bluuebunny/crossref_metadata_2025 huggingface dataset:
TLSLeAF: automatic leaf angle estimates from single‐scan terrestrial laser scanning
Authors: Stovall Atticus E. L. , Masters Benjamin , Fatoyinbo Lola , Yang Xi
Published: June 2021

Leaf angle distribution (LAD) in forest canopies affects estimates of leaf area, light interception, and global‐scale photosynthesis, but is often simplified to a single theoretical value. Here, we present TLSLeAF (Terrestrial Laser Scanning Leaf Angle Function), an automated open‐source method of deriving LADs from terrestrial laser scanning.

TLSLeAF produces canopy‐scale leaf angle and LADs by relying on gridded laser scanning data. The approach increases processing speed, improves angle estimates, and requires minimal user input. Key features are automation, leaf–wood classification, beta parameter output, and implementation in R to increase accessibility for the ecology community.

TLSLeAF precisely estimates leaf angle with minimal distance effects on angular estimates while rapidly producing LADs on a consumer‐grade machine. We challenge the popular spherical LAD assumption, showing sensitivity to ecosystem type in plant area index and foliage profile estimates that translate to c. 25% and c. 11% increases in canopy net photosynthesis (c. 25%) and solar‐induced chlorophyll fluorescence (c. 11%).

TLSLeAF can now be applied to the vast catalog of laser scanning data already available from ecosystems around the globe. The ease of use will enable widespread adoption of the method outside of remote‐sensing experts, allowing greater accessibility for addressing ecological hypotheses and large‐scale ecosystem modeling efforts.
Incidence and Risk Factors of In‐Hospital Prosthesis‐Related Complications Following Total Knee Arthroplasty: A Retrospective Nationwide Inpatient Sample Database Study
Authors: Yang Qin‐feng , Lin Ze‐ming , Yang Sheng , Wang Pin‐kai , Chen Rong , Wang Jian
Published: June 2021

Objective

To examine the incidence and risk factors of in‐hospital prosthesis‐related complications (PRCs) following total knee arthroplasty (TKA) using a large‐scale national database.

Methods

A retrospective database analysis was performed based on Nationwide Inpatient Sample (NIS) from 2005–2014. Patients who underwent TKA were included. The recruited cases were divided into two groups according to the occurrence of PRCs. Patient demographics (age, sex, and race), hospital characteristics (type of admission and payer, and bedsize, teaching status, location, and region of hospital), length of stay (LOS), total charges during hospitalization, in‐hospital mortality, comorbidities, and perioperative complications were analyzed.

Results

A total of 1,227,244 TKAs were captured from the NIS database. There were 8484 cases of in‐hospital PRCs after TKA and the overall incidence was 0.69%, with a slight downward trend annually. Periprosthetic joint infection (PJI) was the main category among PRCs (0.20%), followed by mechanical loosening (0.04%), dislocation (0.02%), and periprosthetic fracture (PPF) (0.01%). Patients suffered from in‐hospital PRCs were 3 years younger (64 years vs 67 years) and 6.51% more likely to be male (43.60% vs 37.09%) compared to the nonaffected population (P < 0.0001). Additionally, patients experiencing in‐hospital PRCs after TKA were 2.11% less likely through elective admission (92.07% vs 94.18%) while 2.34% more likely in teaching hospital (45.53% vs 43.19%) than those without these complications (P < 0.0001). Furthermore, the occurrence of in‐hospital PRCs was associated with longer LOS (4 days vs 3 days; P < 0.0001), more total charges ($53,418 vs $41,204, P < 0.0001), and higher in‐hospital mortality (0.30% vs 0.07%; P < 0.0001). Multivariate logistic regression was performed to identify independent risk factors of in‐hospital PRCs after TKA which included younger age, male, non‐elective admission, teaching hospital, deficiency and chronic blood loss anemia, coagulopathy, congestive heart failure, depression, diabetes with chronic complications, fluid and electrolyte disorders, pulmonary circulation disorders, metastatic cancer, and weight loss. Besides, in‐hospital PRCs after TKA were associated with secondary osteoarthritis, inflammatory arthritis, prior knee arthroscopy, acute renal failure, acute myocardial infarction, deep vein thrombosis, sepsis, transfusion, and wound dehiscence.

Conclusion

It is beneficial to study the risk factors of in‐hospital PRCs after TKA to ensure the appropriate management and optimize consequences although a relatively low incidence was identified.
Osteotomy Around the Knee: The Surgical Treatment of Osteoarthritis
Authors: Peng Haining , Ou Aichun , Huang Xiaohong , Wang Chen , Wang Lei , Yu Tengbo , Zhang Yingze , Zhang Yi
Published: June 2021

