bluuebunny/crossref_metadata_2025 huggingface dataset:
History predicts contemporary community diversity within a biogeographic province of freshwater fish
Authors: Williams Trevor J. , Johnson Jerald B.
Published: February 2022

Aim

Historical biogeography and community ecology both seek to uncover the patterns and processes governing the structure and composition of communities, though typically at different temporal and spatial scales. Recent work has called to integrate these two fields; however, it is typically assumed that history plays little role in assembling contemporary, local communities. We incorporated phylogeographic data into traditional metacommunity analyses of freshwater fish communities to analyse if history can shape local community structure.

Location

Streams in the Nicaraguan Depression in north‐eastern Costa Rica.

Taxon

Freshwater fish communities.

Methods

We sampled community composition in 14 streams of the San Juan River Basin during the dry season of 2019 and evaluated variability in community composition in response to local and landscape‐scale environmental variability, spatial distance and historic processes using redundancy analyses. We measured environmental and spatial variables using typical methods utilized in metacommunity studies and approximated the effects of history with samova genetic groupings of three livebearing fishes native to the area. We also used PERMANOVAs to test if community composition exhibits similar spatial structure as seen in the genetic data of the three livebearing fishes used as historical proxies.

Results

Large‐scale patterns of genetic diversity predicted the patterns of local community diversity with community composition showing similar spatial structuring. Additionally, history variables were the only variables that significantly explained community composition and accounted for 20.6% of the total variability.

Main Conclusions

Species‐specific incidence patterns within Costa Rican freshwater fish communities vary according to biogeographic history, indicating that history can impact local community assembly. These observed patterns are likely due to colonization history following eustatic sea level change. Phylogeography can bridge the gap between classical biogeography and community ecology by enhancing inferences regarding community assembly through time and space, therefore studies should incorporate both genetic and local community data when assessing community assembly.
Empirical evidence on human learning and work characteristics in the transition to automated order picking
Authors: Loske Dominic
Published: February 2022

Although technological innovation has enabled a new wave of warehouse automation, human involvement remains necessary for most order picking operations in grocery retailing. This has spawned new forms of interaction between humans, machines, and intelligent software, that is, cyber‐sociotechnical systems. However, scant empirical field‐based research has been conducted on how this transition impacts human learning and the perception of work characteristics. Considering that humans are an essential element of these systems, it is fundamentally important to quantify the impact of these transformations when aspiring to improve performance, quality, and workers' well‐being as primary outcomes of order picking systems. This study utilized a mixed‐methods design, developing and applying parametric and non‐parametric approaches to operationalize learning progress, and semi‐structured interviews were conducted to examine perceived work characteristics. The findings indicate that the perception–cognition–motor–action cycle for learning by doing tasks can be accelerated through real‐time feedback provided by the order picking system. Furthermore, perceived work autonomy and feedback from the picking system are constant or perceived as greater when human decisions are accepted. The results have valuable implications for logistics practitioners, emphasizing the need for human‐centered work system design.
3D‐printed resins for provisional dental restorations: Comparison of mechanical and biological properties
Authors: Atria Pablo J. , Bordin Dimorvan , Marti Felipe , Nayak Vasudev Vivekanand , Conejo Julian , Benalcázar Jalkh Ernesto , Witek Lukasz , Sampaio Camila S.
Published: February 2022

Objectives

To characterize the mechanical and biological properties of three commercially available resins, which are currently used for provisional restorations and to compare them to an experimental resin intended for definitive fixed dental prostheses.

Materials and methods

Three commercially available resins: Crowntec (CT, Saremco), Temporary C&B (FL, Formlabs), C&B MFH (ND, Nextdent), and the experimental resin: Permanent Bridge (PB, Saremco) were printed and subjected to biaxial flexural strength test, finite element analysis, Weibull analysis, scanning electron microscopy, cell proliferation, immunohistochemistry and cytotoxicity assays. Samples from CT, PB, and ND were provided directly from the manufacturers ensuring ideal workflow. FL was printed using the workflow as recommended by the manufacturer, using a Formlabs 2 printer and their post‐processing units Form Wash and Form Cure.

Results

From the tested resins, PB yielded the best overall results in terms of mechanical properties. Cell proliferation and cytotoxicity did not show any significant differences among materials. PB showed higher values for probability of survival predictions (35%) when subjected to 250 MPa loads, whereas the other materials did not reach 10%.

Significance

Despite mechanical differences between the evaluated materials, the outcomes suggest that 3D printed provisional resins may be used in clinical settings, following the manufacturers indications. New materials intended for long‐term use, such as the PB resin, yielded higher mechanical properties compared to the other materials. Alternative printing and post‐processing methods have not yet been evaluated and should be avoided until further literature is available.

