to advances in high performance computers and new Artificial Intelligence techniques. There is a large amount of existing work that focuses on addressing the challenges involved, including heterogeneous multi-faceted outputs, complex (e.g., spatial, temporal, and semantic) dependencies, and streaming data feeds. Due to the strong interdisciplinary nature of event prediction problems, most existing event prediction methods were initially designed to deal with specific application domains, though the techniques and evaluation procedures utilized are usually generalizable across different domains. However, it is imperative yet difficult to cross-reference the techniques across different domains, given the absence of a comprehensive literature survey for event prediction. This article aims to provide a systematic and comprehensive survey of the technologies, applications, and evaluations of event prediction in the big data era. First, systematic categorization and summary of existing techniques are presented, which facilitate domain experts’ searches for suitable techniques and help model developers consolidate their research at the frontiers. Then, comprehensive categorization and summary of major application domains are provided to introduce wider applications to model developers to help them expand the impacts of their research. Evaluation metrics and procedures are summarized and standardized to unify the understanding of model performance among stakeholders, model developers, and domain experts in various application domains. Finally, open problems and future directions are discussed. Additional resources related to event prediction are included in the paper website: http://cs.emory.edu/∼lzhao41/projects/event_prediction_site.html.
CoSam: An Efficient Collaborative Adaptive Sampler for Recommendation
Authors: Chen Jiawei , Jiang Chengquan , Wang Can , Zhou Sheng , Feng Yan , Chen Chun , Ester Martin , He Xiangnan
Published: May 2021

Sampling strategies have been widely applied in many recommendation systems to accelerate model learning from implicit feedback data. A typical strategy is to draw negative instances with uniform distribution, which, however, will severely affect a model’s convergence, stability, and even recommendation accuracy. A promising solution for this problem is to over-sample the “difficult” (a.k.a. informative) instances that contribute more on training. But this will increase the risk of biasing the model and leading to non-optimal results. Moreover, existing samplers are either heuristic, which require domain knowledge and often fail to capture real “difficult” instances, or rely on a sampler model that suffers from low efficiency.

To deal with these problems, we propose CoSam, an efficient and effective collaborative sampling method that consists of (1) a collaborative sampler model that explicitly leverages user-item interaction information in sampling probability and exhibits good properties of normalization, adaption, interaction information awareness, and sampling efficiency, and (2) an integrated sampler-recommender framework, leveraging the sampler model in prediction to offset the bias caused by uneven sampling. Correspondingly, we derive a fast reinforced training algorithm of our framework to boost the sampler performance and sampler-recommender collaboration. Extensive experiments on four real-world datasets demonstrate the superiority of the proposed collaborative sampler model and integrated sampler-recommender framework.
Privacy Laws and Privacy by Design Schemes for the Internet of Things
Authors: Aljeraisy Atheer , Barati Masoud , Rana Omer , Perera Charith
Published: May 2021

Internet of Things applications have the potential to derive sensitive information about individuals. Therefore, developers must exercise due diligence to make sure that data are managed according to the privacy regulations and data protection laws. However, doing so can be a difficult and challenging task. Recent research has revealed that developers typically face difficulties when complying with regulations. One key reason is that, at times, regulations are vague and could be challenging to extract and enact such legal requirements. In this article, we have conducted a systematic analysis of the privacy and data protection laws that are used across different continents, namely (i) General Data Protection Regulations, (ii) the Personal Information Protection and Electronic Documents Act, (iii) the California Consumer Privacy Act, (iv) Australian Privacy Principles, and (v) New Zealand’s Privacy Act 1993. Then, we used framework analysis method to attain a comprehensive view of different privacy and data protection laws and highlighted the disparities to assist developers in adhering to the regulations across different regions, along with creating a Combined Privacy Law Framework (CPLF). After that, the key principles and individuals’ rights of the CPLF were mapped with Privacy by Design (PbD) schemes (e.g., privacy principles, strategies, guidelines, and patterns) developed previously by different researchers to investigate the gaps in existing schemes. Subsequently, we have demonstrated how to apply and map privacy patterns into IoT architectures at the design stage and have also highlighted the complexity of doing such mapping. Finally, we have identified the major challenges that should be addressed and potential research directions to take the burden off software developers when applying privacy-preserving techniques that comply with privacy and data protection laws. We have released a companion technical report [3] that comprises all definitions, detailed steps on how we developed the CPLF, and detailed mappings between CPLF and PbD schemes.
Intermediate Representations for Explicitly Parallel Programs
Authors: Susungi Adilla , Tadonki Claude
Published: May 2021

While compilers generally support parallel programming languages and APIs, their internal program representations are mostly designed from the sequential programs standpoint (exceptions include source-to-source parallel compilers, for instance). This makes the integration of compilation techniques dedicated to parallel programs more challenging. In addition, parallelism has various levels and different targets, each of them with specific characteristics and constraints. With the advent of multi-core processors and general purpose accelerators, parallel computing is now a common and pervasive consideration. Thus, software support to parallel programming activities is essential to make this technical transition more realistic and beneficial. The case of compilers is fundamental as they deal with (parallel) programs at a structural level, thus the need for intermediate representations. This article surveys and discusses attempts to provide intermediate representations for the proper support of explicitly parallel programs. We highlight the gap between available contributions and their concrete implementation in compilers and then exhibit possible future research directions.