bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental trajectories of infants born at less than 30 weeks’ gestation on the Bayley-III Scales
Authors: Durrant Chloe , Wong Hilary S , Cole Tim J , Hutchon Betty , Collier Lynn , Wright Anna , George Cara , De Haan Michelle , Huertas Ceballos Angela
Published: May 2020

Objective

To describe the cognitive, language and motor developmental trajectories of children born very preterm and to identify perinatal factors that predict the trajectories.

Design

Data from a cohort of 1142 infants born at <30 weeks’ gestation who were prospectively assessed on the Bayley Scales of Infant and Toddler Development, third edition (Bayley-III) at 3, 6, 12 and 24 months corrected age, were analysed using the Super Imposition by Translation and Rotation (SITAR) growth curve analysis model.

Main outcome measures

Developmental trajectory SITAR models for Bayley-III cognitive, language (receptive and expressive communication subscales) and motor (fine and gross motor subscales) scores.

Results

The successfully fitted SITAR models explained 62% of variance in cognitive development, 68% in receptive communication, 53% in fine motor and 68% in the gross motor development. There was too much variation in the expressive communication subscale to fit a SITAR model. The rate of development (gradient of the curve) best explains the variation in trajectories of development in all domains. Lower gestational age, lower birth weight and male sex significantly predicted a slower rate of development.

Conclusion

The rate of development, rather than single time point developmental assessment, best predicts the very preterm infant’s developmental trajectory and should be the focus for monitoring and early intervention.
Recommendations for management of diabetes during Ramadan: update 2020, applying the principles of the ADA/EASD consensus
Authors: Ibrahim Mahmoud , Davies Melanie J , Ahmad Ehtasham , Annabi Firas A , Eckel Robert H , Ba-Essa Ebtesam M , El Sayed Nuha Ali , Hess Fischl Amy , Houeiss Pamela , Iraqi Hinde , Khochtali Ines , Khunti Kamlesh , Masood Shabeen Naz , Mimouni-Zerguini Safia , Shera Samad , Tuomilehto Jaakko , Umpierrez Guillermo E
Published: May 2020

Fasting the Holy month of Ramadan constitutes one of the five pillars of the Muslim faith. Although there is some evidence that intermittent fasting during Ramadan may be of benefit in losing weight and cardiometabolic risk factors, there is no strong evidence these benefits apply to people with diabetes. The American Diabetes Association/European Association for the Study of Diabetes consensus recommendations emphasize the importance of patient factors and comorbidities when choosing diabetes medications including the presence of comorbidities, atherosclerotic cardiovascular disease, heart failure, chronic kidney disease, hypoglycemia risk, weight issues and costs. Structured education and pre-Ramadan counseing are key components to successful management of patients with diabetes. These should cover important aspects like glycemic targets, self-monitoring of blood glucose, diet, physical activity including Taraweeh prayers, medication and dose adjustment, side effects and when to break the fast. The decision cycle adapted for the specific situation of Ramadan provides an aid for such an assessment. Children with type 1 diabetes should strongly be advised not to fast due to the high risk of acute complications such as hypoglycemia and probably diabetic ketoacidosis (DKA), although there is very little evidence that DKA is increased in Ramadan. Pregnant women with diabetes or gestational diabetes should be advised to avoid fasting because of possible negative maternal and fetal outcomes. Hypoglycemia is a common concern during Ramadan fasting. To prevent hypoglycemic and hyperglycemic events, we recommend the adoption of diabetes self-management education and support principles. The use of the emerging technology and continuous glucose monitoring during Ramadan could help to recognize hypoglycemic and hyperglycemic complications related to omission and/or medication adjustment during fasting; however, the cost represents a significant barrier.
Oral nitroglycerin solution for oesophageal food impaction: a prospective single-arm pilot study
Authors: Willenbring Benjamin Aaron , Schnitker Callie Korliss , Stellpflug Samuel J
Published: May 2020

Background

Thirteen episodes of oesophageal food impaction (EFI) per 100 000 people present to a medical setting each year. Several pharmacological interventions meant to relieve such impactions have been explored; none have proven superior.

Objectives

Perform a single-arm feasibility study of oral nitroglycerin solution for EFI.

Methods

Twenty adult patients presenting to a single urban tertiary medical centre thought to have EFI were given up to three doses of 0.4 mg nitroglycerin solution orally and evaluated for resolution of symptoms, new symptoms and vital signs. Patients with intractable vomiting, haemodynamic instability, airway compromise, oesophageal perforation, coronary ischaemia or presentation delayed greater than 12 hours were excluded.

Results

17 of 20 enrolled subjects received the intervention. The average duration of symptoms prior to intervention was 285 min (SD=187). Four subjects did not tolerate the intervention (inability to swallow or headache). Two of 17 (11.8%) subjects obtained temporally proximal symptom resolution: 11 min after the second dose, and 7 min after the third dose. Seven also received glucagon during their visit, with 0% temporally proximal symptom resolution. Fifteen underwent endoscopy, with food bolus identified in 12. One subject had brief and mild hypotension with spontaneous resolution. Two subjects developed a headache after nitroglycerin administration. The median length of stay for those who found relief without endoscopy was 195 min (range 129–261) vs 374 min (range 122–525) among those with endoscopy.

