bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical and Mathematical Mechanisms of Instability in Nonlinear Automatic Control Systems
Authors: Kalman R. E.
Published: February 2022

This paper is a critical examination of the stability problem in automatic control systems containing nonlinear elements. An attempt is made to classify and isolate essentially different phenomena, and to illustrate each type by means of simplified but representative examples. Particular attention is paid to the effects of system parameters and system inputs in provoking or destroying instability. The phenomena discussed are so diverse that they defy any over-all conclusions. Still, it is hoped that the tentative classification adopted here will be of help in recognizing important and unimportant aspects of problems in nonlinear control-system design.
Determination of the Characteristics of Multi-Input and Nonlinear Systems From Normal Operating Records
Authors: Goodman T. P.
Published: February 2022

A method is presented for discovering, from the random variations in normal operating records, the impulse responses, or weighting functions, relating an output of a system to two or more inputs that are mutually correlated. This method makes use of the statistical autocorrelation and cross-correlation functions of the system inputs and outputs. From these correlation functions, the weighting functions are obtained by a process of deconvolution by means of an electronic delay-line synthesizer. The method is described first for linear systems and is then applied to nonlinear systems. It is an extension of a method presented in an earlier paper for discovering the weighting function of a linear system with one input.
Operating Considerations in Application of Gas-Turbine-Driven, Centrifugal, Pipeline Compressors
Authors: Vaughan A. L.
Published: February 2022

Northern Natural Gas Company has operated two gas-turbine stations through three winter heating seasons. Each of these stations consists of four 5700-hp gas-fired turbine-driven, centrifugal compressors arranged in series. The intent of this paper is to present the fundamental reasons behind the decision to use turbines in this application and to reflect some light on anticipated related operating and maintenance costs. Sufficient operating time has transpired to arrive at some definite conclusions as to operating costs and the reliability of the machines. However, there is insufficient experience to predict future maintenance costs accurately. Included herein are results of the recent major inspection and overhaul of two gas turbines.
The Application of an Analog Computer to the Measurement of Process Dynamics
Authors: Cowley P. E. A.
Published: February 2022

The usual method of obtaining frequency-response measurements is described. The data obtained are reduced by visual inspection, but difficulties arise due to distortion and noise in the process. The range of frequencies over which measurements can be made is limited by noise and distortion and may prove inadequate for studying the stability of the process when controlled. These shortcomings may be overcome by methods of frequency-response measurement in which the data are reduced by means of a computer rather than by visual inspection. Two methods of frequency-response measurement using an analog computer for data reduction are described. Results are given of laboratory measurements on a dummy process and of field measurements on a real process. The advantages of computer reduction of the data are clearly demonstrated. The further advantages to be derived from digital computation rather than analog computation are indicated.
Avon No. 8—A Supercritical-Pressure Plant
Authors: Dauber C. A.
Published: February 2022

This paper describes the 250,000-kw supercritical-pressure addition to the Avon Plant of The Cleveland Electric Illuminating Company. Special features of the third supercritical-pressure unit designed for an American central station include the use of a monotube once-through boiler, combination motor and turbine-driven boiler feed pumps, extruded pipe for main steam leads, condenser by-pass demineralization system, and a high-temperature water-heating system for the plant addition.
Optimum Stresses of Structural Elements at Elevated Temperatures
Authors: Schnitt Arthur , Brull M. A. , Wolko H. S.
Published: February 2022

A method is developed by which optimum-stress curves for a given material at any temperature may be calculated from the room-temperature optimum-stress curves for a different material. The only data required to perform this transformation are stress-strain curves of both materials. As examples, optimum-stress envelopes are obtained for wide columns and multiweb beams over a wide range of temperatures. Relations are developed between the properties of optimized elements of different materials so that the detailed dimensions of any element may be calculated by considering a properly selected equivalent aluminum element. An approximate procedure is developed for the determination of maximum life when creep is significant. The method is then extended so as to permit comparison of unprotected structures with insulated and cooled structures, on the basis of minimum weight-strength and as a function of temperature and exposure time. Thus these developments lead to a systematic procedure by which the optimum structural arrangement and material may be selected for a given loading and known thermal environment.
Weight-Efficiency Analysis of Thin-Wing Construction
Authors: Anderson R. A.
Published: February 2022

Information on the weight efficiency of multiweb thin-wing construction is reviewed and presented in a form suitable for preliminary design purposes. The effects of corrugated-web systems and steel-sandwich cover skins on weight efficiency are analyzed, and simple criteria are given for estimating the effect on weight of changes in the material properties of the structure.
Some Structural Penalties Associated With Thermal Flight
Authors: Mar J. W. , Schmit L. A.
Published: February 2022

