bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of the ascospore dispersal of Stagonosporopsis citrulli, a causal agent of gummy stem blight of cucurbits
Authors: Rennberger Gabriel , Turechek William W. , Keinath Anthony P. 
Published: June 2021

AbstractSexually reproduced, airborne ascospores of Stagonosporopsis citrulli may play a role in its dispersal. S. citrulli causes gummy stem blight (GSB), one of the most important foliar diseases of cucurbits. Four studies were conducted with S. citrulli to investigate for how long ascospores are released and how far they can be dispersed from a source field. In the first study, colonized watermelon debris was sampled during three seasons and samples were assayed for ascospore release. Ascospores were detected 292, 313, and 306 days after inoculation of the source. In the second study, the active release of ascospores from pseudothecia in a Petri dish was monitored for 7 days. The release of ascospores decreased by ≤90% from 1 day after the start of the assay until 7 days after. In the third study, trap plant assays were conducted to measure the dispersal gradient of ascospores up to 366 m from the source. Generally, frequency of pathogen recovery from trap plants decreased with increasing distance from the source. The ascospore dispersal data fitted the exponential model better than the power law model. In the final study, dispersal experiments were conducted under controlled conditions. The incidence of GSB decreased with increasing distance, up to 55 m, from the source. It was concluded that ascospores of S. citrulli can serve as primary inoculum for epidemics and could easily spread among fields. Debris from cucurbit crops can be the source of ascospores for up to 10 months and should be cleared expeditiously.
Water deficit stress responses of monoterpenes and sesquiterpenes in different Iranian cultivars of basil
Authors: Khakdan Fatemeh , Govahi Mostafa , Mohebi Zahra , Ranjbar Mojtaba 
Published: June 2021

AbstractOcimum basilicum, a popular aromatic plant, contains aromatic terpenes of terpenoids with in vivo and in vitro verified cytotoxicity. Considering the characteristics and potential of its utilization, it would be attractive to reveal its regulation and biosynthesis, originally at the molecular level under water deficit stress. For this aim, for the first time, the gene encoding the enzyme involved in the end step of the MEP biosynthetic pathways (HDR) was cloned, and the accumulation ratio of linalool, germacrene D and γ‐cadinene compounds as well as the expression trait of four critical genes (i.e., HDR, LinS, GerS, and GadS) was assessed under water deficit stress in three Iranian cultivars of basil. The highest value of linalool and γ‐cadinene were detected for Cultivar 1 (Cult. 1) under mild stress (W1; 52.6 and 21.1%), while insignificant amounts were obtained for Cultivar 3 (Cult. 3). The germacrene D level of Cultivar 2 (Cult. 2) increased under severe and moderate water stresses as compared with mild water deficit stress. Apart from some expectation, all the studied genes demonstrated divergent transcription ratios under water deficit stress. Principal component analyses (PCA) showed that the relative water content (RWC) and HDR gene expression correlated significantly with essential oil components and gene expression in Cult. 1 and 2, which could represent an elevated demand for corresponding metabolites in the plant tissues. The present work elaborates on the regulation of the mentioned genes, and the results indicate that the production of terpenoids might be a drought stress‐dependent and cultivar‐dependent procedure.
Racialized parenting in the United States
Authors: Manning Alex 
Published: June 2021

AbstractContrary to anti‐black, cultural deficit logics that frame Black parenting as tied to the reproduction of social disadvantage, research shows that Black parents, and other parents of color, are agentic as they parent in direct response to the dominant racial order of the United States. In this paper, I review this scholarship and primarily focus on how Black parents approach raising children in the racialized worlds that they live in. To mitigate the disadvantages caused by racism, Black parents use various intentional racialized parenting approaches to instill in their children a resilience to a racist social world. The strategies used to cultivate resilience to racism exist in varied social and institutional contexts, and intertwine with how parents understand race, class, and identity. Laborious racialized parenting techniques do not solely matter at the micro‐level as such practices are unevenly recognized by white‐dominant social institutions. This uneven dynamic indicates how hegemonic norms of American parenting culture fit within a project of racial neoliberalism. Consequently, Black parents are structurally pushed to burden more responsibility to prepare their children to survive a deeply racist and hyper‐competitive social world with no guarantee that such intensive, strategic parenting will be rewarded.
Reconstruction of ancestral karyotype illuminates chromosome evolution in the genus Cucumis
Authors: Zhao Qinzheng , Meng Ya , Wang Panqiao , Qin Xiaodong , Cheng Chunyan , Zhou Junguo , Yu Xiaqing , Li Ji , Lou Qunfeng , Jahn Molly , Chen Jinfeng 
Published: June 2021