Conclusion

The observed rate of relief after oral nitroglycerin solution for EFI is disappointing but comparable to previous glucagon, benzodiazepines and effervescent beverage studies, and that of placebo. Oral nitroglycerin solution appears to be well tolerated among those able to swallow, although in our sample several subjects were unable to tolerate swallowing entirely.
Weight cycling is associated with adverse cardiometabolic markers in a cross-sectional representative US sample
Authors: Kakinami Lisa , Knäuper Bärbel , Brunet Jennifer
Published: May 2020

Background

Whether weight cycling (repeated weight loss and regain) is associated with cardiometabolic health is unclear. Study objective was to examine whether weight cycling since young adulthood (ie, 25 years of age) was associated with cardiometabolic markers.

Methods

Data from a nationally representative cross-sectional US sample (National Health and Nutrition Examination Survey, 1999–2014) were used. Weight history was based on self-reported weight at age 25, 10 years prior and 1 year prior to the survey (n=4190, 51% male). Using current self-reported weight as the anchor, participants were classified as (1)stable weight,(2)weight losers, (3)weight gainersand (4)weight cyclers. Cardiometabolic markers included fasting lipids, insulin sensitivity and blood pressure. Multiple linear regressions were used to analyse weight history (reference:stable weight) and adjusted for covariates. Analyses incorporated the sampling design and survey weights and were stratified by sex or weight status.

Results

Compared with females withstable weight, femaleweight cyclershad worse lipids and homeostasis model assessment for insulin resistance (HOMA-IR) (all ps<0.05). Compared with males with stable weight, male weight cyclers had worse high-density lipoprotein cholesterol (HDL) and HOMA-IR (ps<0.05). Weight cyclers with normal weight had worse HDL and low-density lipoprotein cholesterol (ps<0.05), and weight cyclers with overweight or obesity had worse HOMA-IR (p=0.05). Blood pressure was not associated.

Conclusion

Weight cycling is adversely associated with cardiometabolic markers but associations differ by sex and weight status. While weight cycling is consistently associated with worse cardiometabolic markers among females, results are mixed among males. Weight cycling is associated with worse lipid measures for normal weight persons, and marginally worse insulin sensitivity for those with overweight/obesity.
Primary care use and cardiovascular disease risk in Russian 40–69 year olds: a cross-sectional study
Authors: Petersen Jakob , Kontsevaya Anna , McKee Martin , Richardson Erica , Cook Sarah , Malyutina Sofia , Kudryavtsev Alexander V , Leon David A
Published: May 2020

Background

The Russian Federation has very high cardiovascular disease (CVD) mortality rates compared with countries of similar economic development. This cross-sectional study compares the characteristics of CVD-free participants with and without recent primary care contact to ascertain their CVD risk and health status.

Methods

A total of 2774 participants aged 40–69 years with no self-reported CVD history were selected from a population-based study conducted in Arkhangelsk and Novosibirsk, Russian Federation, 2015–2018. A range of co-variates related to socio-demographics, health and health behaviours were included. Recent primary care contact was defined as seeing primary care doctor in the past year or having attended a general health check under the 2013 Dispansarisation programme.

Results

The proportion with no recent primary care contact was 32.3% (95% CI 29.7% to 35.0%) in males, 16.3% (95% CI 14.6% to 18.2%) in females, and 23.1% (95% CI 21.6% to 24.7%) overall. In gender-specific age-adjusted analyses, no recent contact was also associated with low education, smoking, very good to excellent self-rated health, no chest pain, CVD 10-year SCORE risk 5+%, absence of hypertension control, absence of hypertension awareness and absence of care-intensive conditions. Among those with no contact: 37% current smokers, 34% with 5+% 10-year CVD risk, 32% untreated hypertension, 20% non-anginal chest pain, 18% problem drinkers, 14% uncontrolled hypertension and 9% Grade 1–2 angina. The proportion without general health check attendance was 54.6%.

Conclusion

Primary care and community interventions would be required to proactively reach sections of 40–69 year olds currently not in contact with primary care services to reduce their CVD risk through diagnosis, treatment, lifestyle recommendations and active follow-up.
Remote monitoring of medication adherence and patient and industry responsibilities in a learning health system
Authors: Kim Junhewk , Kassels Austin Connor , Costin Nathaniel Isaac , Schmidt Harald
Published: May 2020

A learning health system (LHS) seeks to establish a closer connection between clinical care and research and establishes new responsibilities for healthcare providers as well as patients. A new set of technological approaches in medication adherence monitoring can potentially yield valuable data within an LHS, and raises the question of the scope and limitations of patients’ responsibilities to use them. We argue here that, in principle, it is plausible to suggest that patients have a prima facie obligation to use novel adherence monitors. However, the strength of the obligations depends considerably on the extent to which data that adherence monitors generate are, in fact, used to further the goals of LHSs. The way in which data ownership is structured in the USA poses a considerable challenge here, while the European Union framework offers a more promising alternative.
Paediatric deep brain stimulation: ethical considerations in malignant Tourette syndrome
Authors: Behmer Hansen Rosemary T. , Dubey Arjun , Smith Cynthia , Henry Patrick J. , Mammis Antonios
Published: May 2020

