bluuebunny/crossref_metadata_2025 huggingface dataset:
Sialochemistry and cortisol levels in patients with Sjogren’s syndrome
Authors: Miller BE , Deutsch O , Redlich M , Konttinen YT , Benoliel R , Zaks B , Davidovich E , Palmon A , Aframian DJ
Published: October 2011

Oral Diseases (2012) 18, 255–259

Objectives:  (i) To determine whether salivary cortisol and electrolyte levels differ between patients with Sjogren’s syndrome (SjS) and healthy individuals. (ii) To assess correlations between whole‐saliva cortisol and some clinical manifestations in patients with SjS.

Methods:  A total of 24 healthy women (mean age 49.3 ± 9.8) served as controls (C) vis‐à‐vis 17 patients with SjS (mean age 55.5 ± 15.7). Salivary cortisol concentration was determined, and sialochemistry analysis was performed.

Results:  Significantly lower saliva flow rates and higher salivary chloride (Cl−), potassium (K+), and Ca2+ levels were found in the SjS group. No significant differences or correlations were found in other parameters, including sodium (Na+), magnesium (Mg2+), phosphate (−), urea (U), and salivary cortisol levels.

Conclusion:  Increased whole‐salivary output of Cl− and K+ in SjS may reflect release from apoptotic rests of acinar cells after secondary necrosis. Normal levels of salivary Na+, Mg2+, and − argue against concentration effect, deranged tubular function or cortisol (mineralocorticosteroid) effect as the cause for these findings. Increased salivary Ca2+ levels probably reflect leakage of plasma Ca2+ through the injured oral mucosa in SjS. In spite of disease‐associated stress, salivary cortisol, a stress biomarker, was not increased, suggesting insufficient hypothalamus–pituitary–adrenal (HPA) axis response and/or local consumption of cortisol by lymphocyte infiltrates.
Multi‐stemming and mechanical traits ensure persistence of subalpine woody plants exposed to a disturbance gradient
Authors: Stokes Alexia , Mine François‐Xavier , Mao Zhun , Brancheriau Loic
Published: October 2011

Question

Many woody plants persist in a temporal ‘persistence’ niche, through resprouting after disturbance events. Will multi‐stemming (as a consequence of resprouting or life form) and biomechanical traits enable certain species to survive disturbance and occupy a persistence niche?

Location

A 1200‐m long avalanche corridor in the French Alps, with disturbance events ca. every 2 yr.

Methods

We measured tree/shrub size and multi‐stemming in transects along and around the avalanche corridor. The mechanical traits, wood density, modulus of elasticity (Ed), bending strength (σ) and stiffness (EI), along stems of several subalpine tree/shrub species were measured to test for differences in flexibility and strength.

Results

The multi‐stemmed pioneer shrubs Alnus viridis, Salix appendiculata and to a lesser extent, Corylus avellana, were more abundant where disturbance was most severe. Multi‐stemming broadleaf species, in particular Fagus sylvatica, had more tapered, shorter and more numerous stems in severely disturbed zones. Single‐stemmed conifers were usually found furthest from the avalanche track. A. viridis, codominant at the centre of the track, had the lowest Ed, σ and EI. In A. viridis, Alnus incana, F. sylvatica and Betula pendula, Ed was lower at the stem base and increased with height up the stem. Alnus viridis and C. avellana stems were most flexible (low EI), whereas single‐stem tree forms, Picea abies and B. pendula, were stiffest. Corylus avellana had the highest σ and lowest wood mechanical construction cost (ρ) per unit function (Ed), whereas P. abies had highest construction cost.

Conclusions

High flexibility of A. viridis, and to a lesser extent C. avellana and the multi‐stemmed form of F. sylvatica, allows individuals to bend during snow loading, before an avalanche; therefore, stem damage and uprooting during an avalanche are minimized. Increased stem basal flexibility in these species will also facilitate bending during snow loading. More rigid distal sections will confer extra mechanical advantage to stems that need to grow quickly upwards, dominate and maintain their position in the canopy during the growing season.
Comparative study of the microvascular blood flow in the intestinal wall during conventional negative pressure wound therapy and negative pressure wound therapy using paraffin gauze over the intestines in laparostomy
Authors: Lindstedt Sandra , Hansson Johan , Hlebowicz Joanna
Published: October 2011

Higher closure rates of the open abdomen have been reported with negative pressure wound therapy (NPWT) than with other kinds of wound management. We have recently shown that NPWT decreases the blood flow in the intestinal wall, and that the blood flow could be restored by inserting a protective disc over the intestines. The aim of the present study was to investigate whether layers of Jelonet™ (Smith & Nephew) dressing (paraffin tulle gras dressing made from open weave gauze) over the intestines could protect the intestines from hypoperfusion. Midline incisions were made in ten pigs and were subjected to treatment with NPWT with and without four layers of Jelonet over the intestines. The microvascular blood flow was measured in the intestinal wall before and after the application of topical negative pressures of −50, −70 and −120 mmHg, using laser Doppler velocimetry. Baseline blood flow was defined as 100% in all settings. The blood flow was significantly reduced, to 61 ± 7% (P < 0·001), after the application of −50 mmHg using conventional NPWT, and to 62 ± 7% (P < 0·001) after the application of −50 mmHg with Jelonet dressings between the dressing and the intestines. The blood flow was significantly reduced, to 38 ± 5% (P < 0·001), after the application of −70 mmHg, and to 42 ± 6% (P < 0·001) after the application of −70 mmHg with Jelonet dressings. The blood flow was significantly reduced, to 34 ± 9% (P < 0·001), after the application of −120 mmHg, and to 38 ± 6% (P < 0·001) after the application of −120 mmHg with Jelonet dressings. The use of four layers of Jelonet over the intestines during NPWT did not prevent a decrease in microvascular blood flow in the intestinal wall.
The Dynamic Structure of Arterioles
Authors: Martinez‐Lemus Luis A.
Published: October 2011

