bluuebunny/crossref_metadata_2025 huggingface dataset:
How youth cognitive and sociodemographic factors relate to the development of overweight and obesity in the UK and the USA: a prospective cross-cohort study of the National Child Development Study and National Longitudinal Study of Youth 1979
Authors: Altschul Drew M , Wraw Christina , Gale Catharine R , Deary Ian J
Published: December 2019

Objectives

We investigated how youth cognitive and sociodemographic factors are associated with the aetiology of overweight and obesity. We examined both onset (who is at early risk for overweight and obesity) and development (who gains weight and when).

Design

Prospective cohort study.

Setting

We used data from the US National Longitudinal Study of Youth 1979 (NLSY) and the UK National Child Development Study (NCDS); most of both studies completed a cognitive function test in youth.

Participants

12 686 and 18 558 members of the NLSY and NCDS, respectively, with data on validated measures of youth cognitive function, youth socioeconomic disadvantage (eg, parental occupational class and time spent in school) and educational attainment. Height, weight and income data were available from across adulthood, from individuals’ 20s into their 50s.

Primary and secondary outcome measures

Body mass index (BMI) for four time points in adulthood. We modelled gain in BMI using latent growth curve models to capture linear and quadratic components of change in BMI over time.

Results

Across cohorts, higher cognitive function was associated with lower overall BMI. In the UK, 1 SD higher score in cognitive function was associated with lower BMI (β=−0.20, 95% CI −0.33 to −0.06 kg/m²). In America, this was true only for women (β=−0.53, 95% CI −0.90 to −0.15 kg/m²), for whom higher cognitive function was associated with lower BMI. In British participants only, we found limited evidence for negative and positive associations, respectively, between education (β=−0.15, 95% CI −0.26 to −0.04 kg/m²) and socioeconomic disadvantage (β=0.33, 95% CI 0.23 to 0.43 kg/m²) and higher BMI. Overall, no cognitive or socioeconomic factors in youth were associated with longitudinal changes in BMI.

Conclusions

While sociodemographic and particularly cognitive factors can explain some patterns in individuals’ overall weight levels, differences in who gains weight in adulthood could not be explained by any of these factors.
Genetic biomarkers in the VEGF pathway predicting response to anti-VEGF therapy in age-related macular degeneration
Authors: Balikova Irina , Postelmans Laurence , Pasteels Brigitte , Coquelet Pascale , Catherine Janet , Efendic Azra , Hosoda Yoshikatsu , Miyake Masahiro , Yamashiro Kenji ,   ANGEL study group members, Thienpont Bernard , Lambrechts Diether
Published: December 2019

Objective

Age-related macular degeneration (ARMD) is a leading cause of visual impairment. Intravitreal injections of anti-vascular endothelial growth factor (VEGF) are the standard treatment for wet ARMD. There is however, variability in patient responses, suggesting patient-specific factors influencing drug efficacy. We tested whether single nucleotide polymorphisms (SNPs) in genes encoding VEGF pathway members contribute to therapy response.

Methods and analysis

A retrospective cohort of 281 European wet ARMD patients treated with anti-VEGF was genotyped for 138 tagging SNPs in the VEGF pathway. Per patient, we collected best corrected visual acuity at baseline, after three loading injections and at 12 months. We also registered the injection number and changes in retinal morphology after three loading injections (central foveal thickness (CFT), intraretinal cysts and serous neuroepithelium detachment). Changes in CFT after 3 months were our primary outcome measure. Association of SNPs to response was assessed by binomial logistic regression. Replication was attempted by associating visual acuity changes to genotypes in an independent Japanese cohort.

Results

Association with treatment response was detected for seven SNPs, including in FLT4 (rs55667289: OR=0.746, 95% CI 0.63 to 0.88, p=0.0005) and KDR (rs7691507: OR=1.056, 95% CI 1.02 to 1.10, p=0.005; and rs2305945: OR=0.963, 95% CI 0.93 to 1.00, p=0.0472). Only association with rs55667289 in FLT4 survived multiple testing correction. This SNP was unavailable for testing in the replication cohort. Of six SNPs tested for replication, one was significant although not after multiple testing correction.

Conclusion

Identifying genetic variants that define treatment response can help to develop individualised therapeutic approaches for wet ARMD patients and may point towards new targets in non-responders.
Variation in exposure to endoscopic haemostasis for acute upper gastrointestinal bleeding during UK gastroenterology training
Authors: Siau Keith , Morris A John , Murugananthan Aravinth , McKaig Brian , Dunckley Paul
Published: December 2019

Introduction

Gastroenterologists are typically expected to be competent in endoscopic haemostasis for acute upper gastrointestinal bleeding (AUGIB), with the Certificate of Completion of Training (CCT) often heralding the onset of participation in on-call AUGIB rotas. We analysed the volume of haemostasis experience recorded by gastroenterology CCT holders on the Joint Advisory Group on Gastrointestinal Endoscopy Training System (JETS) e-portfolio, the UK electronic portfolio for endoscopy, and assessed for variations in exposure to haemostasis.