Gilles de la Tourette syndrome (TS) is a childhood neuropsychiatric disorder characterised by the presence of motor and vocal tics. Patients with malignant TS experience severe disease sequelae; risking morbidity and mortality due to tics, self-harm, psychiatric comorbidities and suicide. By definition, those cases termed ‘malignant’ are refractory to all conventional psychiatric and pharmacological regimens. In these instances, deep brain stimulation (DBS) may be efficacious. Current 2015 guidelines recommend a 6-month period absent of suicidal ideation before DBS is offered to patients with TS. We therefore wondered whether it may be ethically justifiable to offer DBS to a minor with malignant TS. We begin with a discussion of non-maleficence and beneficence. New evidence suggests that suicide risk in young patients with TS has been underestimated. In turn, DBS may represent an invaluable opportunity for children with malignant TS to secure future safety, independence and fulfilment. Postponing treatment is associated with additional risks. Ultimately, we assert this unique risk-benefit calculus justifies offering DBS to paediatric patients with malignant TS. A multidisciplinary team of clinicians must determine whether DBS is in the best interest of their individual patients. We conclude with a suggestion for future TS-DBS guidelines regarding suicidal ideation. The importance of informed consent and assent is underscored.
Gender, gestation and ectogenesis: self-determination for pregnant people ahead of artificial wombs
Authors: Horn Claire
Published: May 2020

In this short response, I agree with Cavaliere’s recent invitation to consider ectogenesis, the process of gestation occurring outside the body, as a political perspective and provocation to building a world in which reproductive and care labour are more justly distributed. But I argue that much of the literature Cavaliere addresses in which scholars argue that artificial wombs may produce greater gender equality has the limitation of taking a fixed, binary and biological approach to sex and gender. I argue that in taking steps toward the possibility of more just practices of caregiving and family making, we must look first not to artificial womb technologies but to addressing the ways that contemporary legal and social practices that enforce essentialising, binary ways of thinking about reproductive bodies inhibit this goal.
Preparing for PrEP; the cost of delaying universal access in England
Authors: Jewsbury Sally , Garner Anna , Redmond Michael , Saxon Cara , Teo Siew Yan , Ward Chris James , McQuillan Orla
Published: May 2020

Objectives

Pre-exposure prophylaxis (PrEP) is not commissioned within National Health Service (NHS) England. Individuals can access it privately online or by enrolment into a clinical trial. We established a list of individuals not enrolled in trials, awaiting PrEP. In response to the observation that patients awaiting PrEP trials were being referred with newly diagnosed HIV, we aimed to measure attendance, incident HIV, STI acquisition and missed opportunities for prevention.

Methods

The search was conducted for patients on the list from November 2017 to November 2019. We examined the electronic clinical records of those on the list and extracted demographic information, STI and HIV diagnoses. In addition, for those diagnosed with HIV, we reviewed risk factors including chemsex and prior postexposure prophylaxis.

Results

There were 1073 patients on list, and 520 (48.6%) were still awaiting recruitment in a PrEP trial. Eight (0.75%) had an enrolment appointment booked while 200 (18.64%) had been contacted and deemed ineligible according to PrEP trial criteria. 45 (32.15%) had not responded to contact. We identified 15 new HIV infections in patients awaiting PrEP. Of these, 9/15 (60.00%) did not meet eligibility criteria at point of contact, though had been eligible at first referral.

Conclusion

It is unacceptable that 15 patients acquired HIV while waiting. The individual lifetime cost of treating HIV is estimated at £360 800(1). This equals £5 412 000 for these 15 infections notwithstanding the psychological and physical burden. We advocate the immediate role out of universal PrEP for those who need it on the NHS. While this decision is delayed, harm is coming to those waiting. Wider provision of PrEP may encourage increased attendance, but must consider additional resources to accommodate added visits. We are relieved that at the point of final submission (21 March 2020) NHS England have recently announced funding of PrEP for eligible patients from, further details are pending.
Clinical time course of COVID-19, its neurological manifestation and some thoughts on its management
Authors: Zhou Yifan , Li Wei , Wang David , Mao Ling , Jin Huijuan , Li Yanan , Hong Candong , Chen Shengcai , Chang Jiang , He Quanwei , Wang Mengdie , Hu Bo
Published: May 2020