Abstract:  Arterioles are the blood vessels in the arterial side of the vascular tree that are located proximal to the capillaries and, in conjunction with the terminal arteries, provide the majority of resistance to blood flow. Consequently, arterioles are important contributors to the regulation of mean arterial pressure and tissue perfusion. Their wall consists of cellular and extracellular components that have been traditionally classified as conforming three layers: an intima containing endothelial cells sited on a basement membrane; a media made of an internal elastic lamina apposed by one or two layers of smooth muscle; and an adventitia composed mostly of collagen bundles, nerve endings and some fibroblasts. These components of the arteriolar wall are dynamically interconnected, providing a level of plasticity to the arteriolar wall that blurs the traditional boundaries of a rigid layered classification. This MiniReview focuses on the structural conformation of the arteriolar wall and shows how wall components interact spatially, functionally and temporally to control vascular diameter, regulate blood flow and maintain vascular permeability.
What do you think you are?
Authors: Starmans Christina , Bloom Paul
Published: October 2011

Here, what might be considered a universal belief in dualism is integrated with developmental perspectives on the emergence of identifying the mental and physical components of the self. Additionally, work to “localize” the self is introduced.
Importance of marginal habitats for grassland diversity: fallows and overgrown tall‐grass steppe as key habitats of endangered ground‐beetle Carabus hungaricus
Authors: POKLUDA PAVEL , HAUCK DAVID , CIZEK LUKAS
Published: October 2011

Abstract.  1. To facilitate effective conservation management of dry‐grassland diversity we studied the habitat selection of Carabus hungaricus, the globally declining, highly endangered, dry‐grassland specialist beetle listed in the EU Habitats Directive, and several co‐occurring beetles at a pannonian dry‐grassland fragment, the Pouzdrany steppe, SE Czech Republic. The beetles were sampled using 186 pitfall traps from March to November 2006. Number of C. hungaricus captures in each trap was related to vegetation and abiotic habitat characteristics; captures of all sampled beetles in each trap were related to each other.

2. We found that C. hungaricus prefers relatively humid patches of tall‐grass steppe within the xeric grassland and tall‐grass ruderal vegetation nearby. During the breeding period, females preferred drier and warmer sites than males.

3. Its potential competitors, i.e., Carabus spp., Calosoma spp. (Coleoptera: Carabidae), and other species of conservation interest, including Meloe spp. (Coleoptera: Meloidae), Dorcadion spp. (Coleoptera: Cerambycidae), were associated with vegetation avoided by C. hungaricus, such as short‐grass and bare‐soil patches and woody plants.

4. Vegetation structure within 2.5 m affected C. hungaricus captures more than on smaller and larger scales. Carabus hungaricus enters unfavoured non‐forest habitats such as arable land, which allows it to spread into suitable habitats within agricultural landscapes. It strictly avoids closed forest; even narrow strips of forest thus likely act as migration barriers.

5. The preference of C. hungaricus for overgrown steppe and fallow land highlights that habitats often considered of low conservation value are important to sustain grassland biodiversity.
Comparison of the corneal biomechanical properties with the Ocular Response Analyzer® (ORA) in African and Caucasian normal subjects and patients with glaucoma
Authors: Detry‐Morel Michèle , Jamart Jacques , Hautenauven Frédéric , Pourjavan Sayeh
Published: October 2011

Purpose:  To compare corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer® tonometer (ORA) between (i) African normals and treated primary open‐angle glaucoma (POAG) patients and (ii) between normals and treated POAG Caucasians. To analyse the correlation of CH and CRF with visual field (VF) defects in the two groups.

Methods:  This comparative study included 59 African (29 (POAG), 30 normals) and 55 Caucasians (30 POAG and 25 normals) subjects. Goldmann applanation tonometry (GAT) and ORA measurements were performed in a randomized sequence. Visual field was tested with the Swedish interactive threshold algorithms standard strategy of the Humphrey perimeter. Hoddap classification was used to estimate the severity of VF defects.

Results:  Primary open‐angle glaucoma Africans were younger than POAG Caucasians (p < 0.001). Goldmann applanation tonometry and central corneal thickness (CCT) did not differ significantly between the four subgroups. African normals had lower CH than Caucasian controls (p < 0.001). CH was 9.2 ± 1.1 and 8.3 ± 1.7 mmHg respectively in POAG Caucasians and Africans (p < 0.001). African controls had higher ORA corneal‐compensated intraocular pressure (IOPcc) than Caucasian controls (p < 0.001). Primary open‐angle glaucoma Africans had higher IOPcc values than Caucasian POAGs (p < 0.001). CH and IOPcc were associated with race (p < 0.001) but not with CCT. Based on mean deviation values (MD), POAG Africans had more severe VF defects. CH was correlated with MD (r = 0.442; p = 0.031) and severity of VF defects only in POAG Africans (r = −0.464; p = 0.013).