Methods

UK gastroenterologists awarded CCT between April 2014 and April 2017 were retrospectively identified from the specialist register. Credentials were cross-referenced with JETS to retrieve AUGIB haemostasis procedures prior to CCT. Procedures were collated according to variceal versus non-variceal therapies and compared across training deaneries.

Results

Over the 3-year study period, 241 gastroenterologists were awarded CCT. 232 JETS e-portfolio users were included for analysis. In total, 12 932 haemostasis procedures were recorded, corresponding to a median of 42 (IQR 21–71) per gastroenterologist. Exposure to non-variceal modalities (median 28, IQR 15–52) was more frequent than variceal therapies (median 11, IQR 5–22; p<0.001). By procedure, adrenaline injection (median 12, IQR 6–23) and variceal band ligation (median 10, IQR 5–20) were most commonly recorded, whereas sclerotherapy experience was rare (median 0, IQR 0–1). Exposure to haemostasis did not differ by year of CCT (p=0.130) but varied significantly by deanery (p<0.001), with median procedures ranging from 20–126.

Conclusion

Exposure to AUGIB haemostasis during UK gastroenterology training varied across deaneries and procedural modalities which should prompt urgent locoregional review of access and delivery of training. Endoscopy departments should ensure the availability of supportive provisions in haemostasis (i.e. training/upskilling, supervision, mentorship) during the early post-CCT period.
Relationship between non-alcoholic fatty liver disease during pregnancy and abnormal glucose metabolism during and after pregnancy
Authors: Sattari Maryam , Bril Fernando , Egerman Robert , Kalavalapalli Srilaxmi , Cusi Kenneth
Published: December 2019

While non-alcoholic fatty liver disease (NAFLD) is associated with increased risk of impaired glucose tolerance and type 2 diabetes mellitus (DM) in non-pregnant patients, the clinical significance of NAFLD during pregnancy is still unclear. We hypothesized that sonographic findings of NAFLD during pregnancy would be associated with gestational diabetes mellitus (GDM) and predict abnormal postpartum glucose metabolism. NAFLD was assessed by ultrasound during and after pregnancy. Standard 2-hour 75 g oral glucose tolerance test (OGTT) was used during pregnancy and post partum to establish GDM and the diagnosis of normal, impaired fasting glucose, or DM. We also measured plasma insulin, C peptide, and free fatty acids (FFA) concentration during an OGTT to evaluate glucose tolerance, insulin secretion and insulin resistance. Of the 84 subjects, 12 had sonographic evidence of NAFLD (5 of whom had OGTT post partum). There was a non-significant trend toward higher mean weight and body mass index during and after gestation in the NAFLD group, but no statistically significant differences in mean age, ethnicity, prepregnancy and postpregnancy hemoglobin A1C values, and postpartum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose, insulin, or FFA. We did not find an association between sonographic evidence of NAFLD during the third trimester of pregnancy and abnormal glucose metabolism during or after pregnancy. This study also suggests that while AST and ALT are not reliable diagnostic tools for NAFLD during the postpartum period, ultrasound is a reasonably safe, practical, and cost-effective modality to assess maternal hepatic fat during pregnancy.
Randomised evaluation of government health programmes does present a challenge to standard research ethics frameworks
Authors: Watson Samuel I , Dixon-Woods Mary , Lilford Richard J
Published: December 2019

In a recent issue of Journal of Medical Ethics (JME), we discussed the ethical review of evaluations of interventions that would occur whether or not the evaluation was taking place. We concluded that standard research ethics frameworks including the Ottawa Statement, which requires justification for all aspects of an intervention and its roll-out, were a poor guide in this area. We proposed that a consideration of researcher responsibility, based on the consequences of the research taking place, would be a more appropriate way delineate the scope of research ethics review. Weijer and Taljaard present a counterargument to our proposal, which we address in this reply. They claim that a focus on researcher responsibility will weaken the protection of research participants and link it to ‘unethical research’ and a ‘government experimenting on its own people’. However, the moral responsibility of researchers is defined in terms of the consequences of the research on human welfare and harm, not in opposition to it. Weijer and Taljaard argue that researchers must justify what they are studying whether or not they have any control over it and that governments must justify their programmes, including by demonstrating equipoise, to a research ethics committee if they implement them in a randomised way. We strongly disagree that this is a defensible way to define the scope of research ethics review and argue that this provides no further protections to research participants beyond what we propose, but places a potential barrier to learning from government programmes.
Immune modulation by chronic exposure to waterpipe smoke and immediate-early gene regulation in murine lungs
Authors: Reyes-Caballero Hermes , Park Bongsoo , Loube Jeffrey , Sanchez Ian , Vinayachandran Vinesh , Choi Youngshim , Woo Juhyung , Edwards Justin , Brinkman Marielle C , Sussan Thomas , Mitzner Wayne , Biswal Shyam
Published: December 2019

Objective

We investigated the effects of chronic waterpipe (WP) smoke on pulmonary function and immune response in a murine model using a research-grade WP and the effects of acute exposure on the regulation of immediate-early genes (IEGs).