In designing aircraft for high-speed flight, the structural designer is confronted by many factors which tend to increase the weight. As Prof. R. L. Bisplinghoff points out, the static strength of the structure still appears to be the most important design requirement for high-speed, manned, fighter-type aircraft of the foreseeable future. In subsonic aircraft, the margin of static strength is measured by comparing the stresses caused by maneuvering with the permissible stresses which the material can carry. In high-speed supersonic aircraft, the static strength must take into account not only the thermal stresses but also the degradation in the mechanical properties of the material which accompany elevated temperatures. This paper investigates the short-time static strength of the structure as it is subjected to the combined action of maneuvering loads and internal heat flow.
Effect of the Volute on Performance of a Centrifugal-Pump Impeller
Authors: Bowerman R. D. , Acosta A. J.
Published: February 2022

An experimental study of volute influence on radial flow-impeller performance was conducted by operating a single impeller with three different sets of volute vanes. In each case, over-all performance was measured and an internal-flow study within the volute was made. The results show that at their respective design flow rates the influence of the volutes is least and the deviation of performance from the free-impeller operation is small. At off-design flow rates there are major changes in the impeller performance resulting from the presence of the volutes. Large real fluid effects, coupled with a nonuniform velocity pattern at the impeller exit, result in a flow through the volute that does not resemble a potential flow. Even so, the fluid losses through the volute are comparatively small.
Mollier Diagrams for Water Near Bubble Point
Authors: Van Haute André , Sage B. H.
Published: February 2022

In many problems of engineering interest a knowledge of the thermodynamic properties of water in the heterogeneous region near bubble point is of value. A series of Mollier diagrams for water at states from bubble point to a quality of 0.05 was prepared and similar diagrams relating to the behavior of the condensed liquid were included. The Mollier diagram was employed because of its utility in connection with graphical operations of a thermodynamic nature pertaining to the flow of homogeneous and heterogeneous fluids near bubble point. An example of the application of the diagrams to the solution of the simple problem of flow in short tubes was included.
Statistical Analysis of a Wear Process
Authors: Rightmire B. G.
Published: February 2022

An expression for metal transfer during a wear process studied experimentally by Kerridge (5) is formulated in terms of the statistical behavior of the sliding contacts. The results lend quantitative support to the view that oxidation of the contacts plays a critical role in determining the metal transfer and wear. Based on this formulation, new experiments are suggested and the anticipated results for two cases are discussed.
Testing Dynamically Loaded Bearings—I: A Short History of Bearing Test Machines
Authors: Hersey M. D. , Snapp R. B.
Published: February 2022

Bearing test machines with dynamic loading or nonuniform motion are described in this paper and classified according to the type of loading employed. Over thirty such machines have been disclosed in the published literature, including both endurance machines and research machines for investigating oil-film performance. The authors have endeavored to find answers to six questions concerning each machine—(a) its loading mechanism, (b) test bearing details, (c) range of variables, (d) performance criteria, (e) characteristic limitations or advantages, and (f) extent of use.
A Comparison of Hydraulic and Pneumatic Accessory Power Generation
Authors: Brown E. I.
Published: February 2022

Aircraft accessory-power transmission systems utilizing hydraulic pumps and motors are shown to be more efficient than those using pneumatic turbines driven by compressor bleed. The hydraulic system shows significant advantages in terms of both engine maximum thrust and cruise fuel consumption. A convertible hydraulic unit used as a turbojet starter motor and as an engine-driven hydraulic pump offers weight and performance advantages which further increase the value of hydraulics for all aircraft accessory-power systems.
Graphical Shoe-Brake Analysis
Authors: Fazekas G. A. G.
Published: February 2022

The purpose of this paper is to show an exact and very rapid analysis that is applicable to any shoe brake, “sliding shoes” included, together with a method for interpreting the analytical findings.
Effects of Complex Stress-Time Cycles on the Fatigue Properties of Metals
Authors: Starkey W. L. , Marco S. M.
Published: February 2022

An investigation was conducted to determine the effects of complex stress-time cycles on the fatigue properties of metals. The uniaxial stresses studied were complex in the sense that their stress-time patterns may be analyzed as composed of several harmonic components. Four theoretical design methods, and the results of an experimental investigation involving complex stresses are presented. Comparisons are made of the test results with the theory predictions.
Fatigue of Metals Under Combinations of Stresses
Authors: Findley W. N.
Published: February 2022

Analysis of available information suggests that the phenomenon of fatigue of materials results primarily from alternating shearing stress producing cracks along shear planes, and that the resistance to fatigue cracking is influenced by other factors. Some of these factors are changes in structure of the material resulting from plastic and elastic stressing as well as heat-treatment; the mode of crack propagation and the complementary normal stress on planes of shear stress. Several theories of failure under combined stress are examined and modified to account for observed facts. A general design expression is proposed. The influence of mean stress (including extreme compression), yielding, complementary normal stress, and anisotropy are considered.
Metallurgical Considerations of Main Steam Piping for High-Temperature, High-Pressure Service
Authors: Blumberg H. S.
Published: February 2022