Conclusions:  African normal subjects and POAG patients had an altered CH, which is associated with a significant underestimation of GAT IOP. This may potentially contribute to the earlier development and greater severity of glaucoma damage in Africans compared with Caucasians at diagnosis.
Ventrocaudal cystorrhaphy without urethral sphincterotomy in two broodmares
Authors: Higuchi T. , Inoue S. , Satoh M. , Kato T. , Yuasa Y.
Published: October 2011

Two broodmares were diagnosed with rupture of the urinary bladder. One mare revealed abnormalities post partum and the other associated with ante partum uterine torsion. The clinical symptoms included mild abdominal pain, anorexia, decreased urinary volume and increased peritoneal fluid. In one mare, based on the creatinine level of the peritoneal fluid and serum biochemical abnormalities, uroperitoneum was diagnosed. In the other mare, the bladder rupture was found during the celiotomy for surgical repair of uterine torsion that was diagnosed upon rectal examination. Surgery was performed without a urethral sphincterotomy. The vaginal floor was incised in a standing position and the bladder was diverted into the vagina in order to suture the tears located in the ventrocaudal aspect of the bladder. Both mares survived after treatment for uraemia. Bladder rupture, although uncommon, may affect peripartum mares. Approach to the ruptured bladder without urethral sphincterotomy in a standing position should be considered as a choice for surgical repair.
The effect of motion at encoding and retrieval for same‐ and other‐race face recognition
Authors: Butcher Natalie , Lander Karen , Fang Hui , Costen Nick
Published: October 2011

In an experimental study, we assessed the role of motion when encoding and recognizing unfamiliar faces, using an old/new recognition memory paradigm. Our findings revealed a clear advantage for learning unfamiliar faces moving non‐rigidly, compared with static faces. This advantage for motion was found with both same‐ and other‐race faces. Furthermore, results indicate that it is more important that the face is learnt in motion than recognized from a moving clip. Interestingly, despite a reliable other‐race effect being revealed, participants were able to utilize motion information exhibited by other‐race faces in a manner akin to the motion advantage found for same‐race faces. The implications of these findings are discussed in relation to the nature of the stored face representations, considering whether the facilitative role found here can be explained by factors other than motion per se.
Regulation of sarcoplasmic reticulum Ca2+ leak by cytosolic Ca2+ in rabbit ventricular myocytes
Authors: Bovo Elisa , Mazurek Stefan R. , Blatter Lothar A. , Zima Aleksey V.
Published: October 2011

Non‐technical summary  Contraction and relaxation of the heart strongly depend on calcium (Ca2+) stored in the sarcoplasmic reticulum (SR). Ca2+ stored within the SR is determined by the balance between Ca2+ uptake and Ca2+ leak that occurs mainly via Ca2+ release channels, called ryanodine receptors (RyRs). Alterations in the RyR activity can lead to enhanced SR Ca2+ leak and arrhythmias. Ca2+ tightly regulates the RyR activity from both sides of the SR (cytosolic and luminal). In this work, we studied the effects of cytosolic Ca2+ on SR Ca2+ leak in isolated ventricular myocytes. Elevation of cytosolic Ca2+ increased SR Ca2+ leak by a direct activation of RyRs. In intact myocytes, at the end of contraction and at the beginning of the relaxation phase, SR Ca2+ leak remains relatively constant due to the coordinated regulation of RyRs by cytosolic and luminal Ca2+. Thus, this dual regulation of the RyR contributes to the control of the SR Ca2+ content, preventing excessive loss of Ca2+ that could lead to pathological conditions such as cardiac arrhythmia.
Elastic-Plastic Deformation at Finite Strains
Authors: Lee E. H.
Published: October 2011

In some circumstances, elastic-plastic deformation occurs in which both components of strain are finite. Such situations fall outside the scope of classical plasticity theory which assumes either infinitesimal strains or plastic-rigid theory for large strains. The present theory modifies the kinematics to include finite elastic and plastic strain components. For situations requiring this generalization, dilatational influences are usually significant including thermomechanical coupling. This is introduced through the consideration of two coupled thermodynamic systems: one comprising thermoelasticity at finite strain and the other the irreversible process of dissipation and absorption of plastic work. The present paper generalizes a previous theory to permit arbitrary deformation histories.
Stresses Around an Elliptic Hole in a Cylindrical Shell
Authors: Murthy M. V. V.
Published: October 2011

A theoretical analysis is presented for the membrane and bending stresses around an elliptic hole in a long, thin, circular cylindrical shell with the major axis of the hole parallel to the axis of the shell. The analysis has been carried out for the case of axial tension. The method of solution involves a perturbation in a curvature parameter and the results obtained are valid, if the hole is small in size compared to the shell. Formulas, from which the complete stress distribution at the hole can be calculated, are presented.
Plane Waves Due to Combined Compressive and Shear Stresses in a Half Space
Authors: Ting T. C. T. , Nan Ning
Published: October 2011