Methods

WP smoke was generated using three WP smoke puffing regimens based on the Beirut regimen. WP smoke samples generated under these puffing regimens were quantified for nicotine concentration. Mice were chronically exposed for 6 months followed by assessment of pulmonary function and airway inflammation. Transcriptomic analysis using RNAseq was conducted after acute exposure to characterise the IEG response. These biomarkers were then compared with those generated after exposure to dry smoke (without water added to the WP bowl).

Results

We determined that nicotine composition in WP smoke ranged from 0.4 to 2.5 mg per puffing session. The lung immune response was sensitive to the incremental severity of chronic exposure, with modest decreases in airway inflammatory cells and chemokine levels compared with air-exposed controls. Pulmonary function was unmodified by chronic WP exposure. Acute WP exposure was found to activate the immune response and identified known and novel IEG as potential biomarkers of WP exposure.

Conclusion

Chronic exposure to WP smoke leads to immune suppression without significant changes to pulmonary function. Transcriptomic analysis of the lung after acute exposure to WP smoke showed activation of the immune response and revealed IEGs that are common to WP and dry smoke, as well as pools of IEGs unique to each exposure, identifying potential biomarkers specific to WP exposure.
The magnetic field effect of K X-ray fluorescence parameters of elements in the range 39 ≤ Z ≤ 48
Authors: Uğurlu Mine , Akkuş Tuba , Demir Lütfü
Published: December 2019

In this work, the fluorescence parameters (the fluorescence cross section (σ), the fluorescence yield (ω), and vacancy transfer probability (η)) of the fifth period elements, which have great potential to be developed as a technology, are investigated by taking advantage of interactions between atoms and radiation. For this process, the samples were excited via 241Am source without magnetic field and in the external magnetic field. The radiation emitted from targets was collected by an Si(Li) detector and energy channels were located on a computer program by means of a multi-channel analyzer. The data on the computer program were analyzed for calculations. The discrepancies have been observed between the experimental results and the theoretical results calculated without magnetic field. It was determined that results changed with the magnetic field (B = 0.4 and 0.8 T) and the variation of the X-ray fluorescence (XRF) parameters with the magnetic field for diamagnetic Ag and Cd is lower than for paramagnetic elements.
Lie symmetries, exact solutions and conservation laws of the Oskolkov–Benjamin–Bona–Mahony–Burgers equation
Authors: Ray S. Saha
Published: December 2019

In this paper, the Oskolkov–Benjamin–Bona–Mahony–Burgers (OBBMB) equation has been investigated by Lie symmetry analysis. Lie group analysis method is implemented to derive the vector fields and symmetry reductions. The OBBMB equation has been reduced into nonlinear ordinary differential equation (ODE) by exploiting symmetry reduction method. Using the similarity reduction equation, the exact solutions are obtained by extended [Formula: see text]-method. Finally, the new conservation theorem proposed by Ibragimov has been utilized to construct the conservation laws of the aforesaid equation.
Numerical investigation of rotor–stator interaction for canned motor pump under partial load condition
Authors: Zhu Xiangyuan , El Shahat Saeed A. , Lai Fen , Jiang Wei , Li Guojun
Published: December 2019

Numerical simulations of a canned motor pump at partial load condition have been conducted for studying the strong rotor–stator interaction. SST [Formula: see text] turbulence model with wall function was adopted for solving three-dimensional (3D) unsteady Reynolds-averaged Naiver–Stokes (URANS) equations. The inner flow field for four typical rotor positions, where the head changes significantly, was explored. It has been shown that when blade approached tongue region, the radial velocity decreased where the pressure at suction side was bigger than pressure side. As a result, a negative work was exerted on the fluid which led to minimum work done by the impeller. At this condition, maximum work was resulted in due to the upstream blade. The fluid from balance hole affected the main flow near hub region which caused a vortex near channel pressure side. Due to impeller channel rotation through tongue, the vortex was enlarged which contributed separation flow at impeller inlet region. The separated flow caused pressure reduction in the channel. Static pressure at impeller outlet near shroud side was always greater than at near hub side which resulted in negative radial velocity at impeller outlet near shroud side. Due to the blade accession to the tongue, the static pressure at impeller channel increased meanwhile the area characterized by negative radial velocity enlarged.
HAUSDORFF DIMENSIONS OF SOME EXCEPTIONAL SETS IN THE FIRST OSTROGRADSKY SERIES
Authors: FENG YAN , TAN BO
Published: December 2019

For [Formula: see text], let [Formula: see text] be its first Ostrogradsky series with digits [Formula: see text], [Formula: see text] be its [Formula: see text]-convergents. We calculate the Hausdorff dimensions of the sets [Formula: see text] and [Formula: see text] We also study the sets [Formula: see text] and [Formula: see text]
SPACE-FILLING CURVES OF SELF-SIMILAR SETS (III): SKELETONS
Authors: RAO HUI , ZHANG SHU-QIN
Published: December 2019