Osteoarthritis causes joint pain and functional disorder, of which knee osteoarthritis is the most common. Nowadays, clinically effective treatments mainly include conservative treatment, arthroplasty, and osteotomy. However, conservative treatment only offers symptomatic relief and arthroplasty is limited to the patients with a moderate to severe degree of osteoarthritis. For relatively young patients who require greater knee preservation, a surgical treatment with low operation trauma and revision rate is needed. Osteotomy around the knee, based on the notion of “knee preservation,” has been chosen as an alternative surgical treatment. Cutting and realigning the bones corrects the mechanical line of lower limb force bearing. As such, osteotomy around the knee retains normal anatomical structure and obtains good functional recovery of the knee joint. The techniques of osteotomy around the knee includes anti‐varus deformity and anti‐valgus deformity osteotomy, aiming to reallocate the force bearing in the compartment of the knee joint. By choosing the surgical section of the lower limbs, the osteotomy around the knee can achieve the correction of mechanical axis, such as the high tibial osteotomy (HTO), proximal fibular osteotomy (PFO), and distal femur osteotomy (DFO). Numerous modified techniques have been developed to meet the demands of patients based on traditional methods. These modified osteotomy have their own advantages and indications. This paper aims to guide clinical treatment by reviewing different types of osteotomies, and their effects, that have been studied and applied widely in clinical practices.
Incidence, predictors, and clinical impact of bleeding recurrence in patients with prior gastrointestinal bleeding undergoing LAAC
Authors: Faroux Laurent , Cruz‐González Ignacio , Arzamendi Dabit , Freixa Xavier , Nombela‐Franco Luis , Peral Vicente , Caneiro‐Queija Berenice , Mangieri Antonio , Trejo‐Velasco Blanca , Asmarats Lluis , Regueiro Ander , McInerney Angela , Morcuende Gonzalez Antonio , Estevez‐Loureiro Rodrigo , Laricchia Alessandra , O'Hara Gilles , Rodés‐Cabau Josep
Published: June 2021

Background

Gastrointestinal bleeding (GIB) is associated with a high recurrence rate and a prior GIB episode is common in real‐world left atrial appendage closure (LAAC) recipients. The present study sought to evaluate the clinical characteristics and outcomes of patients with prior GIB undergoing LAAC, and to determine the factors associated with and clinical impact of GIB recurrence.

Methods

Multicenter study including 277 consecutive patients who underwent percutaneous LAAC and had prior GIB. All‐cause death, all bleeding, GIB recurrence, and clinical ischemic stroke were recorded.

Results

After a median follow‐up of 17 (interquartile range: 6–37) months post‐LAAC, the rates of death, bleeding, GIB recurrence, and ischemic stroke were 14.0 per 100 person‐year (PY), 29.3 per 100 PY, 17.7 per 100 PY, and 1.1 per 100 PY, respectively. GIB recurrence occurred within 3 months post‐LAAC in 55.8% of patients. A previous lower GIB (vs. upper or unclassified) (HR: 1.76; 95% CI: 1.09‐2.82; p = .020) and eGFR < 45 mL/min (HR: 1.70; 95% CI:1.04‐2.67; p = .033) determined an increased risk of GIB recurrence. By multivariable analysis, eGFR < 45 mL/min (HR: 2.72; 95% CI: 1.70‐4.34; p < .001), GIB recurrence following LAAC (HR: 2.15; 95% CI: 1.33‐3.46; p = .002), diabetes mellitus (HR: 1.77; 95% CI: 1.10‐2.84; p = .018), and age (HR: 1.06; 95% CI: 1.03‐1.10; p < .001) were associated with an increased mortality.

Conclusions

Patients with prior GIB undergoing LAAC exhibited a relatively low rate of GIB recurrence, and prior lower GIB and moderate‐to‐severe chronic kidney disease determined an increased risk. GIB recurrence was associated with an increased mortality.
QRS dispersion detected in ARVC patients and healthy gene carriers using 252‐leads body surface mapping: an explorative study of a potential diagnostic tool for arrhythmogenic right ventricular cardiomyopathy
Authors: Kommata Varvara , Elshafie Marwa , Sciaraffia Elena , Perez Mauricio , Augustine Robin , Blomström‐Lundqvist Carina
Published: June 2021

Background

The diagnosis of ARVC remains complex requiring both imaging and electrocardiographic (ECG) techniques. The purpose was therefore to investigate whether QRS dispersion assessed by body surface mapping (BSM) could be used to detect early signs of ARVC, particularly in gene carriers.

Methods

ARVC patients, gene carriers without a history of arrhythmias or structural cardiac changes and healthy controls underwent 12‐lead resting ECG, signal‐averaged ECG, echocardiographic examination, 24‐hours Holter monitoring, and BSM with electrocardiographic imaging. All 252‐leads BSM recordings and 12‐leads ECG recordings were manually analyzed for QRS durations and QRS dispersion.

Results

Eight controls, 12 ARVC patients with definite ARVC and 20 healthy gene carriers were included. The ECG‐QRS dispersion was significantly greater in ARVC patients (42 vs. 25 ms, p < .05), but failed to fully differentiate them from controls. The BSM‐derived QRS dispersion was also significantly greater in ARVC patients versus controls (65 vs. 29 ms, p < .05) and distinguished 11/12 cases from controls using the cut‐off 40msec. The BSM derived QRS dispersion was abnormal (> 40 ms) in 4/20 healthy gene carriers without signs of ARVC, which may indicate early depolarization changes.