The plane wave propagation in a half space due to a uniformly distributed step load of pressure and shear on the surface was first studied by Bleich and Nelson. The material in the half space was assumed to be elastic-ideally plastic. In this paper, we study the same problem for a general elastic-plastic material. The half space can be initially prestressed. The results can be extended to the case in which the loads on the surface are not necessarily step loads, but with a restricting relation between the pressure and the shear stresses.
On the Unbonded Contact Between Plates and an Elastic Half Space
Authors: Weitsman Y.
Published: October 2011

In this paper an approximate solution is presented for the radius of contact between an elastic plate and a semi-infinite elastic half space. The plate is assumed to rest on the supporting half space without bond, and to be pressed against the elastic region by a concentrated load. In the absence of bonding no tensile stress can be transmitted across the interface between the plate and its elastic support so that contact takes place only within a circle centered about the concentrated load. Outside of this circle the plate lifts up and is no longer in contact with the elastic region.
Three-Dimensional and Shell-Theory Analysis of Elastic Waves in a Hollow Sphere: Part 1—Analytical Foundation
Authors: Shah A. H. , Ramkrishnan C. V. , Datta S. K.
Published: October 2011

In Part 1 of this paper an exact analysis of the nonaxisymmetric wave propagation in a hollow elastic sphere is presented. It is found that the characteristic frequency equation is independent of the longitudinal wave number. Approximate equations for thin shells and membranes are derived by way of asymptotic expansions. In general, the vibrations fall into two distinct classes, one of which is equivoluminal. Also included in the paper is a six-mode shell theory in which the effects of transverse normal strain are included. A technique due to van der Neut is used to separate the governing partial differential equations whereby two frequency equations corresponding to the two classes of vibrations are obtained.
Wave-Front Analysis in Composite Materials
Authors: Ting T. C. T. , Lee E. H.
Published: October 2011

The propagation of an initially sharp plane pressure pulse through a linear elastic composite medium is analyzed. Wave front and ray theory analogous to geometrical optics is shown to determine the change in shape of the leading wave front and also the stresses immediately behind it. For certain circumstances the stress amplitudes on this front, or the corresponding tensile stresses on its reflection at the free back surface of a slab, may be critical in design. Examples are presented of an initially sharp plane pressure pulse transmitted through an elastic circular cylinder and an elastic spherical inclusion. The method can be applied to more general composite configurations, and can be extended to determine the stress gradient behind the front. For the latter, general formulas are derived by which the reflection and transmission coefficients can be determined for the stress gradient and the higher-order derivatives at an arbitrary interface.
Transient Excitation of an Elastic Half Space by a Point Load Traveling on the Surface
Authors: Gakenheimer D. C. , Miklowitz J.
Published: October 2011

The propagation of transient waves in a homogeneous, isotropic, linearly elastic half space excited by a traveling normal point load is investigated. The load is suddenly applied and then it moves rectilinearly at a constant speed along the free surface. The displacements are derived for the interior of the half space and for all load speeds. Wave-front expansions are obtained from the exact solution, in addition to results pertaining to the steady-state displacement field. The limit case of zero load speed is considered, yielding new results for Lamb’s point load problem.
Axisymmetric Elastic-Plastic Wave Propagation in 6061-T6 Aluminum Bars of Finite Length
Authors: Bertholf L. D. , Karnes C. H.
Published: October 2011

The axisymmetric impact of two identical 6061-T6 aluminum bars is experimentally and analytically studied. Experimental records are obtained from foil strain gages and thin quartz crystal gages located near the impact end, and at distances of one, two, and three radii from the impact end of a bar with a total length of four radii. These measurements are compared with the numerical solution of the “exact” equations of two-dimensional axisymmetric motion obtained by using the artificial viscosity approximation. The constitutive relation employed in the numerical solution is strain-rate independent with linear isotropic strain hardening.
The Static Strength of Syntactic Foams
Authors: DeRuntz J. A. , Hoffman O.
Published: October 2011

A failure condition is proposed for the composite material “syntactic foam” based upon an experimental program carried out under combined biaxial and triaxial stress states. The material itself is composed of hollow glass “microspheres” embedded in an epoxy resin matrix. It exhibits finite strength under hydrostatic compression, unlike any other engineering material and thus gives rise to a closed failure surface in principal stress space. In addition to loadings corresponding to radial lines starting from the origin in stress space out to the failure envelope, other load paths were also used. Some effects due to loading and unloading and then reloading to another stress state were also investigated. Under biaxial stress states it was found that the ultimate strength of the material is sensitive to its past stress history to some degree, the reason being attributed to the initially isotropic material developing weak planes perpendicular to the compressive principal stress resulting in a “latent anisotropy.”
Peristaltic Waves in Circular Cylindrical Tubes
Authors: Yin F. , Fung Y. C.
Published: October 2011

