bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved sleep efficiency is associated with reduced cardio‐metabolic risk: Findings from the MODERN trial
Authors: Yiallourou Stephanie R. , Carrington Melinda J
Published: June 2021

Poor sleep increases cardio‐metabolic risk, but limited information on the impact of sleep for the improvement of cardio‐metabolic health exists. This analysis examined the impact of sleep on a health and lifestyle modification programme to reduce cardio‐metabolic disease risk factors. Secondary analysis of the MODERN randomised controlled trial to reduce cardio‐metabolic risk was undertaken at baseline and 24‐month follow‐up. Participants aged 40–70 years (n = 121) with three or more cardio‐metabolic risk factors were randomised to a health and lifestyle modification intervention (n = 59) or usual care (n = 62), and underwent 7 day/night actigraphy to assess total sleep time, sleep efficiency (%), number of awakenings/night and physical activity levels. Blood pressure, blood lipid and glycaemic levels, anthropometric and diet measures were collected. The mean age was 59 ± 7 years and 37% were male. Baseline sleep measures were not different between groups. At the 24‐month follow‐up, both groups showed improvements in cardio‐metabolic risk factors, albeit the change in blood pressure was greater in the intervention compared with the usual care group (systolic blood pressure: –11 versus –4 mmHg, p = .014). There were no differences between groups for diet, physical activity or sleep parameters. An increase in sleep efficiency was independently associated with lower systolic blood pressure (β = −2.117, p = .002) and higher high‐density lipoprotein levels (β = 0.040, p = .033); an increase in total sleep time was associated with lower low‐density lipoprotein levels (β = −0.003, p = .038) at 24 months. Overall, improvement in sleep quality over time was beneficial to reduce blood pressure and lipid levels. These findings highlight sleep as a potential target to reduce cardio‐metabolic risk.
Sleep difficulties, incident dementia and all‐cause mortality among older adults across 8 years: Findings from the National Health and Aging Trends Study
Authors: Robbins Rebecca , Weaver Matthew D. , Barger Laura K. , Wang Wei , Quan Stuart F. , Czeisler Charles A.
Published: June 2021

Sleep difficulties have been implicated in the development and progression of dementia and in all‐cause mortality. This study examines the relationship between sleep difficulties, incident dementia and all‐cause mortality over 8 years of follow‐up among a nationally representative sample of older (≥65 years) adults in the United States. We used data collected from the National Health and Aging Trends Study (NHATS) from 2011 to 2018, a prospective cohort study of Medicare beneficiaries. At baseline, the NHATS sample comprised 6,376 older adults who were representative of 32 million older adults. Respondents reported routine difficulty initiating sleep or difficulty falling back asleep “most nights” or “every night” in each study year. In each year, dementia was determined by either self‐reported diagnosis or performance on immediate and delayed recall word and clock drawing tests, whereas all‐cause mortality was determined by proxy. We conducted Cox proportional hazards modelling, adjusting for age, sex, marital status and chronic conditions. In models predicting all‐cause mortality, we also controlled for dementia. Among respondents at baseline, 19% were 65–75 years of age, 71% identified as non‐Hispanic white and 59% were female. Difficulty initiating sleep (hazard ratio [HR], 1.49; 95% confidence interval [CI],1.25–1.77), difficulty falling back asleep (HR, = 1.39; 95% CI,1.14–1.70) and concurrent sleep difficulties (HR, 1.58; 95% CI, 1.25–1.99) were associated with greater risk of dementia. Difficulty initiating sleep (HR, 1.44; 95% CI,1.20–1.72), difficulty falling back asleep (HR, 1.56; 95% CI,1.29–1.89), and concurrent sleep difficulties (HR, 1.80; 95% CI, 1.44–2.24) were associated with greater risk of all‐cause mortality. Our findings demonstrate that reported difficulties are prospectively associated with an increased risk of dementia and all‐cause mortality among older people.
Serum C‐reactive protein in dogs with paraplegia secondary to acute intervertebral disc extrusion
Authors: Foreman Max , Vettorato Enzo , Caine Abby , Monti Paola , Cherubini Giunio Bruto , Eminaga Salih
Published: June 2021

Background

Apart from the absence of nociception, there is no readily available prognostic test for dogs presenting with paraplegia secondary to acute intervertebral disc extrusion (IVDE).

