bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical modeling of the stress state of the tubular stand of the cultivator
Authors: Pirogov S P , Kokoshin S N , Cherencov D A
Published: September 2019

The paper presents the results of the calculation of stresses and strains of the cultivator stand structure with a flexible tubular element under loading with internal pressure and external force. For research, we used the finite element method, implemented in the program “ANSYS”. The tasks of building a grid model of a tubular element were solved, the displacements of the free end and stresses under the action of internal pressure were determined, and the maximum allowable pressure value was found. The horizontal component of the impact force of the soil on the cultivator, at which buckling occurs, is determined, and the influence of the section shape on the characteristics of the cultivator stand is investigated.
The Design of Rollers for Rolling Corrugations in the Ribbon
Authors: Yu Popov A , Shchipkova Yu V
Published: September 2019

Corrugated stainless steel ribbon is used as a working element in modern heat exchangers designed for high working temperatures (up to 1000°C). Making corrugations on the ribbon is the most time-consuming operation, which determines the relevance of the study subject. The article offers a method for calculating the tool profile, provided that the centroid is on the outer diameter of the tool. According to the results of calculations and practical studies, this method should be applied. The profile of the rollers was profiled depending on the specified ribbon profile, limits of ribbon profile parameters are determined. The study subject is to determine the grooves profile of the rolling rollers and to determine rational methods for visualizing the rolling process in order to simulate it. To accomplish this aim, the following tasks are to be solved: 1. To determine the rational position of the centroid during the rolling of corrugations on rollers. 2. To determine the parameters of the profiles when the tool centroids are located on the outer diameter of the rollers in the rolling process.
A method of quality control of plain bearings by their thermophysical properties
Authors: Salikhov R F , Akimov V V , Musagitova G N , Negrov D A
Published: September 2019

The article proposes a method for controlling the quality of plain bearings materials in internal combustion engines that affect the failure of such important and expensive parts as a crankshaft and a cylinder block. Quality control of materials, which have been used for plain bearings manufacture, during repair action of construction machinery and equipment, as well as reduction of cost and duration of technical control operations implementation are among the issues of the day for repair service organizations. In this paper a thermal method of plain bearings materials quality assessment in internal combustion engines is suggested. This method is remarkable for its comparative simplicity; it does not require destruction of the material and application of expensive equipment. A thermal calculation of the compared plain bearings has been improved and carried out, taking into account the obtained thermophysical parameters, the minimum clearances for the coupling “crankpin - liner” for the studied samples of foreign production, which can be used in manufacture as guidelines, have been defined. The calculation of the specific heat, the coefficients of thermal conductivity and linear expansion of plain bearings permits to select the right kind of lubricant, the required clearances, and thus prevent accidental breakdowns after major repairs of internal combustion engines.
The mechanical stresses in the molybdenum films formed by magnetron sputtering on a sitall substrate
Authors: Strunin V I , Zeema V N , Chirikov N A , Kozlov A G
Published: September 2019

The results of investigations of mechanical stress in molybdenum films formed by magnetron sputtering at a constant current when the pressure of the argon in the vacuum chamber of less than 0.13 Pa are presented. It is shown that the magnitude of mechanical stress in Mo films depends on substrate temperature, power on the target and argon gas in a vacuum chamber. The minimum value of the mechanical stress in the Mo films were (13-15) · 10−8 H/M2 when they were formed at a power on a target less than 700 W, the flow of argon 6-9 sccm, the substrate temperature (550-620) K and a pressure of argon in the vacuum chamber is 0.07 Pa.
Construction of the equation of fractals structure based on the rvachev r-functions theories
Authors: Anarova Sh , Nuraliev F , Narzulloev O
Published: September 2019

The article is devoted to the construction of the equation of fractal complex structures based on the theories of Rvachev R-functions (RFM), the application of the recursion procedure. Using the equation of objects elementary geometries and constructive means of the method of R-functions R0: R-conjunctions, R-disjunctions and R-reflections, various fractal equations are constructed. Based on these equations, specifying the number of iteration and the angle of inclination various pre-fractals are generated
Areas for the existence of biquadratic transformations
Authors: Baidabekov A K , Kemelbekova E A
Published: September 2019

Analysis and research carried out quadratic transformations of applied geometry shows that quadratic transformations of the plane have been studied sufficiently and have found wide application in science and technology. However, little attention has been paid to the study and application of four to four-digit correspondences to the plane. Therefore, the article is devoted to the development of the theory of four-four-digit correspondences between non-aligned planes and the development of the theory of biquadratic plane transformations. As a result of the consistent implementation of the proposed constructive device, each point A plane П1
is converted to four points

A
1
/

,

A
2
/

and

A
3
/

,

A
4
/

plane of П1/. Given the two parametric set of points of the combined plane П1
/=П1
we obtain a biquadratic transformation of the plane, denoted by the letter L. In a similar way, it can be shown that in the opposite direction each point A/
of the plane

