bluuebunny/crossref_metadata_2025 huggingface dataset:
Variable Selection with ABC Bayesian Forests
Authors: Liu Yi , Ročková Veronika , Wang Yuexi
Published: April 2021

Few problems in statistics are as perplexing as variable selection in the presence of very many redundant covariates. The variable selection problem is most familiar in parametric environments such as the linear model or additive variants thereof. In this work, we abandon the linear model framework, which can be quite detrimental when the covariates impact the outcome in a non-linear way, and turn to tree-based methods for variable selection. Such variable screening is traditionally done by pruning down large trees or by ranking variables based on some importance measure. Despite heavily used in practice, these ad hoc selection rules are not yet well understood from a theoretical point of view. In this work, we devise a Bayesian tree-based probabilistic method and show that it is consistent for variable selection when the regression surface is a smooth mix of p > n covariates. These results are the first model selection consistency results for Bayesian forest priors. Probabilistic assessment of variable importance is made feasible by a spike-and-slab wrapper around sum-of-trees priors. Sampling from posterior distributions over trees is inherently very difficult. As an alternative to Markov Chain Monte Carlo (MCMC), we propose approximate Bayesian computation (ABC) Bayesian forests, a new ABC sampling method based on data-splitting that achieves higher ABC acceptance rate. We show that the method is robust and successful at finding variables with high marginal inclusion probabilities. Our ABC algorithm provides a new avenue towards approximating the median probability model in non-parametric setups where the marginal likelihood is intractable.
Ethnic Diversity and Local Economies
Authors: Dinku Yonatan , Regasa Dereje
Published: April 2021

The effect on economic outcomes of ethnic diversity remains debatable. Some view ethnic diversity as a deterrent of development, whereas others consider it a source of innovation and productivity, which can be translated into a higher level of development. This study aims to shed further light on the issue. Applying instrumental variables estimation to district‐level data, we find that ethnic diversity has a significant positive association with nighttime light intensity, which is used as a proxy for level of economic activity. The finding is robust to alternative specifications. Our finding suggests that centuries of interethnic contacts and coexistence may have helped ethnically diverse communities to gain experimental knowledge of the diverse beliefs and social practices and transition it into better economic outcomes.
Phylogeny of true ladybird beetles (Coccinellidae: Coccinellini) reveals pervasive convergent evolution and a rapid Cenozoic radiation
Authors: Tomaszewska Wioletta , Escalona Hermes E. , Hartley Diana , Li Jiahui , Wang Xingmin , Li Hao‐Sen , Pang Hong , Ślipiński Adam , Zwick Andreas
Published: April 2021

Coccinellini, the ‘true ladybirds’, is a large, cosmopolitan tribe of lady beetles with immense variability in colour and form that include many commonly recognized species and major biocontrol agents, as well as some ubiquitous invasive species. In this study, we performed phylogenetic analyses of molecular and morphological data. For the molecular analysis, we gathered DNA sequence data from 164 species in 57 genera (and outgroups) from five nuclear genes [CAD (two fragments), TOPO, WGL, 3059fin] and one mitochondrial (COI) gene. The morphological analyses comprised 301 terminals and 61 discrete characters that were analysed by parsimony (MP). Our phylogenetic analyses indicate a monophyletic Coccinellini (former Coccinellinae) containing previously recognized tribes [Coccinellini, Discotomini, Halyziini, Singhikaliini and Tytthaspidini (incl. Bulaeini)]. Coccinellini is further divided into four main clades as follows: the Coccinella group (Clade A; incl. former Tytthaspidini), the Cycloneda group (Clade B), the Hippodamia group (Clade C) and the Synonycha group (Clade D; incl. former Halyziini, Singhikaliini and Discotomini). The phylogenetic relationships between them are: (A, (B, (C, D))). Our analyses also indicate that several currently recognized genera of Coccinellini are para‐ or polyphyletic. Based on our phylogenetic results, new generic groups are defined for Coccinellini, and new generic amendments are proposed as follows: Micraspis Chevrolat sensu n. (Oriental and Australian species), Microcaria Crotch sensu n. (=Bothrocalvia Crotch) (incl. Coelophora Mulsant species) and Phrynocaria Timberlake sensu n. (incl. Coelophora species). Further possible synonyms are discussed, for example, Coccinella Linnaeus (incl. Lioadalia Crotch), Psyllobora Chevrolat (including Oxytella Weise) and Xanthadalia Crotch (incl. Declivitata Fürsch and the African species of Micraspis). The large Clade D, the Synonycha group, with 26 predominant Old World genera, contains the two notable, large and non monophyletic genera Calvia Mulsant and Coelophora that confound the relationships throughout the clade. Additionally, we performed ancestral state reconstruction of selected morphological characters traditionally used in the classification of this group, revealing their homoplastic nature. We also found that the traditional synapomorphy of the tribe, that is, female colleterial glands, closely resemble structures used in symbiotic relationships in other beetles. We used the results of our phylogenetic inferences to estimate divergence times of the tribe and major clades of Coccinellini.
Diagnostic pitfalls of urogenital tuberculosis
Authors: Chandran Shruthi , Rahman Ananna , Norris Joseph M. , Tiberi Simon , Kunst Heinke
Published: April 2021

Objectives

To describe characteristics, details of diagnosis and outcomes of urogenital tuberculosis (UGTB) in a low‐prevalence country.