Objective

To assess if serum C‐reactive protein (CRP) can predict the postoperative outcome in paraplegic dogs undergoing surgery for IVDE and to assess the association between serum CRP and presence/absence of nociception on admission, and serum CRP and presence/absence of intramedullary changes seen on magnetic resonance imaging (MRI).

Animals

One hundred dogs that underwent surgery at our hospital between 2018 and 2020 because of acute paraplegia secondary to IVDE and in which serum CRP was measured.

Methods

Retrospective observational cohort study. Dogs were classified as 4 or 5 according to the modified Frankel score (MFS) depending on presence/absence of nociception, respectively. MRI images were reviewed and the T2‐weighted hyperintensity: L2 vertebral body length was measured. Postoperative outcome was defined as positive if nociception, ambulation or both returned after decompressive surgery.

Results

The median (95% CI) serum CRP was 4 (4‐5) and 6 (4‐7) mg/L in MSF4 and MSF5, respectively (P = .03). A weak linear relationship (R2 = 0.049, P = .03) was found between CRP and the T2‐weighted hyperintensity: L2 vertebral length. Outcome data was available for 85 dogs: CRP was 4 (4‐5) and 5 (4‐10) mg/L in positive and negative outcome dogs, respectively (P = .32).

Conclusion and Clinical Importance

Serum CRP did not predict outcome after surgery in dogs with paraplegia secondary to IVDE.
Glucocorticoid treatment in horses with asthma: A narrative review
Authors: Mainguy‐Seers Sophie , Lavoie Jean‐Pierre
Published: June 2021

Despite substantial research efforts to improve the treatment and outcome of horses with asthma, glucocorticoids (GC) remain the cornerstone of drug treatment of this prevalent disease. The high efficacy of GC to relieve airway obstruction explains their extensive use despite potential deleterious effects. However, much is yet to be uncovered concerning GC use in horses with asthma, including the comparative efficacy of the different drugs, the determination of minimal effective doses and the mechanisms underlying their variable modulation of airway inflammation. The objectives of this structured review were to report and compare the plethora of effects of the various GC used in asthmatic horses with a focus on impact on lung function, airway inflammation, and bronchial remodeling. Adverse effects are also briefly described, with an emphasis on those that have been specifically reported in horses with asthma. Ultimately, we aimed to highlight gaps in the literature and to identify future research areas.
Outcomes of facilitative plant interactions in shrublands of NW Patagonia, Argentina
Authors: de Paz Manuel , Raffaele Estela , Gobbi Miriam E.
Published: June 2021

Aims

This study examined the plant–plant interaction networks and analyzed to what extent different nurse species groups with different traits (evergreen and deciduous) mediate the outcomes of the facilitated species composition.

Location

Four shrublands located in Nahuel Huapi National Park, in Northern Patagonia, Argentina (41°11'55.34" S, 71°19'43.07" W).

Methods

We selected 10 woody species as nurse species: five evergreens and five deciduous species. We recorded species composition and total cover below nurse species and in open spaces during two consecutive years, with different interannual precipitation variability. We determined the facilitated species with the relative interaction intensity in plants (RII) index, constructed facilitation networks, and analyzed the species composition below nurses and in open spaces.

Results

In our networks, nurse and facilitated species are generalist species. The species composition below the nurse canopies and open areas varied between years. The structure and parameters of networks built on two consecutive years were similar. However, we found changes in plant species interactions between the studied years. The species composition of the facilitated species growing below the deciduous and evergreen nurse species groups was similar.

Conclusions

Our findings provide insights into knowledge of the facilitation networks in Patagonian shrublands. We found that networks were not nested and had many generalist species (nurses and facilitated). This implies that the disappearance of any nurse species would not change the community maintenance.
Exploring parameters of gamma transcranial alternating current stimulation (tACS) and full‐spectrum transcranial random noise stimulation (tRNS) on human pharyngeal cortical excitability
Authors: Zhang Mengqing , Cheng Ivy , Sasegbon Ayodele , Dou Zulin , Hamdy Shaheen
Published: June 2021

Background

Transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS) have been shown to have physiological and functional effects on brain excitability and motor behavior. Yet, little is known about their effects in the swallowing system.