The paper presents a broad approach to the selection and behavior aspects of materials for modern high-temperature, high-pressure, steam power-plant piping. The author summarizes the steels currently used and analyzes the possibilities of superstrength alloys for high-temperature steam piping. He also presents a progress report of a program for selecting materials for the Eddystone Unit of the Philadelphia Electric Company (1200 F, 5600 psi design conditions).
Two Applications of a Digital Computer to Machine-Design Problems
Authors: Lester Joseph T.
Published: February 2022

Two examples are presented that illustrate two types of problems wherein a high-speed computer can provide important aid to the design engineer: (a) Tedious table-making computations; (b) solution of complex differential equations. The two applications represented are, respectively, a cycloidal crank-drive mechanism and a swing-type hammer mill.
Heat Transfer to Lead-Bismuth in Turbulent Flow in an Annulus
Authors: Seban R. A. , Casey D. F.
Published: February 2022

Heat-transfer coefficients for molten lead-bismuth eutectic are presented for flow in annuli externally heated at a constant rate. Diameter ratios of 1.30 and 1.74 were investigated and results were obtained for Peclet numbers from 400 to 1600. These results are shown to be related to analogy predictions for this system in the same manner as exists for pipe flow, and that the theories providing a rationalization of the results for pipe flow do so as well for the flow in an annulus.
Design of Supersonic Expansion Nozzles and Calculation of Isentropic Exponent for Chemically Reacting Gases
Authors: Edse R.
Published: February 2022

For the calculation of sonic velocities or changes in pressure, volume, or temperature in gases, the isentropic or polytropic exponent of the gas or gas mixture must be known. So far it has been needed also for designing supersonic expansion nozzles. However, it is shown in this paper that more accurate designs of such nozzles can be obtained without the use of the isentropic or polytropic exponent. As long as no chemical reaction occurs in the gas, the isentropic exponent is equal to the ratio of the specific heat at constant pressure to that at constant volume. However, in jet engines or in hypersonic wind tunnels using very high stagnation temperatures, the isentropic exponent is no longer identical to the ratio of the specific heats because of the energy released or absorbed by the chemical reactions. Methods are presented for calculating differential and integral values of the isentropic exponents in gases without and with consideration of chemical reactions. A numerical evaluation of the method is given for dissociating hydrogen. The results of this investigation indicate that the isentropic exponent of a chemically reacting gas mixture differs greatly from the ratio of the specific heats. It is also shown that accurate designs of supersonic expansion nozzles for chemically reacting gases require a detailed thermodynamic analysis of the system.
Apparent Frictional Forces on Clamping Elements as Used in the Oil Industry
Authors: Moser E. I. , Wilhoit J. C.
Published: February 2022

This study endeavors to show a method whereby the clamping effect of such tools as drill-pipe slips, casing slips, and so forth, may be determined analytically. This subject is of interest in view of the fact that serrations on the faces of such clamping elements are often suspected of producing focal points of failure. It is shown that the individual teeth of the serration need not be of the conventional “saw-tooth” or “sharp-wedge” variety. The apparent frictional forces for penetrators having round tips were found to be worth considering for clamping elements.
Importance of Matching Steam Temperatures With Metal Temperatures During Starting of Large Steam Turbines
Authors: Jackson R. L. , Coulter S. B. , Sheppard R.
Published: February 2022

The best kind of operation for a steam turbine is to keep it continuously under constant load at constant steam pressure and temperature. However, system-load variations and present-day requirements call for daily starting and stopping of some units. Usually this type of operation has fallen on the older units built for lower pressures and temperatures than are common for new units today. The industry is reaching the point where the turbines subjected to this service are of the 1250-psig 950-F or even 1450-psig 1000-F level. This practice has proved to be the cause of some shell cracking. As a result, studies have been made to determine the factors occurring during the start-up period which produce cracking and what can be done to prevent trouble of this kind in the future.
Instrumenting a Field Study of Industrial Water-Cooling Tower Performance
Authors: Willa J. L. ,   Technical Sub-Committee No. 2 of the Cooling Tower Institute
Published: February 2022

In pursuit of its objective “to advance the technology, design, and performance of industrial cooling towers,” the Cooling Tower Institute undertook a comprehensive investigation of the several factors influencing tower performance. In the hope of developing either corrections or compensations for the loss of capacity due to changes in atmospheric conditions, including wind velocity and direction, a thorough study was made to determine the exact cause and magnitude of the losses on various sizes, types, and configurations of water-cooling towers.
Heat Transfer by Radiation From Flames: A Summary of the Work of the International Flame Research Foundation
Authors: Sherman R. A.
Published: February 2022