П
1
/

is transformed into four points of the plane П1
. This transformation is denoted by the letter L/
. Also this article is devoted to determining of the area existence in the development of the theory of biquadratic transformation plane, improvement of methods of geometric design of curves and curved surfaces in construction design. To achieve this purpose it’s requiring to solve the following theoretical and practical problems: definition and development of graphic model of biquadratic transformations of the plane, determination of the existence area of the transformation. The results can be widely used in design and research institutes by designing and construction of surfaces of technical forms, also new dome shells and other surfaces in architectural design.
Parametric design of technological processes based on multidimensional geometric modelling
Authors: Chizhik M A , Moskovtsev M N
Published: September 2019

A method of parametric design of technological processes has been developed based on the theory of multidimensional geometry using elements of parametrization, multidimensional computational geometry and geometric modelling. The method allows a technological process to be described by a hypersurface defined by a set of lines of one- or two-dimensional frames in a multidimensional complex plot. Its parameters are regarded as a certain set of points and lines of a space which is defined as an intersection of the frame lines by hyperplanes of a given level. The article proposes a computer implementation of the method which provides a solution to engineering problems with required accuracy. A geometric model of a thread stitching technological process has been obtained. The model allows to set a parameter range and determine the modes of obtaining compounds of a given quality in a wide range of possible solutions depending on the package of product materials, the number of process equipment parameters and process criteria.
Designing architectural surfaces according to preset geometrical conditions
Authors: Korotkiy V A , Khmarova L I
Published: September 2019

Considering various ways of shaping, the paper analyzes and geometrically interprets the space-planning and process requirements posed to the frame of the designed architectural surface. It considers the issues of designingshells formed by various ways of extracting a frame from a set of lines. Astructural kinematic method is used as the main one, which allows us to depict a surface and show the points and lines belonging to it. The surface frame is extracted from a set of algebraic curved lines. Straight lines and second-order curves are more preferable. We proposed to use a focal second-order surface toextracta linear surface frame. Straight lines tangent to the second-order surface form a three-parameter set of straight lines (a complex of straight lines).To extract a one-parameter ruled surface from a three-parameter complex of straight lines, we proposed to use additional curvilinear guides allowing us to control the shape of the surface. The structural kinematic method allows us to design smooth architectural shells based on an arbitrary spatial contour. We considered examples of building smooth composite surfaces passing through a given contour and including a given compartment of a second-order focal surface. We proposed a design of a transitional ruled surface connecting the roof and dome of a church building. The working drawing of the transitional surface evolvent is made on the basis of the descriptive geometry methods. The surface frame is built using three-dimensional computer graphical means. An expedient combination of computer graphics and theoretical methods of descriptive geometry allows us to obtain surfaces meeting the preset geometric conditions.
Geometric model of the gas turbine combustion chamber
Authors: Korotkiy V A , Usmanova E A
Published: September 2019

Gas turbine plants operated on a mixture of natural gas and air are widely used for self-contained power supply of buildings and structures both in urban conditions and in temporary settlements. When designing perspective gas turbine plants, we need to develop a non-toxic, environmentally friendly combustion chamber with the minimal emissions of harmful substances in a wide range of changes in operating parameters. It is a complicated engineering challenge to meet this condition: it is necessary to ensure geometrically accurate profiling of special holes in the cylindrical wall of the combustion chamber to insert fuel nozzles. As opposed to the known methods, the article proposes a profiling method, which combines the advantages of the known methods of descriptive geometry and precise methods of three-dimensional computer simulation. The real profile of a hole in the wall of the combustion chamber is a fourth-order spatial algebraic curve. The article proposes an algorithm for profile approximation using second-order curves by means of three-dimensional computer graphics, which allows us to streamline the preparation of a program for a water jet NC machine.
Visualization of amplitude-frequency characteristics of EEG of pathological and cognitive functions of the brain from a position of nonlinear dynamics
Authors: Krysko V A , Papkova I V , Saltykova O A , Yakovleva T V , Pavlov S P , Zhigalov M V , Yu Petrov D , Krysko A V
Published: September 2019

In recent years, medical imaging methods have been intensively developed to provide comprehensive and extensive data for studying the work of the brain, which makes the present study relevant. The purpose of this work is to develop a new approach for analyzing EEG signals based on nonlinear dynamics methods. To achieve this goal, it is necessary to adapt the methods of nonlinear dynamics to solving EEG analysis tasks. In this paper, the following methods are used: the principal component method for noise clearance, the wavelet transform, the Wolf, Kanz, Rosenstein, neural networks methods to calculate the spectrum of the Lyapunov exponent (LCEs). Studies have shown that the chaos of the schizophrenic’s EEG signals is higher than for healthy people. It has been revealed that the best visualization of the amplitude-frequency characteristics of the brain’s EEG pathological functions is provided by the Morle and Gauss 32 wavelets.
Geometric interpretation of modeling calculation of cylinders axial vibration effect on transfer of viscous incompressible fluid
Authors: Panichkin A V , Varepo L G
Published: September 2019