Conclusions

QRS dispersion, when assessed by BSM versus 12‐lead ECG, seem to better distinguish ARVC patients from controls, and could potentially be used to detect early ARVC in gene carriers. Further studies are required to confirm the value of BSM‐QRS dispersion in this respect.
Certification systems for machine learning: Lessons from sustainability
Authors: Matus Kira J.M. , Veale Michael
Published: June 2021

Concerns around machine learning’s societal impacts have led to proposals to certify some systems. While prominent governance efforts to date center around networking standards bodies such as the Institute of Electrical and Electronics Engineers (IEEE), we argue that machine learning certification should build on structures from the sustainability domain. Policy challenges of machine learning and sustainability share significant structural similarities, including difficult to observe credence properties, such as data collection characteristics or carbon emissions from model training, and value chain concerns, including core‐periphery inequalities, networks of labor, and fragmented and modular value creation. While networking‐style standards typically draw their adoption and enforcement from functional needs to conform to enable network participation, machine learning, despite its digital nature, does not benefit from this dynamic. We therefore apply research on certification systems in sustainability, particularly of commodities, to generate lessons across both areas, informing emerging proposals such as the EU’s AI Act.
Checking design. Libro 1
Authors: Paredes López Sonia Patricia , Manrique López Aida , Carrillo Bernal Natalia
Published: June 2021

El primero libro de Checking design, dirigido a empresarios, entidades de apoyo empresarial, profesionales del diseño, estudiantes, académicos y a todos aquellos que deseen conocer más acerca del diseño y su gestión en las organizaciones. A lo largo de estas páginas se ha querido evidenciar la importancia de gestionar el diseño para que aporte valor a las organizaciones; mostrar con ejemplos de empresas de diferentes latitudes cómo cada una de ellas ha hecho del diseño un importante factor de innovación y competitividad, y reflexionar acerca de la necesidad de conocer la situación del diseño, como punto de partida para establecer un coherente plan de acción empresarial.
A Theoretical Analysis of the Viscous Flow in a Narrowly Spaced Radial Diffuser
Authors: Woolard Henry W.
Published: June 2021

A theoretical method for calculating the radial pressure distribution for laminar viscous flow in a narrowly spaced radial diffuser having arbitrarily shaped walls deviating only moderately from a plane surface is developed. The analysis as it stands is also directly applicable to turbulent flow in the initial inlet region of a diffuser. Additional work is necessary to obtain a complete turbulent-flow analysis. Pressure distributions calculated by the laminar-flow theory show reasonably good agreement with the limited experimental pressure distributions available at the time of the analysis. Fairly good agreement also is obtained for the performance of a disk-valve element.
The Synthesis of Four-Bar Mechanisms by the Method of Components
Authors: Hirschhorn J.
Published: June 2021

The synthesis of four-bar mechanisms based on the vectorial representation of links in complex form was first suggested by S. Bloch. His work was further developed by R. Beyer and N. Rosenauer. These kinematicians investigated the synthesis of the four-bar mechanism for prescribed instantaneous angular velocities and accelerations of the three moving links. This paper presents a somewhat different approach to the problem, in that the vectors are being resolved into Cartesian components. This method permits the synthesis for prescribed conditions concerning angular velocities, accelerations, and lengths of links. The author believes that the simpler treatment will make this method more readily acceptable to engineers.
The State Principle—Some General Aspects of the Relationships Among the Properties of Systems
Authors: Kline S. J. , Koenig F. O.
Published: June 2021

An independent generalization, here called the “State Principle,” is necessary for the development of thermodynamics. Previously, this principle has been either tacitly assumed, or at best stated incompletely. A discussion and explicit formulation of this principle are given. The Phase rule is deduced from the State Principle and certain related empirical information. In this derivation no reference whatsoever is made to the First Law or the Second Law of Thermodynamics. A new, simple, systematic means for counting the number of components in the phase rule, which has no known exceptions and which does not rely on either advanced thermodynamics or the First and Second Laws, is presented. Examples of its use are included.
Dependence of the Frequency Spectrum of a Circular Disk on Poisson’s Ratio
Authors: Sharma R. L.
Published: June 2021

The results of computations of frequencies of axially symmetric flexural vibrations of circular disks are given for an intermediate frequency range and for several values of Poisson’s ratio.
Longitudinal Impact of a Semi-Infinite Circular Elastic Bar
Authors: Skalak Richard
Published: June 2021

The impact of a semi-infinite elastic bar of circular cross section is studied using the equations of motion of linear-elasticity theory and a method of double-integral transforms. An evaluation of the solution is obtained using approximations which are valid for large values of the time after the initial impact. The numerical results show a continuous dispersion of the wave front and an oscillation which are not found in the usual elementary-theory solution.
Yield Loads of Slabs With Reinforced Cutouts
Authors: Hodge P. G. , Perrone Nicholas
Published: June 2021

A method of computing upper and lower bounds on the carrying capacity of a plane slab with a reinforced cutout is presented. The slab is subjected to a uniaxial load which is either uniform or applied by means of a perfectly rigid clamp. The results are applied to several examples and are found to agree quite well with experimental values.
Point Source and Point Vortex in the Hodograph Plane
Authors: Poritsky H. , Powell R. A.
Published: June 2021

Hodograph plane solutions possessing point-source and point-vortex singularities are obtained by means of series expansions in product solutions.
Analog Computer for Nonlinear System With Hysteresis
Authors: Thomson W. T.
Published: June 2021