A unique example of international co-operation is given in the program of research on radiation from flames in industrial furnaces that is being conducted at the Royal Netherlands Blast Furnace and Steel Works. Financial support and direction came first from the Netherlands, France, and Great Britain. These countries have now been joined by Belgium, Sweden, the United States, and the High Authority of the European Community of Coal and Steel. This paper outlines the organization of the work, the experimental facilities, the methods of research, and presents the outstanding results on the effect of the variables studied on flame radiation. These variables have been the type of fuel oils or coke-oven gas, the rate of heat input, the type and rate of supply of atomizing agent, the type of burner, the excess of air, the type and amount of carbureting agent for gas, and the temperature of the combustion air. Of these several variables, the C/H ratio of the oil and gas fuels and the mixing conditions most markedly affect the emissivity and the radiation of the flames. The results point to the need for further knowledge of the relation of the radiating characteristics of flames to the rate of heat transfer to “work” in furnaces. The research has now been extended to include the use of pulverized coal.
Resistance Coefficients for Laminar and Turbulent Flow Through One-Half-Inch Valves and Fittings
Authors: Kittredge C. P. , Rowley D. S.
Published: February 2022

Apparatus and test procedures to determine resistance coefficients for laminar and turbulent flow through ½-in. I.P.S. valves, fittings, and fabricated bends are described. Resistance coefficients are given as functions of Reynolds number. Results of the investigation are discussed briefly.
Responses of Temperature-Sensing-Element Analogs
Authors: Coon G. A.
Published: February 2022

From the standpoint of stability, temperature-sensing elements used in control systems should not contribute much phase lag at the frequency where the open-loop phase lag is 180 deg. For those cases where the temperature-sensing element does not contribute appreciable (less than 30 deg) phase lag around 180 deg, it would be advantageous to have a low-frequency approximation which works for complicated thermal systems. This paper presents such an approximation and establishes its validity for the electrical analogs of many sensing elements. In addition, it shows how the approximation is related to the thermal lag measured during a ramp input and the 63 per cent response time. These results, which are obtained in terms of transfer functions, can be applied to other systems having the same analogs.
Signal Stabilization of a Control System
Authors: Oldenburger Rufus
Published: February 2022

Linear automatically controlled systems with two or more dominant lags may be stabilized by the introduction of noise, or a signal of sufficiently high frequency, or a signal with sufficiently high-frequency components, provided that the hunt of the system is not excessively severe. The amplitude of the signal must be enough to run a bounded element, such as a governor pilot valve, through its full stroke. One or multiple-lag systems with optimum nonlinear controls also may be stabilized by an appropriate signal. Unless the stabilizing signal is great the response to the larger disturbances will be affected negligibly.
Influence of Repeated Bending Loads on Biaxial Residual Stresses in Shot-Peened Plates
Authors: Elsesser T. M.
Published: February 2022

The futility of shot-peening certain members to increase their fatigue strength may be explained by the reduction of the initial residual stresses with increased numbers of repeated loads. The purpose of this investigation was to determine the changes in the biaxial residual stresses, induced by shot-peening, in steel plates subjected to cyclic bending loads. The plates were sectioned by etching, and curvature measurements were made to evaluate the residual-stress distributions in the region of the peened surface. The residual stresses were found to “fade” or decrease to at least 50 per cent of their initial value in 10,200 load cycles in the medium-hard (SAE 4340) steel investigated.
Analysis of a Process-Fluid-Flow Network by Electrical Analogy
Authors: Kayan C. F. , Balmford J. A.
Published: February 2022

In a process-fluid-flow network of numerous interconnected branches of different proportions, the determination of the flow distribution by calculation is difficult because of the pressure-drop versus flow-rate characteristics of each individual component of the complex. Not only does the pressure drop vary with the effective pipe dimensions and surface condition, for a given fluid, but also markedly with the flow rate, and usually, in turbulent flow, with flow rate modified by some exponent with value on the order of 2.0. The concept of flow “resistance,” to represent opposition to fluid flow, is a useful tool. The pressure drop in any process branch line may be considered as proportional to the product of the flow rate and the pipeline resistance, and for turbulent flow the resistance itself may be considered a function of the flow rate. Thus the flow characteristics of a network may be simulated by electrical analogy, with the electrical resistance in each branch simultaneously adjusted to some desired function of the electrical current. Voltage and current determinations at given points are representative of the corresponding fluid pressure and flow rates. An illustrative process-plant network with numerous branches and discharge points is analyzed, with predictions of flow distributions and pressures.
Association between thermal responses, medical events, performance, heat acclimation and health status in male and female elite athletes during the 2019 Doha World Athletics Championships
Authors: Racinais Sebastien , Havenith George , Aylwin Polly , Ihsan Mohammed , Taylor Lee , Adami Paolo Emilio , Adamuz Maria-Carmen , Alhammoud Marine , Alonso Juan Manuel , Bouscaren Nicolas , Buitrago Sebastian , Cardinale Marco , van Dyk Nicol , Esh Chris J , Gomez-Ezeiza Josu , Garrandes Frederic , Holtzhausen Louis , Labidi Mariem , Lange Gűnter , Lloyd Alexander , Moussay Sebastien , Mtibaa Khouloud , Townsend Nathan , Wilson Mathew G , Bermon Stephane
Published: February 2022

Purpose

To determine associations between thermal responses, medical events, performance, heat acclimation and health status during a World Athletics Championships in hot-humid conditions.