Skeleton is a new notion designed for constructing space-filling curves of self-similar sets. In a previous paper by Dai and the authors [Space-filling curves of self-similar sets (II): Edge-to-trail substitution rule, Nonlinearity 32(5) (2019) 1772–1809] it was shown that for all the connected self-similar sets with a skeleton satisfying the open set condition, space-filling curves can be constructed. In this paper, we give a criterion of existence of skeletons by using the so-called neighbor graph of a self-similar set. In particular, we show that a connected self-similar set satisfying the finite-type condition always possesses skeletons: an algorithm is obtained here.
ESTIMATION OF FRACTAL DIMENSION OF WEYL FRACTIONAL INTEGRAL OF CERTAIN CONTINUOUS FUNCTIONS
Authors: LIANG YONG-SHUN
Published: December 2019

In this work, we consider fractal dimension such as Box dimension, of Weyl fractional integral of certain continuous functions. Upper Box dimension of Weyl fractional integral of continuous functions satisfying [Formula: see text]-order Hölder condition of positive order [Formula: see text] is no more than both [Formula: see text] and [Formula: see text]. Furthermore, it is no more than [Formula: see text] which means strictly less than [Formula: see text]. Meanwhile, [Formula: see text], Box dimension of Weyl fractional integral of continuous functions satisfying [Formula: see text]-order Hölder condition must be one.
HÖLDER CONTINUITY AND BOX DIMENSION FOR THE WEYL FRACTIONAL INTEGRAL
Authors: TIAN LONG
Published: December 2019

In this paper, we investigate the Hölder continuity and the estimate for the box dimension of the Weyl fractional integral of some continuous function [Formula: see text], denoted by [Formula: see text]. We obtain that if [Formula: see text] is [Formula: see text]-order Hölder continuous, then [Formula: see text] is [Formula: see text]-order Hölder continuous. Moreover, if [Formula: see text] belongs to [Formula: see text], then [Formula: see text] is [Formula: see text]-order Hölder continuous with [Formula: see text].
Intersection graphs of general linear groups
Authors: Bien Mai Hoang , Viet Do Hoang
Published: December 2019

Let [Formula: see text] be a field and [Formula: see text] the general linear group of degree [Formula: see text] over [Formula: see text]. The intersection graph [Formula: see text] of [Formula: see text] is a simple undirected graph whose vertex set includes all nontrivial proper subgroups of [Formula: see text]. Two vertices [Formula: see text] and [Formula: see text] of [Formula: see text] are adjacent if [Formula: see text] and [Formula: see text]. In this paper, we show that if [Formula: see text] is a finite field containing at least three elements, then the diameter [Formula: see text] is [Formula: see text] or [Formula: see text]. We also classify [Formula: see text] according to [Formula: see text]. In case [Formula: see text] is infinite, we prove that [Formula: see text] is one-ended of diameter [Formula: see text] and its unique end is thick.
Generalized derivations preserving Engel condition in prime and semiprime rings
Authors: Prestigiacomo Rita
Published: December 2019

Let [Formula: see text] be a prime ring with [Formula: see text], [Formula: see text] a non-central Lie ideal of [Formula: see text], [Formula: see text] its Martindale quotient ring and [Formula: see text] its extended centroid. Let [Formula: see text] and [Formula: see text] be nonzero generalized derivations on [Formula: see text] such that [Formula: see text] Then there exists [Formula: see text] such that [Formula: see text] and [Formula: see text], for any [Formula: see text], unless [Formula: see text], where [Formula: see text] is the algebraic closure of [Formula: see text].
Diagnosing interacting Tsallis holographic dark energy in the non-flat universe
Authors: Sharma Umesh Kumar , Dubey Vipin Chandra , Pradhan Anirudh
Published: December 2019

This paper explores the interacting Tsallis holographic dark energy (THDE) model in a non-flat universe following an infrared cutoff as the apparent horizon. The equation of state (EoS) and the deceleration parameter of THDE model are determined to understand the cosmological evolution for interacting THDE model in the non-flat universe. By applying the statefinder [Formula: see text] parameter-pairs diagnostic and [Formula: see text] pair dynamical analysis for the derived THDE model, we plot the evolutionary trajectories for different cases of Tsallis parameter [Formula: see text] and interaction term [Formula: see text] and also, for spatial curvature [Formula: see text], [Formula: see text] and [Formula: see text] corresponding to flat, open and closed universes, respectively, in the framework of Planck 2018 base cosmology results VI-LCDM observational data.
Efficiency of High Voltage Transmission in Power Lines
Authors: Goh Ker Liang
Published: December 2019

In introductory Physics courses, one might come across a question of why electricity is transmitted from the power station at high voltage? Analysis of a typical quantitative question is illustrated in this paper, showing its deficiencies. An alternative method that mimics more closely to realistic situations is proposed to better illustrate the increase in efficiency of transmitting electrical power at high voltages.
How Quickly Can a Submarine Dive?
Authors: Mungan Carl E. , Lipscombe Trevor C.
Published: December 2019

A two-equation model is developed to describe the descent of a submarine as it floods its ballast tanks. The flow into the tanks is assumed to be inviscid, and the drag on the vertical sinking motion of the craft is neglected. The two coupled differential equations are the generalized form of Newton’s second law and the Bernoulli relation. Time derivatives are converted to spatial derivatives to decouple the equations, and the resulting second-order equation is solved using the Euler–Cromer algorithm. The theory and the method of numerical integration are suitable for an intermediate-level undergraduate course in mechanics that includes some basic fluid dynamics.
Free Oscillations of a Damped Simple Pendulum: An Analog Simulation Experiment
Authors: Sawkmie Ivan Skhem , Mahato Mangal C.
Published: December 2019