Methods

We conducted a retrospective observational study of 37 consecutive patients diagnosed with UGTB between 1st January 2014 and 31st October 2019 in an East London hospital.

Results

68% (25/37) of patients were male and the median age was 42 years (IQR 34–55). 89% (33/37) of patients were born outside the United Kingdom with 65% (24/37) born in the South Asian region. Renal (32.4%), epididymal (24.3%) and endometrial TB (21.6%) were the most prevalent forms of UGTB. Only 13.5% of UGTB patients had concurrent pulmonary TB. The median length of time from symptom onset to treatment was 163 days, while endometrial TB had an average delay to diagnosis of 564 days. Approximately half of patients with UGTB were culture positive (51.4%). However, 70% of early morning urines (EMUs) sent in urinary TB were culture positive. 11 patients (30.6%) underwent two or more invasive procedures, such as biopsy to obtain specimen samples. The mean treatment length for all UGTB cases was 7.3 months (SD 3.1). Notably, 25% of patients with endometrial TB required surgery despite antituberculous treatment.

Conclusions

UGTB is challenging to diagnose as early disease is often asymptomatic. Clinicians faced with non‐specific symptoms, or features suggestive of urogenital malignancy amongst patients from TB‐endemic areas, should maintain a high suspicion of UGTB.
Purification and analysis of a protein cocktail capable of scavenging cell‐free hemoglobin, heme, and iron
Authors: Pires Ivan S. , Govender Krianthan , Munoz Carlos J. , Williams Alexander T. , O'Boyle Quintin T. , Savla Chintan , Cabrales Pedro , Palmer Andre F.
Published: April 2021

Background

Hemolysis releases toxic cell‐free hemoglobin (Hb), heme, and iron, which overwhelm their natural scavenging mechanisms during acute or chronic hemolytic conditions. This study describes a novel strategy to purify a protein cocktail containing a comprehensive set of scavenger proteins for potential treatment of hemolysis byproducts.

Study Design and Methods

Tangential flow filtration was used to purify a protein cocktail from Human Cohn Fraction IV (FIV). A series of in vitro assays were performed to characterize composition and biocompatibility. The in vivo potential for hemolysis byproduct mitigation was assessed in a hamster exchange transfusion model using mechanically hemolyzed blood plasma mixed with the protein cocktail or a control colloid (dextran 70 kDa).

Results

A basis of 500 g of FIV yielded 62 ± 9 g of a protein mixture at 170 g/L, which bound to approximately 0.6 mM Hb, 1.2 mM heme, and 1.2 mM iron. This protein cocktail was shown to be biocompatible in vitro with red blood cells and platelets and exhibits nonlinear concentration dependence with respect to viscosity and colloidal osmotic pressure. In vivo assessment of the protein cocktail demonstrated higher iron transport to the liver and spleen and less to the kidney and heart with significantly reduced renal and cardiac inflammation markers and lower kidney and hepatic damage compared to a control colloid.

Discussion

Taken together, this study provides an effective method for large‐scale production of a protein cocktail suitable for comprehensive reduction of hemolysis‐induced toxicity.
Deep transfer learning can be used for the detection of hip joints in pelvis radiographs and the classification of their hip dysplasia status
Authors: McEvoy Fintan J. , Proschowsky Helle F. , Müller Anna V. , Moorman Lilah , Bender‐Koch Johan , Svalastoga Eiliv L. , Frellsen Jes , Nielsen Dorte H.
Published: April 2021

Reports of machine learning implementations in veterinary imaging are infrequent but changes in machine learning architecture and access to increased computing power will likely prompt increased interest. This diagnostic accuracy study describes a particular form of machine learning, a deep learning convolution neural network (ConvNet) for hip joint detection and classification of hip dysplasia from ventro‐dorsal (VD) pelvis radiographs submitted for hip dysplasia screening. 11,759 pelvis images were available together with their Fédération Cynologique Internationale (FCI) scores. The dataset was dicotomized into images showing no signs of hip dysplasia (FCI grades “A” and “B”, the “A‐B” group) and hips showing signs of dysplasia (FCI grades “C”, “D,” and “E”, the “C‐E” group). In a transfer learning approach, an existing pretrained ConvNet was fine‐tuned to provide models to recognize hip joints in VD pelvis images and to classify them according to their FCI score grouping. The results yielded two models. The first was successful in detecting hip joints in the VD pelvis images (intersection over union of 85%). The second yielded a sensitivity of 0.53, a specificity of 0.92, a positive predictive value of 0.91, and a negative predictive value of 0.81 for the classification of detected hip joints as being in the “C‐E” group. ConvNets and transfer learning are applicable to veterinary imaging. The models obtained have potential to be a tool to aid in hip screening protocols if hip dysplasia classification performance was improved through access to more data and possibly by model optimization.
Water management under climate change: The role of water commons and policy options
Authors: Zulfiqar Farhad , Abid Muhammad , Ullah Raza , Shahzad Saqib
Published: April 2021

