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The authors determine how the scheduling and sequencing of surgeries by surgeons impacts the rate of post-surgical complications and patient length-of-stay in the hospital.

Leveraging a dataset of 29,169 surgeries performed by 111 surgeons from a large hospital network in Ontario, Canada, the authors perform a matched case-control regression analysis. The empirical findings are contextualized by interviews with surgeons from the authors’ dataset.

Surgical complications and longer hospital stays are more likely to occur in technically complex surgeries that follow a similarly complex surgery. The increased complication risk and length-of-hospital-stay is not mitigated by scheduling greater slack time between surgeries nor is it isolated to a few problematic surgery types, surgeons, surgical team configurations or temporal factors such as the timing of surgery within an operating day.

There are four major limitations: (1) the inability to access data that reveals the cognition behind the behavior of the task performer and then directly links this behavior to quality outcomes; (2) the authors’ definition of task complexity may be too simplistic; (3) the authors’ analysis is predicated on the fact that surgeons in the study are independent contractors with hospital privileges and are responsible for scheduling the patients they operate on rather than outsourcing this responsibility to a scheduler (i.e. either a software system or an administrative professional); (4) although the empirical strategy attempts to control for confounding factors and selection bias in the estimate of the treatment effects, the authors cannot rule out that an unobserved confounder may be driving the results.

The study demonstrates that the scheduling and sequencing of patients can affect service quality outcomes (i.e. post-surgical complications) and investigates the effect that two operational levers have on performance. In particular, the authors find that introducing additional slack time between surgeries does not reduce the odds of back-to-back complications. This result runs counter to the traditional operations management perspective, which suggests scheduling more slack time between tasks may prevent or mitigate issues as they arise. However, the authors do find evidence suggesting that the risk of back-to-back complications may be reduced when surgical pairings are less complex and when the method involved in performing consecutive surgeries varies. Thus, interspersing procedures of different complexity levels may help to prevent poor quality outcomes.

The authors empirically connect choices made in scheduling work that varies in task complexity and to patient-centric health outcomes. The results have implications for achieving high-quality outcomes in settings where professionals deliver a variety of technically complex services.

Nobody concerned with political economy can neglect the history of economic doctrines. Structural changes in the economy and society influence economic thinking and, conversely, innovative thought structures and attitudes have almost always forced economic institutions and modes of behaviour to adjust. We learn from the history of economic doctrines how a particular theory emerged and whether, and in which environment, it could take root. We can see how a school evolves out of a common methodological perception and similar techniques of analysis, and how it has to establish itself. The interaction between unresolved problems on the one hand, and the search for better solutions or explanations on the other, leads to a change in paradigma and to the formation of new lines of reasoning. As long as the real world is subject to progress and change scientific search for explanation must out of necessity continue.

“Since films attract an audience of millions, the need and appetite for information about them is enormous.” So said Harold Leonard in his introduction to The Film Index published in 1941. The 1970's has produced more than enough — too much — food to satisfy that appetite. In the past five years the number of reference books, in this context defined as encyclopedias, handbooks, directories, dictionaries, indexes and bibliographies, and the astounding number of volumes on individual directors, complete histories, genre history and analysis, published screenplays, critics' anthologies, biographies of actors and actresses, film theory, film technique and production and nostalgia, that have been published is overwhelming. The problem in film scholarship is not too little material but the senseless duplication of materials that already exist and the embarrassing output of items that are poorly or haphazardly researched, or perhaps should not have been written at all.

Today’s modern liquid propellant rocket engines have a very complicated structure. They cannot be arbitrarily downsized, ensuring efficient propellants’ mixing and combustion. Moreover, the thermodynamic cycle’s efficiency is relatively low. Utilizing detonation instead of deflagration could lead to a significant reduction of engine chamber dimensions and mass. Nowadays, laboratory research is conducted in the field of rotating detonation engine (RDE) testing worldwide. The aim of this paper is to cover the design of a flight demonstrator utilizing rocket RDE technology.

It presents the key project iterations made during the design of the gaseous oxygen and methane-propelled rocket. One of the main goals was to develop a rocket that could be fully recoverable. The recovery module uses a parachute assembly. The paper describes the rocket’s main subsystems. Moreover, vehicle visualizations are presented. Simple performance estimations are also shown.

This paper shows that the development of a small, open-structure, rocket RDE-powered vehicle is feasible.

Flight propulsion system experimentation is on-going. However, first tests were conducted with lower propellant feeding pressures than required for the first launch.

Importantly, the vehicle can be a test platform for a variety of technologies. The rocket’s possible further development, including educational use, is proposed.

Up-to-date, no information about any flying vehicles using RDE propulsion systems can be found. If successful in-flight experimentation was conducted, it would be a major milestone in the development of next-generation propulsion systems.

Surveys the use of mathematics in what are now commonly called the social sciences up to the time of the earliest use of the term “social science” in the late 1700s. Explains the rationale for the organization and structure of the paper and proceeds to reason for the broad definition of mathematics as it relates to the social sciences. The introduction also describes the periodization used. The next section contains a brief description of the state of what were to become the social sciences in the late 1700s. This is followed by a brief description of the state of mathematics at that time. Then follow sections demonstrating that mathematics was used by important developers of social thought from the earliest times right up to the dawn of the modern social sciences. Concludes with a discussion of some of the lessons to be learned from history. The most important lesson that history teaches us about the role of mathematics in the modern social sciences at the dawn of their existence is that the social sciences require the use of mathematics and could not exist without them.