Peristaltic pumping in a circular cylindrical tube is analyzed. The problem is a viscous fluid flow induced by an axisymmetric traveling sinusoidal wave of moderate amplitude imposed on the wall of a flexible tube. A perturbation method of solution is sought. The amplitude ratio (wave amplitude/tube radius) is chosen as a parameter. The nonlinear convective acceleration terms in the Navier-Stokes equation is retained. The governing equations are developed up to the second order in the amplitude ratio. The zeroth-order terms yield the classical Poiseuille flow, the first-order terms yield the Sommerfeld-Orr equation. If there is no pressure gradient in the absence of wall motion, the mean flow and mean pressure gradient (averaged over time) are both shown to be proportional to the square of the amplitude ratio. Numerical results are obtained for this simple case by approximating a complicated group of products of Bessel functions by a polynomial. The results show that the mean axial velocity is dominated by two terms. One term corresponds to a parabolic profile which is due to the mean pressure gradient set up by the wall motion. The other term arises from satisfying the no-slip boundary condition at the wavy wall rather than at the mean position of the wall. In addition, there are perturbations arising from the convective acceleration. If the mean pressure gradient set up by the wall motion itself reaches a certain positive critical value, the velocity becomes zero on the axis. Values of the mean pressure gradient larger than the critical value will induce backward flow in the fluid. Values of the critical pressure gradient for several cases are presented.
Vorticity and Kutta Condition for Unsteady Multienergy Flows
Authors: Giesing J. P.
Published: October 2011

The dynamical conditions for vortex shedding in unsteady multienergy flows are given: It is shown that the vorticity shed is composed of an unsteady part, which is proportional to the time rate of change of the circulation, and a steady part, which is proportional to the total-pressure difference across the vortex sheet. The kinematics of vortex shedding are also investigated. It is determined that the vortex sheet is shed parallel to one side of the trailing edge or the other depending on the sense of the shed vorticity. It is further determined that the shedding velocity is equal to one half of the strength of the vorticity at the trailing edge (except for trailing-edge angles of zero). Numerical calculations are presented to illustrate the results.
Eigenfunction Solution for Beam on Elastic Foundation
Authors: Hess M. S.
Published: October 2011

A solution for the end problem of a rectangular beam resting on a simple elastic foundation is obtained as a series expansion in the eigenfunctions of the system. For a beam aligned with the ξ-axis, the eigenfunctions are of the form eγξf(y), where γ is one of the complex eigenvalues. The eigenvalue equation is determined by requiring continuity of the normal displacement and pressure at each point of the beam-foundation interface and seeking a nontrivial solution. In order to evaluate the accuracy and limitations of several approximate beam theories, the eigenvalue predicted by each of these theories is compared with the first eigenvalue of the exact solution. It is shown that the approximate theories give adequate accuracy if the beam modulus, E, exceeds the foundation stiffness, k, and that all tend to the same result as E/k → ∞. From a comparison of the first and second eigenvalues of the exact solution, it is found that the first mode (corresponding to beam behavior) ceases to dominate the higher modes for E/k < 1. Thus the approximate theories are necessarily restricted to E/k > 1 since they predict only the first mode.
Response of an Elastic Half Space to a Decelerating Surface Point Load
Authors: Beitin K. I.
Published: October 2011

The displacement field on the surface of an elastic half space (Poisson ratio = 1/4), caused by the motion of a decelerating point surface load, is investigated by means of the dynamic Betti-Rayleigh reciprocal theorem. The load is applied impulsively and made to move rectilinearly at constant deceleration along the surface. The load speed varies from superseismic to a value less than the Rayleigh wave speed. The results show that significant differences exist between displacements obtained in this problem and those resulting from the usual assumption of constant load speed. The differences are primarily due to the presence of Mach cones which appear at superseismic load speeds and remain ahead of the initial wave fronts even after the speed becomes subseismic.
Instantaneous Energy Dissipation Rate in a Lap Joint—Uniform Clamping Pressure
Authors: Metherell A. F. , Diller S. V.
Published: October 2011

Equations are derived for the load/deflection relations, the energy dissipation per cycle, and the instantaneous rate of dissipation. The energy dissipation per cycle is only valid for steady-state cyclic loading, whereas the load/deflection equations and instantaneous dissipation rate are valid for arbitrary loading and take into account the previous loading history. The difference between the instantaneous dissipation rate in a lap joint and the equivalent linear system is illustrated for cases of sinusoidal loading and triangular loading.
An Asymptotic Solution for Laminar Flow of an Incompressible Fluid Between Rotating Disks
Authors: Matsch L. , Rice W.
Published: October 2011

Laminar flow is considered between parallel rotating disks having a circular exhaust hole at an inner radius and supplied with fluid at the outer radius with pressure higher than the available sink pressure. The problem statement for asymptotic (fully developed) flow is formulated. A procedure for perturbing a creeping flow solution and an iteration scheme are developed to produce a solution for higher Reynolds numbers. The solution depends on two parameters, a Reynolds number and a mass flow parameter, and is asymptotic in the sense that a third parameter would be necessary for a solution with an arbitrary tangential velocity component specified at the outer radius of the disks and/or an arbitrary distribution of the radial velocity component between the disks. From computations conducted by digital computer, the region having uninflected radial velocity profiles is delineated. Typical results are presented for the velocity components as functions of Reynolds number, the average radial component of velocity at the entrance, and the inner radius of the disks.
Symmetric Deformations of Circular Cylindrical Elastic Shells of Varying Thickness
Authors: Lardner T. J. , Steele C. R.
Published: October 2011