This research assessed the robustness of a new water governance system in Pakistan through Ostrom’s design principles, examined the potential of water commons against climate‐induced water scarcity, the role compliance of Khal Panchayat (KP, watercourse level user association) and problems in their implementation. Data collection included personal interviews and focus group discussions (FGDs) with 125 farmers in five KPs from Punjab. Findings revealed that the presence of the eight design principles varied from 3.32 to 5.80 principles per KP. However, only one KP had a robust potential against water scarcity. The FGDs identified that conflicts were likely to increase due to water scarcity. Moreover, conflict resolution and collection of water charges were the least followed roles due to lack of legal protection. However, KPs fulfilled the roles related to watercourse maintenance, conducting internal meetings and elections. Thus, more climate‐resilient water co‐management under commons requires legal protection, and authority to redraw demand‐based water allocation.
A Study of the Supersonic Axial-Flow Compressor
Authors: Loeb W. A.
Published: April 2021

This paper presents a summary of the basic principles of the supersonic compressor and an analytical study of the types of this compressor most likely to prove successful. This study assumes rather idealized conditions, ignoring such variables as radial effects and flow irregularities. Hence the results are not intended as design criteria. They should, however, give a fair guide to what may be expected of the various cases considered; their outstanding limitations, their range of operation, and their performance expectations. Conclusions are that good pressure ratios with high efficiencies may be attained; that the compressor having a normal shock in the stator is superior to that having a normal shock in the rotor; and that the largest restriction on this normal-shock-in-stator compressor is the Mach number limitation in the rotor.
Three-Dimensional Solution for the Stress Concentration Around a Circular Hole in a Plate of Arbitrary Thickness
Authors: Sternberg E. , Sadowsky M. A.
Published: April 2021

This paper contains an approximate three-dimensional solution for the stress distribution around a circular cylindrical hole in an infinite plate of arbitrary thickness, which is otherwise in a uniform state of plane stress parallel to the bounding planes. The approach used rests on a modification of the Ritz method in the theory of elasticity. A knowledge of the triaxial characteristics of the ensuing stress concentration is held important in connection with modern views on failure. The results furthermore illuminate critically the significance of two-dimensional analysis in problems of the type under consideration.
The Basic Elastic Theory of Vessel Heads Under Internal Pressure
Authors: Watts G. W. , Burrows W. R.
Published: April 2021

Means are outlined for calculating internal pressure stresses and deformations at or near the junctures of semi-infinite cylindrical vessel shells with hemispherical heads, ellipsoidal heads, toriconical heads, torispherical heads, conical heads, and flat heads. The accurate Love analysis is used in this development. A system of dimensionless variables is proposed for each head shape to define the changes in that shape and the changes in the relative thicknesses of the heads and cylinders. Ways are devised to show the critical head stresses in terms of these dimensionless variables either by graphs or by tabulations. The fundamental theory is sufficiently described to indicate how all results are derived.
On the Stability of Plates Reinforced by Ribs
Authors: Klitchieff J. M.
Published: April 2021

The stability of plates reinforced by a large number of transverse ribs and subjected to compressive loading is considered. An expression is developed which gives directly the required rigidity of the ribs by transformation of the expression for critical compressive forces previously developed by S. Timoshenko. Use of trigonometric series is made to calculate effective width of plate. A numerical example is given to compare the results of the method with Lloyd’s Rules (1931–1932) used in cargo-ship design.
The Manifold Problem
Authors: Keller J. D.
Published: April 2021

This paper deals with the general problem of manifolds supplying fluids to a set of parallel pipes or ducts, or discharging through numerous openings distributed along the manifold length. Examples are the familiar “pipe burner” for gaseous fuels; the manifold of the “radiant-fire” type of gas burner; headers or manifolds for certain types of multitube air heaters; the distributing flues above and below the checkers of open-hearth furnaces and of glass tanks; furnace combustion chambers containing heat ports; distributing pipes in water-filtering systems; and many others. The very specialized problem of the gasoline-engine manifold is not considered here.
Theory of the Damped Dynamic Vibration Absorber for Inertial Disturbances
Authors: Brock J. E.
Published: April 2021

If a mass which is mounted flexibly is set into forced vibrations by a harmonic force having an amplitude which does not vary with frequency, a damped dynamic vibration absorber may be designed to reduce the vibrations to some preassigned amplitude, regardless of the range over which the frequency of the disturbing force may vary. The theory of this type of vibration absorber, together with valuable discussion, has been given in a paper by Ormondroyd and Den Hartog, and is readily available in Den Hartog’s text on mechanical vibrations. In this paper the author presents a similar analysis for the case in which the amplitude of the disturbing force varies as the square of its frequency. For lack of a better name, this will be referred to as the case of “inertial disturbance.” Such cases are of considerable practical importance. For example, disturbances due to unbalance in rotating machinery are of this type. In some cases, such as those in which the unbalance varies with temperature, it may be impractical or impossible to secure perfect or nearly perfect balance, and a vibration absorber, designed on the basis of the analysis to be presented, may offer a suitable remedy. A practical example of this nature is given. The analysis follows a pattern similar to that given by Den Hartog, but enough of the details are different to warrant an extended treatment.
The Shape of a Piston Ring in Its Unrestrained State
Authors: Chang Che-Tyan
Published: April 2021