Clinical significance

3D printed resins for provisional restorations have become popular with the emergence of new technologies. In this study, we evaluated three different commercially available resins for provisional restorations and one new experimental resin. The results from this study indicate that commercially available resins could be used in clinical settings under certain conditions and limited periods of time. Following the manufacturers protocols is of paramount importance to not compromise these properties.
The Valorising Pitch: How Digital Start‐ups Leverage Intermediary Coverage
Authors: Pollock Neil , Chapple Duncan , Chen Suwen , D’Adderrio Luciana
Published: February 2022

As an unknown quantity, new ventures rely on influential intermediaries to endorse them. However, in some areas, like digital entrepreneurship, there is fierce competition for intermediary attention. Failing to garner intermediary support can mean ventures lack the resources needed to prosper. Still, it is unclear how they attract coverage, how intermediaries evaluate those vying for attention, and what influence this has on venture development. We conducted qualitative inductive research on how digital ventures sought coverage from industry analysts. Our process model of intermediary evaluation shows how ventures must perform a ‘valorising pitch’ to move from being an unknown quantity to engaging the intermediary to being valorised. Drawing on valuation studies scholarship, we propose an enhanced model of intermediary evaluation that depicts industry analysts as not just identifying but also ‘creating’ the value of ventures. We offer contributions to the literature on new venture development, intermediaries and digital entrepreneurship.
CEO–TMT Congruence in Growth‐Need Strength and Firm Growth
Authors: Wan Xue , Zhang Stephen X. , Wei Feng
Published: February 2022

The literature on the CEO–TMT interface has called for research on the implications of CEO–TMT congruence or fit. We examine the effect of CEO–TMT degree of congruence, forms of congruence, and forms of incongruence in growth‐need strength on firm growth based on decades of research on leader–team congruence. Using five‐wave survey data from the CEOs and other TMT members of 128 new firms, we find CEO–TMT incongruence in growth‐need strength is negatively related to firm growth by reducing CEO openness to the TMT. Our study charts a new avenue for upper echelons research, particularly on the CEO–TMT interface, by providing a nuanced theoretical framework and evidence on CEO–TMT congruence.
Are Root‐Supported Overdentures Still an Alternative to Implant‐Supported Overdentures? A Scoping Review
Authors: Ettinger Ronald L. , Marchini Leonardo , Childs Christopher A.
Published: February 2022

Purpose

To compare the outcomes of prosthodontic treatment for subjects wearing a complete maxillary denture opposing a root‐supported mandibular overdenture (RSO) or an implant‐supported mandibular overdenture (ISO).

Methods

A literature search was performed in seven electronic databases: MEDLINE via PubMed interface, Embase, Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, Scopus, Web of Science, and AgeLine. The search terms were developed by the primary investigators and the health sciences librarian, who then started with PubMed and adapted the original search strategy for the other databases. Included articles were those that compared the outcomes for mandibular RSOs and those with ISOs, for persons wearing a maxillary complete denture.

Results

Seven articles were included in the review. There were limitations in this review because of small sample sizes, short study durations, and different methodologies. Also, no comparative studies were identified for clinically important outcomes, such as survival rates of abutments, prosthodontics/maintenance problems, and longitudinal cost of care. For prosthodontic complications, patient satisfaction, and ability to clean, no differences were reported. For oral tactile sensibility, RSOs presented significantly improved sensibility, whereas ISOs had higher maximum bite force capability, but the difference was not statistically significant, except when subjects had a cross‐bite or a lingualized occlusion.

Conclusions

The results of this scoping review were not conclusive, except for maximum bite force, where ISOs seem to perform better than RSOs by the measured criteria. ISOs had higher survival rates than RSOs, and required less maintenance, but were more expensive. It was disappointing to find so few studies comparing these clinical treatment modalities, which suggests that either treatment may be clinically acceptable and depends upon a shared decision between patients and their dentists.
A calibrated model with a single‐generator simulating polysomnographically recorded periodic leg movements
Authors: Italia Matteo , Danani Andrea , Dercole Fabio , Ferri Raffaele , Manconi Mauro
Published: February 2022

The aim of this study was to assess, with numerical simulations, if the complex mechanism of two (or more) interacting spinal/supraspinal structures generating periodic leg movements can be modelled with a single‐generator approach. For this, we have developed the first phenomenological model to generate periodic leg movements in‐silico. We defined the onset of a movement in one leg as the firing of a neuron integrating excitatory and inhibitory inputs from the central nervous system, while the duration of the movement was defined in accordance to statistical evidence. For this study, polysomnographic leg movement data from 32 subjects without periodic leg movements and 65 subjects with periodic leg movements were used. The proportion of single‐leg and double‐leg inputs, as well as their strength and frequency, were calibrated on the without periodic leg movements dataset. For periodic leg movements subjects, we added a periodic excitatory input common to both legs, and the distributions of the generator period and intensity were fitted to their dataset. Besides the many simplifying assumptions – the strongest being the stationarity of the generator processes during sleep – the model‐simulated data did not differ significantly, to a large extent, from the real polysomnographic data. This represents convincing preliminary support for the validity of our single‐generator model for periodic leg movements. Future model extensions will pursue the ambitious project of a supportive diagnostic and therapeutic tool, helping the specialist with realistic forecasting, and with cross‐correlations and clustering with other patient meta‐data.
The Subordination of the Holy Spirit: A Johannine Category
Authors: Hermanin de Reichenfeld Giovanni
Published: February 2022