The differential equation governing the symmetric deformations of circular cylindrical elastic shells of exponentially varying thickness is solved in terms of Kelvin functions. An application of the solution to the calculation of the edge displacement and rotation for a semi-infinite shell is also presented.
Parametric Excitation of an Axially Moving String
Authors: Mote C. D.
Published: October 2011

Stability boundaries for an axially moving string are presented in chart form similar to those of an Ince-Strutt diagram.
A Photoelastic Study of Stress Concentration Factors at a Doubly Symmetric Hole in Finite Strips Under Tension
Authors: Cheng Y-F.
Published: October 2011

A doubly symmetric hole having parts of three intersecting circles as its boundary is suitable as a stress concentrator in the investigations of the fatigue properties of materials. Using Homalite 100 as the model material, a series of photoelastic experiments was made to determine the stress concentration factors at such hole in finite strips under tension. The results were compared with those calculated from a semiempirical equation suggested by Mitchell and other experimental results.
On the Stability of Some Linear Nonautonomous Random Systems
Authors: Infante E. F.
Published: October 2011

A theorem and two corollaries for the almost sure stability of linear nonautonomous random systems are presented. These results are applied to the study of the stability properties of some often encountered second-order equations and the obtained stability conditions are compared to previously known criteria.
Laminar Inward Flow of an Incompressible Fluid Between Rotating Disks, With Full Peripheral Admission
Authors: Boyd K. E. , Rice W.
Published: October 2011

The laminar flow of an incompressible Newtonian fluid, radially inward between parallel co-rotating disks is considered. The through-flow is supported by an externally applied pressure difference between the outer periphery and a circular fluid exhaust hole at an inner radius. The fluid supplied at the outer periphery is considered with arbitrary velocity components, such that the tangential component may be greater or less than the disk peripheral velocity. A sufficiently complete problem statement is formulated from the Navier-Stokes’ equations. The problem has three parameters: a Reynolds number, a flow-rate parameter, and a peripheral tangential velocity component parameter. A numerical method of solution is detailed and typical numerical results are given illustrating the phenomena that occur in the inlet region for various inlet conditions. It is shown that the solution becomes the asymptotic solution given by previous investigators at interior radii following the inlet. Correspondence between the complete solution given herein and the earlier asymptotic solutions is established as dependent on corresponding values of Reynolds number and flow rate only. The results are discussed from the point of view of application of the solution in the development of multiple-disk turbines.
Contact Problems in the Linear Theory of Viscoelasticity
Authors: Ting T. C. T.
Published: October 2011

An explicit solution is obtained of an integral equation which arises in several contact problems in linear viscoelastic bodies. The solution is valid for contact problems in which the time-dependent contact area is an arbitrary function of time. The contact area can be a multiply connected region or regions.
Steady-State Dynamic Response of a Limited Slip System
Authors: Iwan W. D.
Published: October 2011

The steady-state response of a system constrained by a limited slip joint and excited by a trigonometrically varying external load is discussed. It is shown that the system may possess such features as disconnected response curves and jumps in response depending on the strength of the system nonlinearity, the level of excitation, the amount of viscous damping, and the initial conditions of the system.
Uniaxial Wave Propagation in a Viscoelastic Material Using Measured
Material Properties
Authors: Knauss W. G.
Published: October 2011

The dynamic response of a long viscoelastic bar due to a step displacement at the end is considered. Neglecting geometric dispersion, the effect of realistic viscoelastic material properties is studied theoretically. The solution is obtained in the form of a Fourier sine integral, the convergence of which is studied numerically by piecewise integration to produce an alternating series. It is found that the initial step wave propagates with a high velocity corresponding to the glassy modulus of the material and its amplitude decays with time and distance along the rod. From a practical viewpoint the wave front may decay to immeasurable proportions and any measurable disturbance appears to travel thereafter, with a velocity which is smaller than the glassy wave speed. The effect of initial temperature is discussed. It is shown for thermorheologically simple materials that both the time and spatial variable are scaled by the same temperature dependent (shift) factor. As a consequence, the difference of wave propagation in hard and viscoelastic polymers is illustrated. It is also shown that limited material characterization is sufficient for certain dynamic problems. Comparison of the exact solution with two approximations is made.
Propagation of Discontinuities in Coupled Thermoelastic
Problems
Authors: Boley B. A. , Hetnarski R. B.
Published: October 2011

The character and magnitude of traveling discontinuities in one-dimensional coupled transient thermoelastic problems are studied. For this purpose, 16 different fundamental problems are considered in detail, by examination of the nature of the solutions in the Laplace-transform domain. These problems correspond to various combinations of applied strain or stress as mechanical variables, and of applied temperature or heat flux as thermal variables. A system of classification of discontinuities is devised, which permits the results of the 16 problems to be extended to some general conclusions as to the character of the discontinuities in cases of arbitrary boundary conditions.
Cavitation at the Ends of an Elliptic Inclusion Inside a Plate Under
Tension
Authors: Hussain M. A. , Pu S. L. , Sadowsky M. A.
Published: October 2011