The frequency of free oscillation of a damped simple pendulum with large amplitude depends on its amplitude unlike the amplitude-independent frequency of oscillation of a damped simple harmonic oscillator. This aspect is not adequately emphasized in the undergraduate courses due to experimental and theoretical difficulties. We propose an analog simulation experiment to study the free oscillations of a simple pendulum that could be performed in an undergraduate laboratory. The needed sinusoidal potential is obtained approximately by using the available AD534 IC by suitably augmenting the electronic circuitry. To keep the circuit simple enough we restrict the initial angular amplitude of the simple pendulum to a maximum of [Formula: see text]. The results compare well qualitatively with the theoretical results. The small quantitative discrepancy is attributed to the inexact nature of the used “sinusoidal potential”.
Einsteinian Physics in the Classroom: Integrating Physical and Digital Learning Resources in the Context of an International Research Collaboration
Authors: Choudhary Rahul , Kraus Ute , Kersting Magdalena , Blair David , Zahn Corvin , Zadnik Marjan , Meagher Richard
Published: December 2019

This study reports on a pilot program conducted by members of the international Einsteinian Physics Education Research (EPER) Collaboration that aims to pool and combine innovative learning approaches in Einsteinian Physics. The collaboration also aims to disseminate learning resources and research results across a range of countries. In this study, we describe an integrated pilot programme that combines physical models and digital resources to explore secondary school students’ (Grade 10, 15 years old) conceptual understanding in the learning domain of Einsteinian physics. After the teaching units “gravity and warped time”, “gravity is geometry”, and “quantum weirdness”, we found that students had gained knowledge of key concepts in the learning domain of Einsteinian Physics. The units rely on physical models or digital learning resources. Both approaches proved successful in introducing Einsteinian concepts. By reporting on this integrated programme, we wish to share our model of an international physics education collaboration. Raising awareness for the need and possibility of introducing Einsteinian physics to school curricula, we hope to offer valuable impetus to the field of physics education that will inspire researchers and teachers alike.
Interaction Models for Detecting Nodal Activities in Temporal Social Media Networks
Authors: Chung Wingyan , Rao Bingbing , Wang Liqiang
Published: December 2019

Detecting nodal activities in dynamic social networks has strategic importance in many applications, such as online marketing campaigns and homeland security surveillance. How peer-to-peer exchanges in social media can facilitate nodal activity detection is not well explored. Existing models assume network nodes to be static in time and do not adequately consider features from social theories. This research developed and validated two theory-based models, Random Interaction Model (RIM) and Preferential Interaction Model (PIM), to characterize temporal nodal activities in social media networks of human agents. The models capture the network characteristics of randomness and preferential interaction due to community size, human bias, declining connection cost, and rising reachability. The models were compared against three benchmark models (abbreviated as EAM, TAM, and DBMM) using a social media community consisting of 790,462 users who posted over 3,286,473 tweets and formed more than 3,055,797 links during 2013–2015. The experimental results show that both RIM and PIM outperformed EAM and TAM significantly in accuracy across different dates and time windows. Both PIM and RIM scored significantly smaller errors than DBMM did. Structural properties of social networks were found to provide a simple and yet accurate approach to predicting model performances. These results indicate the models’ strong capability of accounting for user interactions in real-world social media networks and temporal activity detection. The research should provide new approaches for temporal network activity detection, develop relevant new measures, and report new findings from large social media datasets.
Learning Graphs from Noisy Epidemic Cascades
Authors: Hoffmann Jessica , Caramanis Constantine
Published: December 2019

Epidemic models accurately represent (among other processes) the spread of diseases, information (rumors, viral videos, news stories, etc.), the spread of malevolent agents in a network (computer viruses, malicious apps, etc.), or even biological processes (pathways in cell signaling networks, chains of activation in the gene regulatory network, etc.). We focus on epidemics that spread on an underlying graph [5].

Most settings assume we know the underlying graph and aim to study properties of the spread. Much work has been done in detection, where the goal is to decide whether or not there is indeed an infection. This problem is of importance in deciding whether or not a computer network is under attack, for instance, or whether a product gets sold through word-of-mouth or thanks to the advertisement campaign (or both). More specifically, the problem of source detection or obfuscation has been extensively studied. On the other side of the spectrum, both experimental and theoretical work has tackled the problem of modeling, predicting the growth, and controlling the spread of epidemics.
Random Walk Based Sampling for Load Balancing in Multi-Server Systems
Authors: Tang Dengwang , Subramanian Vijay G.
Published: December 2019