Coronavirus disease-2019 (COVID‐19) has become a global pandemic. COVID-19 runs its course in two phases, the initial incubation phase and later clinical symptomatic phase. Patients in the initial incubation phase often have insidious clinical symptoms, but they are still highly contagious. At the later clinical symptomatic phase, the immune system is fully activated and the disease may enter the severe infection stage in this phase. Although many patients are known for their respiratory symptoms, they had neurological symptoms in their first 1–2 days of clinical symptomatic phase, and ischaemic stroke occurred 2 weeks after the onset of the clinical symptomatic phase. The key is to prevent a patient from progressing to this severe infection from mild infection. We are sharing our experience on prevention and management of COVID-19.
A gradient based optimization procedure for finding axle weights in probabilistic bridge weigh-in-motion method
Authors: Gonçalves Matheus Silva , Carraro Felipe , Lopez Rafael Holdorf
Published: May 2020

Bridge weigh-in-motion (BWIM) consists of the use of sensors on bridges to assess the loads of passing vehicles. Probabilistic bridge weigh-in-motion (pBWIM) is an approach for solving the inverse problem of finding vehicle axle weights based on deformation information. The pBWIM approach uses a probabilistic influence line and seeks the most probable axle weights, given in situ measurements. To compute such weights, the original pBWIM employed a grid search, which may lead to computational complexity, especially when applied to vehicles with high number of axles. Hence, this note presents an improved version of pBWIM, modifying the manner in which the most probable weights are sought. Here, a gradient based optimization procedure is proposed for replacing the computationally expensive grid-search of the original algorithm. The required gradients are fully derived and validated in numerical examples. The proposed modification is shown to highly decrease the computational complexity of the problem.
Rheological and chemical properties of bitumen modified with crumb rubber in the dry process
Authors: Cheriet Fayssal , Carter Alan , Haddadi Smail
Published: May 2020

This research aims to evaluate the performance of the hot mix asphalt modified with crumb rubber by the dry process by studying the temperature’s influence as well as the impact of the digestion time between bitumen and crumb rubber. The residual bitumen from the drainage test and the non-modified aged bitumen are then subjected to the dynamic shear rheometer (DSR) tests at different frequencies with different temperatures and to Fourier transform infrared spectroscopy (FTIR) analysis. The results show the bitumen and the rubber interaction is directly related to the temperature and the contact time. The maximum increase in rubber mass observed here is approximately 42% at 195 °C for 120 min of contact. The decrease of the light fractions in the bitumen causes a stiffening of the latter as DSR tests show. Lastly, FTIR analysis indicates only a physical interaction.
Physicochemical properties, heavy metals, and metal-tolerant bacteria profiles of abandoned gold mine tailings in Krugersdorp, South Africa
Authors: Fashola Muibat Omotola , Ngole-Jeme Veronica Mpode , Babalola Olubukola Oluranti
Published: May 2020

Mine tailings are a potential source of heavy metals (HM) that can be toxic to microbes, plants, and animals in aquatic and terrestrial ecosystems. Bacteria have evolved several mechanisms to tolerate the uptake of HM ions. This study aimed to assess the physicochemical properties, concentrations of selected HM and metalloids [arsenic (As), nickel (Ni), lead (Pb), zinc (Zn), cadmium (Cd), and cobalt (Co)], and isolate potential metal-tolerant bacteria present at three abandoned gold mining sites with a view of understanding how tailings characteristics vary and the implications on microbial activities in tailings dumps. Heavy-metal-tolerant bacteria were isolated from the samples using minimum inhibitory and maximum tolerable concentrations of the Ni, Pb, Zn, Cd, and Co. The substrates of the studied sites were acidic and deficient in nutrients. High metals and metalloid concentrations in the order Zn > Ni > Co > As > Pb > Cd were recorded in some of the studied sites and its adjacent soil which exceeded South African recommended values for soil and sediments. Heavy-metal-tolerant bacteria that showed multiple tolerances to Ni, Pb, and Zn were isolated and putatively identified using biochemical tests as belonging to the phyla Proteobacteria, Actinobacteria, and Firmicutes. Gold mine tailings enriched the soil with HM and also affect soil physicochemical properties. Proper management of mine wastes must be ensured to prevent their adverse effects on the diversity, composition, and activity of soil microorganisms that help in maintenance of the ecosystem.
Shadows of Sgr A$$^{*}$$ black hole surrounded by superfluid dark matter halo
Authors: Jusufi Kimet , Jamil Mubasher , Zhu Tao
Published: May 2020

In this paper we construct a black hole solution surrounded by superfluid dark matter and baryonic matter, and study their effects on the shadow images of the Sgr A$$^{*}$$∗ black hole. To achieve this goal, we have considered two density profiles for the baryonic matter described by the spherical exponential profile and the power law profile including a special case describing a totally dominated dark matter galaxy. Using the present values for the parameters of the superfluid dark matter and baryonic density profiles for the Sgr A$$^{*}$$∗ black hole, we find that the effects of the superfluid dark matter and baryonic matter on the size of shadows are almost negligible compared to the Kerr vacuum black hole. In addition, we find that by increasing the baryonic mass the shadow size increases considerably. This result can be linked to the matter distribution in the galaxy, namely the baryonic matter is mostly located in the galactic center and, therefore, increasing the baryonic matter can affect the size of black hole shadow compared to the totally dominated dark matter galaxy where we observe an increase of the angular diameter of the Sgr A$$^{*}$$∗ black hole of the magnitude $$10^{-5}\,\upmu $$10-5μarcsec.
Analytic solutions in Einstein-aether scalar field cosmology
Authors: Paliathanasis Andronikos , Leon Genly
Published: May 2020