Methods

From 305 marathon and race-walk starters, 83 completed a preparticipation questionnaire on health and acclimation. Core (Tcore; ingestible pill) and skin (Tskin; thermal camera) temperatures were measured in-competition in 56 and 107 athletes, respectively. 70 in-race medical events were analysed retrospectively. Performance (% personal best) and did not finish (DNF) were extracted from official results.

Results

Peak Tcoreduring competition reached 39.6°C±0.6°C (maximum 41.1°C). Tskindecreased from 32.2°C±1.3°C to 31.0°C±1.4°C during the races (p<0.001). Tcorewas not related to DNF (25% of starters) or medical events (p≥0.150), whereas Tskin, Tskinrate of decrease and Tcore-to-Tskingradient were (p≤0.029). A third of the athletes reported symptoms in the 10 days preceding the event, mainly insomnia, diarrhoea and stomach pain, with diarrhoea (9% of athletes) increasing the risk of in-race medical events (71% vs 17%, p<0.001). Athletes (63%) who performed 5–30 days heat acclimation before the competition: ranked better (18±13 vs 28±13, p=0.009), displayed a lower peak Tcore(39.4°C±0.4°C vs 39.8°C±0.7°C, p=0.044) and larger in-race decrease in Tskin(−1.4°C±1.0°C vs −0.9°C±1.2°C, p=0.060), than non-acclimated athletes. Although not significant, they also showed lower DNF (19% vs 30%, p=0.273) and medical events (19% vs 32%, p=0.179).

Conclusion

Tskin, Tskinrate of decrease and Tcore-to-Tskingradient were important indicators of heat tolerance. While heat-acclimated athletes ranked better, recent diarrhoea represented a significant risk factor for DNF and in-race medical events.
Prevalence and predictors of medication non-adherence among people living with multimorbidity: a systematic review and meta-analysis
Authors: Foley Louise , Larkin James , Lombard-Vance Richard , Murphy Andrew W , Hynes Lisa , Galvin Emer , Molloy Gerard J
Published: February 2022

Objectives

This systematic review aimed to describe medication non-adherence among people living with multimorbidity according to the current literature, and synthesise predictors of non-adherence in this population.

Methods

A systematic review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses. PubMed, EMBASE, CINAHL and PsycINFO were searched for relevant articles published in English language between January 2009 and April 2019. Quantitative studies reporting medication non-adherence and/or predictors of non-adherence among people with two or more chronic conditions were included in the review. A meta-analysis was conducted with a subgroup of studies that used an inclusive definition of multimorbidity to recruit participants, rather than seeking people with specific conditions. Remaining studies reporting prevalence and predictors of non-adherence were narratively synthesised.

Results

The database search produced 10 998 records and a further 75 were identified through other sources. Following full-text screening, 178 studies were included in the review. The range of reported non-adherence differed by measurement method, at 76.5% for self-report, 69.4% for pharmacy data, and 44.1% for electronic monitoring. A meta-analysis was conducted with eight studies (n=8949) that used an inclusive definition of multimorbidity to recruit participants. The pooled prevalence of non-adherence was 42.6% (95% CI: 34.0 - 51.3%,k=8,I2=97%,p<0.01). The overall range of non-adherence was 7.0%–83.5%. Frequently reported correlates of non-adherence included previous non-adherence and treatment-related beliefs.

Conclusions

The review identified a heterogeneous literature in terms of conditions studied, and definitions and measures of non-adherence used. Results suggest that future attempts to improve adherence among people with multimorbidity should determine for which conditions individuals require most support. The variable levels of medication non-adherence highlight the need for more attention to be paid by healthcare providers to the impact of multimorbidity on chronic disease self-management.

PROSPERO registration number

CRD42019133849.
Psychological problems and the associated factors related to the COVID-19 pandemic lockdown among college students in Amhara Region, Ethiopia: a cross-sectional study
Authors: Woday Tadesse Abay , Mihret Setegn Tarekegn , Biset Gebeyaw , Kassa Ayesheshim Muluneh
Published: February 2022

Objective

The central aim of this study was to assess the level of psychological problems among college students during school closure due to the emerging COVID-19 pandemic.

Design

Institution-based, cross-sectional study.

Setting

Colleges in the Amhara regional state of Ethiopia.

Participants

Participants were college students (N=422, >18 years) who were actively enrolled in the selected colleges preceding the survey.

Methods

Data entry was done using Epi Info V.7.02 and data analysis was done using SPSS V.24.0. Variables with a p value less than 0.25 in the bivariate analysis were entered into the multivariable logistic regression model. Model fitness was checked using the Hosmer-Lemeshow model fitness test. Statistically significant level was declared at p<0.05.

Outcome

Level of psychological problem.