Aim

To examine the effects and optimal stimulation parameters of tACS and tRNS for modulating excitability of human pharyngeal motor cortex.

Methods

10 Hz (alpha), 20 Hz (beta), 70 Hz (gamma) tACS, 0.1–640 Hz (full‐spectrum) tRNS, and sham were applied over pharyngeal motor cortices at 1.5 mA current intensity for 10 min in 15 healthy participants. Pharyngeal motor–evoked and thenar motor–evoked potentials (PMEPs and TMEPs) were assessed before and up to 2 h after stimulation with single‐pulse transcranial magnetic stimulation. Averaged MEP amplitude and latency changes were analyzed using repeated measures ANOVA (rmANOVA).

Key Results

Two‐way rmANOVA across all active interventions demonstrated a significant MEP interaction both in the stimulated pharyngeal cortex (F (4, 56) = 1.731, p = 0.038) and in the ipsilateral thenar cortex (F (4, 56) = 1.506, p = 0.048). Compared to sham, subsequent post hoc tests showed site‐specific and sustained (60–120 min) increases in PMEPs with gamma tACS and tRNS (p = 0.005, p = 0.027, respectively) and for TMEPs with beta tACS (p = 0.006).

Conclusions and Inferences

Our findings suggest that the effects of tACS and tRNS are frequency‐dependent and cortical (representation) site‐specific with both gamma tACS and full‐spectrum tRNS enhancing human pharyngeal cortical excitability. These techniques hold promise as potential treatments for neurological dysphagia.
Reflux characteristics triggering post‐reflux swallow‐induced peristaltic wave (PSPW) in patients with GERD symptoms
Authors: Ribolsi Mentore , Frazzoni Marzio , De Bortoli Nicola , Tolone Salvatore , Arsiè Elena , Mariani Lucia , De Carlo Giovanni , Maniero Daria , Penagini Roberto , Cicala Michele , Savarino Edoardo
Published: June 2021

Background

Esophageal chemical clearance has been evaluated with the post‐reflux swallow‐induced peristaltic wave (PSPW) index. The factors triggering PSPW in Gastro‐esophageal reflux disease (GERD) have not yet been investigated. This multicenter study was aimed at evaluating the characteristics of reflux episodes associated with PSPW occurrence in patients with typical GERD symptoms.

Methods

Impedance‐pH tracings from patients with typical reflux symptoms were analyzed. Sixteen healthy subjects were included for comparison. Multivariate analysis was performed to determine predictors of PSPW events.

Key results

Impedance‐pH tracings from 60 patients and 16 healthy subjects were evaluated. A total of 3454 refluxes were recorded. In patients, comparing reflux episodes followed with those not followed by a PSPW, significantly higher proportions of acid (79% vs. 74%,p: 0.02), mixed (47% vs. 32%,p: 0.0001) and proximal refluxes (34% vs. 20%,p: 0.0001) were observed. A multivariate analysis, acid (OR: 1.3, 95% CI: 1.05–1.6), mixed (OR: 2, 95% CI: 1.6–2.3), and proximal (OR: 2.1, 95% CI: 1.7–2.5) refluxes were independently associated with PSPWs. Reflux episodes followed by a PSPW were characterized by a significantly higher bolus clearing time [(mean ± SD) 41 s ± 6 s vs. 30 s ± 5 s,p < 0.05] whereas nadir pH value of reflux events preceding PSPWs was tangentially but not significantly lower [(mean ± SD) 2.61 ± 1.22 vs. 2.74 ± 1.26,p: 0.057].

Conclusions and inferences

Acid, mixed and proximal refluxes, and their duration are key factors in eliciting PSPWs. PSPW represents a response to reflux directly related to the potential harmfulness of reflux contents.
HSP90 affects root growth in Arabidopsis by regulating the polar distribution of PIN1
Authors: Samakovli Despina , Roka Loukia , Dimopoulou Anastasia , Plitsi Panagiota Konstantinia , Žukauskaitė Asta , Georgopoulou Paraskevi , Novák Ondřej , Milioni Dimitra , Hatzopoulos Polydefkis
Published: June 2021

Auxin homeostasis and signaling affect a broad range of developmental processes in plants. The interplay between HSP90 and auxin signaling is channeled through the chaperoning capacity of the HSP90 on the TIR1 auxin receptor. The sophisticated buffering capacity of the HSP90 system through the interaction with diverse signaling protein components drastically shapes genetic circuitries regulating various developmental aspects. However, the elegant networking capacity of HSP90 in the global regulation of auxin response and homeostasis has not been appreciated.