The transfer of viscous incompressible fluid between contacting cylinders is influenced by a large number of factors that can be investigated by numerical simulation based on the use of the most complete mathematical models. One of the factors affecting the transfer of viscous fluid between the contacting cylinders is the axial vibration of one of the cylinders. At the same time, experimental studies cannot be performed to the full because of the inaccessibility and complexity of monitoring fast processes. Along with a number of other factors, a mathematical model was developed and applied for the numerical study of the effects of axial vibrations (oscillations) on the indicators characterizing the transfer of a viscous incompressible fluid on the test example in a two-dimension setting. The practical implementation of the computer geometric modeling algorithm is shown. A computer visualization of the calculation data on viscous incompressible fluid transfer between the rotating cylindrical surfaces on the example of the printing system is presented.
Method of defining region of allowed configurations in multidimensional space of generalized coordinates using hypercube graph
Authors: Pritykin F N , Nefedov D I
Published: September 2019

The work is devoted to the development of a knowledge base on possible positions of an android arm mechanism with allowance for the position of the previously known forbidden zone. The knowledge base is used for intelligent control of the arm movement of an android robot that functions autonomously in an organized space without human-operator assistance. The specified knowledge base is determined by the region of allowed configurations in the multidimensional space of generalized coordinates. Based on the methods of geometrical modeling, a representation method of the allowable configuration region with the use of hypercube graph is proposed.
Areas of existence of ruled surfaces
Authors: Salkov N A , Ivanov G S , Slavin R B
Published: September 2019

Ruled surfaces are used in mechanical engineering, in aircraft and motor-vehicle constructions, in agriculture, in construction and light industries. It is easier to denominate areas where ruled surfaces are not applied than to list them all. The value of ruled surfaces in human activities can not be overestimated. In this paper the consideration of the formation of ruled surfaces with a uniform way of setting them, which was proposed earlier in two articles with the same title “General Principles of Defining Ruled Surfaces”, is continued.

The concept of a limit ruled surface is introduced in this article, and on the basis of a single method for defining ruled surfaces, the question of identifying the areas of their existence that lie between two limiting ruled surfaces is considered. These areas of existence are, in fact, a line congruence.
Study of the stress-strain state of the wheel pair of a freight car during braking
Authors: Vorobev A A , Krutko A A , Shadrina N U , Badamshin A M
Published: September 2019

Objective: study of the stress-strain state of the wheel pair of a freight car in the process braking. Methods: to determine the stress-strain state of the wheel pairs of a freight car. Results: A volumetric finite element model of a wheel pair with rail sections was created using a finite element of the ten knot tetrahedron type, and maximum shear stresses and maximum equivalent stresses were determined according to the Mises and Dang Wan theory. Practical significance: It is shown that the maximum tangential stresses are observed at a point located at a depth of 4.5-5.3 mm below the rolling surface of the wheel. In case of emergency (short) braking, maximum stresses occur on the rolling surface of the wheel. During prolonged braking (movement of the train along a prolonged descent), maximum stresses occur at the point of transition from the disk to the rim on the inner side of the wheel, and the magnitude of these stresses is 2.5 times higher than in the emergency braking mode.
Parametric geometric model of a spherical helical platform
Authors: Yanishevskaya A G , Dyakonov N V
Published: September 2019

The paper presents a parametric spherical model of a helical surface, which is used in the design of structures of helical platforms. This design is intended to serve the inner surface of spherical tanks. Presentation of the control program using dependent and mathematical models for constructing external and internal contours of the sites.
Information and analytical system for assessing the quality of planning and monitoring of the process of teaching students during the semester
Authors: Liberman A E , Kozlov V V , Alonceva E A
Published: September 2019

Monitoring the student learning process is the basis of feedback in the management of the quality of specialist training, which determines its relevance and relevance. The aim of the work is to develop a model of continuous monitoring of the quality of student training in the semester in the context of student-teacher interaction. The monitoring is built on the basis of a special mathematical model that allows solving problems of forming the recommended student assessment and assessment of the teacher’s performance discipline implemented in the corresponding information system. Formation of the recommended assessment of a student in a discipline is carried out as an accumulation from individual stages of a discipline based on data grouping methods, work with associative data sets, data convolution, database manipulation. Statistical methods allow to monitor the performance discipline of university teachers on the basis of numerical convolutions, getting it in measurable indicators. Thus, a feedback model in the student-teacher chain was obtained, which is necessary to substantiate management decision-making in the educational process.
Thermal escape from a trap over the parabolic barrier: Langevin type approach to energy diffusion regime
Authors: Gontchar I I , Chushnyakova M V , Blesman A I
Published: September 2019

Thermally activated escape from a metastable state is a useful tool to account for some features of the micro/nano-motors or superconducting nanowires. In the present work, we consider the case of week friction (action diffusion regime) which corresponds to the latter example. To describe the thermal decay, we apply two approaches both based on the Langevin type equations: the action diffusion (approximate) and the phase space diffusion (exact). For the first time, the quasistationary decay rates obtained numerically for the parabolic barrier from these two approaches are compared quantitatively with each other as well as with the analytical formula.
Causes of future Mediterranean precipitation decline depend on the season
Authors: Brogli Roman , Sørland Silje Lund , Kröner Nico , Schär Christoph
Published: September 2019