The aim of this article is to set out Origen’s understanding of ‘subordinationism’ in his Trinitarian theology, focusing particularly on the hypostasis of the Holy Spirit, and to illustrate how this conceptual framework is designed to preserve key features of Johannine logic and language. First, I illustrate the role and functions of the Holy Spirit in Origen’s Trinity by means of the Johannine framework that runs his Trinitarian theology. By pointing out the Johannine ‘debt’ of Origen, I argue that his exegesis of the fourth Gospel is pivotal both in understanding the intra‐Trinitarian relation between hypostases and their respective role in the salvation of the spiritual world. Secondly, using the concept of ‘subordinationism of priority/superiority’, I establish the methodological boundaries of Origen’s investigation of the Trinity, showing that the Johannine framework provides the means to think an ontological subordinationism which neither entails an ontological loss of substance between the hypostases of the Trinity, nor is intended in an anti‐Nicene and proto‐Arian fashion. Overall, the article proposes a new Johannine and methodological framework for understanding Origen’s pneumatology.
“Come and See”: Uncovering Julian of Norwich’s Teaching of Wonder in Revelations of Divine Love
Authors: Scott Jessica
Published: February 2022

Julian of Norwich’s Revelations of Divine Love contain within them two curious suggestions pertaining to sight. First, Julian’s own ‘goostely’ sight is presented in strikingly physical terms, such that her spiritual encounter with God is placed in parallel with what it is physically to see in the material world. Second, Julian insists throughout her text that her reader will be able to ‘see’ God without anywhere expositing what exactly this might mean. It is the argument of this essay that these two suggestions might be understood with reference to each other. Namely, Julian might have steeped her own invisible seeing in strikingly physical terms to indicate the particular capacity of our physical sight to perceive a correlate of the ‘goostely’ sight of God she encounters. I discuss how the experience of perceiving wonder, through the physical senses, might be the reader’s way to partake in her same sight of God. On the one hand, recognising the possible significance of such wonder for Julian enables us to understand more fully dimensions of her theology of embodiment. On the other, understanding ‘wonder’ against the theology she gives it offers us new resources with which to consider the significance of this experience.
MAKING KIN: Rawness, Porosity, and the Agencies
Authors: Bell Joshua A.
Published: February 2022

abstract

This afterword to the special issue “Materiality, Belonging, and the Activation of Difference” begins and ends with Kim TallBear's notion of kin‐making as a frame for understanding the relations between objects, peoples, places, heritage regimes, and museums that allows us to keep different ontological perspectives in view. More specifically, “making kin” allows us to unsettle still‐dominant settler‐colonial violence with an idiom of mutual obligation.
Ecological impact of changes in intrinsic growth rates of species at different trophic levels
Authors: Selaković Sanja , Säterberg Torbjörn , Heesterbeek Hans
Published: February 2022

Decreased and increased intrinsic growth rate and abundance of a single species can severely and negatively impact other species in the same food web. Here we compare the wider system effects of decreased and increased intrinsic growth rates of species occupying different trophic levels. Specifically, we derive the change in growth rate of a single (focal) species necessary to cause a 90% reduction in the abundance – a quasi‐extinction – of another species in model communities. We find that even relatively small changes, negative as well as positive, in the growth rate of the focal species can cause quasi‐extinctions of others. Furthermore, the magnitude of change needed to cause a quasi‐extinction depends on the trophic level of the perturbed species. The potential ecosystem impact of such ‘negative' and ‘positive' changes is largely unknown. We argue that such a targeted decrease or increase could be induced by human interference, such as hunting or harvesting, but also by an outbreak or fade‐out of an infectious disease. As ecosystems maintain many and diverse infectious agents, these results suggest that these agents may play an important role in the structure and balance of ecosystems.
Beyond spatial overlap: harnessing new technologies to resolve the complexities of predator–prey interactions
Authors: Suraci Justin P. , Smith Justine A. , Chamaillé‐Jammes Simon , Gaynor Kaitlyn M. , Jones Menna , Luttbeg Barney , Ritchie Euan G. , Sheriff Michael J. , Sih Andrew
Published: February 2022