Structural materials loaded beyond the elastic limit generally display a hysteresis effect such that recovery from maximum deflection proceeds elastically. Assuming a spring-mass model for such a structure to exist, where the stiffness is represented by segments of straight lines, its solution under dynamic excitation still offers sufficient difficulties to welcome a computer technique which will automatically perform this task. This paper describes an electronic analog computer scheme which will carry out such a solution for a unidirectional force excitation.
Collapse Strength of Redundant Beams After Lateral Buckling
Authors: Masur E. F. , Milbradt K. P.
Published: June 2021

According to classical linear theory, slender beams buckle laterally under vertical loads which remain constant as the buckling amplitude increases. Unless prior yielding takes place, the loads corresponding to neutral equilibrium represent therefore the collapse strength of the beam. However, the inclusion of nonlinear terms in the strain-displacement relations modifies the predicted postbuckling behavior of redundant beams. If continued elasticity is postulated, increasing amplitudes are associated with increasing load magnitudes, which generally approach limiting values. These “ultimate loads” may be estimated by means of two principles establishing lower and upper bounds. Tests performed on a single-span beam of varying degrees of end restraint show good agreement with the proposed theory.
A Numerical Procedure for Calculating the Large Deflections of Straight and Curved Beams
Authors: Seames A. E. , Conway H. D.
Published: June 2021

Paper presents a numerical method for calculating the large deflections of beams, assuming that the elastic axis can be approximated to by a number of circular arcs tangent to one another at their points of intersection. The calculations are made in tabular form, and are illustrated by particular examples of straight and curved cantilever beams and of rings subjected to concentrated or distributed loads. In those cases where an exact solution is possible, excellent agreement with the present method was obtained.
Analysis of Stresses and Strains Near the End of a Crack Traversing a Plate
Authors: Irwin G. R.
Published: June 2021

A substantial fraction of the mysteries associated with crack extension might be eliminated if the description of fracture experiments could include some reasonable estimate of the stress conditions near the leading edge of a crack particularly at points of onset of rapid fracture and at points of fracture arrest. It is pointed out that for somewhat brittle tensile fractures in situations such that a generalized plane-stress or a plane-strain analysis is appropriate, the influence of the test configuration, loads, and crack length upon the stresses near an end of the crack may be expressed in terms of two parameters. One of these is an adjustable uniform stress parallel to the direction of a crack extension. It is shown that the other parameter, called the stress-intensity factor, is proportional to the square root of the force tending to cause crack extension. Both factors have a clear interpretation and field of usefulness in investigations of brittle-fracture mechanics.
Axisymmetric Thermal Stresses in a Spherical Shell of Arbitrary Thickness
Authors: McDowell E. L. , Sternberg E.
Published: June 2021

This paper contains an explicit series solution, exact within the classical theory of elasticity, for the steady-state thermal stresses and displacements induced in a spherical shell by an arbitrary axisymmetric distribution of surface temperatures. The corresponding solutions for a solid sphere and for a spherical cavity in an infinite medium are obtained as limiting cases. The convergence of the series solutions obtained is discussed. Numerical results are presented appropriate to a solid sphere if two hemispherical caps of its boundary are maintained at distinct uniform temperatures.
Saint Venant’s Principle: A Biharmonic Eigenvalue Problem
Authors: Horvay G.
Published: June 2021

Saint Venant’s principle is formulated as a biharmonic eigenvalue problem for the symmetrical truncated wedge x ≥ 0, |y| ≤ yb (yb = 1 + x tan ω) which is stress-free along the lateral edges, and is loaded by self-equilibrating shear and normal tractions τko(y), σko(y) along edge x = 0. It is found that for the wedge angle 2ω = 0 the law of decay is of the type e−αkτ; for 2ω ≠ 0 the law of decay is of type r−μk; μk is minimum for 2ω = π. The indexes k attached to τo, σo indicate that we deal with systems of characteristic tractions which produce characteristic decay rates. Practical implications of the results, as they apply to structural design, are discussed in a separate paper, “Some Aspects of Saint Venant’s Principle.”
Buckling of Thin Cylindrical Shell Under Hoop Stresses Varying in Axial Direction
Authors: Hoff N. J.
Published: June 2021

The buckling of a thin cylindrical shell simply supported along the perimeter of its end sections is analyzed under hoop compressive stresses varying in the axial direction. The thermal stresses arising from a uniform increase in the temperature of the cylinder are determined. It is found that such thermal stresses are not likely to cause elastic buckling. Simple approximate formulas are developed for buckling stress and thermal stress.
Interaction Curves for Shear and Bending of Plastic Beams
Authors: Hodge P. G.
Published: June 2021

Interaction curves are presented for plastic beams subject to combined shear and bending. A general formula is obtained and specific curves are drawn for rectangular and I-sections. A simply supported beam with a concentrated load is considered as an example. The results are compared with those of simple beam theory and with available plane-stress solutions. It is concluded that the elementary theory is adequate for height-to-length ratios of less than 0.1, while the present theory is useful in the range from 0.1 to 1.0.
A Note on Torsion of Circular Shafts of Variable Diameter
Authors: Chattarji P. P.
Published: June 2021