Future mean precipitation in the Mediterranean is projected to decrease year-round in response to global warming, threatening to aggravate water stress in the region, which can cause social and economic difficulties. We investigate possible causes of the Mediterranean drying in regional climate simulations. To test the influence of multiple large-scale drivers on the drying, we sequentially add them to the simulations. We find that the causes of the Mediterranean drying depend on the season. The summer drying results from the land-ocean warming contrast, and from lapse-rate and other thermodynamic changes, but only weakly depends on circulation changes. In contrast, to reproduce the simulated Mediterranean winter drying, additional changes in the circulation and atmospheric state have to be represented in the simulations. Since land-ocean contrast, thermodynamic and lapse-rate changes are more robust in climate simulations than circulation changes, the uncertainty associated with the projected drying should be considered smaller in summer than in winter.
Cost of Unnecessary Amylase and Lipase Testing at Multiple Academic Health Systems
Authors: Ritter Jacob P , Ghirimoldi Federico M , Manuel Laura S M , Moffett Eric E , Novicki Thomas J , McClay James C , Shireman Paula K , Brimhall Bradley B
Published: September 2019

Objectives

To determine adherence to Choosing Wisely recommendations for using serum lipase to diagnose acute pancreatitis rather than amylase, avoiding concurrent amylase/lipase testing and avoiding serial measurements after the first elevated test as both are ineffective for tracking disease course.

Methods

Deidentified laboratory data from four large health systems were analyzed to determine concurrent testing rates, serial testing rates, and provider-ordering patterns.

Results

While most providers adhered to recommendations with 58,693 lipase-only tests ordered and performed, 86% of amylase tests were performed concurrently with lipase. Ambulatory, inpatient, and emergency department settings revealed concurrent rates of 51%, 41%, and 8%, respectively. Services with order sets containing both amylase and lipase were associated with higher rates of concurrent testing.

Conclusions

Concurrent amylase/lipase testing is an area of opportunity to improve compliance, especially in ambulatory settings. Revision of order sets and provider education could be interventions to reduce unnecessary testing and save costs.
Evaluation of Pesticides Found in Oregon Cannabis from 2016 to 2017
Authors: Evoy Richard , Kincl Laurel
Published: September 2019

Pesticide use and worker exposures to pesticides in the US cannabis industry have not been studied due to cannabis being illegal at the federal level. Without knowing the types of pesticides being used in this industry, it is difficult to assess whether workers are being exposed to potentially dangerous pesticides. When recreational cannabis became legal in the state of Oregon in 2014, the Oregon Department of Agriculture (ODA) published a list of recommended pesticides for use in the cannabis industry and developed the state's pesticide testing regulations for all cannabis products, medicinal and recreational. Using the state's pesticide testing data, the aim of this study was to investigate the types of pesticides being used in the Oregon cannabis industry and if they present a hazard to cannabis workers. Both recreational and medicinal cannabis samples contained high levels of residual pesticides and pesticides not legally allowed to be used on cannabis products. Medicinal cannabis products were found to have mean levels of residual pesticides that were 3–12 times higher than recreational products. Nine of the 50 pesticides identified were classified highly or extremely hazardous by the World Health Organization.
Symbiosis at its limits: ecophysiological consequences of lichenization in the genus Prasiola in Antarctica
Authors: Fernández-Marín Beatriz , López-Pozo Marina , Perera-Castro Alicia V , Arzac Miren Irati , Sáenz-Ceniceros Ana , Colesie Claudia , de los Ríos Asunción , Sancho Leo G , Pintado Ana , Laza José M , Pérez-Ortega Sergio , García-Plazaola José I
Published: September 2019

Background and Aims

Lichens represent a symbiotic relationship between at least one fungal and one photosynthetic partner. The association between the lichen-forming fungus Mastodia tessellata (Verrucariaceae) and different species of Prasiola (Trebouxiophyceae) has an amphipolar distribution and represents a unique case study for the understanding of lichen symbiosis because of the macroalgal nature of the photobiont, the flexibility of the symbiotic interaction and the co-existence of free-living and lichenized forms in the same microenvironment. In this context, we aimed to (1) characterize the photosynthetic performance of co-occurring populations of free-living and lichenized Prasiola and (2) assess the effect of the symbiosis on water relations in Prasiola, including its tolerance of desiccation and its survival and performance under sub-zero temperatures.

Methods

Photochemical responses to irradiance, desiccation and freezing temperature and pressure–volume curves of co-existing free-living and lichenized Prasiola thalli were measured in situ in Livingston Island (Maritime Antarctica). Analyses of photosynthetic pigment, glass transition and ice nucleation temperatures, surface hydrophobicity extent and molecular analyses were conducted in the laboratory.

Key Results

Free-living and lichenized forms of Prasiola were identified as two different species: P. crispa and Prasiola sp., respectively. While lichenization appears to have no effect on the photochemical performance of the alga or its tolerance of desiccation (in the short term), the symbiotic lifestyle involves (1) changes in water relations, (2) a considerable decrease in the net carbon balance and (3) enhanced freezing tolerance.