It is the purpose of this paper to develop, with mathematical means, a general equation between the free shape of a piston ring in its unrestrained state and the consequent radial-pressure pattern against the cylinder wall after its installation. It is up to the designer, first to decide upon the proper pressure distribution for his particular need, and then to use such an equation as a first guide to evaluate the proper free shape of the ring so that it will give him the required radial-pressure pattern after its installation in the cylinder.
Numerical Solution of Elastoplastic Torsion of a Shaft of Rotational Symmetry
Authors: Eddy R. P. , Shaw F. S.
Published: April 2021

Using relaxation methods, an approximate numerical solution is found of the stress distribution in a shaft of rotational symmetry, which is subjected to a torque of sufficient magnitude to cause portions of the material to yield. It is assumed that the material of which the shaft is composed is isotropic and yields according to the condition of von Mises. The particular problem investigated is a shaft with a collar; results are presented showing the elastoplastic boundary, and the stress distribution, for two different amounts of plastic deformation.
Fracture of Gray-Cast-Iron Tubes Under Biaxial Stresses
Authors: Grassi R. C. , Cornet I.
Published: April 2021

The fracture of gray-cast-iron thin-wall tubes was investigated, for various ratios of axial to tangential stress ranging from pure tension to pure compression, yielding data for some stress ratios not previously reported. Analysis of the results reveals that the present theories of fracture do not account completely for the data obtained, thus indicating the need for further investigations of similar materials.
Bending of Rectangular Plates Subjected to a Uniformly Distributed Lateral Load and to Tensile or Compressive Forces in the Plane of the Plate
Authors: Conway H. D.
Published: April 2021

This paper presents a method of determining the distribution of deflection and stress in simply supported rectangular plates subjected simultaneously to a uniform lateral load and to uniform tensile or compressive forces in the plane of the plate. The problems are of particular importance in the design of a ship’s bottom plating and, for this reason, graphs are given whereby the maximum stress and deflection may easily be calculated. Illustrative examples are included to demonstrate the use of these graphs. An example is also given to illustrate how the method may be extended to include the case of hydrostatic pressure.
Biaxial Tension-Tension Fatigue Strengths of Metals
Authors: Marin Joseph
Published: April 2021

This paper describes a new fatigue testing machine for the application of tension-tension biaxial stresses and presents the results of an investigation on the biaxial fatigue strength of Alcoa 24S-T. The influence of various ratios of the maximum values of the principal stresses upon the fatigue strength was determined. Fluctuating biaxial tensile stresses were produced by subjecting a thin-walled tubular specimen to a pulsating internal pressure and a pulsating axial load. The maximum and minimum values of the principal stresses were kept in phase. Fatigue strengths and S-N diagrams for four principal stress ratios were obtained.
A Comparative Study of Some Variational Principles in the Theory of Plasticity
Authors: Hill Rodney
Published: April 2021

The variational principle of Markov for velocity distributions in a plastic state is extended to a work-hardening material and to more general boundary conditions. A relationship is shown to exist between Markov’s principle and the maximum work principle of Hill.
Influence of the Dimensional Factors on Mode of Yielding and Fracture in Medium-Carbon Steel—II: The Size of the Round Tensile Bar
Authors: Miklowitz Julius
Published: April 2021

Test results show an increase in axial strain, average true stress, and maximum true stress at the minimum section of the neck of a round tension bar at fracture when the size of the bar is decreased. An explanation is given for this size effect on the axial strain. It suggests that the restraint on the flowing material at the heart of the neck, created by lateral stresses induced by the adjacent stagnant material, is dependent upon the diameter of the stagnant material; hence the bar diameter. Some metallurgical variations in the data are analyzed and discussed.
Stresses and Deflections of Cylindrical Bodies in Contact With Application to Contact of Gears and of Locomotive Wheels
Authors: Poritsky H.
Published: April 2021

From the well-known Hertz theory of contact stresses, where contact is over a finite area, the more elementary two-dimensional case of contact between two cylinders with parallel generators may be obtained as a limiting case by allowing the contact area to become infinitely long in one direction. However, it is easier to obtain it directly; this is done in the paper.
The Flow and Fracture of a Brittle Material
Authors: Coffin L. F.
Published: April 2021

The mechanism of flow and fracture of a gray cast iron can be understood if one considers the microstructure to consist of a ductile structure with a random dispersion of cracks due to the graphite flakes following the concept of Fisher. A notch effective stress can be calculated for a critically situated crack by a knowledge of the external stresses, a plastic stress-concentration factor of 3, and a residual tensile stress at the sharp edge of the crack, based upon either the “maximum-shear” theory or the “distortion-energy” theory. This allows the formulation of generalized plastic stress-strain relationships and renders gray cast iron applicable to the many known solutions for plastic flow of ductile metals. Fracture in the region of tension-tension and tension-compression can be evaluated by a similar analysis, using the same stress-concentration factor and the same residual stress. A combined stress-testing program is described wherein thin-walled cast-iron tubes are subjected to two-dimensional states of combined stress covering the complete two-dimensional field.
Bending of an Elliptical Plate by Edge Loading
Authors: Nash W. A.
Published: April 2021