Certain stress functions which are in the form of polynomials have been obtained for various curves forming the generating surface of the shaft.
Reduction of Three-Dimensional Stress Distributions to Two-Dimensional Analysis by Superposition
Authors: Zizicas G. A.
Published: June 2021

In a recent note the author proposed a graphical procedure which supplements the classical three-dimensional Mohr-circle representation by specifying the direction of the total shear on any element of surface. The same results are reached here by superposition which simplifies and clarifies the analysis considerably. The associated analytical results are presented in a more useful form and are shown to lead readily to the classical Mohr representation. An application is made to the practically important stress components on the octahedral planes.
A Method for Solving Problems of Irrotational Gas Flow by Means of High-Speed Digital Computers
Authors: Koga Toyoki
Published: June 2021

A numerical procedure is proposed for solution of certain problems in steady gas flow where subsonic, sonic, and supersonic regions appear simultaneously. The difficulties that occur in analytical methods for taking into account the differences of the type of the fundamental equation (elliptic, parabolic, hyperbolic) are avoided. Given a streamline and the state of the gas along that streamline, the co-ordinates of the neighboring streamline and the state of the gas along it can be computed. The procedure can be applied successively to cover a flow field. The method is described in detail for two-dimensional, steady, irrotational flow (without shocks) of a perfect gas, and an example is given.
A Photoelastic Study of Maximum Tensile Stresses in Simply Supported Short Beams Under Central Transverse Impact
Authors: Betser A. A. , Frocht M. M.
Published: June 2021

Simply supported short Castolite beams of uniform rectangular cross section were subjected to central transverse impact by a heavy mass. Photoelastic streak photographs were taken of the transverse section of symmetry for a wide range of spans, widths, and impact velocities at exposures of less than 1 microsec. The maximum tensile stresses were determined. Comparison with the elementary theory for long beams shows that while this theory is satisfactory for long beams, it does not agree with the results from short beams. An approximate theory for short beams under central impact is developed which gives satisfactory agreement. The duration of impact also was determined and the appearance of isotropic points is discussed.
Superharmonic Oscillations as Solutions to Duffing’s Equation as Solved by an Electronic Differential Analyzer
Authors: Atkinson C. P.
Published: June 2021

This paper presents the experimental response curves for the solutions of Duffing’s equation for that frequency range where higher-order harmonics (called superharmonics as opposed to lower order or subharmonics) of the fundamental are important components of the solution. The experimental results were obtained by solving Duffing’s equation on an electronic differential analyzer. The paper presents corroboration of analytical results for the third-order superharmonic component of solutions which were calculated by a two-term Ritz approximation. The results of this paper indicate that superharmonics of higher order than the third, that is, fifth and seventh order, and even-order harmonics such as second and fourth order can be found in the frequency range studied. This paper points out a definite relationship which exists between the superharmonic generated and the free-vibration curve (“backbone”) of the system. For example, if we compare the maximum displacement of the solution containing an nth order superharmonic with the same amplitude of the free-vibration curve, it is seen that the frequency of the fundamental (the forcing frequency) is 1/n times this natural frequency or, conversely, the frequency of the superharmonic component is n times that of the fundamental and has in fact the frequency of the free vibration for that amplitude. Thus a superharmonic of order n can be pictured as a sustained free vibration which is generated when the frequency of the forcing function is 1/n of the frequency of the free-vibration response curve. The phenomenon of superharmonic oscillations is pictured here as a nonlinear resonance. Experimental evidence of the superharmonic-jump phenomenon as discovered analytically by John Burgess (1) also is presented in this paper.
A Donnell Type Theory for Asymmetrical Bending and Buckling of Thin Conical Shells
Authors: Seide Paul
Published: June 2021

Equations, somewhat more accurate than those recently presented by N. J. Hoff, are derived for bending and buckling of thin circular conical shells under arbitrary loading. These equations reduce to Donnell’s equations for thin cylindrical shells when the cone semivertex angle becomes very small and the minimum radius of curvature of the median surface approaches a constant value. At the other end of the scale the equations reduce to the well-known equations for flat circular plates when the cone semivertex angle approaches a right angle. In addition, for the entire range of cone semivertex angles the equations reduce to the known equations for axisymmetrical bending when variations of the displacements around the circumference vanish. The problem of bending is reduced to the solution of a single fourth-order partial differential equation with variable coefficients.
The Sector Problem
Authors: Horvay G. , Hanson K. L.
Published: June 2021

On the basis of the variational method, approximate solutions f k ( r ) h k ( θ ) , f k ( r ) g k ( θ ) , F k ( θ ) H k ( r ) , F k ( θ ) G k ( r ) of the biharmonic equation are established for the circular sector with the following properties: The stress functions fkhk create shear tractions on the radial boundaries; the stress functions fkgk create normal tractions on the radial boundaries; the stress functions FkHk create both shear and normal tractions on the circular boundary, and the stress functions FkGk create normal tractions on the circular boundary. The enumerated tractions are the only tractions which these function sets create on the various boundaries of the sector. The factors fk(r) constitute a complete set of orthonormal polynomials in r into which (more exactly, into the derivatives of which) self-equilibrating normal or shear tractions applied to the radial boundaries of the sector may be expanded; the factors Fk(θ) constitute a complete set of orthonormal polynomials in θ into which shear tractions applied to the circular boundary of the sector may be expanded; and the functions Fk″ + Fk constitute a complete set of non-orthogonal polynomials into which normal tractions applied to the circular boundary of the sector may be expanded. Function tables, to facilitate the use of the stress functions, are also presented.
The Elastic Coefficients of the Theory of Consolidation
Authors: Biot M. A. , Willis D. G.
Published: June 2021