Conclusions

Our results support improved tolerance of sub-zero temperature as the main benefit of lichenization for the photobiont, but highlight that lichenization represents a delicate equilibrium between a mutualistic and a less reciprocal relationship. In a warmer climate scenario, the spread of the free-living Prasiola to the detriment of the lichen form would be likely, with unknown consequences for Maritime Antarctic ecosystems.
The Utility of the Repeatable Battery of Neuropsychological Status in Patients with Temporal and Non-temporal Lobe Epilepsy
Authors: Maiman Moshe , Del Bene Victor A , Farrell Eileen , MacAllister William S , Sheldon Sloane , Rentería Miguel Arce , Slugh Mitchell , Gazzola Deana M , Barr William B
Published: September 2019

Objective

The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) is a brief neuropsychological battery that has been validated in the assessment of dementia and other clinical populations. The current study examines the utility of the RBANS in patients with epilepsy.

Methods

Ninety-eight patients with epilepsy completed the RBANS as part of a more comprehensive neuropsychological evaluation. Performance on the RBANS was evaluated for patients with a diagnosis of temporal lobe epilepsy (TLE; n = 51) and other epilepsy patients (non-TLE, n = 47) in comparison to published norms. Multivariate analysis of variance compared group performances on RBANS indices. Rates of impairment were also compared across groups using cutoff scores of ≤1.0 and ≤1.5 standard deviations below the normative mean. Exploratory hierarchical regressions were used to examine the relations between epilepsy severity factors (i.e., age of onset, disease duration, and number of antiepileptic drugs [AEDs]) and RBANS performance.

Results

TLE and non-TLE patients performed below the normative sample across all RBANS indices. Those with TLE performed worse than non-TLE patients on the Immediate and Delayed Memory indices and exhibited higher rates of general cognitive impairment. Number of AEDs was the only epilepsy severity factor that significantly predicted RBANS total performance, accounting for 14% of the variance.

Conclusions

These findings suggest that the RBANS has utility in evaluating cognition in patients with epilepsy and can differentiate TLE and non-TLE patients. Additionally, number of AEDs appears to be associated with global cognitive performance in adults with epilepsy.
Reclassifying Pseudopolyps in Inflammatory Bowel Disease: Histologic and Endoscopic Description in the New Era of Mucosal Healing
Authors: Rezapour Mona , Quintero Maria Alejandra , Khakoo Nidah S , Sussman Daniel A , Barkin Jodie A , Clarke Jennifer , Varma Tanya , Deshpande Amar R , Kerman David H , Damas Oriana , Abreu Maria T
Published: September 2019

Introduction

In this study, we identify the frequency of pseudopolyps (PPs) with normal histology and their association to surrounding tissue.

Methods

Patients were enrolled in a study identifying endoscopic characteristics of PPs (n = 29) or were collected as part of our IBD biobank (n = 16). Statistical analysis included Stata v.15.0. chi-square and Student t-test.

Results

A total of 45 patients with 117 PP biopsies were identified. More patients with healed PP were in endoscopic remission compared with those with inflammatory PP (82.6% vs 17.4%, respectively).

Conclusion

This is the first study to find mucosal healing of PPs and its association with deep remission.
The role of primary surgical repair technique on late outcomes of Tetralogy of Fallot: a multicentre study
Authors: Padalino Massimo A , Pradegan Nicola , Azzolina Danila , Galletti Lorenzo , Pace Napoleone Carlo , Agati Salvatore , Palma Gaetano , Marianeschi Stefano Maria , Seddio Francesco , Cascarano Maria Teresa , Carro Cristina , Gregori Dario , Vida Vladimiro Lorenzo , Stellin Giovanni
Published: September 2019

OBJECTIVES

Repair of Tetralogy of Fallot (TOF) has currently excellent results with either transventricular or transatrial approach. However, it is unclear as to which has better late outcomes and what role of residual pulmonary valve (PV) regurgitation in the long term is. We report on late clinical outcomes after repair in a large series of patients with TOF, focusing on the type of surgical technique.

METHODS

This analysis is a retrospective multicentre study on patients undergoing TOF repair in infancy. The exclusion criteria of the study were TOF with pulmonary atresia or absent PV.

RESULTS

We selected 720 patients who had undergone TOF repair (median age 5.7 months, interquartile range 3.7–11.7). Preoperative cyanotic spells occurred in 18%. A transatrial repair was performed in 433 (60.1%) patients. The PV was preserved in 249 (35%) patients, while the right ventricular outflow tract was reconstructed with a transannular patch (60.4%) or a conduit (4.6%) in the rest of the patients. At a median follow-up of 4 years (range 1–21, 86% complete), 10 (1.6%) patients died, while 39 (6.3%) patients required surgical reoperation and 72 (11.7%) patients required an interventional procedure. The propensity match analysis showed that the incidence of postoperative complications and adverse events at follow-up were significantly increased in patients undergoing transventricular approach repair with transannular patch (P = 0.006) and PV preservation was a significant protective factor against postoperative complications (P = 0.009, odds ratio 0.5) and late adverse events (P = 0.022).