A series solution is presented for the problem of the small deflections of a thin elliptical plate with the following boundary conditions: (a) The edge of the plate is supported and is given a small prescribed deflection in a direction perpendicular to the middle plane of the plate. (b) The external load applied to the plate consists of a general distribution of bending moments acting around the edge of the plate. Since the loading consists of moments distributed around the edge of the plate, the general Lagrange differential equation for the middle surface of the plate reduces to the biharmonic equation. Elliptic co-ordinates are used and the problem reduces to finding a solution of the biharmonic equation, in elliptic co-ordinates, which satisfies the boundary conditions. Solutions to this equation are of two types: (a) harmonic functions, and (b) biharmonic functions which are not harmonic. Functions of type (a) are found by the method of separation of variables in Laplace’s equation expressed in elliptic co-ordinates. Functions of type (b) are found by the use of complex variable theory.
Torsion of Noncylindrical Shafts of Circular Cross Section
Authors: Reissner H. J. , Wennagel G. J.
Published: April 2021

The theory of torsion of noncylindrical bodies of revolution, initiated by J. H. Michell and A. Föppl, is stated by a basic differential equation of the circumferential displacement and by a boundary condition of the shear stress along the generator surface. The solution of these two equations by the “direct” method of first assuming the boundary shape has not lent itself to closed solutions in terms of elementary functions, so that only approximation, infinite series, and experimental methods have been applied. A semi-inverse method analogous to Saint Venant’s semi-inverse method for cylindrical bodies has the disadvantage of the restriction to special boundary shapes but the advantage of exact solutions by means of elementary functions. By this method, bodies of conical, ellipsoidal, and hyperbolic boundary shapes have been obtained in a simple analysis. One class of integrals leading to other boundary shapes seems not to have been analyzed up to now, namely, the integrals in the form of a product of two functions of, respectively, axial (z) and radial (r) co-ordinates. A first suggestion of this possibility was given in Love’s treatise on the mathematical theory of elasticity. In the present paper, the classes of boundary shapes, displacements, and stress distributions are investigated analytically and numerically. The extent of the numerical investigation contains only the results of single-term integrals for full and hollow cross sections of technical interest. The detailed analysis of the boundary shapes, following from series integrals, presents essential mathematical obstacles. Overcoming these difficulties might lead to a multitude of solutions of interesting boundary shapes, and stress and strain distribution.
Transverse Vibration of a Two-Span Beam Under the Action of a Moving Alternating Force
Authors: Ayre R. S. , Jacobsen L. S.
Published: April 2021

An alternating force (for example, due to unbalance in a locomotive driving apparatus) moves across a symmetrical two-span beam (or equivalent bridge) with uniform velocity. The stress-time equations for the three time eras of the problem have been derived by classical methods. The experimental part of the investigation employs a mechanical system with wire resistance strain gages. Resonances from the first through the sixth mode have been investigated. There is good agreement between theory and experiment in so far as number and location of resonances are concerned. The discrepancy in amplitude is to be expected due to the omission of damping in the theory. The most important observation is the “multiplicity of resonances” associated with “each” natural mode.
Elastic-Plastic Analysis of Structures Subjected to Loads Varying Arbitrarily Between Prescribed Limits
Authors: Symonds P. S. , Prager W.
Published: April 2021

Very often in practice a structure is subjected to loads consisting of several components, whose respective maximum and minimum values are known, but whose order and instantaneous magnitudes cannot be specified in advance. For example, an airplane wing might be subjected to dead loads, maneuvering loads, gust loads, etc., whose maximum and minimum values can be estimated closely, but which are applied independently in a manner which is not predictable. Again, a machine part might be subjected to unspecified combinations of bending and torsional loads, whose respective greatest and least values only are known. The present paper deals with the analysis of structures of this kind, when plastic deformation in parts of the structure is permitted in order to obtain the most economical design consistent with safety. Emphasis is placed upon the use of a geometrical representation of the instantaneous state of stress in an appropriate “stress space.” For simplicity the present discussion is based upon a pin-jointed plane truss as a typical structure. With appropriate changes of language the concepts developed here may be extended to more general structures and to problems of continua.
The Stresses Around a Small Opening in a Beam Subjected to Pure Bending
Authors: Joseph J. A. , Brock J. S.
Published: April 2021

This paper contains an exact closed solution for the stress distribution around a small opening in the web of a beam that is subjected to pure bending. The complex variable method of solution for plane stress problems (Muschelišvili) is outlined. It is applied to the case of a general ovaloid opening (Greenspan). Curves showing the tangential stresses around the boundary are given for several common openings found in engineering structures.
Beam Vibrations With Time-Dependent Boundary Conditions
Authors: Mindlin R. D. , Goodman L. E.
Published: April 2021

A procedure is described for extending the method of separation of variables to the solution of beam-vibration problems with time-dependent boundary conditions. The procedure is applicable to a wide variety of time-dependent boundary-value problems in systems governed by linear partial differential equations.
Natural Frequencies of Continuous Beams of Uniform Span Length
Authors: Ayre R. S. , Jacobsen L. S.
Published: April 2021

A simple graphical network is used to determine the natural frequencies of flexural vibration of continuous beams having any number of spans of uniform length. The network is based upon a relatively few calculated values.
Vibration of Rectangular Plates by the Ritz Method
Authors: Young Dana
Published: April 2021