The theory of the deformation of a porous elastic solid containing a compressible fluid has been established by Biot. In this paper, methods of measurement are described for the determination of the elastic coefficients of the theory. The physical interpretation of the coefficients in various alternate forms is also discussed. Any combination of measurements which is sufficient to fix the properties of the system may be used to determine the coefficients. For an isotropic system, in which there are four coefficients, the four measurements of shear modulus, jacketed and unjacketed compressibility, and coefficient of fluid content, together with a measurement of porosity appear to be the most convenient. The porosity is not required if the variables and coefficients are expressed in the proper way. The coefficient of fluid content is a measure of the volume of fluid entering the pores of a solid sample during an unjacketed compressibility test. The stress-strain relations may be expressed in terms of the stresses and strains produced during the various measurements, to give four expressions relating the measured coefficients to the original coefficients of the consolidation theory. The same method is easily extended to cases of anisotropy. The theory is directly applicable to linear systems but also may be applied to incremental variations in nonlinear systems provided the stresses are defined properly.
Parametrization of the vocal tract area function using a subset selection approach (L)
Authors: Lucero Jorge C.
Published: June 2021

This letter introduces a parametrization of the vocal tract area function based on the position of a few points along the vocal tract. A QR decomposition algorithm is applied to area function data in various vowel configurations in order to identify those points with the most independent position patterns across vowels. Each point defines the shape of an associated kinematic region, and the overall area function is determined by the combination of the kinematic regions' shapes. The results show that only four data points, located at the tongue body, lips, and two at the tongue back, are enough to obtain accurate reconstructions of the vowels' area functions.
A sense of self
Authors: Underwood Emily
Published: June 2021

Communication between the brain and other organs shapes how we think, remember, and feel.
Approaching invisible illness
Sick and Tired: An Intimate History of Fatigue
Emily K. Abel
University of North Carolina Press, 2021. 206 pp.
Authors: Stark Laura
Published: June 2021

A historian traces the cultural contexts of chronic fatigue
Machine-generated theories of human decision-making
Authors: Bhatia Sudeep , He Lisheng
Published: June 2021

Deep neural networks highlight features of human behavior
Recovery of Applied Human Leukocyte Interferon from the Nasal Mucosa of Chimpanzees and Humans
Authors: Johnson Paul E. , Greenberg Stephen B. , Harmon Maurice W. , Alford Bobby R. , Couch Robert B.
Published: June 2021

Intranasally applied human leukocyte interferon was recovered locally in 9 of 10 chimpanzees and 3 of 3 human volunteers tested. A 5- to 50-fold reduction in interferon was observed over 60 min.
Evaluation of methods for the rapid identification of Neisseria gonorrhoeae in a routine clinical laboratory
Authors: Pollock H M
Published: June 2021

Of 78 isolates of Neisseria gonorrhoeae, 21 failed to grow and produce acid in unsupplemented cystine-Trypticase agar (CTA); whereas positive reactions were obtained by using serum-supplemented CTA and fluorescent antibody (FA). An additional 290 strains of Neisseria were evaluated by FA and by a rapid carbohydrate degradation technique (RF). There was agreement between the two methods 92% of the time on the initial trial and 99% of the time with repeats on discrepancies. The RF and FA tests provided rapid and reliable identification of N. gonorrhoeae, alleviating the problems of CTA due to lack of growth and need for overnight incubation.
Comparison of three methods for grouping streptococci
Authors: Hryniewicz W , Heczko P B , Lütticken R , Wannamaker L W
Published: June 2021

Two new methods for serological grouping of beta-hemolytic streptococci, the nitrous acid extraction procedure of El Kholy et al. and the slide agglutination method of Christensen et al., were compared with the Lancefield hot-hydrochloric acid extraction method in classifying 92 strains of groups A, B, C, and G. The nitrous acid extraction method was easily performed, specific, and sensitive when highly potent antisera were used. For the Christensen method these highly potent antisera had to be diluted to avoid cross-reactions between groups A and C and groups B and G, respectively. A few strains, most of them group B, could not be grouped by the latter method. Using these three grouping methods, two sets of commercial sera were compared with the more potent sera supplied by R. C. Lancefield. The low antibody content of these commercial sera, especially anti-group B and G sera, contributed to the inferior results obtained in some of the grouping reactions.
Antigen distribution in a latex suspension and its relationship to test sensitivity
Authors: Hechemy K , Stevens R W , Gaafar H A
Published: June 2021

Specific aggregation of latex particles due to antigen-antibody reaction occurred only when antigen was latex bound, as found in a study using Escherichia coli 0111:B4 extract. Maximum serological sensitivity was achieved when free antigen was present in a narrow range of ratios with the bound antigen.
Comparative activity of immunofluorescent antibody and complement-fixing antibody in cytomegalovirus infection
Authors: Betts R F , George S D , Rundell R B , Freeman R B , Douglas R G
Published: June 2021

