bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of Proppant Placement in Scaled Fracture Networks
Authors: Song Y. , Dahi Taleghani A.
Published: September 2020

While hydraulic fracturing is recognized as the most effective stimulation technique for unconventional reservoirs, the production enhancement is influenced by several factors including proppant placement inside the fractures. The goal of this work is to understand the proppant transport and its placement process in T-shaped fracture network through simulations. The proppant transport is studied numerically by coupling a computational fluid dynamic model for the base shear-thinning fluid and the discrete element methods for proppant particles. A scaling analysis has been performed to scale down the model from field scale to lab scale by deriving relevant dimensionless parameters. Different proppant size distributions and injection velocities are considered, as well as the friction and cohesion effects among particle and fracture surface. The simulation results show that in the primary fracture, the injected proppant could divide into three layers: the bottom sand bed zone, the middle rolling surface zone, and the top slurry flow zone. The total number of the proppants do not increase much after the dune reach an equilibrium height. The equilibrium height of sand dune in the minor fracture could be greater than the primary fracture, and the distribution of proppant dunes is symmetric. Two deposit mechanisms have also identified in the bypass fracture network: falling deposition and rolling deposition. Additionally, significant momentum changes due to the change in the flow direction at the intersection with natural fractures is identified as a potential factor in accelerating particle deposition.
Numerical Model of a Deep Surge Cycle in Low-Speed Centrifugal Compressor
Authors: Liśkiewicz Grzegorz , Kulak Michał , Sobczak Krzysztof , Stickland Matthew
Published: September 2020

In this article, a numerical model of the full surge cycle is presented for the low-speed centrifugal blower and compared with the experiment. Surge phenomenon is very dangerous for the compressor operation. Therefore, the possibility of studying its physics experimentally is strongly limited. The application of numerical methods allows one to safely analyze surge physics without causing risks to the operating crew. This article presents a description of the applied numerical method and exhaustive analysis of the flow structures observed at consecutive stages of the surge cycle. The surge is known to be very difficult to be simulated due to large timescale and region of influence. This study also shows the importance of an appropriate choice of the simulation definition and the boundary conditions. The presented method allows gathering information about features such as the regions of flow reversal, pressure distributions, pressure rise, cycle frequency, and others. All the aforementioned information provides important input to the efficient antisurge system design. The model has been validated by a comparison with the experimental data. Thanks to simulation, standardized antisurge solutions could be possibly replaced with more efficient protection schemes tailored to a given machine.
Enhancement of Static and Dynamic Performance of Composite Tapered Pretwisted Rotating Blade With Variable Stiffness
Authors: Farsadi Touraj
Published: September 2020

Composite pretwisted tapered rotating thin-walled beams (TWB) can be used as a load-carrying structural part of a composite helicopter, wind turbine, fan, and turbomachinery blades. In the present study, the variable stiffness concept with curvilinear fiber path is used to achieve improved structural statics and dynamics performance of uniform and asymmetric composite thin-walled rotating beams. A parametric study is performed to investigate the effect of different fiber paths on the structural performance metrics including frequency spacing, coupling factor, and critical buckling load. For this purpose, The Euler–Lagrange governing equations of the dynamic system are derived via Hamilton's principle. To solve the governing set of equations, the extended Galerkin’s method (EGM) is employed. To validate the TWB model with curvilinear fibers, commercial finite element analysis tools abaqus is used. The author believes that the results presented here are likely to provide valuable information to the engineers involved in the design of advanced turbomachinery rotating blades using a variable stiffness concept with curvilinear fiber placement.
High-temperature low-pressure chemical vapor deposition of β-Ga2O3
Authors: Zhang Yuxuan , Feng Zixuan , Karim Md Rezaul , Zhao Hongping
Published: September 2020

Recent advancements in β-Ga2O3 materials’ growth and device developments are briefly reviewed with the focus on low-pressure chemical vapor deposition (LPCVD) of β-Ga2O3. β-Ga2O3 films are grown on off-axis c-sapphire and (010) β-Ga2O3 substrates via high-temperature LPCVD (HT-LPCVD) with growth temperatures ranging between 950 and 1050 °C. The effects of HT-LPCVD growth conditions on material properties are comprehensively studied. With relatively higher growth temperatures, an increased O2 flow rate is required to maintain β-Ga2O3 crystalline quality with high electron mobility. The growth rate of the HT-LPCVD β-Ga2O3 film scales with the increase of growth temperature and O2 flow rate. The film growth rate is strongly related to the sapphire substrate off-axis angle, which determines the preferred nucleation sites from the step edges. The transport properties of samples grown on substrates with different off-axis angles are compared. The optimized growth temperature for obtaining films with high electron mobility varies with the off-axis angle. From this comprehensive study, high-quality β-Ga2O3 films grown on c-sapphire are achieved with room temperature mobilities of 126 cm2/V s (6° off-axis c-sapphire), 116 cm2/V s (8° off-axis c-sapphire), and 119 cm2/V s (10° off-axis c-sapphire) at carrier concentrations of mid-1016 cm−3. β-Ga2O3 LPCVD homoepitaxy optimized at elevated growth temperatures is performed on Fe-doped semi-insulating (010) Ga2O3 substrates. With controllable Si doping, record-high room temperature mobilities of 156 cm2/V s (150 cm2/V s) are achieved with doping concentrations of 3 × 1016 cm−3 (1.5 × 1017 cm−3) at a growth temperature of 1050 °C. Secondary ion mass spectroscopy analysis shows more than an order of magnitude reduction of C and H impurity incorporation with increased growth temperature. Results from this work demonstrate that HT-LPCVD growth is a promising method to produce high-quality β-Ga2O3 films on both off-axis c-sapphire and native Ga2O3 substrates with a fast growth rate and superior transport properties critical for high power device applications.
Identifying multiply scattered wavepaths in strongly scattering and dispersive media
Authors: Masfara La Ode Marzujriban , Curtis Andrew , Thomsen Henrik Rasmus , van Manen Dirk-Jan
Published: September 2020