CONCLUSIONS

Surgical repair of TOF in infancy is a safe procedure, with good late clinical outcomes. However, transatrial approach and PV preservation at repair are associated with lower early and late morbidity.
Favourable changes in physical working conditions and the risk of all-cause sickness absence: a pseudo-experiment
Authors: Shiri Rahman , Hiilamo Aapo , Pietiläinen Olli , Mänty Minna , Rahkonen Ossi , Lallukka Tea
Published: September 2019

Background

We determined whether favourable changes in physical workload and environmental factors reduce sickness absence (SA) days using observational cohort data as a pseudo-experiment.

Methods

The data from the Finnish Helsinki Health Study included three cohorts of employees of the City of Helsinki [2000/2002–07 (N = 2927), 2007–12 (N = 1686) and 2012–17 (N = 1118), altogether 5731 observations]. First, we estimated the propensity score of favourable changes (reduction in exposures) in physical workload and environmental factors during each 5-year follow-up period on the baseline survey characteristics using logistic regression. Second, we created and stabilized inverse probability of treatment weights for each participant using the propensity scores. Lastly, we used generalized linear model and fitted negative binomial regression models for over-dispersed count data to estimate whether the favourable changes decrease the risk of short-term (1–3 days), intermediate-term (4–14 days) and long-term (>14 days) SA using employer’s register data.

Results

During a 5-year follow-up, 11% of the participants had favourable changes in physical workload factors, 13% in environmental factors and 8% in both factors. The incidence of short-term, intermediate-term and long-term SA were lower in employees with favourable workplace changes compared with those without such changes. The reductions were largest for long-term SA. Reporting favourable changes in both workload and environmental factors reduced the number of SA days by 41% within 1 year after the changes and by 32% within 2 years after the changes.

Conclusion

This pseudo-experimental study suggests that improving physical working conditions reduces SA.
Management and reproductive counseling in cervical, caesarean scar and interstitial ectopic pregnancies over 11 years: identifying the need for a modern management algorithm
Authors: Shah Jaimin S , Nasab Susan , Papanna Ramesha , Chen Han-Yang , Promecene Pamela , Berens Pamela , Johnson Anthony , Bhalwal Asha
Published: September 2019

STUDY QUESTION

Do management strategies (treatment type and order), including provision of reproductive counseling, differ in patients with non-tubal pregnancies?

SUMMARY ANSWER

Medical and surgical treatment strategies varied widely for each type of non-tubal pregnancy and reproductive counseling in this patient population is lacking.

WHAT IS KNOWN ALREADY

Owing to the rarity of non-tubal pregnancies, there is no consensus regarding treatment strategies or protocol. Furthermore, there is limited data on how patients with a non-tubal pregnancy are counseled about future fertility.

STUDY DESIGN, SIZE, DURATION

This is a descriptive retrospective study. Data were collected from January 2006 to December 2017. A total of 50 patients were included in the study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients with an ultrasound diagnosis of a non-tubal ectopic pregnancy (e.g. cervical ectopic pregnancy [CEP], Caesarean scar pregnancy [CSP] or interstitial ectopic pregnancy [IEP]) were included. This study was performed at a university-based institution tertiary referral center. Demographic and clinical characteristics, treatment type and order, reproductive counseling and outcomes were collected. Descriptive statistics were used for analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the 50 patients identified, 13 were CEP (26%), 8 were CSP (16%) and 29 were IEP (58%). Patients with a CSP had a higher parity (median = 3, P = 0.02) and number of prior Caesarean deliveries (mean = 2.1, P < 0.001). A total of 66% (23/35) of patients expressed a desire for future fertility prior to treatment and only 56% (28/50) of patients received reproductive counseling according to the electronic medical records. Among all non-tubal pregnancies, there were variations in the type and the order of treatments that patients received.

LIMITATIONS, REASONS FOR CAUTION

This study was performed in a tertiary referral center therefore the management strategy could have been influenced by the prior interventions and patient response. The descriptive retrospective design precluded any assumption of causation.

WIDER IMPLICATIONS OF THE FINDINGS

The management for non-tubal pregnancies has wide variations. Reproductive counseling in this patient population is lacking. The findings highlight the need for the development of a treatment algorithm and a reproductive counseling protocol for each non-tubal pregnancy to better standardize treatment strategy.

STUDY FUNDING/COMPETING INTEREST(S)

There was no funding for this study. The authors have no conflict of interest to report.
Education protects against coronary heart disease and stroke independently of cognitive function: evidence from Mendelian randomization
Authors: Gill Dipender , Efstathiadou Anthoula , Cawood Kristopher , Tzoulaki Ioanna , Dehghan Abbas
Published: September 2019

Background

There is evidence that education protects against cardiovascular disease. However, it is not known whether such an effect is independent of cognition.

Methods

We performed two-sample Mendelian randomization (MR) analyses to investigate the effect of education and cognition, respectively, on risk of CHD and ischaemic stroke. Additionally, we used multivariable MR to adjust for the effects of cognition and education in the respective analyses to measure the effects of these traits independently of each other.