An oblong elliptic inclusion is perfectly filled in a hole in an infinite plate in the unstressed state. Cavities at the ends of the inclusion will appear as a result of the application of uniaxial stress at infinity in the direction of the major axis of the ellipse. Analytical formulation of the problem leads to a mixed boundary-value problem of the mathematical theory of elasticity. A Fredholm integral equation of the first kind is derived for the normal stress with the range of integration being unknown (corresponding to the unknown region of contact). Applying the theorem which has recently been established based on a variational principle, a transcendental equation is obtained for determining the contact region. Numerical results are given for various values of the elastic constants of both the matrix and the inclusion. Application of the results to fiber-reinforced composite materials is discussed.
Forced Motion of Elastic Plates
Authors: Reismann H.
Published: October 2011

A general method is presented for the solution of dynamic boundary-value problems of elastic plates subjected to time-dependent normal surface loads and/or time-dependent boundary conditions. As a demonstration of the method, an explicit, exact solution of the axisymmetric response of a ring plate is presented. The plate is clamped at the outer boundary and subjected to a suddenly applied transverse shear force which is uniformly distributed over the rotationally restrained inner boundary.
Numerical Solutions of Transients in Pneumatic
Networks—Transmission-Line Calculations
Authors: Tsao S.
Published: October 2011

Equations governing the damped wave propagation along transmission lines are obtained from the Navier-Stokes and energy equations by making certain simplifying assumptions. The flow considered is essentially one-dimensional. However, radial variations of the velocity and temperature profiles must be considered, because the damping factor is directly dependent on them. The equations are integrated by numerical methods. A hypothetical case is computed as an example.
A Numerical Solution for the Laminar Wake Behind a Finite Flat Plate
Authors: Plotkin A. , Flu¨gge-Lotz I.
Published: October 2011

A finite-difference solution is presented for the laminar, two-dimensional, viscous, incompressible wake behind a finite flate plate. The plate is infinitely thin and is aligned parallel to a uniform stream. The Reynolds number based on plate length is assumed large enough to allow the formation of boundary layers on the top and bottom of the plate. The wake is formed by the merging of these boundary layers at the trailing edge. The upstream influence of the trailing-edge disturbance necessitates solving the complete Navier-Stokes equations in the trailing-edge region. As yet, no satisfactory solution to the problem exists. The aim of this investigation is to calculate an improved first approximation to the solution in the trailing-edge region for high values of the Reynolds number. The solution can be continued in the downstream direction. Solutions are obtained for Reynolds numbers larger than 105. The behavior of the flow variables in the immediate neighborhood of the trailing edge indicates the existence of a singularity at the edge. The exact nature of this singularity has not, as yet, been determined.
On the Vibrations of a Laminated Body
Authors: Achenbach J. D. , Sun C. T. , Herrmann G.
Published: October 2011

A continuum theory for a laminated medium is further developed in this paper. Constitutive equations, stress equations of motion, and natural boundary conditions are presented, and sufficient conditions for a unique solution are discussed. The governing equations and boundary conditions are employed to study the thickness-twist motion of a laminated layer. For every nodal number there is a low frequency acoustic mode and a high frequency optical mode. The frequencies of the acoustic modes are compared with the corresponding frequencies predicted by the effective modulus theory, and the relative magnitudes of the material parameters for which these frequencies are substantially at variance are indicated.
The Laminar Two-Dimensional Free Jet of an Incompressible Pseudoplastic Fluid
Authors: Lemieux P. F. , Unny T. E.
Published: October 2011

Boundary-layer equations have been used to obtain an exact solution for the free outflow of a non-Newtonian pseudoplastic fluid from a two-dimensional orifice into a mass of the same fluid. Existence of similarity solutions has been proved. The results obtained by Schlichting for the Newtonian fluid flow is shown to be the special case of the more general analysis given here. Though further effort is necessary to investigate the turbulent jet flow, the analysis presented here should make a definite contribution in this definition.
Initial Stresses and Skin Effects in a Hemitropic Cosserat Continuum
Authors: Weitsman Y.
Published: October 2011

In this paper, constitutive relations are derived for a linear Cosserat continuum possessing hemitropic symmetry. In such a continuum, the microstructure has a screwlike property, or handedness, and can support initial couple stresses of twist. These initial stresses serve as a model for cohesion. The introduction of free boundaries in such a medium brings about an unbalancing of the internal “cohesive” forces which results in a highly localized skin effect. This skin effect is represented by an outward, or inward, motion of a boundary layer, which is accompanied by microtwisting. A qualitative comparison is obtained with a specific solution based upon the linear elastic dislocation theory.
Jet Noise and Shear Flow Instability Seen From an Experimenter’s Viewpoint
Authors: Mollo-Christensen Erik
Published: October 2011

Discussion of similarity laws for jet noise as suggested by experiments. Construction of a model line emitter. Near-field pressure covariances and spectra. Phase coherence of the near-pressure-field, nonlinear couplings in the process of generation of turbulence.
Application of Ultraspherical Polynomials to Nonlinear Forced Oscillations
Authors: Liu Y. King
Published: October 2011