In the context of Einstein-aether scalar field cosmology we solve the field equations and determine exact and analytic solutions. In particular, we consider a model proposed by Kanno and Soda where the aether and the scalar fields interact through the aether coefficient parameters, which are promoted to be functions of the scalar field. For this model, we write the field equations by using the minisuperspace approach and we determine the scalar field potentials which leads to Liouville-integrable systems. We solve the field equations for five families of scalar field potentials and, whether it is feasible, we write down the analytic solutions by using closed-form functions.
Constructing de Bruijn Sequences Based on a New Necessary Condition
Authors: Wang Zhongxiao , Wang Xiangyu , Tian Tian
Published: May 2020

In this paper, we propose a new necessary condition for feedback functions of de Bruijn sequences and discuss its application in constructing de Bruijn sequences. It is shown that a large number of de Bruijn sequences could be easily constructed by precomputing an [Formula: see text]-stage nonlinear feedback shift register (NFSR) with a special cycle structure—that is, if a state [Formula: see text] is on a cycle generated by this NFSR, then all the states with the same Hamming weight as [Formula: see text] are also on this cycle. Moreover, if there are [Formula: see text] different cycles in the state graph of the precomputed NFSR, then we can construct [Formula: see text] de Bruijn sequences by the different choices of conjugate state pairs, where [Formula: see text].
EXPERIMENTAL INVESTIGATION ON MULTI-FRACTAL CHARACTERISTICS OF ACOUSTIC EMISSION OF COAL SAMPLES SUBJECTED TO TRUE TRIAXIAL LOADING–UNLOADING
Authors: ZHANG RAN , LIU JIE , SA ZHANYOU , WANG ZAIQUAN , LU SHOUQING , WANG CHENGFENG
Published: May 2020

Coal–rock dynamic disasters seriously threaten safe production in coal mines, and an effective early warning is especially important to reduce the losses caused by these disasters. The occurrence of coal–rock dynamic disasters is determined by mining-induced stress loading and unloading. Therefore, it is of great significance to analyze the precursory information of coal deformation and failure during true triaxial stress loading and unloading. In this study, the deformation and failure of coal samples subjected to true triaxial loading and unloading, including fixed axial stress and unloading confining stress (FASUCS), are experimentally investigated. Meanwhile, acoustic emission (AE) during the deformation of coal samples is monitored, and the multi-fractal characteristics of AE are analyzed. Furthermore, combined with the deformation and failure of coal samples, the precursory information of coal deformation and rupture during true triaxial stress loading and unloading is obtained. Finally, the relationship between multi-fractal characteristics and damage evolution of coal samples under FASUCS is discussed. The results show that the multi-fractal spectral widths of AE time series under the conditions of FASUCS with different initial confining stresses or unloading rates are quite different, but the dynamic changes of multi-fractal parameters [Formula: see text] and [Formula: see text] are similar. This indicates that the microscopic complexity of AE events of coal samples under different conditions of FASUCS differs, but the macroscopic generation mechanism of AE events has inherent uniformity. The dynamic changes of [Formula: see text] and [Formula: see text] can reflect the stress and damage degree of coal samples. The dynamic change process of [Formula: see text] well accords with the damage evolution process of coal samples. A gradual decrease of [Formula: see text] corresponds to a slow increase of damage, while a sharp increase of it corresponds to a rapid growth of damage. At the same time, the mutation point of damage curve at distinct stress difference levels shares the same variation trend with the [Formula: see text] mutation point. The change of [Formula: see text] can reflect the damage process of coal samples, which can be used as precursor information for predicting coal–rock rupture. The finding is of great significance for the early warning of coal–rock dynamic disasters.
A FRACTAL TWO-PHASE FLOW MODEL FOR THE FIBER MOTION IN A POLYMER FILLING PROCESS
Authors: LI XUEJUAN , LIU ZHI , HE JI-HUAN
Published: May 2020

This paper suggests a fractal two-phase fluid model for the polymer melt filling process to deal effectively with the unsmooth front interface. An infinitesimal fluid element model in a fractal space is proposed to establish the governing equations according to the conservation laws in fluid mechanics, the fractal divergence and fractal Laplace operator are defined. The unsmooth interface is solved numerically, and fibers’ motion properties on the interface are also elucidated. Moreover, the distribution of fibers on the interface at different stages shows the fractal property of the fibers’ motion. However, the motion of fibers is affected by the flow of macroscopic polymer melt, and the fiber orientation in the interface shows a certain statistical regularity. Based on the characters of fiber orientation, the fractal interface can be used for the optimal design of the polymer melt filling process.
NONLINEAR RECURRENT HIDDEN VARIABLE FRACTAL INTERPOLATION CURVES WITH FUNCTION VERTICAL SCALING FACTORS
Authors: KIM JINMYONG , MUN HAKMYONG
Published: May 2020