Predation risk, the probability that a prey animal will be killed by a predator, is fundamental to theoretical and applied ecology. Predation risk varies with animal behavior and environmental conditions, yet attempts to understand predation risk in natural systems often ignore important ecological and environmental complexities, relying instead on proxies for actual risk such as predator–prey spatial overlap. Here we detail the ecological and environmental complexities driving disconnects between three stages of the predation sequence that are often assumed to be tightly linked: spatial overlap, encounters and prey capture. Our review highlights several major sources of variability in natural predator–prey systems that lead to the decoupling of spatial overlap estimates from actual encounter rates (e.g. temporal activity patterns, predator and prey movement capacity, resource limitations) and that affect the probability of prey capture given encounter (e.g. predator hunger levels, temporal, topographic and other environmental influences on capture success). Emerging technologies and statistical methods are facilitating a transition to a more spatiotemporally detailed, mechanistic understanding of predator–prey interactions, allowing for the concurrent examination of multiple stages of the predation sequence in mobile, free‐ranging animals. We describe crucial applications of this new understanding to fundamental and applied ecology, highlighting opportunities to better integrate ecological contingencies into dynamic predator–prey models and to harness a mechanistic understanding of predator–prey interactions to improve targeting and effectiveness of conservation interventions.
Neonatal anthropometry of malformed newborns: A large South American population‐based study
Authors: Heisecke Silvina , Alfaro Emma L. , Martínez Jorge , Figueroa Marcelo , Bronberg Rubén , Ratowiecki Julia , López Camelo Jorge S. , Dipierri José E.
Published: February 2022

Background

Population‐based anthropometric evaluation of malformed newborns is scarce.

Objectives

To evaluate malformed newborns' foetal growth using the ICD 10 malformations' classification.

Methods

A study including 33,769 newborns (14,857 malformed and 18,912 nonmalformed), selected from 678,840 births from nine South American countries, period 2010–2018, was conducted. Prevalence of severe small and small for gestational age was calculated for malformed and nonmalformed newborns classified by preterm birth categories. Prevalence and relative risk (RR) with its 95% confidence interval (CI) were calculated. The associations between anthropometric phenotypes and congenital malformations were evaluated with generalized linear models.

Results

Prevalence of preterm and term severe small and small for gestational age newborns was higher in malformed than that in nonmalformed neonates. For grouped ICD 10 malformations categories, the RR for severe small for gestational age was 2.88 (95% CI 2.51, 3.30) and 2.10 (95% CI 1.92, 2.30) for small for gestational age. For at‐term and preterm malformed newborns, the RR for severe small for gestational age was 2.21 (95% CI 1.87, 2.61) and 3.21 (95% CI 2.52, 4.10), respectively; for small for gestational age, the RR was 2.31 (95% CI 2.11, 2.53) for at‐term newborns and 2.58 (95% CI 2.16, 3.08) for preterm ones.

Conclusions

Prevalence and relative risk of severe small and small for gestational age vary according to the group of malformations and gestational age; they increase in congenital malformations of the nervous, respiratory and digestive systems, and in chromosomal abnormalities and are lower for malformations of eye, ear, face and neck and cleft lip and palate. Foetal growth considered together with malformed newborns' gestational age would allow for inferring different risks of morbidity and mortality.
Canine sciatic and gluteal lymph nodes can be identified with computed tomography
Authors: Claude Riley J. , Ober Christopher P.
Published: February 2022

Sciatic and gluteal lymph nodes are present in multiple veterinary species, but these lymph nodes are explicitly stated to be absent in dogs. However, structures compatible with lymph nodes have been identified in the appropriate locations in some canine patients undergoing abdominopelvic CT, and the presence of such lymph nodes may have prognostic and therapeutic ramifications in canine patients with abdominopelvic disease. The purpose of this study was to determine the prevalence and characteristics of sciatic and gluteal lymph nodes in dogs on CT. Images of 121 dogs that underwent abdominopelvic CT between September 1, 2020 and December 31, 2020 were reviewed retrospectively by two readers to produce a consensus opinion regarding the presence or absence of sciatic and gluteal lymph nodes. Lymph nodes that were present were measured. Unilateral or bilateral sciatic lymph nodes were present in 19 of 121 dogs (prevalence 15.7%), and bilateral gluteal lymph nodes were identified in one of 121 patients (prevalence 0.8%). Recognition of the presence of sciatic and gluteal lymph nodes in some canine patients may play an important role in the staging of abdominopelvic disease, both in the identification of disease spread and in therapeutic planning.
Impact of farm‐level strategies against thermotolerant Campylobacter in broiler chickens, using a quantitative risk assessment model and meta‐analysis
Authors: Zbrun María Virginia , Olivero Carolina Raquel , Soto Lorena Paola , Lencina Florencia , Frizzo Laureano Sebastián , Zimmermann Jorge Alberto , Signorini Marcelo Lisandro
Published: February 2022