Results

This study involved 408 students, with a response rate of 96.6%. In this study, 77.2%, 71.8% and 48.5% of students experienced depression, anxiety and stress-related psychological problems during the lockdown, respectively. The multivariable logistic regression model showed that being female (adjusted OR (AOR)=1.68, 95% CI 1.09 to 2.91), inadequate practice of prevention measures (AOR=1.74, 95% CI 1.01 to 3.02) and living in an urban residency (AOR=0.76, 95% CI 0.48 to 0.94) were independent predictors of psychological problems among students.

Conclusions

The study revealed that the level of anxiety, stress and depression disorders is optimally high among college students. Therefore, local governments should develop effective psychological interventions for students. Moreover, it is important to consider the educational enrolment type and the academic year of students.
Hypertensive disorders in pregnancy and risk of asthma in offspring: a systematic review and meta-analysis
Authors: Li Ping , Xiong Tao , Hu Yong
Published: February 2022

Objectives

The association between hypertensive disorders in pregnancy (HDP) and an increased risk of asthma in offspring remains controversial. No systematic review of this topic has been performed. The aim of this systematic review was to summarise the available evidence regarding the association between HDP and the risk of asthma in offspring.

Design

Systematic review and meta-analysis.

Methods

On the basis of a prepared protocol, a systematic search of PubMed, EMBASE, the Cochrane Library and Web of Science was performed using a detailed search strategy from the database inception to 17 January 2020. Cohort, case–control and cross-sectional studies published in English reporting the diagnoses of maternal HDP and asthma in offspring were included. The Meta-analysis of Observational Studies in Epidemiology guidelines were followed throughout the study. The estimated pooled ORs of HDP and asthma in offspring were calculated from the studies, and the meta-analysis was performed using random-effects models.

Results

Ten cohort studies involving a total of 6 270 430 participants were included. According to the Newcastle-Ottawa Scale, the overall methodological quality was good since 8 studies were of high quality and 2 studies were of moderate quality. After controlling for potential confounders, HDP was associated with a possible increased risk of asthma in offspring, with a pooled adjusted OR (aOR) of 1.19 (95% CI 1.12 to 1.26). The subgroup analyses according to HDP subgroups, sibling design, study quality, study location, offspring ages, singleton status, exposure assessment, outcome assessment and adjusted factors showed similar results.

Conclusions

Exposure to HDP may be associated with an increased risk of asthma in offspring. Further research is needed to verify the results and determine whether the observed relationship is causal.

PROSPERO registration number

CRD42020148250.
Expectation-induced enhancement of pain, itch and quality of life in psoriasis patients: study protocol of a randomised controlled trial
Authors: Hölsken Stefanie , Krefting Frederik , Schedlowski Manfred , Sondermann Wiebke
Published: February 2022

Introduction

Experimental and clinical data demonstrate that skin diseases like psoriasis are affected by psychological factors and can be modulated by interventions other than conventional drug therapy. The expectation of patients towards the benefit of a forthcoming treatment as well as treatment pre-experiences have been demonstrated as crucial factors mediating placebo responses in inflammatory skin diseases. However, it is unknown whether and to what extent treatment outcomes of psoriasis patients under therapy with monoclonal antibodies like secukinumab can be experimentally modulated at subjective and physiological levels by modifying the expectation of patients via verbal instruction or prior experience.

Methods and analysis

Treatment expectations will be modulated in patients with moderate-to-severe psoriasis undergoing treatment with the anti-interleukin-17A monoclonal antibody secukinumab. Patients with a Psoriasis Area and Severity Index (PASI) >12 will be randomly allocated to one of three groups (N=40 each). As a standard schedule, patients in the pharmacological control group (group 1) will be treated weekly with 300 mg secukinumab, while patients in groups 2 and 3 will receive only 75 mg secukinumab (75% dose reduction) during all treatment weeks. In addition to the injections, patients in group 3 will ingest a novel tasting drink, with a cover story explaining that previous studies showed additional beneficial effects of this combination (drug and drink). Patients will be assessed and treated at nine visits over a 16-week period, during which the severity of pain and itch symptoms, skin lesions and quality of life will be analysed with standardised questionnaires and the PASI.

Ethics and dissemination

This study was approved by the Ethics committee of the Medical Faculty of the University Duisburg-Essen. Study outcomes will be published in peer-reviewed scientific journals.
Prediction of exacerbation frequency of AECOPD based on next-generation sequencing and its relationship with imbalance of lung and gut microbiota: a protocol of a prospective cohort study
Authors: Deng Li , Yan Jiali , Xu Huachong , Huang Chunzhen , Lv Yiwen , Wu Qianxin , Xu Yinji , Chen Xiaoyin
Published: February 2022

Introduction

Patients with frequent acute exacerbation phenotype chronic obstructive pulmonary disease (AECOPD) have a higher hospitalisation rate than infrequent exacerbation, the disease progresses quickly and treatment is more difficult. At present, it is impossible to predict patients with COPD with frequent acute exacerbation phenotypes. The composition of the lower respiratory tract flora and the intestinal flora is closely related to AECOPD, but the specific association mechanism between them is not very clear. This study used metagenomic next-generation sequencing (mNGS) technology to explore the microbial characteristics of the intestinal tract and airways of patients with COPD, and analyse the correlation between the sequencing results and inflammatory factors, immune factors and nutritional factors.