In this paper, we present a construction of new nonlinear recurrent hidden variable fractal interpolation curves. In order to get new fractal curves, we use Rakotch’s fixed point theorem. We construct recurrent hidden variable iterated function systems with function vertical scaling factors to generate more flexible fractal interpolation curves. We also give an illustrative example to demonstrate the effectiveness of our results.
A NOVEL FRACTAL SOLUTION FOR LAMINAR FLOW RESISTANCE IN ROUGHENED CYLINDRICAL MICROCHANNELS
Authors: XIAO BOQI , LIU YONGHUI , CHEN HANXIN , CHEN XUBING , LONG GONGBO
Published: May 2020

In this work, a novel fractal model for the laminar flow in roughened cylindrical microchannels is proposed. The average height of rough elements is derived using the fractal theory. The effects of relative roughness on the friction factor and the Poiseuille number are discussed. It is found that the Darcy friction factor and the Poiseuille number increase with the increase in the relative roughness in the cylindrical microchannel. Besides, it is observed that the Darcy friction factor decreases with the increase in the Reynolds number. Each parameter of the proposed model has a clear physical meaning. The present model can properly reveal some mechanisms that affect the laminar flow in roughened cylindrical microchannels. The present model improves the understanding of the physical mechanisms of fluid flows through roughened cylindrical microchannels. Our model predictions are compared with the existing experimental data, and good agreement can be found.
AVERAGE DISTANCES OF A FAMILY OF P.C.F. SELF-SIMILAR NETWORKS
Authors: FAN JIAQI , GU JIANGWEN , XI LIFENG , WANG QIN
Published: May 2020

In this paper, we discuss a family of p.c.f. self-similar fractal networks which have reflection transformations. We obtain the average geodesic distance on the corresponding fractal in terms of finite pattern of integrals. With these results, we also obtain the asymptotic formula for average distances of the skeleton networks.
FRACTAL-BASED ANALYSIS OF THE RELATIONSHIP BETWEEN THE SURFACE FINISH OF WORKPIECE AND CHIP FORMATION IN MILLING OPERATION
Authors: OWAIS QADRI MUHAMMAD , NAMAZI HAMIDREZA
Published: May 2020

Surface finish is one of the most important issues that is discussed in machining of materials. In fact, reaching the required surface finish is the key scale in analysis of the quality of machined workpiece. Chip formation is an important factor that highly affects the surface finish of machined workpiece. In this research, we analyze the relationship between surface finish and chip formation by fractal analysis of their surfaces. Since both patterns have complex structures, we calculate their fractal dimension in case of different experiments in which machining parameters change. The result of analysis indicates that the variations of fractal dimension of machined surface show a reverse pattern compared to the fractal dimension of chip surface in case of variations of depth of cut and feed rate. However, in case of variations of spindle speed, the variations of fractal dimension of machined surface show a similar pattern with the fractal dimension of chip surface. Therefore, it can be said that the complexity of machined surface is linked to the complexity of chip surface. The method of analysis used in this research can be further applied to other manufacturing operations.
FRACTAL-BASED ANALYSIS OF THE RELATION BETWEEN TOOL WEAR AND MACHINE VIBRATION IN MILLING OPERATION
Authors: OWAIS QADRI MUHAMMAD , NAMAZI HAMIDREZA
Published: May 2020

Tool wear is one of the unwanted phenomena in machining operations where tool has direct contact with the workpiece. Tool wear is an important issue in milling operation that is caused due to different parameters such as machine vibration. Tool wear shows complex structure, and machine vibration is a chaotic signal that also is complex. In this research, we analyze the correlation between tool wear and machine vibration using fractal theory. We run the experiments in which machining parameters, namely depth of cut, feed rate and spindle speed change, and accordingly analyze the variations of fractal dimension of tool wear versus the fractal dimension of machine vibration signal. Based on the obtained results, variations of complexity of tool wear are reversely correlated with the variations of complexity of vibration signal. Fractal analysis could potentially be applied to other machining operations in order to investigate the relation between tool wear and machine vibration.
String inspired cosmological models through Lagrangian invariance
Authors: Antonio Belinchón José , Polychroni Danae
Published: May 2020

We study a string inspired cosmological with variable potential through the Lagrangian invariance method in order to determine the form of the potential. We have studied four cases by combining the different fields, that is, the dilaton [Formula: see text] the potential [Formula: see text] the [Formula: see text]-field and the matter field (a perfect fluid). In all the studied cases, we found that the potential can only take two possible forms: [Formula: see text] and [Formula: see text] where [Formula: see text] and [Formula: see text] are numerical constants. We conclude that when we take into account the Kalb–Ramond field, i.e. the [Formula: see text]-field, then it is only possible to get a constant potential, [Formula: see text] Nevertheless, if this field is not considered, then we get two possible solutions for the potential: [Formula: see text] and [Formula: see text] In all the cases, if the potential is constant, [Formula: see text] then we get a de Sitter like solution for the scale factor of the metric, [Formula: see text], which verifies the [Formula: see text]-duality property, while if the potential varies, then we get a power-law solution for the scale factor, [Formula: see text] [Formula: see text]
Local Fourier Slice Photography
Authors: Lessig Christian
Published: May 2020