The aim of this study was to evaluate the effect of control strategies (probiotic supplementation and vaccination) at farm on thermotolerant Campylobacter infection due to the consumption of salad cross‐contaminated from broiler meat. The broiler food chain was modelled considering the most common practices applied in Argentina (baseline model) and their effect on the prevalence and counts of Campylobacter. Probiotic supplementation and vaccination against Campylobacter spp. were included in different models to evaluate their effectiveness. The parameter distributions of each intervention were obtained based on a systematic review and meta‐analysis previously described. The control measures applied at farms were evaluated considering their effectiveness in reducing both the prevalence and the count of thermotolerant Campylobacter in comparison with the baseline model estimation and expressed as relative change in campylobacteriosis risk. Additionally, the identification of the most important input parameters for the model was performed by sensitivity analysis. The model estimated a risk of campylobacteriosis per consumed serving of salad contaminated with poultry meat of 4.99 x 10–3 (95% CI: 6.12 x 10–6–1.13 x 10–2), corresponding to an annual incidence risk estimated of 1,876,009 persons. Scenario analysis indicated that the application of vaccines against Campylobacter (probability of campylobacteriosis = 9.55 x 10–4; 95% CI: 5.31 x 10–4–1.29 x 10–3) and the supplementation of broilers with probiotics (probability of campylobacteriosis = 1.32 x 10–3; 8.55 x 10–4–1.69 x 10–3) can offer a modest reduction in risk estimates. The intervention efficacy was 80.86% and 73.54% for vaccination and probiotic supplementation, respectively. On‐farm interventions were effective to mitigate the risk of campylobacteriosis.
Experiences of birthing care during COVID-19: a systematic review protocol
Authors: Macdonald Danielle , Snelgrove-Clarke Erna , Ross-White Amanda , Bigelow-Talbert Kristen
Published: February 2022

Objective:

The objective of this review is to explore and understand the birthing care experiences of midwives, nurses, women, and birthing people during COVID-19.

Introduction:

The COVID-19 pandemic has had implications for providing and receiving birthing care globally. In addition to navigating fears of contracting COVID-19, health care providers and families have had to adapt to changing policies and clinical practices in response to varying recommendations and evidence. These changes, including restrictive visitor policies and mandated mask-wearing, influenced the experience of birthing care. Synthesizing qualitative evidence about the birthing experiences of midwives, nurses, women, and birthing people (people who give birth but who do not identify as women) during COVID-19 can provide important information for policies and decision-making for future global pandemics.

Inclusion criteria:

Studies including licensed midwives, licensed nurses, women, and birthing people who provided or received birthing care during the COVID-19 pandemic will be considered. Studies published from January 2020 onward will be included. The review will consider all studies that present qualitative data, including, but not limited to, research designs such as phenomenology, ethnography, grounded theory, feminist research, and action research.

Methods:

The following databases will be searched: MEDLINE, Embase, CINAHL, PsycINFO, and LitCovid. MedArchiv, PsyArXiv, and Google Scholar will be searched for gray literature. Studies will be assessed independently by two reviewers. Any disagreements will be resolved through discussion or with a third reviewer. Data extraction will be completed by two reviewers. The JBI tools and resources will be used for meta-aggregation, including the creation of categories and synthesized findings.

Systematic review registration number:

PROSPERO CRD42021292832
The Integration of Concepts in the Terminology of Measurement and Control
Authors: Mason H. L.
Published: February 2022

Problems in measurement and control arise in every field of science and technology, but many aspects are common or interdependent. Examination is here made of the origins, nature, spread, and fixity of the relevant American words and their glosses. Existing agencies are noted, and suggestions are made as to useful approaches to and procedures in terminology.
Turbulence in a Tilting-Pad Thrust Bearing
Authors: Abramovitz Stanley
Published: February 2022

Using water as a lubricant, experiments were made with a tilting-pad thrust bearing. It was found that the friction torque increased abnormally when the rubbing speed exceeded what appeared to be a critical value. This abnormal torque indicated the possible effect of turbulence in the hydrodynamic film between the runner and pads. An analysis was made of experimental data based on the work of G. I. Taylor. These data show the effect on friction torque of the variables of fluid viscosity and sliding speed for both laminar and turbulent film conditions.
Investigation of Translatory Fluid Whirl in Vertical Machines
Authors: Boeker G. F. , Sternlicht B.
Published: February 2022

The problem of translatory fluid whirl has been investigated for a rigid shaft running in a vertical position in rigidly supported bearings. This investigation consists of a theoretical bearing analysis and an experimental verification of the theory for two types of bearings.
Improving Airplane Handling Characteristics With Automatic Controls
Authors: Muzzey C. L.
Published: February 2022

The paper describes an important mode of airplane flight in which the aircraft is under the joint control of a human pilot and an automatic control system. The first part of the paper describes the interaction of air loads and inertia reactions which govern the dynamic stability of the airplane, and seeks to give a physical picture of the response of the airplane to control and random disturbances. The paper then describes a research project in which the pilot’s controls were disconnected from the control surfaces, and separate servos provided both to drive the aerodynamic surfaces, and to resist the actions applied to the cockpit-controls by the pilot. The surface servos receive signals from cockpit-control motions and from a stability computer which senses airplane-body motions. Airplane response as seen by the pilot can be varied by adjusting the computer, and the pilot is unaware of the control-surface motions caused by the computer. Thus both airplane stability and control feel can be varied independently and easily in flight. Research airplanes so equipped are now being used to map out regions of acceptability for future design in the handling characteristics problem, and are incidentally demonstrating means for stabilizing existing airplanes which may be deficient in one or more respects.
Ultrasonic Testing of Small-Diameter Tubing With Automatic Recording Equipment
Authors: Fleischmann W. L. , Rocha H. A. F.
Published: February 2022