Arabidopsis hsp90 mutants were screened for gravity response. Phenotypic analysis of root meristems and cotyledon veins was performed. PIN1 localization in hsp90 mutants was determined.

Our results showed that HSP90 affected the asymmetrical distribution of PIN1 in plasma membranes and influenced its expression in prompt cell niches. Depletion of HSP90 distorted polar distribution of auxin, as the acropetal auxin transport was highly affected, leading to impaired root gravitropism and lateral root formation. The essential role of the HSP90 in auxin homeostasis was profoundly evident from early development, as HSP90 depletion affected embryo development and the pattern formation of veins in cotyledons.

Our data suggest that the HSP90‐mediated distribution of PIN1 modulates auxin distribution and thereby auxin signaling to properly promote plant development.
The Effects of Question, Respondent and Interviewer Characteristics on Two Types of Item Nonresponse
Authors: Silber Henning , Roßmann Joss , Gummer Tobias , Zins Stefan , Weyandt Kai Willem
Published: June 2021

In this article, we examine two types of item nonresponse in a face-to-face population survey: ‘don’t know’ (DK) and ‘item refusal’ (REF). Based on the cognitive model of survey response, the theory of survey satisficing and previous research, we derive explanatory variables on three levels: question, respondent and interviewer characteristics. The results of our cross-classified model show that while the two levels question and respondents’ characteristics affected both types of item nonresponse, interviewer characteristics affected only DK answers. Our results also confirm that DK and REF are substantially different item nonresponse types resulting from distinguishable disruptions of the cognitive response process. Since most results are in line with prior theoretical predictions, they suggest that survey practitioners are well-advised by continuing to follow the large body of practical guidance derived from the theories tested here.
An exploration of theory of mind performance among men convicted of rape
Authors: Friestad Christine , Vaskinn Anja
Published: June 2021

Several of the known risk factors for sexual violence concern a lack of capacity for engaging in mutually satisfying interpersonal relationships. Socio‐cognitive deficits may be approached from a theory of mind (ToM) perspective, where lack of ability to attribute mental states to others is seen as the core feature. This study focuses on imprisoned men (n = 26) convicted of rape against an adult. A video‐based measure of ToM (MASC) was applied, depicting social interaction in a dynamic real‐life setting. The results showed that the rape‐convicted men have a markedly inferior ability to infer the mental states of others. Clinical as well as theoretical implications of the findings are discussed.
Thwarted belongingness predicts greater neural reactivity to a novel social exclusion image set: Evidence from the late positive potential
Authors: Albanese Brian J. , Capron Daniel W. , Macatee Richard J. , Bauer Brian W. , Schmidt Norman B.
Published: June 2021

Introduction

Thwarted belongingness (TB) is among the most well‐researched risk factors for suicidal ideation (SI). Yet, there is little research examining neural mechanisms underlying this construct. The present study used a novel social exclusion image set in concert with the late positive potential (LPP) to test the role of neural reactivity social exclusion in TB and SI.

Methods

Participants (n = 243) were recruited based on elevated suicide risk and completed an emotional picture viewing task. The LPP was used to index neural reactivity to a novel set of social exclusion images and international affective picture system (IAPS) neutral, positive, and negative images.

Results

Greater TB predicted a larger social exclusion ΔLPP (social exclusion LPP relative to neutral LPP) and social exclusion LPP even when accounting for SI, biological sex, age, negative affect, and perceived burdensomeness. Moreover, the social exclusion LPP was uniquely related to TB beyond the LPP to other images. Last, a larger social exclusion LPP predicted greater SI via elevations in TB.