The ability to extract information from scattered waves is usually limited to singly scattered energy even if multiple scattering might occur in the medium. As a result, the information in arrival times of higher-order scattered events is underexplored. This information is extracted using fingerprinting theory. This theory has never previously been applied successfully to real measurements, particularly when the medium is dispersive. The theory is used to estimate the arrival times and scattering paths of multiply scattered waves in a thin sheet using an automated scheme in a dispersive medium by applying an additional dispersion compensation method. Estimated times and paths are compared with predictions based on a sequence of straight ray paths for each scattering event given the known scatterer locations. Additionally, numerical modelling is performed to verify the interpretations of the compensated data. Since the source also acts as a scatterer in these experiments, initially, the predictions and the numerical results did not conform to the experimental observations. By reformulating the theory and the processing scheme and adding a source scatterer in the modelling, it is shown that predictions of all observed scattering events are possible with both prediction methods, verifying that the methods are both effective and practically achievable.
A two-stage deep learning algorithm for talker-independent speaker separation in reverberant conditions
Authors: Delfarah Masood , Liu Yuzhou , Wang DeLiang
Published: September 2020

Speaker separation is a special case of speech separation, in which the mixture signal comprises two or more speakers. Many talker-independent speaker separation methods have been introduced in recent years to address this problem in anechoic conditions. To consider more realistic environments, this paper investigates talker-independent speaker separation in reverberant conditions. To effectively deal with speaker separation and speech dereverberation, extending the deep computational auditory scene analysis (CASA) approach to a two-stage system is proposed. In this method, reverberant utterances are first separated and separated utterances are then dereverberated. The proposed two-stage deep CASA system significantly outperforms a baseline one-stage deep CASA method in real reverberant conditions. The proposed system has superior separation performance at the frame level and higher accuracy in assigning separated frames to individual speakers. The proposed system successfully generalizes to an unseen speech corpus and exhibits similar performance to a talker-dependent system.
Age-Related Differences in Perceived Exertion While Walking and Running Near the Preferred Transition Speed
Authors: Kung Stacey M. , Fink Philip W. , Legg Stephen J. , Ali Ajmol , Shultz Sarah P.
Published: September 2020

Purpose: To investigate whether youth and adults can perceive differences in exertion between walking and running at speeds near the preferred transition speed (PTS) and if there are age-related differences in these perceptions. Methods: A total of 49 youth (10–12 y, n = 21; 13–14 y, n = 10; 15–17 y, n = 18) and 13 adults (19–29 y) completed a walk-to-run transition protocol to determine PTS and peak oxygen uptake. The participants walked and ran on a treadmill at 5 speeds (PTS–0.28 m·s−1, PTS–0.14 m·s−1, PTS, PTS+0.14 m·s−1, PTS+0.28 m·s−1) and rated perceived exertion using the OMNI Perceived Exertion (OMNI-RPE) scale. Oxygen consumption was measured during the walk-to-run transition protocol to obtain the relative intensity (percentage of peak oxygen uptake) at PTS. OMNI-RPE scores at all speeds and percentage of peak oxygen uptake at PTS were compared between age groups. Results: The 10- to 12-year-olds transitioned at a higher percentage of peak oxygen uptake than adults (64.54 [10.18] vs 52.22 [11.40], respectively; P = .035). The 10- to 14-year-olds generally reported higher OMNI-RPE scores than the 15- to 17-year-olds and adults (P < .050). In addition, the 10- to 14-year-olds failed to distinguish differences in OMNI-RPE between walking and running at PTS and PTS+0.14 m·s−1. Conclusions: Children aged 10–14 years are less able to distinguish whether walking or running requires less effort at speeds near the PTS compared with adults. The inability to judge which gait mode is less demanding could hinder the ability to minimize locomotive demands.
Bill threatens key Brazilian universities
Authors: Amigo Ignacio
Published: September 2020