Ritz’s method is one of several possible procedures for obtaining approximate solutions for the frequencies and modes of vibration of thin elastic plates. The accuracy of the results and the practicability of the computations depend to a great extent upon the set of functions that is chosen to represent the plate deflection. In this investigation, use is made of the functions which define the normal modes of vibration of a uniform beam. Tables of values of these functions have been computed as well as values of different integrals of the functions and their derivatives. With the aid of these data, the necessary equations can be set up and solved with reasonable effort. Solutions are obtained for three specific plate problems, namely, (a) square plate clamped at all four edges, (b) square plate clamped along two adjacent edges and free along the other two edges, and (c) square plate clamped along one edge and free along the other three edges.
The Design and Validation of a Low-Cost Foot Measurement System
Authors: Dickerson Laura C. , Queen Robin M.
Published: April 2021

It is estimated that approximately 40% of the population suffers from abnormal foot posture, specifically high arched or low arched feet. While the evaluation of foot posture can involve many aspects, it commonly requires the measurement of basic dimensions of the foot. Clinicians and researchers often rely on the use of specialized devices or three-dimensional (3D) scanners to evaluate specific aspects of a patient's foot posture. However, current technologies are extremely expensive, therefore highlighting the need for a cost-effective device to be used in rural and clinical settings. As a result, the purpose of this study was to develop an inexpensive system to measure total foot length, truncated length, dorsum height, navicular height, and foot width. Bland–Altman plots showed significant differences between this measurement system and a 3D scanner for total foot length, truncated length, and navicular height (p < 0.001) and significant differences when assessing the repeatability of dorsum height (p = 0.022). However, the magnitudes of these differences were minimal compared to the overall measurement. Additionally, interclass correlation coefficients revealed that this system had excellent validity when compared to a 3D scanner (interclass correlation coefficients = 0.908–0.994), and good to excellent repeatability when compared between days (interclass correlation coefficients = 0.867–0.996). These results demonstrate that it is possible to design an inexpensive, valid, and repeatable system that can be used in clinical, research, and rural settings to successfully evaluate basic dimensions of the foot that can be used for the determination of foot type.
Preliminary Evaluation of the LASSO Method for Prediction of the Relative Power Density Distribution in Mixed Oxide (Pu, DU)O2 Fuel Pellets
Authors: Anghel C. V. , Bromley B. P. , Prudil A. A. , Welland M. J.
Published: April 2021

Predicting the power distribution within nuclear fuel is essential for predicting reactor fuel performance, since power distributions can impact pellet temperature distributions and fission product transport and migration. Analytical expressions for radial power distribution in fuel pellets were sought using lattice physics calculations to generate data and a machine learning technique to find representative expressions. Analytical approximations can be useful in nuclear fuel performance codes, such as element simulation and stresses (ELESTRES)/ element simulation code in a loss of coolant accident (ELOCA) for providing very rapid predictions of power distributions with reduced computational effort and memory requirements, relative to using an embedded or coupled neutron transport/burnup reactor physics code. Radial power distributions were calculated a priori using lattice physics codes to model mixed oxide (MOX) 37-element fuel bundles in pressure tube heavy water reactors. Such advanced fuels are of interest for future fuel cycles. Several datasets were generated with different amounts of PuO2 and variable neutron energy spectrum. Results of preliminary studies with the least absolute shrinkage and selection operator (LASSO) regression machine learning method have obtained analytical fitting functions with a mean maximum relative error (MRE) of 0.056 and a maximum MRE of 0.152 on the test set. However, using LASSO to estimate the coefficients of a physically motivated modified Bessel plus an exponential function, results in a lower MRE (mean MRE 0.041 and maximum MRE 0.11) on the same test set. Further potential improvements in both the curve fit and the machine learning methods are discussed.
Deposition of ITER Vacuum Vessel Dust Inside the Pressure Suppression System During a Loss of Coolant Accident: Experimental and Numerical Analyses
Authors: Ibba Miriam , Pesetti Alessio , Raucci Michele , Parozzi Flavio , Lazzeri Roberta , Aquaro Donato
Published: April 2021

This paper deals with an experimental and numerical analysis of the deposition of International thermonuclear experimental reactor (ITER) dust simulant inside a reduced scale vacuum vessel pressure suppression system (VVPSS) of ITER. This research, funded by the ITER organization, aims to analyze the dust deposition in a water container in a relevant configuration for the ITER VVPSS, the dust removal by means of robotized apparatuses and their decontamination efficiency. The experimental rig, built at the department of civil and industrial engineering (DICI) of the University of Pisa (Italy), is described and the results of a preliminary experimental test are illustrated. It was measured that two and 82% of the overall injected dust mass was strongly and lightly bound to the water container surfaces, respectively, and 16% were not deposited in the water tank. Furthermore, three numerical analyses were carried out implementing a model of the experimental rig in the Enel code for analysis of radionuclide transport (ECART) to determine the relevance of different parameters on the deposition, resuspension and removal of dust. The numerical simulations allowed to specify dust mass deposition on the different rig components, revealing a strong dust retention (about 66%) in the first part of the injection piping in case of coarse granulometry. Finest lognormal dust distribution was instead able to reach the water container (about 90%). Moreover, the numerical simulations permitted to define more precisely the test matrix and to analyze the experimental results.
A Review of Fatigue Crack Growth Thresholds for Metals in Fitness-for-Service Codes: On the Uncertainty of Using the Thresholds at Negative Stress Ratios
Authors: Hasegawa Kunio , Strnadel Bohumir , Mareš Vratislav , Dvořák David , Usami Saburo
Published: April 2021