SUMMARYKaryotype dynamics driven by complex chromosome rearrangements constitute a fundamental issue in evolutionary genetics. The evolutionary events underlying karyotype diversity within plant genera, however, have rarely been reconstructed from a computed ancestral progenitor. Here, we developed a method to rapidly and accurately represent extant karyotypes with the genus, Cucumis, using highly customizable comparative oligo‐painting (COP) allowing visualization of fine‐scale genome structures of eight Cucumis species from both African‐origin and Asian‐origin clades. Based on COP data, an evolutionary framework containing a genus‐level ancestral karyotype was reconstructed, allowing elucidation of the evolutionary events that account for the origin of these diverse genomes within Cucumis. Our results characterize the cryptic rearrangement hotspots on ancestral chromosomes, and demonstrate that the ancestral Cucumis karyotype (n = 12) evolved to extant Cucumis genomes by hybridizations and frequent lineage‐ and species‐specific genome reshuffling. Relative to the African species, the Asian species, including melon (Cucumis melo, n = 12), Cucumis hystrix (n = 12) and cucumber (Cucumis sativus, n = 7), had highly shuffled genomes caused by large‐scale inversions, centromere repositioning and chromothripsis‐like rearrangement. The deduced reconstructed ancestral karyotype for the genus allowed us to propose evolutionary trajectories and specific events underlying the origin of these Cucumis species. Our findings highlight that the partitioned evolutionary plasticity of Cucumis karyotype is primarily located in the centromere‐proximal regions marked by rearrangement hotspots, which can potentially serve as a reservoir for chromosome evolution due to their fragility.
The Effect of a Nonisothermal Free Stream on Boundary-Layer Heat Transfer
Authors: Sparrow E. M. , Gregg J. L. 
Published: June 2021

Abstract
An analysis is made for laminar forced-convection heat transfer from a flat plate to a nonisothermal free stream. An exact solution of the boundary-layer energy equation is found for the situation of linearly varying free-stream temperature. Numerical calculations are carried out for Prandtl numbers in the range 0.01 ⩽ Pr ⩽ 50. Results are presented for the change in heat transfer due to the variation in free-stream temperature. This effect decreases with increasing Prandtl number.
Some Preliminary Results of Visual Studies of the Flow Model of the Wall Layers of the Turbulent Boundary Layer
Authors: Kline S. J. , Runstadler P. W. 
Published: June 2021

Abstract
Preliminary studies of the flow model in the wall layers of the turbulent boundary layer are presented. Results are summarized for investigations of positive pressure gradients, zero and negative pressure gradients, readjusting zones, and the later stages of transition. In all cases, the special visual methods developed for these studies show a definite three-dimensional vortex-flow model. The presently available details of this model are described, a possible interpretation of the physics of the turbulent boundary layer is given, and some of the many implications of the flow model are discussed.
On Journal Bearings of Finite Length With Variable Viscosity
Authors: Tao L. N. 
Published: June 2021

Abstract
An exact solution of the Reynolds equation for journal bearings of finite length with viscosity as a function of pressure is found. The analytical solution is expressed in terms of Heun functions. The load capacity and the attitude angle are derived. It is found that the load vector, in general, is not perpendicular to the line of journal and bearing centers as shown in the constant-viscosity case.
On Critical Speeds of a Shaft Supported by a Ball Bearing
Authors: Yamamoto Toshio 
Published: June 2021