Proposal to strip São Paulo institutions of reserve funds draws fierce opposition
Diversity and prosocial behavior
Authors: Baldassarri Delia , Abascal Maria
Published: September 2020

Immigration and globalization have spurred interest in the effects of ethnic diversity in Western societies. Most scholars focus on whether diversity undermines trust, social capital, and collective goods provision. However, the type of prosociality that helps heterogeneous societies function is different from the in-group solidarity that glues homogeneous communities together. Social cohesion in multiethnic societies depends on whether prosocial behavior extends beyond close-knit networks and in-group boundaries. We identify two features of modern societies—social differentiation and economic interdependence—that can set the stage for constructive interactions with dissimilar others. Whether societal adaptations to diversity lead toward integration or division depends on the positions occupied by minorities and immigrants in the social structure and economic system, along with the institutional arrangements that determine their political inclusion.
Supplemental Material: Glacier development in continental climate regions of central Asia
Authors: Batbaatar Jigjidsurengiin , al. et
Published: September 2020

Photos of samples, assessment of cosmogenic data quality, data tables, and references
Peripheral exudative haemorrhagic chorioretinopathy: a widefield imaging study
Authors: Zicarelli Federico , Preziosa Chiara , Staurenghi Giovanni , Pellegrini Marco
Published: September 2020

Aims

To study widefield imaging features, analyse risk factors for progression and compare treatment modalities of peripheral exudative haemorrhagic chorioretinopathy (PEHCR).

Methods

Clinical and imaging data from each visit were collected, including near-infrared reflectance, fluorescein angiography, indocyanine green angiography, optical coherence tomography using the Spectralis platform (Heidelberg Engineering). Clinical features and treatment performed were recorded. Lesions were classified according to treatments used and according to the prognostic index of macular involvement (MI) and intravitreal bleeding (IVB).

Results

50 eyes of 35 patients were retrospectively enrolled. Using widefield imaging, peripheral subretinal fluid (SRF) was detected in 31 (62%) eyes and peripheral neovascular networks were detected in 42 (84%) eyes and graded as focal, diffuse and subtotal in 22 (44%), 17 (34%) and 11 (22%) eyes, respectively. MI secondary to PEHCR during the follow-up was documented in 17 (34%) eyes, while IVB occurred in 7 (14%) eyes. Both MI and IVB correlated with peripheral SRF and lesion grade. Active treatment included anti-vascular endothelial growth factor (anti-VEGF) injections, photodynamic therapy (PDT) and combined anti-VEGF and PDT for 13 (26%), 1 (2%) and 18 (36%) eyes, respectively. In eyes with risk factors, anti-VEGF and combined treatment inversely correlated with MI incidence.

Conclusions

In our series, peripheral subretinal exudation and the extension of peripheral involvement represented risk factors for MI in eyes with PEHCR. In those high-risk eyes, active treatment is warranted.
Asthma and COVID-19: review of evidence on risks and management considerations
Authors: Hartmann-Boyce Jamie , Gunnell James , Drake Jonny , Otunla Afolarin , Suklan Jana , Schofield Ella , Kinton Jade , Inada-Kim Matt , Hobbs F D Richard , Dennison Paddy
Published: September 2020

Background

Respiratory illnesses typically present increased risks to people with asthma (PWA). However, data on the risks of COVID-19 to PWA have presented contradictory findings, with implications for asthma management.

Objective

To assess the risks and management considerations of COVID-19 in people with asthma (PWA).

Method

We conducted a rapid literature review. We searched PubMed, medRxiv, LitCovid, TRIP, Google and Google Scholar for terms relating to asthma and COVID-19, and for systematic reviews related to specific management questions within our review, in April 2020. References were screened and data were extracted by one reviewer.

Results

We extracted data from 139 references. The evidence available is limited, with some sources suggesting an under-representation of PWA in hospitalised cases and others showing an increased risk of worse outcomes in PWA, which may be associated with disease severity. Consensus broadly holds that asthma medications should be continued as usual. Almost all aspects of asthma care will be disrupted during the pandemic due not only to limits in face-to-face care but also to the fact that many of the diagnostic tools used in asthma are considered aerosol-generating procedures. Self-management and remote interventions may be of benefit for asthma care during this time but have not been tested in this context.

Conclusions

Evidence on COVID-19 and asthma is limited and continuing to emerge. More research is needed on the possible associations between asthma and COVID-19 infection and severity, as well as on interventions to support asthma care in light of constraints and disruptions to healthcare systems. We found no evidence regarding health inequalities, and this urgently needs to be addressed in the literature as the burdens of asthma and of COVID-19 are not equally distributed across the population.
Understanding the mechanisms of a combined physical and psychological intervention for people with neurogenic claudication: protocol for a causal mediation analysis of the BOOST trial
Authors: Comer Christine , Lee Hopin , Williamson Esther , Lamb Sarah
Published: September 2020

Introduction

Conservative treatments such as exercise are recommended for the management of people with neurogenic claudication from spinal stenosis. However, the effectiveness and mechanisms of effect are unknown. This protocol outlines an a priori plan for a secondary analysis of a multicentre randomised controlled trial of a physiotherapist-delivered, combined physical and psychological intervention (Better Outcomes for Older people with Spinal Trouble (BOOST) programme).