Methods and analysis

This will be a prospective cohort study. We intend to recruit 152 patients with stable COPD. In the baseline, we will detect the participants’ induced sputum and faecal flora through mNGS, and changes in blood immune levels, and the patient’s condition is evaluated. Every 2 months, we will check the number of acute exacerbation through the phone range. After 12 months, we will check again the changes in the blood immune level, evaluate the patient’s condition and count the number of episodes.

Ethics and dissemination

This study has been approved by the ethics committee of Guangdong Provincial Hospital of Traditional Chinese Medicine (approval number ZF2019-219-03). The results of the study will be published in peer-reviewed journals.

Trial registration number

ClinicalTrials.gov Registry (ChiCTR2000032870).
Health profiles and racial disparities among individuals on probation in Hennepin County, Minnesota, 2016: a cross-sectional study
Authors: Olson Marin , Shlafer Rebecca J , Bodurtha Peter , Watkins Jonathan , Hougham Courtney , Winkelman Tyler N A
Published: February 2022

Objectives

To estimate the health characteristics and racial/ethnic health disparities among a probation cohort in Hennepin County. We hypothesised the probation population would have higher health needs compared with the general population as well as significant racial/ethnic health disparities.

Design

Cross-sectional study using linked administrative records.

Participants

Of 7992 eligible individuals, 5873 met inclusion criteria of 6 or more months of eligibility for a full-benefit Minnesota healthcare plan.

Setting

Probation system in Hennepin County in 2016.

Outcomes

We compared health condition prevalence among our probation cohort with survey data from the general population and analysed by race/ethnicity. We also measured sociodemographic characteristics, including the use of safety-net services.

Results

Individuals were predominantly male (80.5%), young (mean age: 35.5 years), and disproportionately black or African American (52.9%). A majority of individuals enrolled in Medicaid were eligible via Medicaid expansion (65.9%). Compared with the general population, individuals on probation had higher rates of substance use disorders (66.5% vs 8.1%), mental illness (55.3% vs 14.4%) and many physical conditions (eg, asthma: 17.0% vs 12.5%, chronic kidney disease: 5.8% vs 0.2%). White individuals on probation were significantly more likely than black or African American individuals to have a diagnosed substance use disorder (71.6% vs 62.0%) or mental health disorder (64.9% vs 48.5%), but fewer chronic physical health conditions (average: 0.52 vs 0.73 chronic physical conditions).

Conclusions

Individuals on probation have high health needs, which vary substantially by race/ethnicity. Without attention to this variation, interventions to address health conditions in this population could worsen racial/ethnic disparities.
Prognostic value of derived neutrophil-to-lymphocyte ratio (dNLR) in patients with non-small cell lung cancer receiving immune checkpoint inhibitors: a meta-analysis
Authors: Yang Tao , Hao Lizheng , Yang Xinyu , Luo Changyong , Wang Guomi , Lin Cai Caroline , Qi Shuo , Li Zhong
Published: February 2022

Objectives

Derived neutrophil-to-lymphocytes ratio (dNLR) has recently been reported as a novel potential biomarker associated with prognosis of non-small cell lung cancer (NSCLC). However, evidence for the prognostic utility of dNLR in patients with NSCLC treated with immune checkpoint inhibitors (ICIs) remains inconsistent. The objective of this work was to evaluate the association between pretreatment dNLR and prognosis of patients with NSCLC treated with ICIs.

Design

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Data sources

PubMed, EMBASE, Web of Science and the Cochrane Library were searched for eligible studies up to 16 October 2020.

Eligibility criteria

(1) Human subjects receiving ICIs therapy and who had been diagnosed with NSCLC; (2) the baseline values of dNLR were obtained; (3) the objective of the study was to investigate the relationships between dNLR and overall survival (OS) or progression-free survival (PFS) in NSCLC and (4) HR and 95% CI were displayed in the original article or could be extracted from Kaplan-Meier curves.

Data extraction and synthesis

Two investigators extracted data independently. Data synthesis was performed via systematic review and meta-analysis of eligible cohort studies. Meta-analysis was performed with Cochran’s Q test and I2 statistics. Publication bias of studies was assessed by Begg’s test and Egger’s test. We used V.12.0 of the Stata statistical software.