Results

In unadjusted MR, there was evidence that education is causally associated with both CHD and stroke risk [CHD: odds ratio (OR) 0.65 per 1-standard deviation (SD; 3.6 years) increase in education; 95% confidence interval (CI) 0.61–0.70, stroke: OR 0.77; 95% CI 0.69–0.86]. This effect persisted after adjusting for cognition in multivariable MR (CHD: OR 0.76; 95% CI 0.65–0.89, stroke OR 0.74; 95% CI 0.59–0.92). Cognition had an apparent effect on CHD risk in unadjusted MR (OR per 1-SD increase 0.80; 95% CI 0.74–0.85), however after adjusting for education this was no longer observed (OR 1.03; 95% CI 0.86–1.25). Cognition did not have any notable effect on the risk of developing ischaemic stroke, with (OR 0.97; 95% CI 0.87–1.08) or without adjustment for education (OR 1.04; 95% CI 0.79–1.36).

Conclusions

This study provides evidence to support that education protects against CHD and ischaemic stroke risk independently of cognition, but does not provide evidence to support that cognition protects against CHD and stroke risk independently of education. These findings could have implications for education and health policy.
Real-World Effectiveness From the Asia Pacific Rim Liver Consortium for HBV Risk Score for the Prediction of Hepatocellular Carcinoma in Chronic Hepatitis B Patients Treated With Oral Antiviral Therapy
Authors: Yang Hwai-I , Yeh Ming-Lun , Wong Grace L , Peng Cheng-Yuan , Chen Chien-Hung , Trinh Huy N , Cheung Ka-Shing , Xie Qing , Su Tung-Hung , Kozuka Ritsuzo , Lee Dong-Hyun , Ogawa Eiichi , Zhao Changqing , Ning Hui-Bin , Huang Rui , Li Jiayi , Zhang Jian Q , Ide Tatsuya , Xing Huichun , Iwane Shinji , Takahashi Hirokazu , Wong Christopher , Wong Clifford , Lin Chia-Hsin , Hoang Joseph , Le An , Henry Linda , Toyoda Hidenori , Ueno Yoshiyuki , Gane Edward J , Eguchi Yuichiro , Kurosaki Masayuki , Wu Chao , Liu Chenghai , Shang Jia , Furusyo Norihiro , Enomoto Masaru , Kao Jia-Horng , Yuen Man-Fung , Yu Ming-Lung , Nguyen Mindie H
Published: September 2019

Background

Patients on oral antiviral (OAV) therapy remain at hepatocellular carcinoma (HCC) risk. Risk prediction tools distinguishing treated patients with residual HCC risk are limited. The aim of this study was to develop an accurate, precise, simple-to-use HCC risk score using routine clinical variables among a treated Asian cohort.

Methods

Adult Asian chronic hepatitis B (CHB) patients on OAV were recruited from 25 centers in the United States and the Asia-Pacific region. Excluded persons were coinfected with hepatitis C, D, or human immunodeficiency virus, had HCC before or within 1 year of study entry, or their follow-up was <1 year. Patients were randomized to derivation and validation cohorts on a 2:1 ratio. Statistically significant predictors from multivariate modeling formed the Real-world Effectiveness from the Asia Pacific Rim Liver Consortium for HBV (REAL-B) score.

Results

A total of 8048 patients were randomized to the derivation (n = 5365) or validation group (n = 2683). The REAL-B model included 7 variables (male gender, age, alcohol use, diabetes, baseline cirrhosis, platelet count, and alpha fetoprotein), and scores were categorized as follows: 0–3 low risk, 4–7 moderate risk, and 8–13 high risk. Area under receiver operating characteristics were >0.80 for HCC risk at 3, 5, and 10 years, and these were significantly higher than other risk models (p < .001).

Conclusions

The REAL-B score provides 3 distinct risk categories for HCC development in Asian CHB patients on OAV guiding HCC surveillance strategy.
Organization quality systems and department-level strategies: refinement of the Deepening our Understanding in Quality in Australia (DUQuA) organization and department-level scales
Authors: Clay-Williams Robyn , Taylor Natalie , Winata Teresa , Ting Hsuen P , Arnolda Gaston , Braithwaite Jeffrey
Published: September 2019

Objective

The aim of this study was to develop and refine indices to measure organization and care pathway-level quality management systems in Australian hospitals.

Design

A questionnaire survey and audit tools were derived from instruments validated as part of the Deepening Our Understanding of Quality improvement in Europe (DUQuE) study, adapted for Australian hospitals through expert opinion. Statistical processes were used to explore the factor structure, reliability and non-redundancy and descriptive statistics of the scales.

Setting

Thirty-two large Australian public hospitals.

Participants

Audit of quality management processes at organization-level and care pathway processes at department level for three patient conditions (acute myocardial infarction (AMI), hip fracture and stroke) and senior quality manager, at each of the 32 participating hospitals.

Main Outcome Measure(s)

The degree of quality management evident at organization and care pathway levels.