Methods and analyses

We will use causal mediation analysis to estimate the mechanistic effects of the BOOST programme on the primary outcome of disability (measured by the Oswestry Disability Index). The primary mechanism of interest is walking capacity, and secondary mediators include fear-avoidance behaviour, walking self-efficacy, physical function, physical activity and/or symptom severity. All mediators will be measured at 6 months and the outcome will be measured at 12 months from randomisation. Patient characteristics and possible confounders of the mediator-outcome effect will be measured at baseline. Sensitivity analyses will be conducted to evaluate the robustness of the estimated effects to varying levels of residual confounding.

Ethics and dissemination

Ethical approval was given on 3 March 2016 (National Research Ethics Committee number: 16/LO/0349). The results of this analysis will be disseminated in peer-reviewed journals and at relevant scientific conferences.

Trial registration number

ISRCTN12698674.
Liquid biopsy in the clinical management of hepatocellular carcinoma
Authors: von Felden Johann , Garcia-Lezana Teresa , Schulze Kornelius , Losic Bojan , Villanueva Augusto
Published: September 2020

With increasing knowledge on molecular tumour information, precision oncology has revolutionised the medical field over the past years. Liquid biopsy entails the analysis of circulating tumour components, such as circulating tumour DNA, tumour cells or tumour-derived extracellular vesicles, and has thus come as a handy tool for personalised medicine in many cancer entities. Clinical applications under investigation include early cancer detection, prediction of treatment response and molecular monitoring of the disease, for example, to comprehend resistance patterns and clonal tumour evolution. In fact, several tests for blood-based mutation profiling are already commercially available and have entered the clinical field.

In the context of hepatocellular carcinoma, where access to tissue specimens remains mostly limited to patients with early stage tumours, liquid biopsy approaches might be particularly helpful. A variety of translational liquid biopsy studies have been carried out to address clinical needs, such as early hepatocellular carcinoma detection and prediction of treatment response. To this regard, methylation profiling of circulating tumour DNA has evolved as a promising surveillance tool for early hepatocellular carcinoma detection in populations at risk, which might soon transform the way surveillance programmes are implemented. This review summarises recent developments in the liquid biopsy oncological space and, in more detail, the potential implications in the clinical management of hepatocellular carcinoma. It further outlines technical peculiarities across liquid biopsy technologies, which might be helpful for interpretation by non-experts.
Electronic dynamics in chains with Ornstein–Uhlenbeck correlated disorder
Authors: Soares J. L. S. , dos Santos R. D. , Sousa F. J. S. , Sales M. O. , Moura F. A. B. F.
Published: September 2020

In this paper, we present a detailed study of the electronic dynamics in systems with correlated disorder generated from the Ornstein–Uhlenbeck process (OU). In short, we used numeric methods for solving the time-dependent Schrödinger equation. We apply a Taylor’s expansion of the evolution operator in order to solve the differential equation. We calculate some typical tools, such as the participation function [Formula: see text], the mean square displacement [Formula: see text] and the probability of return [Formula: see text]. In our analysis, we show that for low correlations the system behaves as in the standard Anderson model (i.e. all eigenstates are localized). For strong correlations, our results suggest the existence of a quasi-ballistic dynamics.
On Generating of t-Norms and t-Conorms on Bounded Lattices
Authors: Çaylı Gül Deniz
Published: September 2020

In this paper, we study t-norms and t-conorms on bounded lattices. We propose new methods for generating these operators, applicable on any bounded lattice M by use of the presence of a t-norm on [0M, k] and a t-conorm on [k, 1M] for an element k ∊ M\{0M, 1M}. In addition, some corresponding examples are provided for well understanding the structure of new t-norms and t-conorms.
AN APPLICATION OF R-HiPIMS METHOD FOR TiO2- AND TiO2:Cu-BASED MEMRISTORS: CONTROLLING Cu DOPING USING DC PULSE METHOD
Authors: ARASHLOO BANAFSHEH ALIZADEH , EFEOGLU HASAN
Published: September 2020