Light field cameras provide intriguing possibilities, such as post-capture refocus or the ability to synthesize images from novel viewpoints. This comes, however, at the price of significant storage requirements. Compression techniques can be used to reduce these, but refocusing and reconstruction require so far, again, a dense pixel representation. To avoid this, we introduce local Fourier slice photography that allows for refocused image reconstruction directly from a sparse wavelet representation of a light field, either to obtain an image or a compressed representation of it. The result is made possible by wavelets that respect the “slicing’s” intrinsic structure and enable us to derive exact reconstruction filters for the refocused image in closed-form. Image reconstruction then amounts to applying these filters to the light field’s wavelet coefficients; hence, no reconstruction of a dense pixel representation is required. We demonstrate that this can reduce storage requirements and also computation times. We furthermore analyze the computational complexity of our algorithm and show that it scales linearly with the size of the reconstructed region and the non-negligible wavelet coefficients, i.e., with the visual complexity.
An Epidemiology-inspired Large-scale Analysis of Android App Accessibility
Authors: Ross Anne Spencer , Zhang Xiaoyi , Fogarty James , Wobbrock Jacob O.
Published: May 2020

Accessibility barriers in mobile applications (apps) can make it challenging for people who have impairments or use assistive technology to use those apps. Ross et al.’s epidemiology-inspired framework emphasizes that a wide variety of factors may influence an app's accessibility and presents large-scale analysis as a powerful tool for understanding the prevalence of accessibility barriers (i.e.,
inaccessibility diseases
). Drawing on this framework, we performed a large-scale analysis of free Android apps, exploring the frequency of accessibility barriers and factors that may have contributed to barrier prevalence. We tested a population of 9,999 apps for seven accessibility barriers: few TalkBack-focusable elements, missing labels, duplicate labels, uninformative labels, editable TextViews with
contentDescription
, fully overlapping clickable elements, and undersized elements. We began by measuring the prevalence of each accessibility barrier across all relevant element classes and apps. Missing labels and undersized elements were the most prevalent barriers. As a measure of the spread of barriers across apps, we assessed the five most reused classes of elements for missing labels and undersized elements. The Image Button class was among the most barrier-prone of the high reuse element classes; 53% of Image Button elements were missing labels and 40% were undersized. We also investigated factors that may have contributed to the high barrier prevalence in certain classes of elements, selecting examples based on prior knowledge, our analyses, and metrics of reuse and barrier-proneness. These case studies explore: (1) how the
few TalkBack-focusable elements
accessibility barrier relates to app category (e.g., Education, Entertainment) and the tools used to implement an app, (2) the prevalence of label-based barriers in image-based buttons, (3) design patterns that affect the labeling and size of Radio Buttons and Checkboxes, and (4) accessibility implications of the sizing of third-party plug-in elements. Our work characterizes the current state of Android accessibility, suggests improvements to the app ecosystem, and demonstrates analysis techniques that can be applied in further app accessibility assessments.
Monetization of Knowledge in China: A new way for online learning?
Authors: Lin Xi , Rhodes Christy M.
Published: May 2020

This paper introduces monetization of knowledge (MOK), an emerging online learning approach popular in China in recent years. The use of this innovative online learning method is growing among white-collar Chinese workers and appears to play a role in satisfying the needs of lifelong learners.
A Theory of Slicing for Imperative Probabilistic Programs
Authors: Amtoft Torben , Banerjee Anindya
Published: May 2020

Dedicated to the memory of Sebastian Danicic.

We present a theory for slicing imperative probabilistic programs containing random assignments and “observe” statements for conditioning. We represent such programs as probabilistic control-flow graphs (pCFGs) whose nodes modify probability distributions. This allows direct adaptation of standard machinery such as data dependence, postdominators, relevant variables, and so on, to the probabilistic setting. We separate the specification of slicing from its implementation:

(1) first, we develop syntactic conditions that a slice must satisfy (they involve the existence of another disjoint slice such that the variables of the two slices are
probabilistically independent
of each other);

(2) next, we prove that any such slice is semantically correct;

(3) finally, we give an algorithm to compute the least slice.

To generate smaller slices, we may in addition take advantage of knowledge that certain loops will terminate (almost) always.