Fatigue crack growth thresholds ΔKth for metals are provided in many fitness-for-service codes. However, fatigue crack growth thresholds at negative stress ratios are not consistently defined. There are two forms of thresholds at negative stress ratios: constant thresholds irrespective of stress ratios, or increasing thresholds with decreasing stress ratios. The definitions of the thresholds at negative stress ratios also take two forms: either ΔKth = Kmax−Kmin, or ΔKth = Kmax. ASME Section VIII, Section XI (ferritic steel) and International Institute of Welding (IIW) give constant thresholds expressed by ΔKth = Kmax. American Petroleum Institute (API) 579 and ASME Section XI (stainless steel) give increases in thresholds with decreasing stress ratios and the thresholds are expressed by ΔKth = Kmax−Kmin. British Standard (BS) 7910 gives constant thresholds expressed by ΔKth = Kmax−Kmin. The fatigue crack growth thresholds differ significantly among different fitness-for-service (FFS) codes. Appropriate thresholds for ferritic steels, stainless steels, and aluminum alloys are demonstrated in the literature survey.
Description of Cecidophyes fibigiae n. sp., new combinations, records, and DNA barcodes of eriophyid mites (Eriophyoidea, Eriophyidae) from Karadag Nature Reserve (Crimea)

Authors: Chetverikov Philipp E. , Fedorov Denis S. , Letukhova Viktoria Yu. , Romanovich Anna E.
Published: April 2021

We report on one new cecidophyine species, Cecidophyes fibigiae n. sp. from Fibigia clypeata (L.) Medik. (Brassicaceae) and three new combinations and seven new records of phyllocoptine mites in Crimea: Abacarus hystrix (Nalepa 1896) from Elytrigia elongata (Host) Nevski (Poaceae), Aculodes cf holcusi Skoracka 2004 from Aegilops biuncialis Vis. (Poaceae), Aculops coronillae (Canestrini & Massalongo, 1893) n. comb. from Securigera varia (L.) Lassen (Fabaceae), Aculops longifilis (Canestrini 1891) n. comb. from Onobrychis miniata (Kit.) DC. (Fabaceae), Aculus sp. from Galium humifusum M.Bieb. (Rubiaceae), Anthocoptes recki (Bagdasarian, 1972) from Pistacia atlantica subsp. mutica (Fisch. & C.A. Mey.) (Anacardiaceae), and Anthocoptes thymi (Nalepa) n. comb. from Thymus callieri Borb. ex Velen. (Lamiaceae). Partial mitochondrial Cox1 sequences (about 1150 bp) of all found species were obtained (GB accession numbers MW439274–MW439282).
Novel Specific Metallo-β-Lactamase Inhibitor ANT2681 Restores Meropenem Activity to Clinically Effective Levels against NDM-Positive
Enterobacterales
Authors: Zalacain Magdalena , Lozano Clarisse , Llanos Agustina , Sprynski Nicolas , Valmont Thomas , De Piano Cyntia , Davies David , Leiris Simon , Sable Carole , Ledoux Adeline , Morrissey Ian , Lemonnier Marc , Everett Martin
Published: April 2021

The global dissemination of metallo-β-lactamase (MBL)-producing carbapenem-resistant
Enterobacterales
(CRE) is a serious public health concern. Specifically, NDM (New Delhi MBL) has been a major cause of carbapenem therapy failures in recent years, particularly as effective treatments for serine-β-lactamase (SBL)-producing
Enterobacterales
are now commercially available.
Prevalence of
bla
CTX-M
Genes in Gram-Negative Bloodstream Isolates across 66 Hospitals in the United States
Authors: Tamma Pranita D. , Smith Tiffeny T. , Adebayo Ayomikun , Karaba Sara M. , Jacobs Emily , Wakefield Teresa , Nguyen Kelly , Whitfield Natalie N. , Simner Patricia J.
Published: April 2021

Understanding bacterial species at highest risk for harboring
bla
CTX-M
genes is necessary to guide antibiotic treatment. We identified the species-specific prevalence of
bla
CTX-M
genes in clinical isolates from the United States.
Punctuated Loci on Chromosome IV Determine Natural Variation in Orsay Virus Susceptibility of
Caenorhabditis elegans
Strains Bristol N2 and Hawaiian CB4856
Authors: Sterken Mark G. , van Sluijs Lisa , Wang Yiru A. , Ritmahan Wannisa , Gultom Mitra L. , Riksen Joost A. G. , Volkers Rita J. M. , Snoek L. Basten , Pijlman Gorben P. , Kammenga Jan E.
Published: April 2021

Genetic variation determines the viral susceptibility of hosts. Yet, pinpointing which genetic variants determine viral susceptibility remains challenging. Here, we have exploited the genetic tractability of the model organism
Caenorhabditis elegans
to dissect the genetic architecture of Orsay virus infection. Our results provide novel insight into natural determinants of Orsay virus infection.
Structural Basis of Ligand Selectivity by a Bacterial Adhesin Lectin Involved in Multispecies Biofilm Formation
Authors: Guo Shuaiqi , Vance Tyler D. R. , Zahiri Hossein , Eves Robert , Stevens Corey , Hehemann Jan-Hendrik , Vidal-Melgosa Silvia , Davies Peter L.
Published: April 2021