Nowadays, the High-Power Impulse Magnetron Sputtering (HiPIMS) as an additional technique to plasma-based sputtering, is applied to depositing or coating of thin films. HiPIMS is based on applying high-power and low-duty-cycle unipolar pulses to the magnetron target by a low repetition frequency, which are produced from the high ionization part of sputtered atoms by high discharge power. By applying voltage to substrate and bombarding it in the presence of an inert gas such as Ar, the growth of the film is controlled by the acceleration of the sputtered material across the highly dense plasma. To deposit compound materials, metal targets are sputtered with gases such as CH4, N2, O2, etc. or by Reactive HiPIMS (R-HiPIMS) techniques. The transparent metal oxide (TiO[Formula: see text] film depositions by R-HiPIMS are denser and have flatter surfaces due to a higher degree of crystallinity than other sputtering methods. The applicable potential of TiO2thin films and similar metal oxides on the ultra-high-density electronic devices due to the presence of oxygen deficiency, leads them to be chosen for memristor devices. As theory predicted, a current-controlled memristor is possible with metal–TiO2–metal structures. But stability and repeatability with high ON/OFF ratios remain as problems. A high ON/OFF ratio due to filament formation is revealed by Cu doping of TiO2thin films which leads to two state functions to be applicable for the traditional digital electronics. On the other hand, an ideal memristor has a potential for gray scale with no limitation. This approach has a big potential impact on data storage and computation in electronics. A new spotlight for this prediction is recognized by the high mobility of transition elements such as Cu in semiconductors. In this work, a nano-scale memristor based on Cu-doped TiO2is fabricated from metallic targets (i.e. Ti and Cu) by the R-HiPIMS method. Cu doping is synchronously controlled by using pulsed DC sputtering onto the TiO2structure. DC pulse duration and its frequency are used for adjusting the Cu doping concentration during the growth time of TiO2. The memristor properties of Cu–Pt–TiO2–p[Formula: see text]Si–Al and Cu–Pt–TiO2:Cu–p[Formula: see text]Si–Al devices are considered. The electrode change effect on the memristive properties and performance of Cu-doped memristor is investigated. The [Formula: see text]–[Formula: see text] characteristic of the Cu-doped memristor with Cu top electrode is recognized to be asymmetric in comparison with Cu-doped TiO2-based memristor with Pt top electrode. The structural, optical and electrical characterizations are carried out and preliminary findings are given in detail.
Growth Phase Diagram of Graphene Grown Through Chemical Vapor Deposition on Copper
Authors: Wu Qinke , Jeon Sangjun , Song Young Jae
Published: September 2020

The phase diagram for graphene growth was obtained to understand the physics of the growth mechanism and control the layer number or coverage of graphene deposited on copper via low-pressure chemical vapor deposition (LPCVD). Management of the number of graphene layers and vacancies is essential for producing defect-free monolayer graphene and engineering multilayered functionalized graphene. In this work, the effects of the CH4 and H2 flow rates were investigated to establish the phase diagram for graphene growth. Using this phase diagram, we selectively obtained fully covered and partially grown monolayer graphene, graphene islands through Volmer–Weber growth, and multilayer graphene through Stranski–Krastanov-like growth. The layer numbers and coverage were determined using optical microscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy and Raman spectroscopy. The growth modes were determined by the competition between catalytic growth with CH4 and catalytic etching with H2 on the copper surface during CVD growth. Intriguingly, this phase diagram showed that multilayer graphene flakes can be grown via LPCVD even with low CH4 and H2 flows.
Standards Advice
Authors: Neville-Neil George
Published: September 2020

My mother took language, both written and spoken, very seriously. The last thing I wanted to hear upon showing her an essay I was writing for school was, "Bring me the red pen." In those days I did not have a computer; all my assignments were written longhand or on a typewriter, so the red pen meant a total rewrite. She was a tough editor, but it was impossible to question the quality of her work or the passion that she brought to the writing process. All of the things Strunk and White have taught others throughout the years my mother taught me, on her own, with the benefit of only a high school education and a voracious appetite for reading.
Why Cloud Computing Will Never Be Free
Authors: Durkee Dave
Published: September 2020

The last time the IT industry delivered outsourced shared-resource computing to the enterprise was with timesharing in the 1980s, when it evolved to a high art, delivering the reliability, performance, and service the enterprise demanded. Today, cloud computing is poised to address the needs of the same market, based on a revolution of new technologies, significant unused computing capacity in corporate data centers, and the development of a highly capable Internet data communications infrastructure. The economies of scale of delivering computing from a centralized, shared infrastructure have set the expectation among customers that cloud-computing costs will be significantly lower than those incurred from providing their own computing. Together with the reduced deployment costs of open source software and the perfect competition characteristics of remote computing, these expectations set the stage for fierce pressure on cloud providers to continuously lower prices.
Computers in Patient Care: The Promise and the Challenge
Authors: Cantrill Stephen V.
Published: September 2020

A 29-year-old female from New York City comes in at 3 a.m. to an ED (emergency department) in California, complaining of severe acute abdominal pain that woke her up. She reports that she is in California attending a wedding and that she has suffered from similar abdominal pain in the recent past, most recently resulting in an appendectomy. The emergency physician performs an abdominal CAT scan and sees what he believes to be an artifact from the appendectomy in her abdominal cavity. He has no information about the patient’s past history other than what she is able to tell him; he has no access to any images taken before or after the appendectomy, nor does he have any other vital information about the surgical operative note or follow-up. The physician is left with nothing more than what he can see in front of him. The woman is held overnight for observation and released the following morning symptomatically improved, but essentially undiagnosed.
Extending the Semantics of Scheduling Priorities
Authors: Polanczyk Rafael Vanoni
Published: September 2020