In multi-server systems, a classical job assignment algorithm works as follows: at the arrival of each job, pick d servers independently and uniformly at random and send the job to the least loaded server among the d servers. This model is known as the powerof- d choices algorithm. In this paper, we analyze a variant of this algorithm, where d servers are sampled through d independent non-backtracking random walks on a k-regular graph. The random walkers are periodically reset to independent uniform random positions. Under some assumptions on the underlying graph, we show that the system dynamics under this new algorithm converges to the solution of a deterministic ordinary differential equation (ODE), which is the same ODE as the classical power-of-d choices. We also show that the new algorithm stablizes the system, and the stationary distribution of the system converges to the stationary solution of the ODE. The new scheme can be considered as a derandomized version of power-of-d choices as it reduces the use of randomness while maintaining the performance of power-of-d choices.
Quantifying Data Locality in Dynamic Parallelism in GPUs
Authors: Tang Xulong , Pattnaik Ashutosh , Kayiran Onur , Jog Adwait , Kandemir Mahmut Taylan , Das Chita
Published: December 2019

Dynamic parallelism (DP) is a new feature of emerging GPUs that allows new kernels to be generated and scheduled from the deviceside (GPU) without the host-side (CPU) intervention. To eiciently support DP, one of the major challenges is to saturate the GPU processing elements and provide them with the required data in a timely fashion. In this paper, we irst conduct a limit study on the performance improvements that can be achieved by hardware schedulers that are provided with accurate data reuse information. We next propose LASER, a Locality-Aware SchedulER, where the hardware schedulers employ data reuse monitors to help make scheduling decisions to improve data locality at runtime. Experimental results on 16 benchmarks show that LASER, on an average, can improve performance by 11.3%.
Optimizing the Cost of Executing Mixed Interactive and Batch Workloads on Transient VMs
Authors: Ambati Pradeep , Irwin David
Published: December 2019

Container Orchestration Platforms (COPs), such as Kubernetes, are increasingly used to manage large-scale clusters by automating resource allocation between applications encapsulated in containers. Increasingly, the resources underlying COPs are virtual machines (VMs) dynamically acquired from cloud platforms. COPs may choose from many different types of VMs offered by cloud platforms, which differ in their cost, performance, and availability. While transient VMs cost significantly less than on-demand VMs, platforms may revoke them at any time, causing them to become unavailable. While transient VMs' price is attractive, their unreliability is a problem for COPs designed to support mixed workloads composed of, not only delay-tolerant batch jobs, but also long-lived interactive services with high availability requirements.

To address the problem,we design TR-Kubernetes, a COP that optimizes the cost of executing mixed interactive and batch workloads on cloud platforms using transient VMs. To do so, TR-Kubernetes enforces arbitrary availability requirements specified by interactive services despite transient VM unavailability by acquiring many more transient VMs than necessary most of the time, which it then leverages to opportunistically execute batch jobs when excess resources are available. When cloud platforms revoke transient VMs, TR-Kubernetes relies on existing Kubernetes functions to internally revoke resources from batch jobs to maintain interactive services' availability requirements. We show that TR-Kubernetes requires minimal extensions to Kubernetes, and is capable of lowering the cost (by 53%) and improving the availability (99.999%) of a representative interactive/batch workload on Amazon EC2 when using transient compared to on-demand VMs.
Information, Memory and Capacity in Dynamic Resource Allocation
Authors: Xu Kuang , Zhong Yuan
Published: December 2019

We propose a general framework, dubbed Stochastic Processing under Imperfect Information (SPII), to study the impact of information constraints and memories on dynamic resource allocation. The framework involves a Stochastic Processing Network (SPN) scheduling problem in which the decision maker may access the system state only through a noisy channel, and resource allocation decisions must be carried out through the interaction between an encoding policy (who observes the state) and allocation policy (who chooses the allocation). Applications in the management of large-scale data centers and human-in-the-loop service systems are among our chief motivations.

We quantify the degree to which information constraints reduce the size of the capacity region in general SPNs, and how such reduction depends on the amount of memories available. Using a novel metric, capacity factor, our main theorem characterizes the reduction in capacity region (under "optimal" policies) for all nondegenerate channels, and across almost all combinations of memory sizes. Notably, the theorem demonstrates, in substantial generality, that (1) the presence of a noisy channel always reduces capacity, (2) more memories for the allocation policy always improve capacity, and (3) more memories for the encoding policy have little to no effect on capacity. Finally, all of our positive (achievability) results are established through constructive, implementable policies.

Our proof program involves the development of a host of new techniques by combining ideas from information theory, learning and queueing theory. We create a simple yet powerful generalization of the Max-Weight policy, in which individual Markov chains are selected dynamically, in a manner analogous to how schedules are used in a conventional Max-Weight policy.
TeksDB
Authors: Han Youil , Kim Bryan S. , Yeon Jeseong , Lee Sungjin , Lee Eunji
Published: December 2019

Key-value stores (KVS) are now an integral part of modern dataintensive systems. thanks to its simplicity, scalability, and efficiency over traditional database systems. Databases such as MySQL employ KVS (in this case, RocksDB as their backend storage instead of conventional database engines because KVS is less affected by data fragmentation. OLAP and big data analytics applications often use KVS as the backend store to make use of the efficient range_query operations of LSM(Log Structured Merge Tree)-based KVS. Furthermore, the increasing use of KVS as backend stores in distributed systems diversifies the workload for each local KVS, making it necessary to design a highly-concurrent data store that simultaneously processes mixed operations.