This paper presents the progress made in the ultrasonic test equipment which now appears to make automatic testing of small-diameter tubing a distinct possibility. It then presents some cross sections, showing the type and size of discontinuities detected with this equipment in Type 347 stainless-steel tubing. Finally, the summary points out the inherent difficulties in judging the severity of the defect by the amplitude indications alone and the importance of the experience factor which is required to interpret the test results.
Oil and Gas-Well Casing Suspension Assemblies
Authors: Rhodes A. F. , Wilhoit J. C.
Published: February 2022

This paper provides the engineer with an analytical method for use in designing or evaluating oil and gas-well casing suspension assemblies. It develops equations for deflection and stress and confirms their results by reports of controlled experiments. The design applications of the theory are discussed and detailed consideration given to an optimum casing suspension design.
Dynamic Analysis of Chemical Processes
Authors: Holzmann E. G.
Published: February 2022

The dynamic characteristics of a process must be known in order to predict stability of control. Necessary dynamic equations are formulated from considerations of heat balance and mass balance. The derivation of linear transfer functions for an exemplary catalytic reaction process is discussed in detail.
Lower Flue-Gas Exit Temperatures Through Removal of the Solids Ahead of the Air Preheater
Authors: Tigges A. J. , Karlsson Hilmer
Published: February 2022

The paper is a philosophical discussion of flue gases and stresses the important part played by the “extreme fine” solids in the flue gas. These fines are considered one of the major causes of problems with low-temperature surfaces of the boiler system, cause visible smoke, and are believed to contribute to the dangers of “smog.” Methods for removing fines in a high-temperature zone are discussed. Results are given from experimental work for removal of fines at high temperature and high velocity with high collecting efficiency.
Factors Influencing the Notch Fatigue Strengthening of N-155 Alloy at Elevated Temperatures
Authors: Hyler W. S. , Simmons W. F.
Published: February 2022

Data are given to illustrate the effect of stress raisers on the elevated-temperature fatigue behavior of N-155 alloy. These data were obtained on specimens notched with V-grooves having various root radii and various notch severities. The experimental program was in direct-stress fatigue, and covered a range of alternating stress to mean stress from A = 0.0 to A = ∞ at temperatures of 1200 to 1500 F. The effect of surface finish also was studied to a limited extent. A metallographic study of fractured surfaces was carried out.
Orifice Coefficients for Reynolds Numbers from 4 to 50,000
Authors: Iversen H. W.
Published: February 2022

The sharp-edged orifice meter is standardized in shape and application by The American Society of Mechanical Engineers (1, 2) and by the International Standards Association (3). With sufficient precision and care in fabrication of the orifice and metering section, and with standard techniques of use, the accepted coefficients as listed in the codes may be used within prescribed metering accuracy tolerance over the Reynolds number range of the standardization. Many applications arise for use of the orifices in the Reynolds-number range below that of the present standards. Calibration results in the “low” Reynolds-number range are available in the literature as obtained by numerous investigators. These were assembled to produce, if possible, standard coefficients for the Reynolds-number range of 4 to 50,000 (based on the pipe diameter) and for orifice-to-pipe diameter ratios of 0.1 to 0.8.
Effect of a Globe Valve in Approach Piping on Orifice-Meter Accuracy
Authors: Murdock J. W. , Foltz C. J. , Gregory Clarence
Published: February 2022

This paper presents the results of a series of steam and water tests on sharp-edged thin-plate orifices preceded by a globe valve at various distances. Curves are given, showing the magnitude of change in indicated flow, when the approach piping is less than that recommended by the Joint AGA-ASME Committee on Orifice Meters. Comparative curves with the valve throttled also are given.
Plastic Metalworking
Authors: Crane E. V.
Published: February 2022

Our prosaic objective is to stimulate analytical thinking, co-ordinate it with practice, and present it in usable form for the man in the field. Our assignment is in the art and science of forcing metals to flow into new shape, as distinguished from the whittling processes of metal cutting. More economical automobiles, better cooking utensils and refrigerators, faster planes, and even space ships are our field problems. We get exciting glimpses of new possibilities in the flowing of heat-treated steels at 150 tons per square inch and more. To obtain scientific basis for the advancement of the growing art, we must pursue the relationships of plastic flow, strain hardening, aging, residual stresses, and endurance characteristics back to the space-force relationships of the atom and the molecule. We face the sobering responsibility that our enthusiastic flights into higher mathematics, Greek letters, and coined terminologies must be brought back to a generally understandable and usable level.
Zirconium-Fabrication Techniques and Alloy Development
Authors: Lacy C. E. , Keeler J. H.
Published: February 2022

The fabrication techniques by which zirconium and its alloys have been successfully made into various product forms are described. The neutron-absorption characteristics, mechanical properties, and corrosion resistance of zirconium and some zirconium alloys are discussed.
Analytical Study of Journal-Bearing Performance Under Variable Loads
Authors: Shawki G. S. A.
Published: February 2022