Application performance is directly affected by the hardware resources that the application requires, the degree to which such resources are available, and how the operating system addresses its requirements with regard to the other processes in the system. Ideally, an application would have access to all the resources it could use and be allowed to complete its work without competing with any other activity in the system. In a world of highly shared hardware resources and generalpurpose, time-share-based operating systems, however, no guarantees can be made as to how well resourced an application will be.
Anatomy of a Solid-state Drive
Authors: Cornwell Michael
Published: September 2020

Over the past several years, a new type of storage device has entered laptops and data centers, fundamentally changing expectations regarding the power, size, and performance dynamics of storage. The SSD (solid-state drive) is a technology that has been around for more than 30 years but remained too expensive for broad adoption.
The Essence of Software Engineering: The SEMAT Kernel
Authors: Jacobson Ivar , Ng Pan-Wei , McMahon Paul , Spence Ian , Lidman Svante
Published: September 2020

Everyone who develops software knows that it is a complex and risky business, and its participants are always on the lookout for new ideas that will lead to better software. Fortunately, software engineering is still a young and growing profession that sees innovations and improvements in best practices every year. Just look, for example, at the improvements and benefits that lean and agile thinking have brought to software-development teams.
Resolved: the Internet Is No Place for Critical Infrastructure
Authors: Geer Dan
Published: September 2020

What is critical? To what degree is critical defined as a matter of principle, and to what degree is it defined operationally? I am distinguishing what we say from what we do.
Proving the Correctness of Nonblocking Data Structures
Authors: Desnoyers Mathieu
Published: September 2020

Nonblocking synchronization can yield astonishing results in terms of scalability and realtime response, but at the expense of verification state space.
Agile and SEMAT - Perfect Partners
Authors: Jacobson Ivar , Spence Ian , Ng Pan-Wei
Published: September 2020

Today, as always, many different initiatives are under way to improve the ways in which software is developed. The most popular and prevalent of these is the agile movement. One of the newer kids on the block is the SEMAT (Software Engineering Method and Theory) initiative. As with any new initiative, people are struggling to see how it fits into the world and relates to all the other things going on. For example, does it improve or replace their current ways of working? Is it like lean, which supports and furthers the aims of the agile movement, or is it more like waterfall planning, which is in opposition to an agile approach?
Node at LinkedIn: The Pursuit of Thinner, Lighter, Faster
Authors: Prasad Kiran , Norton Kelly , Coatta Terry
Published: September 2020

Node.js, the server-side JavaScript-based software platform used to build scalable network applications, has been all the rage among many developers for the past couple of years, although its popularity has also managed to enrage some others, who have unleashed a barrage of negative blog posts to point out its perceived shortcomings. Still, while new and untested, Node continues to win more converts.
Provenance in Sensor Data Management
Authors: Hensley Zachary , Sanyal Jibonananda , New Joshua
Published: September 2020

In today’s information-driven workplaces, data is constantly being moved around and undergoing transformation. The typical business-as-usual approach is to use e-mail attachments, shared network locations, databases, and more recently, the cloud. More often than not, there are multiple versions of the data sitting in different locations, and users of this data are confounded by the lack of metadata describing its provenance or in other words, its lineage. The ProvDMS project at the Oak Ridge National Laboratory (ORNL) described in this article aims to solve this issue in the context of sensor data.
Eventually Consistent: Not What You Were Expecting?
Authors: Golab Wojciech , Rahman Muntasir R. , AuYoung Alvin , Keeton Kimberly , Li Xiaozhou (Steve)
Published: September 2020

Storage systems continue to lay the foundation for modern Internet services such as Web search, e-commerce, and social networking. Pressures caused by rapidly growing user bases and data sets have driven system designs away from conventional centralized databases and toward more scalable distributed solutions, including simple NoSQL key-value storage systems, as well as more elaborate NewSQL databases that support transactions at scale.
Domain-specific Languages and Code Synthesis Using Haskell
Authors: Gill Andy
Published: September 2020

There are many ways to give instructions to a computer: an electrical engineer might write a MATLAB program; a database administrator might write an SQL script; a hardware engineer might write in Verilog; and an accountant might write a spreadsheet with embedded formulas. Aside from the difference in language used in each of these examples, there is an important difference in form and idiom. Each uses a language customized to the job at hand, and each builds computational requests in a form both familiar and productive for programmers (although accountants may not think of themselves as programmers). In short, each of these examples uses a DSL (domain-specific language).
META II: Digital Vellum in the Digital Scriptorium
Authors: Long Dave
Published: September 2020