The term diverse books is increasingly popular yet persistently nebulous. The purpose of this paper – Part I of II – is to illuminate both that the concept is in need of a unified account and that conceptual analysis, though at first seemingly quite promising, fails as a method for identifying one.

This paper utilizes traditional (or intuitive) conceptual analysis to specify the respective clusters of necessary and sufficient conditions that constitute four broad candidate accounts of diverse books.

Though diverse books is a concept in need of a definition, conceptual analysis is not an appropriate method for adjudicating between the definitions we have on offer. This is because the concept is fundamentally political, serving as a resource for re-shaping collective social arrangements and ways of life. The conceptual problem outlined here requires for its resolution a method that will move us from a descriptive project to an explicitly normative one, wherein we consider what we properly work to achieve with and through the concept in question.

This paper initiates a systematic analytical project aimed at defining diverse books. In illustrating a moment of methodological failure, it paves the way for a critical alternative – namely, Part II's proposal of an analytical intervention in which political concepts are defined partially in terms of their benefits vis-á-vis informational justice.

The aim of this paper was to confirm the hypothesis that it is possible to conduct normal honing by mechanical method, providing the prescribed quality of cylinder liners. For this, cutting parameter optimization is needed.

Normal honing was performed on grey cast iron with lamellar graphite and mostly pearlitic microstructure of metal matrix. Cutting speed, feed rate and specific pressure during metalworking were varied and accordingly, a mathematical model for processing of results by the least squares method was proposed. Surface texture was controlled by scanning electron microscope.

A mathematical model describing the influence of cutting speed, feed rate and specific pressure during metalworking was devised. At the same time, surface texture was adequate, with geometrically appropriate crosshatch pattern, without standing‐out material and mashed graphite lamellas.

It was found that normal honing may be done by mechanical means, providing exceptional quality of lubrication. The most influential metalworking parameter was shown to be specific pressure.

Novel coronavirus is fast spreading pathogen worldwide and is threatening billions of lives. SARS n-CoV2 is known to affect the lungs of the COVID-19 positive patients. Chest x-rays are the most widely used imaging technique for clinical diagnosis due to fast imaging time and low cost. The purpose of this study is to use deep learning technique for automatic detection of COVID-19 using chest x-rays.

The authors used a data set containing confirmed COVID-19 positive, common bacterial pneumonia and healthy cases (no infection). A collection of 1,428 x-ray images is used in this study. The authors used a pre-trained VGG-16 model for the classification task. Transfer learning with fine-tuning was used in this study to effectively train the network on a relatively small chest x-ray data set. Initial experiments show that the model achieves promising results and can be greatly used to expedite COVID-19 detection.

The authors achieved an accuracy of 96% and 92.5% in two and three output class cases, respectively. Based on these findings, the medical community can access using x-ray images as possible diagnostic tool for faster COVID-19 detection to complement the already testing and diagnosis methods.

The proposed method can be used as initial screening which can help health-care professionals to better treat the COVID patients by timely detecting and screening the presence of disease.

In this paper, the influence of cutting regimes on surface texture and productivity of cylinder liner is shown, obtained by normal honing. Furthermore, normal honing power and torque is discussed. The paper aims to discuss these issues.

Normal honing was done on grey cast iron cylinder liners. Both pre- and finishing honing were done by mechanical means, to achieve the required level of surface texture quality, traditionally achieved by a combination of electrochemical pre-honing and mechanical finishing honing. To determine the most influential parameter on normal honing, statistical mathematical model was devised. Surface texture was controlled by light microscope and scanning electron microscope.

Mathematical model describing the influence of cutting speed, feed rate and depth of cut has shown that the most influential parameter on maximum peak height, productivity and specific volume productivity was shown. The most influential parameter has shown to be cutting speed.

There are two practical implications of this work: this work is a further contribution of understanding normal honing and the influence of various parameters on the quality of normal honing, both in view of surface texture and productivity, as the main drawback of this method. This work offers useful information for honing system designers, as torque and power of normal honing are given.

Two main achievements are given in this paper: as the main drawback of normal honing is lower productivity, the optimization of honing parameters may to some extent resolve this problem. Lower productivity is the result of lower cutting speeds and pressures, which in turn, give normal honed surface a higher quality compared to plateau honing. Lower power and torque demand a lower energy demands, as well as a less complex honing machine which may lead to further savings.

The purpose of this paper is to explore the influence of tool kinematics parameters on surface roughness, productivity and cutting angle for grey cast iron cylinder liners machined by normal honing.

For experimental investigation, a long stroke honing system was used. Diamond and SiC tools were used, for pre‐ and finishing, respectively. The values of cutting parameters were varied within the following limits: cutting speed v_s=0.931‐1.11 m/s; specific pressure of pre‐honing process p_d=1.0‐1.4 N/mm² and specific pressure of finishing honing process p_z=0.2‐0.5 N/mm². The analysis of dispersion was conducted for determining the mathematical model for cutting parameter influence on surface roughness and productivity.

Dispersion analysis proved that the most influential parameters on maximum roughness depth are cutting speed for D181 tool and specific pressure of finishing honing for D151 tool. The most influential parameter on productivity in the honing process with D181 and D151 tool is cutting speed.

The paper gives new information related to the normal honing optimization process. Normal honing offers the highest surface quality which is achieved by a low speed machining. However, that means also a relatively low productivity, demanding a thorough process optimization. Furthermore, normal honing is usually done by ECH pre‐honing and mechanical finishing honing, but in this paper, all‐mechanical honing was used for the same result, at a lower lost.