This paper presents basic theoretical investigations into the performance of a complete journal bearing of infinite width under conditions of variable load. The theory excludes the existence of negative pressure (below vapor pressure) in the lubricating film. Analytical solutions are given for few simple cases; they show closer agreement with experiment than those attained by previous theory. Owing to the complexity of the equations involved in the analysis, solutions, in general, may be effected only by numerical computations; tables of relevant functions are included. Further work on the subject is proceeding.
Journal-Bearing Operation at Superlaminar Speeds
Authors: Smith M. I. , Fuller D. D.
Published: February 2022

Journal bearings today are generally designed to operate under such conditions that laminar flow prevails in the lubricant film. However, with the continuing trend in machine design toward higher speeds, there is the possibility that the limits of laminar flow may be exceeded in many bearings of the future. In the investigation reported in this paper, the load-carrying and frictional characteristics of a journal bearing were studied at speeds ranging up to five times the critical speed. The “critical speed” is defined as that rotational velocity which just causes breakdown of laminar flow.
Two-and Three-Dimensional Flow of Air Through Square-Edged Sonic Orifices
Authors: Weir Alexander , York J. L. , Morrison R. B.
Published: February 2022

In this investigation, the two-dimensional flow of air through rectangular, and the three-dimensional axisymmetrical flow of air through circular, square-edged, sonic orifices were examined under pressure ratios ranging from 1.894 to 42.0 (upstream stagnation pressure/downstream static pressure). Mass-flow measurements were made using a primary metering system, rather than another orifice or nozzle, and optical techniques were used to obtain pictures of the flow upstream, within the thickness of the orifice plate, and downstream of the orifice. Evidence is presented in this paper which indicates that square-edged sonic orifices can be treated as sonic nozzles by utilizing the concept that the air “turning the corner” of the orifice plate, in effect, makes its own nozzle. It is believed that this interpretation of experimental observations is in full agreement with established principles of aero- and thermodynamics.
Some Aerodynamic Investigations in Centrifugal Impellers
Authors: Hamrick J. T.
Published: February 2022

Results of both theoretical and experimental investigations of flow in rotating impeller passages are presented. It is the purpose of this presentation to acquaint the designer with the manner in which losses arise, their effect upon the flow within the passage, and their over-all effect upon impeller performance. In addition, analysis and design methods based on isentropic-flow calculations are discussed and their application to the design of mixed-flow impellers is demonstrated.
The Aerothermopressor—A Device for Improving the Performance of a Gas-Turbine Power Plant
Authors: Shapiro A. H. , Wadleigh K. R. , Gavril B. D. , Fowle A. A.
Published: February 2022

Theoretical and experimental investigations of a novel gas-dynamics device having no moving parts yet performing the function of a compressor, are described. This device, called the “Aerothermopressor,” exploits the possibility of raising the total pressure of a high-speed gas stream through cooling of the gas. When placed at the exhaust of a gas turbine, the Aerothermopressor will reduce the exhaust pressure, thereby improving both fuel economy and power capacity per unit of air flow. Basic elements of the apparatus comprise a nozzle which accelerates hot gas into an evaporation section; a water-injection system which delivers finely atomized water into the high-speed stream; an evaporation section in which the gas is cooled and most of the water evaporated; and, finally, a diffuser in which the gas stream is decelerated and the static pressure increased.

Although the Aerothermopressor is simple in structural arrangement, the physical processes occurring within it are exceedingly complex in their details. The simultaneous effects on the gas stream of droplet drag, evaporative cooling, area variation, and wall friction lead to many regimes of operation, including the hitherto unknown passage from subsonic to supersonic speeds in a constant-area duct. Theoretical calculations of a one-dimensional nature, involving for the gas stream the equations of continuity, momentum, and energy, and for the liquid-droplet cloud the equations of motion, heat transfer, and mass transfer, have been carried out on a high-speed, electronic digital computer. The theory reproduces all the behavior patterns of experimental units and is in generally good quantitative agreement with the experimental data.

The results of experiments on a small-scale, constant-area unit of 2.13 in. diam are presented and compared with theoretical calculations. The experiments and theory both show that a net stagnation rise is possible only with gas flows greater than about 2 lb/sec; below this value the detrimental effects of wall friction completely absorb the gains due to cooling. In the range of 25 lb/sec a net stagnation pressure rise of about 10 per cent seems assured, while 20 per cent seems possible.