Abstract
The author points out that two kinds of critical speeds induced by a slight difference in the diameter of balls in a ball bearing appear in a rotating shaft supported by ball bearings. These two critical speeds have peculiar modes of vibrations which are determined by dimensions of ball bearings; one of them is motion of forward precession, the other is backward precession. The paper describes the cause of these critical speeds and the behavior of those vibrations.
Transients in Simple Undamped Oscillators Under Inertial Disturbances
Authors: Dornig Antongiulio 
Published: June 2021

Abstract
Single-degree-of-freedom systems acted upon inertial forces are often found in technical applications. In this paper we shall study the transients in the vibrations of the system due to a change in speed in the machine in which the inertial forces are generated. We shall state the problem in the most general case, and then study the starting and the stopping with constant acceleration. After giving the exact solution of the problem we shall derive very simple approximate formulas for the determination of the maximum amplitude reached in these transients.
Direct Determination of Stresses in Plane Elasticity Problems Based on the Properties of Isostatics
Authors: Theocaris Pericles S. 
Published: June 2021

Abstract
An experimental method is developed for the calculation of stresses in plane elasticity problems. The method consists substantially in determining a function of the complex variable representing the field of isostatics. This function has a convenient form so that the boundary conditions can be expressed by simple relations. From the isostatics, which are traced experimentally, the differential parameter of first order h can be calculated all over the field. The components of stresses are expressed by relations depending on boundary conditions and the parameter h. The method is applied to two particular problems of plane elasticity and a comparison of the results obtained by this method and by analytic methods is provided.
Upper and Lower Bounds for Special Eigenvalues
Authors: Appl F. C. , Zorowski C. F. 
Published: June 2021

Abstract
A method for finding upper and lower bounds for the fundamental eigenvalue in special eigenvalue problems is presented. The method is systematic and is shown to provide convergence from above and below to the exact eigenvalue under certain conditions. The method is based on the relatively well-known enclosure or comparison theorem of Collatz, and makes use of a power series to approximate the eigenfunction. The method is applied to two examples concerning the critical-elastic buckling load of variable-section columns with pinned ends. Results for the first example compare well with the exact solution, which is known; the second example is presented as an addition to the literature.
Large Deflections of a Clamped Elliptical Plate Subjected to Uniform Pressure
Authors: Nash W. A. , Cooley I. D. 
Published: June 2021

Abstract
The problem of the nonlinear large deflections of a clamped edge thin elliptical plate subject to a uniform normal load is treated by the method of successive approximations based upon the smallness of central deflection. Results of the analysis are shown to be in excellent agreement with experimental data obtained from test of an aluminum plate.
Deflection of a Thick Ring in Diametral Compression by Test and by Strength-of-Materials Theory
Authors: Blake Alexander 
Published: June 2021

Abstract
Experimental and theoretical deflection studies are briefly described for several steel rings, of uniform rectangular cross section, compressed by two forces along a diameter and having D/d ratios ranging from 1.3 to 1.9. The calculations are based on the principle of Castigliano and expressions for strain energy due to bending, normal, and shear stresses. Discrepancies between the theoretical estimate and the tests are shown.
Velocity and Temperature Fluctuation Measurements in a Turbulent Boundary Layer Downstream of a Stepwise Discontinuity in Wall Temperature
Authors: Johnson D. S. 
Published: June 2021

Abstract
Results are presented of an experimental investigation of the coexisting thermal and velocity fluctuation fields in a turbulent boundary layer downstream of a small stepwise discontinuity in wall temperature. The statistical behaviors of several relevant fluctuating quantities have been obtained at a typical cross section of the boundary layer in the region where the thermal boundary layer has not yet reached the free stream. The instantaneous surface of demarcation between heated and unheated fluid was found to be sharp and distinct at all points, resulting in intermittent temperature fluctuation signals well within the fully turbulent region of the momentum boundary layer. From the measurements at one section, the balances of turbulent kinetic energy and of turbulent temperature fluctuations across the boundary layer have been evaluated. In addition, the distribution of the local turbulent Prandtl number (ratio of the turbulent diffusivities of momentum and heat) through the boundary layer has been obtained; it is not constant and varies between limits of 0.8 and 1.2.
Density Variation Effects in Stepped-Thrust Bearings
Authors: Kettleborough C. F. 
Published: June 2021