The underlying technology trends also put immense pressure on the design of KVS. Nowadays, many core servers with hundred GBs of memory are common in production environments, and this enhanced density of hardware technologies (both in terms of the number of cores and memory capacity) leads to more data items residing in memory. This phenomenon places greater emphasis on the efficiency of the in-memory data structure in KVS, as more data accesses are serviced from its memory component, which is often called the memtable. The current memtable structure of KVS, however, generally assumes a limited memory capacity that only serves as a temporary write buffer, and the use of single-threaded writes or unscalable data structures for the memtable fails to fulfill this external demand.
PROFET
Authors: Radulovic Milan , Verdejo Rommel Sánchez , Carpenter Paul , Radojković Petar , Jacob Bruce , Ayguadé Eduard
Published: December 2019

Application performance on novel memory systems is typically estimated using a hardware simulator. The simulation is, however, time consuming, which limits the number of design options that can be explored within a practical length of time. Also, although memory simulators are typicallywell validated, current CPU simulators have various shortcomings, such as simplified out-of-order execution, an obsolete data prefetcher and a lack of virtual-to-physical memory translation, all of which can make a huge difference between the simulated and actual memory system.
HyperBench
Authors: Wei Song , Zhang Kun , Tu Bibo
Published: December 2019

Virtualization is ubiquitous in modern data centers. By deploying applications on separate virtual machines hosted in a shared physical machine, it brings benefits over traditional systems in resources utilization[5, 10], system security[2, 3], and server management[7].

Despite the adoption and these advantages of virtualization, cloud providers, tenants, and developers face different challenges. The hardware and software options to build a virtualization platform pose a challenge for cloud providers. A variety of virtualization platforms make it difficult for tenants to make a choice. Developers are forced to continually improve the architecture and hypervisor design to better support virtual machines. In this context, evaluating the virtualization capabilities of different platforms is necessary.
Securing Distributed Gradient Descent in High Dimensional Statistical Learning
Authors: Su Lili , Xu Jiaming
Published: December 2019

We consider unreliable distributed learning systems wherein the training data is kept confidential by external workers, and the learner has to interact closely with thoseworkers to train a model. In particular, we assume that there exists a system adversary that can adaptively compromise some workers; the compromised workers deviate from their local designed specifications by sending out arbitrarily malicious messages.
Visions and challenges in GeoAI, ethics, and spatial quantum computing
Authors: Züfle Andreas
Published: December 2019

Geographic information systems are changing rapidly as new technologies, such as advances in artificial intelligence and quantum computing, proliferate. Towards gaining a glimpse of possible new directions for the next decades, it is paramount to disseminate and discuss new research directions, challenges, and visions, that may be of broad interest to the SIGSPATIAL community. In the last few years, our community has excelled at providing a forum for such visions and challenges in dedicated
Vision and Challenge
tracks, leading to many visionary research directions [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21]. A goal of this newsletter is to continue and complement these visions. Three vision and challenge topics are covered in this special issue:

1. the first article is contributed by the organizers of GeoAI, the most successful ACM SIGSPATIAL Workshop of the last years, having 40+ registrations each year, and having 50+ people in the workshop room at a time. The authors survey and summarize the directions of GeoAI publications of the last three years, and provide a list of open research directions for this rapidly advancing field;

2. in the second article, Fu et al. discuss ethical issues of mining urban spatial data. They identify ethical vulnerabilities from three primary research directions of urban computing: urban safety analysis, urban transportation analysis, and social media analysis for urban events;

3. in the third article, Martin Werner introduces central aspects of quantum algorithms and explores future directions on how quantum algorithms can be used to leverage spatial and spatio-temporal algorithms. This article describes example algorithms, such as map coloring and dynamic time warping, which may benefit from advances in quantum computing.
GeoAI at ACM SIGSPATIAL
Authors: Hu Yingjie , Gao Song , Lunga Dalton , Li Wenwen , Newsam Shawn , Bhaduri Budhendra
Published: December 2019

Geospatial artificial intelligence (GeoAI) is an interdisciplinary field that has received tremendous attention from both academia and industry in recent years. This article reviews the series of GeoAI workshops held at the Association for Computing Machinery (ACM) International Conference on Advances in Geographic Information Systems (SIGSPATIAL) since 2017. These workshops have provided researchers a forum to present GeoAI advances covering a wide range of topics, such as geospatial image processing, transportation modeling, public health, and digital humanities. We provide a summary of these topics and the research articles presented at the 2017, 2018, and 2019 GeoAI workshops. We conclude with a list of open research directions for this rapidly advancing field.
UCR-STAR
Authors: Ghosh Saheli , Vu Tin , Eskandari Mehrad Amin , Eldawy Ahmed
Published: December 2019

This article describes the UCR Spatio-temporal Active Repository (UCR-STAR). UCR-STAR is a visual catalog for big spatial datasets. Rather than a boring tabular listing of datasets, it provides an interactive map interface that allows users to explore these datasets to assess their coverage, quality, and distribution. This article describes both the functionality of UCR-STAR as well as the underlying system architecture. We believe that this article can help the research community by explaining how to realize research ideas into a workable product.
Bit complexity for critical point computation in smooth and compact real hypersurfaces
Authors: Elliott Jesse , Schost Éric
Published: December 2019

Consider the polynomial mapping defined by the projection to the first coordinate on a real, smooth and compact hypersurface. The critical points of this mapping in generic coordinates have several applications in real algebraic geometry. We provide bit complexity estimates for computing them.