Results

Analysis yielded seven quality systems and strategies scales. The three hospital-level measures were: the Quality Management Systems Index (QMSI), the Quality Management Compliance Index (QMCI) and the Clinical Quality Implementation Index (CQII). The four department-level measures were: Specialised Expertise and Responsibility (SER), Evidence-Based Organisation of Pathways (EBOP), Patient Safety Strategies (PSS) and Clinical Review (CR). For QMCI, and for seven out of eight subscales in QMSI, adequate internal consistency (Cronbach’s $\alpha$ >0.8) was achieved. For CQII, lack of variation and ceiling effects in the data resulted in very low internal consistency scores, but items were retained for theoretical reasons. Internal consistency was high for CR (Cronbach’s $\alpha$ 0.74–0.88 across the three conditions), and this was supported by all item-total correlations exceeding the desired threshold. For EBOP, Cronbach’s $\alpha$ was acceptable for hip fracture (0.80) and stroke (0.76), but only moderate for AMI (0.52). PSS and SER scales were retained for theoretical reasons, although internal consistencies were only moderate (SER) to poor (PSS).

Conclusions

The Deepening our Understanding of Quality in Australia (DUQuA) organization and department scales can be used by Australian hospital managers to assess and measure improvement in quality management at organization and department levels within their hospitals and are readily modifiable for other health systems depending on their needs.
Validation of the patient measure of safety (PMOS) questionnaire in Australian public hospitals
Authors: Taylor Natalie , Clay-Williams Robyn , Ting Hsuen P , Winata Teresa , Arnolda Gaston , Hogden Emily , Lawton Rebecca , Braithwaite Jeffrey
Published: September 2019

Objective

Patients can provide a unique perspective on the safety of care in hospitals. Understanding that the extent to which the way hospitals are organized for quality and safety is associated with patient perceptions of care is becoming increasingly valued and necessary for the direction of targeted interventions across healthcare systems. The UK-developed patient measure of safety (PMOS) assesses eight domains of ward safety from the patient point of view and has recently been adapted and piloted in Australia. The aim of this study is to test the psychometric properties of PMOS-Australia (PMOS-A) amongst a large cohort of hospitalized patients.

Design

Cross-sectional questionnaire validation assessment.

Setting and participants

As part of the DUQuA project, the PMOS-A survey was distributed within acute myocardial infarction, hip fracture and stroke departments across 32 large public hospitals in Australia. Patients could complete the PMOS-A independently, or request the assistance of a family member/guardian, or staff on the wards—space was included to record mode of completion.

Main outcome measures

Confirmatory factor analysis (CFA) was undertaken on a calibration sample to generate the model, and a validation sample was used to cross-validate the model. A subset of only those participants who received assistance for PMOS-A completion was also tested using CFA on a calibration and validation sample. Model fit indices (chi-square to degrees of freedom ratio [Chi-square:DF], root mean square error of approximation [RMSEA], comparative fit indices [CFI], standardized root mean squared residual [SRMR]), Cronbach’s α, average inter-item correlations, construct reliability and cross-loadings were examined with reference to recommended thresholds to establish the extent of convergent validity and discriminant validity. A marker of criterion validity was assessed through testing associations between the PMOS-A and adherence to clinical guidelines.

Results

Across the calibration and validation samples of the full (N = 911) and assisted completers only subset (N = 490), three (Chi-square:DF, SRMR, RMSEA) of the four indices consistently or almost always met thresholds for acceptable model fit. CFI indices did not meet the recommended limits (0.72–0.78, against a target > 0.9). Positive relationships were found for all tests between PMOS-A and adherence to clinical guidelines, and these were significant when assessed in the calibration datasets for the full and assisted completion samples.

Conclusion

A sufficiently reliable and valid measure of patient perceptions of safety has been developed. These findings should provide adequate support to justify the use of this measure to assess patient perceptions of safety in Australian hospitals and can be modified for use elsewhere.
Conclusion: the road ahead: where should we go now to improve healthcare quality in acute settings?
Authors: Braithwaite Jeffrey , Taylor Natalie , Clay-Williams Robyn , Ting Hsuen P , Arnolda Gaston
Published: September 2019

This final article in our 12-part series articulating a suite of quality improvement studies completes our report on the Deepening our Understanding of Quality in Australia (DUQuA) program of work. Here, we bring the Supplement’s key findings and contributions together, tying up loose ends. Traversing the DUQuA articles, we first argued the case for the research, conducted so that an in-depth analysis of one country’s health system, completed 5 years after the landmark Deepening our Understanding of Quality Improvement in Europe (DUQuE), was available. We now provide a digest of the learning from each article. Essentially, we have contributed an understanding of quality and safety activities in 32 of the largest acute settings in Australia, developed a series of scales and tools for use within Australia, modifiable for other purposes elsewhere, and provided a platform for future studies of this kind. Our main message is, despite the value of publishing an intense study of quality activities in 32 hospitals in one country, there is no gold standard, one-size-fits-all methodology or guarantee of success in quality improvement activities, whether the initiatives are conducted at departmental, organization-wide or whole-of-systems levels. Notwithstanding this, armed with the tools, scales and lessons from DUQuA, we hope we have provided many more options and opportunities for others going about strengthening their quality improvement activities, but we do not claim to have solved all problems or provided a definitive approach. In our view, quality improvement initiatives are perennially challenging, and progress hard-won. Effective measurement, evaluating progress over time, selecting a useful suite of quality methods and having the persistence to climb the improvement gradient over time, using all the expertise and tools available, is at the core of the work of quality improvement and will continue to be so.