Abstract
The problem of the stepped-thrust bearing is considered but, whereas normally volumetric continuity is assumed, the equations are solved assuming mass continuity; i.e., the variation of density is also considered as well as the effect of the stepped discontinuity on the load-carrying capacity and the coefficient of friction. Computed theoretical curves illustrate the importance of the density on the operation of this bearing and, in part, explain results already published.
Response of Van Der Pol’s Oscillator to Random Excitation
Authors: Caughey T. K. 
Published: June 2021

Abstract
This paper considers the response of Van der Pol’s oscillator to random excitation. It is shown that the output of the oscillator consists of a periodic term, plus a narrow band noise term centered at the natural frequency of the oscillator. The root-mean-square amplitude of this noise term is shown to be proportional to the square root of the spectral density of the excitation, and inversely proportional to the amplitude of self-oscillation.
On Finite Bending of Pressurized Tubes
Authors: Reissner Eric 
Published: June 2021

Abstract
A unified treatment is presented of two well-known problems which have until now been considered separately. The two problems are: (a) the linear problem of pure bending of curved tubes, and (b) the nonlinear problem of pure bending of straight tubes. In both problems the effect of uniform internal pressure is included. The essential step in the present analysis is the treatment of the flattening of the cross sections of the tube by means of a theory of finite bending of circular rings. The general results of the paper are used to obtain improved values for the stability parameters in the problem of flattening instability of originally straight tubes acted upon by end bending moments, and also to obtain results on the effect of slight original curvature of the beam axis in the problem of flattening instability.
On Invariant Perforation in an Infinite Strip
Authors: Ling Chih-Bing 
Published: June 2021

Abstract
The invariant perforation in an infinite strip can be classified into two groups. One is the finite group and the other is the infinite group. There are five cases in the finite group and nine cases in the infinite group. All the cases can be solved by the method of images. This method has, in fact, been used by the author to solve the stresses in an infinite strip containing either an unsymmetrically located single hole or a series of uniformly distributed equal holes. The solution is illustrated by working out in detail one of the cases in the infinite group, in which the strip contains two series of equal holes symmetrically staggered along the strip. The stress function is constructed by using a class of periodic harmonic functions derived from Weierstrass’ sigma function. Numerical examples also are given to show the effect of such a perforation on the stresses in the strip.
Impact and Moving Loads on a Slightly Curved Elastic Half Space
Authors: Eringen A. C. , Samuels J. C. 
Published: June 2021

Abstract
Two-dimensional Fourier transforms are employed to treat the two-dimensional dynamic problem of elastic half space having a slightly wavy boundary. The various boundary curves considered include square and triangular bumps and holes, and sinusoidal and periodic boundaries. The number of different types of surface loadings considered are: (a) Normal tractions and zero shear, (b) impulsive normal tractions and zero shear, (c) suddenly applied normal tractions and zero shear, (d) concentrated normal load and zero shear, (e) concentrated impulsive load and zero shear, (f) pulsating normal load and zero shear, (g) moving loads, (h) pulsating moving loads, (i) vertical and horizontal loads, (j) moving vertical loads. Stress and displacement components for special cases of the loads described in (a, c, f, and g) acting on a sinusoidal boundary lead to a solution which requires evaluation of a single indefinite integral. Closed-form results are given for a uniform pulsating pressure load.
Stability of Forced Oscillations With Nonlinear Second-Order Terms
Authors: Shen Chi-Neng 
Published: June 2021

Abstract
A solution is obtained for forced oscillations with nonlinear second-order terms. The stability of this solution is given by its variational equation. The boundary of stability is analyzed by both the perturbation and continued fraction methods. The amplitude of osclllation with damping terms is also determined by the iteration procedure.
Analysis of a Nonlinear Mechanical System With Three Degrees of Freedom
Authors: Hovanessian S. A. 
Published: June 2021