Three different tests for detection of antibodies to human cytomegalovirus (CMV), complement fixing with antigen prepared by freeze-thaw disruption (CF-FT) or with antigen prepared by extraction with alkaline glycine buffer (CF-GE) and immunofluorescent staining (FA), were compared in renal transplant recipients and their healthy donors, FA and CF-GE tests yielded positive results at an identical and significantly higher frequency than CF-FT in both donors and recipients. CF-GE and FA performed on donors and recipients predicted all virus shedding post-transplant, whereas CF-FT did not. In the individuals who developed primary infection concurrent with the transplanted kidney, FA developed earlier than other antibodies in about one-half and at the same time in the remainder. In addition, the FA test could be completed more quickly and all sera could be interpreted, which made the FA test more useful than the CF-GE, but both of these tests were clearly superior to CF-FT.
MORLUC numeric system for the identification of Enterobacteriaceae
Authors: Amsterdam D , Phillips S B , Richter M W
Published: June 2021

Foul hundred eighty-six members of the Enterobacteriaceae representing nine genera were identified by conventional methods, and the results were compared with MORLUC (Biotrol Company Inc., Jamaica, N.Y.). MORLUC, an acronym for melibiose, ONPG (o-nitrophenyl-beta-galactopyranoside), rhamnose, lysine decarboxylase, urease, and citrate, are six prepackaged reagent-impregnated paper loops which are sealed within a plastic packet. The hydrogen sulfide reaction obtained from a triple sugar iron slant is coupled with MORLUC results and is readily converted into a three-digit numerical code, which is referenced on a preprinted single page listing. Additionally, the triple sugar iron is used to confirm the glucose fermentation by an unknown isolate. Comparisons of individual MORLUC tests and standard methods results in a better than 92% agreement, except for unrease. Four hundred sixty-six of the 486 bacterial isolates, or 96% of the strains which were numerically identified by MORLUC, agreed with conventional diagnoses.
Unclassified, citrate-positive member of the family Enterobacteriaceae resembling Escherichia coli
Authors: Washington JA I I , Timm J A
Published: June 2021

Three isolates of an unclassified, oxidase-negative and citrate-positive, gram-negative bacillus belonging to the family Enterobacteriaceae were studied. With the exception of the citrate reactions, these strains most closely resembled Escherichia coli in their biochemical reactivity.
Critical analysis of hypertonic medium and agitation in detection of bacteremia
Authors: Ellner P D , Kiehn T E , Beebe J L , McCarthy L R
Published: June 2021

Over 18,000 clinical specimens collected in Vacutainer tubes with sodium polyanethol sulfonate were inoculated into modified Columbia broth (MCB) with and without 10% sucrose. The effects of venting and shaking on recovery were studied. The volume of the blood had a definite effect on the recovery rate. When inoculum size was held constant, recovery of aerobic and facultative organisms was maximal in vented and shaken bottles; the presence of sucrose had no demonstrable effect, recovery of anaerobes was maximal using an unvented bottle incubated under stationary conditions; a significantly greater recovery of facultatives and a marginally greater recovery of anaerobes was obtained with the hypertonic formulation. We conclude that a hypertonic formulation of MCB offers no advantage in the recovery of anaerobes but is of value in the recovery of facultatives and anaerobes. It is recommended that blood cultures be routinely inoculated into isotonic MCB and then vented and shaken for at least 4 hours, and hypertonic MCB incubated without venting or shaking.
Examination of bacterial flagellation by dark-field microscopy
Authors: Macnab R M
Published: June 2021

A method is described for visualizing unstained bacterial flagella by dark-field light microscopy. Since individual filaments can be seen, a genus such as Salmonella, which is peritrichously flagellated, can readily be distinguished from a polarly flagellated genus such as Pseudomonas. Polarly flagellated bacteria generally swim much faster than peritrichously flagellated bacteria, and turn by abrupt reversals. The differences in flagellation and motility provide diagnostic criteria that may be useful in clinical microbiology.
Recent experience with the complement fixation test in the laboratory diagnosis of rickettsial diseases in the United States
Authors: Shepard C C , Redus M A , Tzianabos T , Warfield D T
Published: June 2021

Sera from patients suspected of having rickettsial infections were tested in the complement fixation test with antigens prepared from the rickettsiae of Rocky Mountain spotted fever (SF), rickettsial pox (RP), murine typhus, epidemic typhus, and from Rickettsia canada (RC). Eight units of antigen were used in all cases and two units in man. Only those patients with antibody titers of 1:16 or higher were included in the study. Largely on the basis of comparative titers, the patients were divided into two groups: 102 with SF and 35 with infections by one of the members of the typhus group. The antibody titers were higher with SF antigen than RP antigen in 72% of the SF patients, and in only two SF patients was the RP titer higher, and then by only one tube (twofold dilution). There seemed little advantage in including the RP antigen in the battery of rickettsial antigens. Cross-reaction with at least one of the typhus antigens was observed in the sera from 64% of the SF patients. It was extensive enough to be confusing (within one tube) in 17% with eight units of antigen, but the differentiation was more distinct with two units of antigen. The cross-reaction with typhus antigens was as frequent in children with SF as it was in adults; thus, it is unlikely that these cross-reactions resulted from previous typhus vaccination. The serological differentiation between murine typhus and epidemic typhus was frequently difficult, but the epidemiological background was distinct. Five patients had higher titers to RC antigen, and four of these may possibly have had RC infections.
New assay of protective activity of Rocky Mountain spotted fever vaccines
Authors: Anacker R L , Smith R F , Mann R E , Hamilton M A
Published: June 2021