Conclusion

Reactivity to social exclusion stimuli may play an important role in SI via elevated TB, but not perceived burdensomeness. Future research should further explore the neural mechanisms underlying other IPT constructs.
A comparison of the effect of X and gamma irradiation on red cell storage quality
Authors: Meli Athinoula , Balanant Marie Anne , New Helen V. , Ray Michelle , Allen Elisa , Cardigan Rebecca , Wiltshire Michael
Published: June 2021

Background and Objectives

Irradiation of red cell components is indicated for recipients at risk of transfusion‐associated graft vs. host disease. Current technologies available comprise of a gamma (γ) or an x source of radiation. The benefits of x vs. γ include non‐radioactivity and hence no decay of the source. We aimed to compare the effect of the two technologies on red cell component storage quality post‐irradiation.

Materials and Methods

Paired units of red cell concentrates (RCC), neonatal red cell splits (RCS), red cells for intra‐uterine transfusion (IUT) or neonatal exchange transfusion (ExTx) were either γ‐ or x‐irradiated. Units were sampled and tested for five storage parameters until the end of shelf life. Equivalence analysis of storage quality parameters was performed for pairs of the same components (RCC, RCS, IUT or ExTx) that were either γ‐ or x‐irradiated.

Results

Nearly all component comparisons studied showed equivalence between γ and x irradiation for haemolysis, ATP, 2,3‐DPG, potassium release and lactate production. The exceptions found that were deemed non‐equivalent were higher haemolysis with x irradiation for ExTx, lower 2,3‐DPG with x irradiation for RCS irradiated early and higher ATP with x irradiation for IUT. However, these differences were considered not clinically significant.

Conclusion

This study has demonstrated that a range of red cell components for use in different age groups are of acceptable quality following x irradiation, with only small differences deemed clinically insignificant in a few of the measured parameters.
Passive immune basophil activation test for the identification of allergic episodes from various adverse events elicited by haematopoietic cell transplantation: A pilot study
Authors: Yasui Kazuta , Enami Terukazu , Okamura‐Shiki Ikue , Ueda Tomoaki , Fukushima Kentaro , Matsuyama Nobuki , Kimura Takafumi , Takanashi Minoko , Hosen Naoki , Ikeda Takashi , Takihara Yoshihiro , Hirayama Fumiya
Published: June 2021

Background and Objectives

Haematopoietic cell transplantation (HCT) therapy tends to be associated with various complications including engraftment failure, regimen‐related toxicities, and infectious diseases. In addition, HC infusion itself occasionally elicits adverse events (AEs), one of the most common AEs is an allergic reaction. As appropriate laboratory tests have not yet been established to distinguish allergy‐mediated AEs from other complications, clinical responses for HCT‐related AEs can only be nonspecific. In this pilot study, using passive immune basophil activation test (pi‐BAT), we attempted to distinguish an HC infusion‐induced allergic reaction from various HCT‐related AEs.

Materials and Methods

Using pi‐BAT, we examined 34 patients who underwent HCT, that is, 11 with AEs and 23 without AEs as controls.

Results

Two of the eleven AE cases were pi‐BAT positive and, the rest of nine AE cases were negative, while all non‐AE cases were negative. Both of the two positive cases showed erythema, tachycardia, plus cough. Because erythema is one of the representative symptom of allergy, those cases could be classified as allergic reaction cases or anaphylaxis cases if tachycardia and cough were concomitant symptoms of erythema. Among the nine AEs with pi‐BAT negative result, four cases showed urticaria, four showed vomiting plus diarrhoea, and one showed cough. Urticaria case was strongly suspected of allergy, however, the AE cases were pi‐BAT negative.

Conclusion

The pi‐BAT may be useful as an auxiliary diagnostic tool to confirm the possible involvement of HC infusion in HCT‐related AEs and identify an immunologic mechanism for HCT‐related hypersensitivity reactions.
The role of cultural heritage in the geopolitics of the Arctic: the example of Franklin’s lost expedition
Authors: Pawliw Kim , Berthold Étienne , Lasserre Frédéric
Published: June 2021