Bacterial adhesins are key virulence factors that are essential for the pathogen-host interaction and biofilm formation that cause most infections. Many of the adhesin-driven cell-cell interactions are mediated by lectins.
Genome-Wide Analysis of Experimentally Evolved Candida auris Reveals Multiple Novel Mechanisms of Multidrug Resistance
Authors: Carolus Hans , Pierson Siebe , Muñoz José F. , Subotić Ana , Cruz Rita B. , Cuomo Christina A. , Van Dijck Patrick
Published: April 2021

Candida auris
is a recently discovered human fungal pathogen and has shown an alarming potential for developing multi- and pan-resistance toward all classes of antifungals most commonly used in the clinic. Currently,
C. auris
has been globally recognized as a nosocomial pathogen of high concern due to this evolutionary potential.
An Alternative and Conserved Cell Wall Enzyme That Can Substitute for the Lipid II Synthase MurG
Authors: Zhang L. , Ramijan K. , Carrión V. J. , van der Aart L. T. , Willemse J. , van Wezel G. P. , Claessen D.
Published: April 2021

Almost all bacteria are surrounded by a cell wall, which protects cells from environmental harm. Formation of the cell wall requires the precursor molecule lipid II, which in bacteria is universally synthesized by the conserved and essential lipid II synthase MurG.
The Transmembrane Mucin MUC1 Facilitates β1-Integrin-Mediated Bacterial Invasion
Authors: Li Xinyue , Wubbolts Richard W. , Bleumink-Pluym Nancy M. C. , van Putten Jos P. M. , Strijbis Karin
Published: April 2021

Bacteria can exploit membrane receptor integrins for cellular invasion, either by direct binding of bacterial adhesins or utilizing extracellular matrix components. MUC1 is a large transmembrane glycoprotein expressed by most epithelial cells that can have direct defensive or receptor functions at the host-microbe interface and is involved in facilitating integrin clustering.
Finding Needles in Haystacks and Inferring Their Function: Challenges and Successes in Beneficial Symbiosis Research
Authors: Bennett Gordon M. , Heath-Heckman Elizabeth , Sogin E. Maggie
Published: April 2021

Symbioses between hosts and beneficial microbes are key drivers of biological innovation and diversity. While a range of systems have emerged that provide foundational insights into how symbioses function and evolve, we still have a limited understanding of the vast diversity of organisms that engage in such interactions.
Genomes of Gut Bacteria from
Nasonia
Wasps Shed Light on Phylosymbiosis and Microbe-Assisted Hybrid Breakdown
Authors: Cross Karissa L. , Leigh Brittany A. , Hatmaker E. Anne , Mikaelyan Aram , Miller Asia K. , Bordenstein Seth R.
Published: April 2021

Animal and plant hosts often establish intimate relationships with their microbiomes. In varied environments, closely related host species share more similar microbiomes, a pattern termed phylosymbiosis.
The Lived Experience Of Participants in an African RandomiseD trial (LEOPARD): protocol for an in-depth qualitative study within a multisite randomised controlled trial for HIV-associated cryptococcal meningitis
Authors: Lawrence David S , Tsholo Katlego , Ssali Agnes , Mupambireyi Zivai , Hoddinott Graeme , Nyirenda Deborah , Meya David B , Ndhlovu Chiratidzo , Harrison Thomas S , Jarvis Joseph N , Seeley Janet
Published: April 2021

Introduction

Individuals recruited into clinical trials for life-threatening illnesses are particularly vulnerable. This is especially true in low-income settings. The decision to enrol may be influenced by existing inequalities, poor healthcare infrastructure and fear of death. Where patients are confused or unconscious the responsibility for this decision falls to relatives. This qualitative study is nested in the ongoing AMBIsome Therapy Induction OptimisatioN (AMBITION) Trial. AMBITION is recruiting participants from five countries in sub-Saharan Africa and is trialling a novel treatment approach for HIV-associated cryptococcal meningitis, an infection known to affect brain function. We aim to learn from the experiences of participants, relatives and researchers involved in AMBITION.

Methods and analysis

We will collect data through in-depth interviews with trial participants and the next of kin of participants who were confused at enrolment and therefore provided surrogate consent. Data will be collected in Gaborone, Botswana; Kampala, Uganda and Harare, Zimbabwe. Interviews will follow a narrative approach including participatory drawing of participation timelines. This will be supplemented by direct observation of the research process at each of the three recruiting hospitals. Interviews will also take place with researchers from the African and European institutions that form the partnership through which the trial is administered. Interviews will be transcribed verbatim, translated (if necessary) and organised thematically for narrative analysis.

Ethics and dissemination

This study has been approved by the Health Research Development Committee, Gaborone (Reference: HPDME:13/18/1); Makerere School of Health Sciences Institutional Review Board, Kampala (Reference: 2019–061); University of Zimbabwe Joint Research Ethics Committee, Harare (Reference: 219/19), and the London School of Hygiene and Tropical Medicine (Reference: 17957). Study findings will be shared with research participants from the sites, key stakeholders at each research institution and ministries of health to help inform the development and implementation of future trials. The findings of this study will be published in journals and presented at academic meetings.

Trial registration

Registered atwww.clinicaltrials.gov:NCT04296292.