Areas under the fever curves of guinea pigs inoculated with Rocky Mountain spotted fever vaccine over a restricted dose range and infected with a standardized dose of Rickettsia rickettsii varied linearly with log10 dose of vaccine. A calculator was programmed to plot fever curves and calculate the vaccine dose that reduced the fever of infected animals by 50%.
Use of Mueller-Hinton Agar as Amylase Testing Medium
Authors: Lee Wie-Shing
Published: June 2021

Readily available Mueller-Hinton agar was used to detect starch hydrolysis by
Streptococcus bovis.
Examination of various cell culture techniques for co-incubation of virulent Treponema pallidum (Nichols I strain) under anaerobic conditions
Authors: Sandok P L , Knight S T , Jenkin H M
Published: June 2021

Treponema pallidum (Nichols virulent) was incubated with and without cells in cell culture medium reduced to -275 mV Ecal, pH 7.3, under deoxygenated conditions. Five to ten percent of the treponemes attached to cells and remained motile for at least 120 h in cell-treponeme systems of co-incubation. Virulent treponemes could be detected after 120 to 144 h in the supernatant fluids of cell-treponeme co-incubation cultures and in cell-free tubes containing medium harvested from aerobically cultivated mammalian cells. Medium supplemented with ox serum ultrafiltrate, pyruvate, and sodium thioglycolate and gas mixtures containing H2 and CO2 enhanced treponemal survival. Increases in treponemal numbers were observed using dark-field microscopy but were not substantiated using the rabbit lesion test. Continuous passage of the treponeme was not achieved in vitro.
Microscopy of stained urine smears to determine the need for quantitative culture
Authors: Lewis J F , Alexander J
Published: June 2021

Consecutive specimens (2,564) of urine were cultured quantitatively, and Gram-stained smears were prepared from centrifugates as well as from the uncentrifuged specimens. About half of the specimens harbored organisms, and the quantity seen in smears of the centrifugates correlated reasonably well with the numbers of viable organisms cultured from the specimens. For example, smears of 900 centrifugates had one or more organisms per oil immersion field; 712 of their respective specimens proved to have colony counts of 10(5) or greater, and 120 had 10(4) to less than 10(5). For 188 specimens, however, the smears falsely predicted greater than or equal to 10(5) colony-forming units (many of these fell into the group that had 10(4) to less than 10(5)) but failed to predict clinically significant concentration of 10(5) or greater in only 31. Predictive values are presented also for lesser quantities of organisms seen in such smears. With rare exception, smears of centrifugates were superior to those of whole specimens as predictors of the concentration of viable organisms. Evaluation of smears proved not to be biased by the operator; values did not deviate significantly depending upon whether one or several microbiologists performed the evaluations.
Improved medium for detecting pigment production by group B streptococci
Authors: Merritt K , Jacobs N J
Published: June 2021

The production of pigment which can be used for presumptive identification of group B streptococci is sometimes weak and difficult to observe in Columbia agar stab cultures. A medium which is whiter and affords better visibility of this pigment is described.
Single-tube mixed agglutination test for the detection of staphylococcal protein A
Authors: Maxim P E , Mathews H L , Mengoli H F
Published: June 2021

A simple, rapid mixed agglutination test using sheep erythrocytes (SRBC) sensitized with rabbit hemolysin and intact viable staphylococci is described for the detection of bound staphylococcal protein A. Soluble protein A was heat extracted from 50 clinical isolates as well as the Cowan I and Wood 46 strains of Staphylococcus aureus and titered by a hemagglutination test using sensitized SRBC and dilutions of soluble protein A. Protein A could be detected in all of these supernatants including that of S. aureus Wood 46, a strain generally considered to be protein A negative. These organisms were later retested by the mixed agglutination test and even those staphylococcal isolates expressing very low heat-extractable soluble protein A concentrations (1:2 titers) were positive, confirming the sensitivity of the test. In a screen of clinical isolates, only 4 of 235 (1.8%) coagulase-positive isolates were negative in the mixed agglutination test. Of 25 coagulase-negative isolates, none yielded a positive reaction.
Evaluation of four methods for detection of group B streptococcal colonization
Authors: Mason E O , Wong P , Barrett F F
Published: June 2021

Four methods (streak plate, pour plate, selective broth, and direct fluorescent-antibody staining) were evaluated for their ability to detect group B streptococcal colonization in parturient women and their offspring. When colonization was defined as a positive culture by any method from any site, selective broth was the most sensitive method, detecting 100% of colonized mothers and infants at birth and 48 h of age. This method failed to detect only one colonized individual (infant at 24 h of age). The other three methods detected from 20 to 56% of colonized individuals.