Approximate solutions to the conservative free-oscillation problem were obtained recently [1–4] through the use of ultraspherical polynomials. The present paper extends the technique to forced oscillations governed by x¨+g(x)˙+f(x)=F0sinpt+F1 Very accurate results are obtained either by setting the ultraspherical polynomial index λ = 0 or, better yet, by restricting the choice of λ such that the solution to the forced problem is a perturbation from the nonlinear free oscillation solution. Examples are given.
Plane Anisotropic Beams
Authors: Hashin Zvi
Published: October 2011

A straightforward method has been developed to solve the elasticity problem of long plane anisotropic rectangles with continuous polynomial stresses prescribed on the long sides and force and moment resultants prescribed on the terminal sections. Solutions for anisotropic cantilever under terminal concentrated load and for uniformly loaded, simply supported anisotropic beam have been given in detail. Results support the acceptability of a strength of materials theory for anisotropic beams.
Stresses Due to a Sharp Notch in a Work-Hardening Elastic-Plastic Material Loaded by Longitudinal Shear
Authors: Rice J. R.
Published: October 2011

A work-hardening elastic-plastic stress analysis is presented for a sharp notch or, as a limiting case, a crack perturbing a remotely applied uniform stress field. Mathematical complexities are reduced through considering the kinematically simple case of antiplane longitudinal shear deformations and by employing a deformation plasticity theory rather than the more appropriate incremental theory. Consequently, a general solution is available valid for any relation between stress and strain in the work-hardening range, so long as the remotely applied stress does not exceed the initial yield stress. When a power law relates stress to a strain in the work-hardening range, the deformation theory solution is also the correct incremental solution at low applied stress levels causing yielding on a scale small compared to notch depth. For cracks, the near crack tip strain field is shown to depend on loads and geometry only through the elastic stress intensity factor when yielding is on a small scale, and the elastic-plastic boundary and lines of constant strain magnitude are circles. Extensive numerical results are tabulated for a crack, 45 deg V-notch, and 90 deg V-notch in power-law-hardening materials, and exhibited graphically for a crack.
Stresses in a Spherical Shell With a Nonradial Nozzle
Authors: Johnson D. E.
Published: October 2011

An analytical investigation is made of the stresses due to external forces and moments acting on an elastic nonradial circular cylindrical nozzle attached to a spherical shell. The nozzle (a cylindrical shell) is nonradial in the sense that its axis is inclined and does not pass through the center of the sphere. Results are obtained by combining solutions from shell theory by a Galerkin-type method so as to satisfy boundary conditions at the intersection of the two shells. It is found that, as the nozzle inclination increases, the stresses change gradually from those previously given by Bijlaard for the radial nozzle.
Investigation of a Turbulent Radial Wall Jet
Authors: Poreh M. , Tsuei Y. G. , Cermak J. E.
Published: October 2011

In this paper measurements are presented of mean velocities, turbulence intensities, Reynolds’ stresses, and the wall friction in a radial wall jet formed by an impinging circular jet on a smooth flat plate. The mean velocities of the wall jet are found to be similar and can be correlated with the maximum velocity and jet thickness at each station, except for a mild Reynolds number dependence near the wall. The dimensionless radial velocity profile is in good agreement with the form suggested by Glauert [1] although the variation of the thickness of the jet does not conform to his predictions. It is shown here that this discrepancy follows from Glauert’s use of the Prandtl eddy viscosity model in describing the Reynolds’ stress distribution. Our measurements show that the shear stress does not vanish where the velocity gradient is zero, as in the case with a free jet, or as required by the eddy viscosity model. The wall friction in the wall jet is found to be larger than the corresponding friction pipe flow. This increase is probably due to the large turbulent fluctuations in the outer region of the jet, which affect the structure of the wall region.
Thermodynamic Properties of Water in the Region of Maximum Density
Authors: Zaworski R. J. , Keenan J. H.
Published: October 2011

An equation of state and expressions for enthalpy and entropy are presented for water in the region of maximum density (from freezing to about 30 deg C for pressures up to about 2500 bars). A table of thermodynamic properties computed from these expressions (Table 1) is included, and comparisons of calculated values with the data from which the equation of state was derived, and other formulations, are presented.
Finite-Position Theory Applied to Mechanism Synthesis
Authors: Roth B.
Published: October 2011

The well-known finite-position planar theory of kinematic synthesis (the so-called Burmester theory) and the corresponding spherical theory are derived from the results of the general spatial theory which has been given in a companion paper [1]. Other special displacements studied are those for which the author has coined the names “similarity transformation,” “pseudoplanar,” and “pseudospherical.” These results, as well as those obtained in [1], are shown to be applicated to the synthesis of spatial, spherical, and planar linkages. Several numerical examples are presented.
Some Interaction Effects in a Problem of Plastic Beam Dynamics—Part 2: Analysis of a Structure as a System of One Degree of Freedom
Authors: Nonaka Taijiro
Published: October 2011

A theoretical study is made of the permanent deformation of a clamped beam with constraints against axial displacements at the ends. The beam carries a concentrated mass at its center and is subjected to large transverse impact loading at the mass. The analysis is based on the assumption of one degree of freedom and takes account of the interaction between bending and extension, of strain-rate sensitivity, of elastic vibration, and of load duration, in an approximate manner.