Sir John Franklin’s ships departed from Greenhithe port in Great Britain (1845) with the aim of discovering the Northwest Passage in what is now Canada. During their journey, both ships got stuck in ice near King William Island and eventually sank. Over time, searches were held in order to find both wrecks. More recently, under the Conservative Government of Stephen Harper (2006–2015) there was renewed interest regarding what is now referred to as Franklin’s lost expedition. Searches resumed and narratives were formed regarding the importance of this expedition for Canadian identity. This article is embedded in a sociocultural perspective and will examine the role that cultural heritage can play in the geopolitics of the Arctic while highlighting the process of ‘patrimonialization’ that the Franklin’s lost expedition has undergone during Harper’s term in office. Based on discourse analysis, it brings out the main narratives that surrounded the modern searches of Franklin’s wrecks which are related to history, national historic sites, mystery, diversity, importance of Inuit knowledge and information gathering. This article demonstrates that these narratives were intended to form a new Canadian northern identity and to assert Canada’s sovereignty over the Arctic.
Some Problems of Orthotropic Plane Stress
Authors: Conway H. D.
Published: June 2021

Many plane-stress problems in isotropic elasticity are solved conveniently by considering the Airy stress functions in the form of Fourier series (periodic loading) or Fourier integrals (nonperiodic loading) of harmonic and biharmonic functions. The object of this paper is to show how many of these solutions can be extended to the case where the material is orthotropic. For illustrative purposes, the following seven problems are solved: (a) Half plane subjected to normal loading; (b) wedge subjected to axial loading; (c) half plane subjected to a normal force applied through a rigid punch; (d) half plane subjected to tangential loading; (e) wedge subjected to transverse loading; (f) force applied at a point in an infinite plane; and (g) analysis of deep beams.
The Torsion of Spiral Rods
Authors: Ōkubo H.
Published: June 2021

The equations of equilibrium with those of compatibility are derived in two-dimensional forms for the present problem. They are simplified in two extreme cases where (1) The angle between the helix and the axis of helix is small, and (2) The angle between the helix and the plane perpendicular to the axis of helix is small. Using them, expressions for stresses are derived in the forms, which contain two arbitrary functions satisfying the Laplace or a similar equation, and the Airy equation, respectively. As an illustration of the procedure, a detailed solution for a coiled helical spring with a circular section is obtained by means of successive approximations.
Reinforced Circular Holes in Bending With Shear
Authors: Heller S. R.
Published: June 2021

The object of this paper is the determination of the effect of the reinforcement of circular holes on the stress distribution in the webs of beams subjected to bending with shear. A theoretical solution for a bead-type reinforcement, i.e., small radial thickness, is developed. The stress distribution in the web for arbitrary shape reinforcement is based on the work of Reissner and Morduchow (1). The theory developed is valid provided the diameter of the hole does not exceed one fourth of the depth of the beam.
An Improved Electrical Analogy for the Analysis of Beams in Bending
Authors: Russell W. T. , MacNeal R. H.
Published: June 2021

A practical electrical beam analogy which employs ideal transformers is derived from the equations of a segment of nonuniform beam which is loaded by vertical shears and moments applied at its ends. This analogy is suitable for the solution of static-load problems, vibration problems, and transient-load problems. The superiority of this analogy over an analogy derived by replacing differential operators by difference operators is demonstrated by means of error calculations for uniform cantilever and simply supported beams.
Effect of Range of Stress on Fatigue of 76S-T61 Aluminum Alloy Under Combined Stresses Which Produce Yielding
Authors: Findley W. N.
Published: June 2021

Fatigue test data under bending, torsion, and combined bending and torsion are presented for mean stresses from zero to values which cause substantial yielding. The mean nominal stresses in the bending and the torsion tests were corrected for the effect of the nonlinear distribution of stress resulting from yielding. Static tests in tension, compression, bending, and torsion also are described. The applicability of several theories of failure are compared with these test data. The role of anisotropy of the material, mechanism of crack formation, mean stress, and maximum stress are discussed.
The Vibration of Rotating, Tapered-Twisted Beams
Authors: Jarrett G. W. , Warner P. C.
Published: June 2021