Some people do living history -- reviving older skills and material culture by reenacting Waterloo or knapping flint knives. One pleasant rainy weekend in 2012, I set my sights a little more recently and settled in for a little meditative retro-computing, ca. 1962, following the ancient mode of transmission of knowledge: lecture and recitation -- or rather, grace of living in historical times, lecture (here, in the French sense, reading) and transcription (or even more specifically, grace of living post-Post, lecture and reimplementation).
Edge Computing
Authors: Mor Nitesh
Published: September 2020

Creating edge computing infrastructures and applications encompasses quite a breadth of systems research. Let’s take a look at the academic view of edge computing and a sample of existing research that will be relevant in the coming years.
SPREADING OF COVID-19 IN INDIA, ITALY, JAPAN, SPAIN, UK, US
Authors: Kumar Munish , Gupta Surbhi , Kumar Krishan , Sachdeva Monika
Published: September 2020

The spread of COVID-19 around the entire world has placed humankind in an unprecedented situation. Because of the rise of the number of cases and its subsequent load on the organizations and wellbeing experts, some immediate strategies are required to envision the number of cases in the future. In this article, the authors have presented two data-driven estimation techniques, namely, Auto-Regressive Integrated Moving Average (ARIMA) and Long Short-Term Memory (LSTM) for prediction of the cumulative number of COVID-19 cases and the cumulative number of deaths due to COVID-19. Various measures of goodness of fit such as Akaike Information Criteria (AIC), Mean Absolute Percentage Error (MAPE), and Root Mean Square Error (RMSE) are computed for the ARIMA model. For LSTM, two parameters such as Mean Absolute Percentage Error (MAPE) and Root Mean Squared Error (RMSE) are computed. 80% of the available data are used to create the model and the remaining 20% are used for testing. The predicted and actual figures are compared to test the prediction accuracy. This article aims to aid India, Italy, Japan, Spain, the UK, and the US administration by providing a statistical tool to predict the future figures of upcoming suspected and death cases because of COVID-19.
Wearable Devices to Monitor and Reduce the Risk of Cardiovascular Disease: Evidence and Opportunities
Authors: Mizuno Atsushi , Changolkar Sujatha , Patel Mitesh S.
Published: September 2020

There is a growing interest in using wearable devices to improve cardiovascular risk factors and care. This review evaluates how wearable devices are used for cardiovascular disease monitoring and risk reduction. Wearables have been evaluated for detecting arrhythmias (e.g., atrial fibrillation) as well as monitoring physical activity, sleep, and blood pressure. Thus far, most interventions for risk reduction have focused on increasing physical activity. Interventions have been more successful if the use of wearable devices is combined with an engagement strategy such as incorporating principles from behavioral economics to integrate social or financial incentives. As the technology continues to evolve, wearable devices could be an important part of remote-monitoring interventions but are more likely to be effective at improving cardiovascular care if integrated into programs that use an effective behavior change strategy.
Prediction of Daily Blood Sampling Room Visits Based on ARIMA and SES Model
Authors: Zhang Xinli , Yu Yu , Xiong Fei , Luo Le
Published: September 2020

This paper is aimed at establishing a combined prediction model to predict the demand for medical care in terms of daily visits in an outpatient blood sampling room, which provides a basis for rational arrangement of human resources and planning. On the basis of analyzing the comprehensive characteristics of the randomness, periodicity, trend, and day-of-the-week effects of the daily number of blood collections in the hospital, we firstly established an autoregressive integrated moving average model (ARIMA) model to capture the periodicity, volatility, and trend, and secondly, we constructed a simple exponential smoothing (SES) model considering the day-of-the-week effect. Finally, a combined prediction model of the residual correction is established based on the prediction results of the two models. The models are applied to data from 60 weeks of daily visits in the outpatient blood sampling room of a large hospital in Chengdu, for forecasting the daily number of blood collections about 1 week ahead. The result shows that the MAPE of the combined model is the smallest overall, of which the improvement during the weekend is obvious, indicating that the prediction error of extreme value is significantly reduced. The ARIMA model can extract the seasonal and nonseasonal components of the time series, and the SES model can capture the overall trend and the influence of regular changes in the time series, while the combined prediction model, taking into account the comprehensive characteristics of the time series data, has better fitting prediction accuracy than a single model. The new model can well realize the short-to-medium-term prediction of the daily number of blood collections one week in advance.
A Method for Efficient Task Assignment Based on the Satisfaction Degree of Knowledge
Authors: Su Jiafu , Wang Jie , Liu Sheng , Zhang Na , Li Chi
Published: September 2020

For the product R&D process, it is a challenge to effectively and reasonably assign tasks and estimate their execution time. This paper develops a method system for efficient task assignment in product R&D. The method system consists of three components: similar tasks identification, tasks’ execution time calculation, and task assignment model. The similar tasks identification component entails the retrieval of a similar task model to identify similar tasks. From the knowledge-based view, the tasks’ execution time calculation component uses the BP neural network to predict tasks’ execution time according to the previous similar tasks and the Task–Knowledge–Person (TKP) network. When constructing the BP neural network, the satisfaction degree of knowledge and the execution time are set as the input and output, respectively. Considering the uncertain factors associated with the whole R&D process, the task assignment model component serves as a robust optimization model to assign tasks. Then, an improved genetic algorithm is developed to solve the task assignment model. Finally, the results of numerical experiment are reported to validate the effectiveness of the proposed methods.
Stress among Portuguese Medical Students: A National Cross-Sectional Study
Authors: Oura Maria João , Moreira Ana Raquel , Santos Paulo
Published: September 2020