Abstract
In recent years the methods of solution of nonlinear vibratory systems with one degree of freedom have been extended to the solution of nonlinear systems with two degrees of freedom. For these systems, the steady-state amplitude equations can be obtained by several methods, such as perturbation and the iteration method introduced by Duffing. In this paper the amplitude-frequency equations for a nonlinear mechanical system with three degrees of freedom are obtained, using Duffing’s method for obtaining the steady-state amplitude equations [1]. The steady-state response curves of two nonlinear mechanical systems, each having three degrees of freedom, are given.
Stresses in an Ellipsoidal Rotor in a Centrifugal Force Field
Authors: Goldberg M. A. , Sadowsky Michael 
Published: June 2021

Abstract
This paper contains an exact solution for the stress distribution in an elastic ellipsoid rotating about a free axis. The surface of the body is free from boundary stresses. The stresses are expressed with the use of 12 coefficients which have been tabulated for 209 ellipsoids of different shapes. General diagrams give the maximum values of stresses as functions of two shape ratios.
The Drag on Spheres and Cylinders in a Stream of Dust-Laden Air
Authors: Gillespie Thomas , Gunter A. W. 
Published: June 2021

Abstract
A system has been developed for measuring the drag on small spheres and cylinders in a stream of dust-laden air. The drag was found to be proportional to the kinetic energy of the air plus the kinetic energy of the dust, and to be independent of particle size for particles having diameters in the range of 50 to 400μ. The well-known drag-coefficient versus Reynolds-number plots are the same for dust-free and dust-laden air provided the drag coefficient is calculated using the density of the two-phase system and the Reynolds numbers are calculated using the density of air alone. This suggests that the dust has little effect on the flow pattern. The results indicate that an instrument utilizing the drag principle to measure dust concentration could be developed.
Elastic Flexible Cable in Plane Motion Under Tension
Authors: Li Wen-Hsiung 
Published: June 2021

Abstract
The motion and stresses of a non-Hookian elastic flexible cable in plane motion under tension are described with four simultaneous quasilinear, partial differential equations which are totally hyperbolic. The propagation of the longitudinal elastic waves and the transverse waves are described by the four characteristics. From the characteristic equations, solutions for simple longitudinal waves and simple transverse waves are obtained for uniform Hookian cables. The problem of an infinite string moved at one point with a constant velocity can be solved. Solutions also have been obtained for the interaction of transverse and longitudinal waves with sharp fronts.
Rupture Characteristics of Safety Diaphragms
Authors: Weil N. A. 
Published: June 2021

Abstract
Instability (maximum pressure) criteria for materials obeying a parabolic stress-strain law are investigated. Two special solutions are formulated, accompanied by the instability condition obtained from the author’s approximate theory. Bursting pressure is most accurately predicted by the approximate theory. In turn, the polar deflection and strain at instability are more closely predicted by special solution II. It is shown that neither the “pureness” nor the annealed condition of a metal gives adequate assurance of reliability in frangible disk service. The way to insure this requirement is to confirm experimentally that, in the uniaxial test, fracture will not occur before the logarithmic strain exceeds roughly (0.36 + 0.73 m), or that in a bulge test the applied hydrostatic pressure passes through a maximum prior to bursting.
The Solution of Elastic Stability Problems With the Electric Analog Computer
Authors: Shields J. H. , MacNeal R. H. 
Published: June 2021

Abstract
An application of electric analog computing methods to the analysis of elastic stability problems is described. An electrical circuit is first devised which satisfies a general differential equation that is frequently encountered in the literature of elastic stability. This circuit, composed of inductors, capacitors, transformers, and current generators, is then used to obtain solutions for several classical column, framework, and plate-stability problems.
Symmetric Vortex Separation on Circular Cylinders and Cones
Authors: Bryson A. E. 
Published: June 2021

Abstract
The symmetric vortex separation that is observed on the leeward side of slender bodies of revolution at high angle of attack in the subsonic to moderately supersonic-velocity range is analyzed by means of the “lumped-vorticity” approximation suggested by Edwards and Hill. The equivalent unsteady two-dimensional problem of indicial motion of a cylinder in an incompressible fluid with symmetric vortex wake is also considered. Body vortex position and normal force per unit length are presented for a cylinder and a slender cone at high angle of attack and compared with available experimental information.