Our results carry over to the slicing of
structured
imperative probabilistic programs, as handled in recent work by Hur et al. For such a program, we can define its slice, which has the same “normalized” semantics as the original program; the proof of this property is based on a result proving the adequacy of the semantics of pCFGs w.r.t. the standard semantics of structured imperative probabilistic programs.
Mental Maps and the Use of Sensory Information by Blind and Partially Sighted People
Authors: Hersh Marion
Published: May 2020

This article aims to fill an important gap in the literature by reporting on blind and partially sighted people's use of spatial representations (mental maps) from their perspective and when travelling on real routes. The results presented here were obtained from semi-structured interviews with 100 blind and partially sighted people in five different countries. They are intended to answer three questions about the representation of space by blind and partially sighted people, how these representations are used to support travel, and the implications for the design of travel aids and orientation and mobility training. They show that blind and partially sighted people do have spatial representations and that a number of them explicitly use the term mental map. This article discusses the variety of approaches to spatial representations, including the sensory modalities used, the use of global or local representations, and the applications to support travel. The conclusions summarize the answers to the three questions and include a two-level preliminary classification of the spatial representations of blind and partially sighted people.
A snapshot of the frontiers of fairness in machine learning
Authors: Chouldechova Alexandra , Roth Aaron
Published: May 2020

A group of industry, academic, and government experts convene in Philadelphia to explore the roots of algorithmic bias.
Spotlights and Soundscapes
Authors: May Keenan R. , Tomlinson Brianna J. , Ma Xiaomeng , Roberts Phillip , Walker Bruce N.
Published: May 2020

For persons with visual impairment, forming cognitive maps of unfamiliar interior spaces can be challenging. Various technical developments have converged to make it feasible, without specialized equipment, to represent a variety of useful landmark objects via spatial audio, rather than solely dispensing route information. Although such systems could be key to facilitating cognitive map formation, high-density auditory environments must be crafted carefully to avoid overloading the listener. This article recounts a set of research exercises with potential users, in which the optimization of such systems was explored. In Experiment 1, a virtual reality environment was used to rapidly prototype and adjust the auditory environment in response to participant comments. In Experiment 2, three variants of the system were evaluated in terms of their effectiveness in a real-world building. This methodology revealed a variety of optimization approaches and recommendations for designing dense mixed-reality auditory environments aimed at supporting cognitive map formation by visually impaired persons.
A Survey on Renamings of Software Entities
Authors: Li Guangjie , Liu Hui , Nyamawe Ally S.
Published: May 2020

More than 70% of characters in the source code are used to label identifiers. Consequently, identifiers are one of the most important source for program comprehension. Meaningful identifiers are crucial to understand and maintain programs. However, for reasons like constrained schedule, inexperience, and unplanned evolution, identifiers may fail to convey the semantics of the entities associated with them. As a result, such entities should be renamed to improve software quality. However, manual renaming and recommendation are fastidious, time consuming, and error prone, whereas automating the process of renamings is challenging: (1) It involves complex natural language processing to understand the meaning of identifers; (2) It also involves difficult semantic analysis to determine the role of software entities. Researchers proposed a number of approaches and tools to facilitate renamings. We present a survey on existing approaches and classify them into identification of renaming opportunities, execution of renamings, and detection of renamings. We find that there is an imbalance between the three type of approaches, and most of implementation of approaches and evaluation dataset are not publicly available. We also discuss the challenges and present potential research directions. To the best of our knowledge, this survey is the first comprehensive study on renamings of software entities.
Graph Generators
Authors: Bonifati Angela , Holubová Irena , Prat-Pérez Arnau , Sakr Sherif
Published: May 2020

The abundance of interconnected data has fueled the design and implementation of graph generators reproducing real-world linking properties or gauging the effectiveness of graph algorithms, techniques, and applications manipulating these data. We consider graph generation across multiple subfields, such as Semantic Web, graph databases, social networks, and community detection, along with general graphs. Despite the disparate requirements of modern graph generators throughout these communities, we analyze them under a common umbrella, reaching out the functionalities, the practical usage, and their supported operations. We argue that this classification is serving the need of providing scientists, researchers, and practitioners with the right data generator at hand for their work. This survey provides a comprehensive overview of the state-of-the-art graph generators by focusing on those that are pertinent and suitable for several data-intensive tasks. Finally, we discuss open challenges and missing requirements of current graph generators along with their future extensions to new emerging fields.
Debugging Large-scale Datalog
Authors: Zhao David , Subotić Pavle , Scholz Bernhard
Published: May 2020

Logic programming languages such as Datalog have become popular as Domain Specific Languages (DSLs) for solving large-scale, real-world problems, in particular, static program analysis and network analysis. The logic specifications that model analysis problems process millions of tuples of data and contain hundreds of highly recursive rules. As a result, they are notoriously difficult to debug. While the database community has proposed several data provenance techniques that address the
Declarative Debugging Challenge
for Databases, in the cases of analysis problems, these state-of-the-art techniques do not scale.

In this article, we introduce a novel bottom-up Datalog evaluation strategy for debugging: Our provenance evaluation strategy relies on a new provenance lattice that includes proof annotations and a new fixed-point semantics for semi-naïve evaluation. A debugging query mechanism allows arbitrary provenance queries, constructing partial proof trees of tuples with minimal height. We integrate our technique into Soufflé, a Datalog engine that synthesizes C++ code, and achieve high performance by using specialized parallel data structures. Experiments are conducted with D
OOP
/DaCapo, producing proof annotations for tens of millions of output tuples. We show that our method has a runtime overhead of 1.31× on average while being more flexible than existing state-of-the-art techniques.