Introduction. The medical course is extremely stimulating but also demanding, and it can interfere with students’ mental health. Stress leads to lower life quality, academic performance, and ultimately to a lower quality of patient care delivered. Objective. To analyse stress levels of sixth-year medical students who attend Portuguese colleges. Methodology. This observational cross-sectional study involved Portuguese medical students attending the sixth year of all Portuguese faculties. We applied an online self-response questionnaire, including the 10 items Perceived Stress Scale (PSS) to assess stress levels and sociodemographic variables. Logistic regression was used to estimate the weight of the studied determinants on stress levels. Results. A total of 501 participants were included for analysis (69.5% females), with a median age of 24 years old. We found significant levels of stress in 49.9% (95% CI: 45.5–54.3%), with 20.8% of total students presenting extremely high levels, irrespective of age, gender, and faculty. Stress was higher when students presented bad sleeping and eating habits, lack of ability to manage time, dissatisfaction with social life and academic experience, and low family support. Also, these students are more worried about their future and present a higher degree of concern about their graduation test performance. Conclusion. This study found high stress levels among Portuguese medical students, associated with social determinants and the intrinsic complexity of the course. This is worrying, and it elucidates the importance of coping strategies to make students deal with stress and be healthier, currently and in the future.
Knockdown of KCNQ1OT1 Inhibits Proliferation, Invasion, and Drug Resistance by Regulating miR‐129‐5p‐Mediated LARP1 in Osteosarcoma
Authors: Zhang Yunfei , Cai Wei , Zou Yuli , Zhang Hong
Published: September 2020

KCNQ1OT1 exerts an important role in various cancers, but its role in osteosarcoma (OS) and the potential mechanism remain to be clarified. In the present research, we aimed to explore the effect of KCNQ1OT1 on osteosarcoma and further explore the special molecular mechanism. The expression of KCNQ1OT1 was analyzed in tumor and adjacent tissues of 30 patients with osteosarcoma by RT‐PCR. Cell proliferation and invasion were explored using MTT and transwell assay, respectively. Luciferase reporter analysis and pull‐down assay were performed to determine the binding activity of KCNQ1OT1 and miR‐129‐5p. The result revealed that KCNQ1OT1 was highly expressed in osteosarcoma tissues and cells. KCNQ1OT1‐siRNA inhibited the proliferation, invasion, and drug resistance of osteosarcoma cells. The luciferase reporter assay and pull‐down assay demonstrated that KCNQ1OT1 directly interact with miR‐129‐5p. In addition, miR‐129‐5p binds to LARP1 directly, and LARP1 promoted the proliferation, invasion, and drug resistance of osteosarcoma cells. What is more, KCNQ1OT1 promoted proliferation, invasion, and drug resistance via inhibiting the expression of miR‐129‐5p and further promoting the expression of miR‐129‐5p‐mediated LARP1. Collectively, it suggests that downregulation of KCNQ1OT1 inhibits proliferation, invasion, and drug resistance by regulating miR‐129‐5p‐mediated LARP1 in osteosarcoma cells.
Numerical Simulation of the Thermal‐Hydro‐Mechanical Characteristics of High‐Speed Railway Roadbeds in Seasonally Frozen Regions
Authors: Zhang Yuzhi , Bei Jianghui , Li Pei , Liang Xiaojie
Published: September 2020

A multiphysics mathematical model of high‐speed railway (HSR) roadbeds is necessary to facilitate a good level of understanding of the frost heaving mechanism. Based on the classical hydrodynamic model and fundamental thermoelasticity theories, we propose a thermo‐hydro coupled model, based on the soil‐water characteristic curve and solid‐liquid ratio as the relation equations, with the effects of the ice‐water phase change and water migration due to temperature change considered. With the linear expansion coefficient related to the temperature and the mass of ice content in roadbeds as the relation equation, we establish a macroscopic thermal‐hydro‐mechanical model for unsaturated soil to calculate the roadbed deformations. Based upon the field data of a typical cross section of the Harbin‐Dalian HSR roadbed, the variation of the thermal‐hydro‐mechanical characteristics is simulated and studied. The results demonstrate that the increase of water content in the roadbed’s central line mainly appears in soil layers at depths less than 1.2 m and most ice‐containing soil layers are at depths less than 0.6 m. Under the driving force of thermal and hydraulic migration, the vertical displacement of the west shoulder is increased to 18 mm. Then the settled maximum surface unevenness reaches 16 mm between the shoulder and centre line.