Early tests on a recently completed medium-scale unit of 25 lb/sec capacity have already demonstrated a net overall rise in stagnation pressure.
Flow in Corners of Passages With Noncircular Cross Sections
Authors: Eckert E. R. G. , Irvine T. F.
Published: February 2022

Conditions for convective heat transfer are known to be especially poor in the corner regions of noncircular passages. This situation causes the passage walls to become too hot in certain types of heat exchangers and directs attention to flow conditions in the corner regions. An experimental and theoretical investigation was conducted on the flow characteristics of triangular-shaped passages. Flow-visualization techniques revealed the remarkable fact that through a certain range of Reynolds numbers laminar and turbulent flows exist simultaneously side by side. Pressure measurements were made on two ducts to study the influence of the geometry on the hydrodynamic entrance length. The velocity field within the ducts was measured over a Reynolds number range from 500 to 43,000. An analytical study of the flow resulted in the development of a simple expression to describe the velocity field under the conditions of laminar fully developed flow in a narrow corner. This expression was confirmed experimentally using a sensitive micromanometer developed for this purpose.
On the Maximum and Minimum Velocities and the Accelerations in Four-Link Mechanisms
Authors: Freudenstein Ferdinand
Published: February 2022

A method of analysis has been developed for obtaining (a) geometrical criteria for an extreme value of the angular velocity ratio of one link relative to another in a four-bar mechanism; (b) a direct method of determining the angular acceleration of the follower link of a four-bar mechanism, and maximum values of this acceleration in certain special cases. The results have been applied to a slider-crank mechanism.
Determination of Pressure Angles for Swinging-Follower Cam Systems
Authors: Kloomok Martin , Muffley R. V.
Published: February 2022

The maximum pressure angle is required for an analysis of the forces existing in a cam system. In this paper an exact expression is derived for pressure angle in a swinging roller-follower cam system, and a chart is presented indicating a method for finding a quick numerical solution for a particular cam contour, such as the harmonic or the cycloidal.
The Role of Chip Thickness in Grinding
Authors: Reichenbach G. S. , Mayer J. E. , Kalpakcioglu S. , Shaw M. C.
Published: February 2022

Grinding chips are classified into five types depending upon their relative thickness-to-length ratio and equations are derived for computing the length or thickness of chips of all types for external, surface, internal, and plunge-grinding operations. Representative experimental grinding data are presented and discussed to illustrate the use of the equations and to emphasize the importance of chip thickness as a grinding parameter. The force on a single grain is derived and the result applied to explain relative wheel hardness.
Behavior of Air in the Hydrostatic Lubrication of Loaded Spherical Bearings
Authors: Corey T. L. , Tyler C. M. , Rowand H. H. , Kipp E. M.
Published: February 2022

Some experimental data have been obtained relating the load-bearing capacity of air films of various thicknesses and operating at different pressures and rates of flow for 2, 4, and 6-in. spherical-type bearings. Semi-empirical equations have been developed for calculation of (a) minimum air pressure as a function of load; (b) minimum flow of air as a function of pressure; (c) bearing lift as a function of air pressure.
Density-Temperature-Pressure Relations for Liquid Lubricants
Authors: Hartung H. A.
Published: February 2022

Recently published data on the density of lubricating fluids have been treated to separate the effects of temperature and pressure. Correlations are developed which reproduce the original data within less than 1 per cent in most cases for petroleum fractions, pure hydrocarbons, polymer blended oils, and commercial lubricants. It is expected that the relations found will apply to all liquid lubricants which are principally petroleum hydrocarbons. Density at any temperature up to 425 F and at pressures up to 80,000 psi can be found from the density at room temperature and atmospheric pressure and the viscosity at 100 F.
Varieties of Shaft Disturbances Due to Fluid Films in Journal Bearings
Authors: Newkirk B. L.
Published: February 2022

Diversities of behavior and some seeming inconsistencies among the disturbances due to the action of fluid films in journal bearings are described. These are shown to be broadly consistent and in accord with findings of analysis. Some items of observed behavior are mentioned and critical speeds due to fluid-film action are listed.
Yield and Bursting Characteristics of Heavy-Wall Cylinders
Authors: Faupel J. H.
Published: February 2022

Data obtained from nearly 100 static cylinder tests under internal pressure have been examined statistically and design formulas proposed for elastic-breakdown pressure and bursting pressure. The formulas are reliable within ± 15 per cent of the observed value on a 90 per cent certainty basis.
Ebullition Cooling of Gas Engines
Authors: Bates G. O. , English J. E. , Franklin G. M.
Published: February 2022

The ebullition system is defined as a method for cooling internal-combustion engines by boiling water in the engine jackets. No pump is required because thermal circulation is maintained. Relationships of power requirements, equipment prices, and installed costs for ebullition systems and conventional forced-circulation water systems are shown graphically. Satisfactory performance over an initial operating period of ten months is reported for the cooling equipment and engines on five units equipped with ebullition systems. Observations on those units during the same period indicate that engine maintenance will be less than for similar engines with conventional cooling. In view of its economy, simplicity, and satisfactory functional performance, ebullition cooling is expected eventually to supersede conventional water cooling.
Chatter Vibration of Lathe Tools
Authors: Doi S. , Kato S.
Published: February 2022

This paper deals with a chatter vibration which occurs frequently when metals are being machined. It has been ascertained experimentally that the chatter is a self-excited vibration caused by the lag in fluctuation taking place in the horizontal cutting force behind the horizontal vibration of the work. Because of this delay in cutting force, it has been proved that the chatter may be expressed in terms of a difference-differential equation.