Results

This analysis included eight studies (2456 cases) on the prognostic utility of dNLR in ICI therapy for NSCLC. The results indicate that higher dNLR significantly predicted poor OS (HR=1.65, 95% CI 1.46 to 1.88; p<0.001) and PFS (HR=1.38, 95% CI 1.23 to 1.55; p<0.001). Subgroup analyses of OS-related studies indicated that there were similar results in stratifications by ethnicity, sample size, type of HR and dNLR cut-off value. As for PFS-related studies, subgroup analyses showed no significant difference in Asian populations. Publication biases were not detected using Begg’s test and Egger’s linear regression test.

Conclusions

This meta-analysis indicated that elevated pretreatment dNLR may be a negative prognostic predictor for patients with NSCLC treated with ICIs. More large-sample and higher-quality studies are warranted to support our findings.

PROSPERO registration number

CRD42021214034.
Protocol for a prospective observational study: the Australia and New
Zealand Diabetic and Ischaemic Foot Outcomes Study (ANZ-DIFOS)
Authors: Hart Odette , Jansen Shirley , Fitridge Robert , Khashram Manar
Published: February 2022

Introduction

Diabetic foot disease is a common condition globally and is
over-represented in indigenous populations. The propensity for patients
with diabetic foot disease to undergo minor or major limb amputation is
a concern. Diabetic foot disease and lower limb amputation are
debilitating for patients and have a substantial financial impact on
health services. The purpose of this multicentre study is to
prospectively report the presentation, management and outcomes of
diabetic foot disease, to validate existing scoring systems and assess
long term outcomes for these patients particularly in relation to major
limb amputation.

Methods and analysis

This is a multisite, international, prospective observational study,
being undertaken at Waikato Hospital, New Zealand (NZ); Sir Charles
Gairdner Hospital, the Royal Adelaide Hospital and the Queen Elizabeth
Hospital, Australia. Consecutive participants with diabetic foot disease
that meet inclusion criteria and agree to participate will be recruited
from multidisciplinary team diabetic foot clinic, vascular clinic,
dialysis and admission to hospital. Follow-up of participants will occur
at 1, 3, 6 and 12 months. At recruitment and follow-up reviews,
information about service details, demographic and clinical history,
wound data and discharge information will be recorded. The primary
outcomes are the time to wound healing, major amputation, overall
mortality and amputation-free survival at 12 months. This study started
in NZ in August 2020 and will commence in Australian sites in early
2021.

Ethics and dissemination

New Zealand Central Health and Disability Ethics Committee
(20/CEN/122), Waikato DHB Research Department (RDO020044), Quality
Improvement HoD Sir Charles Gairdner Hospital (39715) and the Central
Adelaide Local Health Network (CALHN) Human Research Ethics Committee
(13928). Results will be presented at international conferences and
published in peer-reviewed journals.

Trial registration number

Australian New Zealand Clinical Trials Registry
(ACTRN12621000337875).
Impact of Bariatric surgery on EmbrYONic, fetal and placental Development (BEYOND): protocol for a prospective cohort study embedded in the Rotterdam periconceptional cohort
Authors: Snoek Katinka M , Steegers-Theunissen Régine P M , Klaassen René A , Laven Joop S E , Schoenmakers Sam
Published: February 2022

Introduction

The worldwide obesity epidemic has resulted in a rise of bariatric surgery in women of reproductive age, which can lead to ‘iatrogenic undernutrition’. Long-lasting undernutrition can affect maternal health, pregnancy outcomes and offspring. We hypothesise that embryonic and placental growth are impaired in pregnancies after bariatric surgery due to the changed nutritional and microbiome dynamics. Therefore, our aim is to conduct the Bariatrics and EmbrYONic Development (BEYOND) study to investigate parameters of maternal nutritional and health status after bariatric surgery, both periconceptionally and during pregnancy, particularly concentrating on embryonic and fetal growth trajectories as well as placental development.

Methods and analysis

We designed a single-centre prospective, observational cohort, which investigates the iatrogenic nutritional and health status of women after bariatric surgery, periconceptionally and during pregnancy. The BEYOND study is embedded in the Rotterdam Periconceptional Cohort, a tertiary hospital-based birth cohort study. Eligible participants are women planning pregnancy or <12+0 weeks pregnant, ≥18 and ≤45 years of age, who have undergone bariatric surgery (cases) or without prior bariatric surgery (controls) and their male partners. Medical charts will be reviewed and questionnaires regarding general health, lifestyle and food intake will be collected. Moreover, we will perform serial three-dimensional ultrasounds to assess embryonic growth and placental development and two-dimensional ultrasounds for fetal growth assessment. The microbiome, including the virome, and blood samples will be sampled during the preconception period and in each trimester. Multivariable linear mixed model analyses will be used to assess the associations between bariatric surgery and pregnancy outcomes.

Ethics and dissemination

This proposal was approved by the Medical Ethics Committee from the Erasmus MC, Rotterdam, The Netherlands. Study results will be submitted for publication in high-impact journals, presented at scientific conferences, implemented into guidelines and communicated through the Erasmus MC and collaborating partners.

Trial registration number

NL8217 (www.trialregister.nl).