Generic coordinates are obtained by applying a randomly chosen linear change of variables to the polynomial defining the hypersurface. The coordinates are sufficiently generic when the Jacobian matrix of the system under study has full rank at the critical points and when the number of critical points is finite. We have proven a new quantitative extension of Thom's weak transversality theorem [1]. By applying this extension, we are able to choose sufficiently generic changes of variables with arbitrarily high probability.
Algebraic approach to chaos induced by snapback repeller
Authors: Huang Bo , Niu Wei
Published: December 2019

In this poster we present the results of [1]. We consider the problem of detecting chaotic behaviors in discrete dynamical systems. We propose an algebraic criterion for determining whether all the zeros of a given polynomial are outside the unit circle in the complex plane. This criterion is used to deduce critical algebraic conditions for the occurrence of chaos in multi-dimensional discrete systems based on Marotto's theorem. Using these algebraic conditions we reduce the problem of analyzing chaos induced by snapback repeller to an algebraic problem, and introduce an algorithmic approach to solve this problem by means of symbolic computation. The proposed approach is effective as shown by several examples and can be used to determine the possibility that all the fixed points are snapback repellers.
Algebraic algorithms for the reliability analysis of multi-state
k
-out-of-
n
systems
Authors: Pascual-Ortigosa Patricia , Sáenz-de-Cabezón Eduardo , Wynn Henry P.
Published: December 2019

We develop algorithms for the analysis of multi-state
k
-out-of-
n
systems and their reliability based on commutative algebra.
Actuator Fault Estimation for Vehicle Active Suspensions Based on Adaptive Observer and Genetic Algorithm
Authors: Jin Pan , Xue Wenping , Li Kangji
Published: December 2019

This paper is concerned with the problem of actuator fault estimation (FE) for vehicle active suspension systems. First, the fast FE approach, which combines the output error term with its derivative term in the FE algorithm, is extended to the active suspension system with actuator fault and external disturbance input. Then, considering three typical kinds of actuator faults, i.e., constant gain change fault, drift fault, and stuck fault, genetic algorithm (GA) is employed to optimize the adjustable parameters in the FE algorithm, which are usually determined by trials. Finally, simulation results of FE and fault‐tolerant control (FTC) are presented to illustrate the effectiveness and applicability of the proposed FE method.
Positive Solutions for a Fourth‐Order Riemann–Stieltjes Integral Boundary Value Problem
Authors: Cui Yujun , O’Regan Donal , Xu Jiafa
Published: December 2019

In this paper, we use the fixed point index to study the existence of positive solutions for the fourth‐order Riemann–Stieltjes integral boundary value problem , where f: [0,1] × ℝ+ × ℝ+ × ℝ+ × ℝ+⟶ℝ+ is a continuous function and α[x″] denotes a linear function. Two existence theorems are obtained with some appropriate inequality conditions on the nonlinearity f, which involve the spectral radius of related linear operators. These conditions allow f(t, z1, z2, z3, z4) to have superlinear or sublinear growth in zi,   i = 1,2,3,4.
Experimental Study of Water Infiltration in Unsaturated Horizontal Sand Columns under Various Air Confinement Conditions
Authors: Chen Meng , Zhou Zhifang , Sleep Brent , Kuang Xingxing , Mingwei Li , Shi Anchi
Published: December 2019

The process of water infiltration into initially dry sand was studied in horizontal sand columns under various airtight conditions. To investigate the interrelations among water inflow behavior, air pressure, air confinement effect, and vent effectiveness in unsaturated porous media experiencing dynamic infiltration, a total of five dynamic infiltration experiments with fixed inlet water pressure were performed with different air vents open or closed along the column length. Visualizations of the infiltration process were accompanied by measurements of water saturation, air pressure, and accumulated water inflow. In a column system with an open end, the absence of air pressure buildup reveals that the vent at the column end can significantly reduce the internal air pressure effects during infiltration, and the air phase can be ignored for this case. However, in columns with a tight end, the coupled air and water flow processes can be divided into two completely different periods. Before the water front passed by the most distant open vent, the internal air pressure effects on retarding dynamic infiltration are negligible, similar to the open end case. After this period, the open vents can certainly influence the inflow behavior by functioning as air outlets while they cannot equilibrate pore air pressure with the atmospheric pressure. The remaining air ahead of the front will be gradually confined and compressed, and the significant increase in air pressure highlights the great role of air pressure buildup in reducing the water infiltration rate. The closer the last open vent was to the water inlet, the higher was the increase in air pressure and the greater was the delaying effect on water infiltration. This work may extend the experimental study of water infiltration into the unsaturated soils with different airtight conditions and provide experimental evidence on these coupled mechanisms among the water and air phases in soils.