This paper presents an extension of Myklestad’s adaptation of the Holzer method of calculating natural frequencies and mode shapes of systems to the case of a tapered-twisted beam with certain elastic constraints. The details of the solution are so arranged that the bulk of the numerical calculations can be carried out by a technician with only a high-school mathematical background. This extension makes possible the evaluation of the effect of rotation of a beam on a radial line, of certain elastic constraints such as the lashing wires and shrouding used on turbine blades, and of coupling between the torsional and flexural vibrations. In this paper, however, the effects of coupling between the torsional and flexural vibrations will not be considered. The basic differential equation will be solved by the tabular method due to Holzer.
Transverse Impact on Beams and Plates
Authors: Eringen A. C.
Published: June 2021

Flexural deflections of several plates and beams under an unknown transverse, concentrated, time-dependent force are solved for various edge conditions. The consideration of displacements and the use of Hertz’s law of impact at the point of contact lead to a nonlinear integral equation for the contact force in all cases of transverse impact. Two methods are introduced to treat this equation: (a) Generalized Galerkin method; (b) collocation method. Method (a) is the generalization of the well-known Galerkin method which is suitable for the problems in which part of the boundary is unknown in advance, while certain conditions are given there. The method is applicable to a very large class of differential and integral equations. The collocation method leads to a quick, reasonable, approximate solution. Various auxiliary curves in both cases reduce the solution to a routine. Examples are worked out and plotted for various beams and plates. Deflections are plotted.
Dynamic Load Characteristics in Plastic Bending of Beams
Authors: Symonds P. S.
Published: June 2021

This paper continues work previously reported on the analysis of large plastic deformations of beams subjected to transverse dynamic loads. Here we discuss the numerical analysis for central concentrated force pulses of arbitrary shape, using a somewhat different formulation of the equations than in the previous paper. Results are then collected for three types of force pulse: A rectangular pulse, a half-sine wave, and a triangular pulse. These show that the central angle of permanent deformation for all three cases can be computed from the empirical formula θ0 = CI2Pm2/3, where I is the impulse, Pm is the maximum load value, and C depends on the dimensions and properties of the beam, with a numerical factor that varies by about ±15 per cent from the value for the half-sine wave pulse to those for the other two pulse types.
Solutions of Heat-Conduction Problem With the Aid of the Inverse Method
Authors: Weinig F. S.
Published: June 2021

Using a known solution of the potential equation for heat conduction it is possible to determine boundaries which fulfill the boundary conditions. This idea was applied to the heat flow with parallel streamlines, from a line source and from a point source. From the parallel flow, fins have been derived on a plane surface having circular arc flanks. From the line source, fins axially and radially on a cylindrical surface and from a point source fins on a sphere are obtained. The improvement of the heat transfer has been found in these examples to depend only on the surface direction at the base of the fins.
Toroidal-Shell Expansion Joints
Authors: Dahl N. C.
Published: June 2021

The problem considered in this paper is shown in Fig. 1; a thin toroidal shell of center-line radius a and torus mid-surface radius b is slit at its inner edge and welded to relatively stiff cylindrical pipe sections to form an expansion joint. Stresses and axial deformation under the axial load P are desired.
Analysis of a Nonlinear Dynamic Vibration Absorber
Authors: Pipes L. A.
Published: June 2021

This paper presents a mathematical analysis of the action of a dynamic vibration absorber. The system analyzed consists of a main mass attached to a rigid foundation by a linear spring coupled to the absorber mass by a spring of nonlinear characteristics. The forced oscillations of the system produced by a harmonic disturbing force acting on the main mass are studied analytically. It is assumed that the coupling absorber spring has nonlinear force-displacement characteristics of the hyperbolic sine type. Expressions for the amplitudes of the vibrations of the two masses as functions of the frequency of the disturbing force are obtained.
Dynamic Stress-Strain Relations for Annealed 2S Aluminum Under Compression Impact
Authors: Johnson J. E. , Wood D. S. , Clark D. S.
Published: June 2021

This paper presents the results of an experimental study of the stress-strain relation of annealed 2S aluminum when subjected to compression impact. Two methods of securing a dynamic stress-strain curve are considered, namely, from the measurement of impact stress as a function of maximum plastic strain, and impact stress as a function of the impact velocity. The dynamic stress-strain curves obtained by these methods lie considerably above the static curve. The elevation in stress of the dynamic relations above the static relation increases progressively from zero at the elastic limit to about 20 per cent at a strain of 4.5 per cent. However, the two dynamic relations are not coincident which indicates that the behavior of the material cannot be described by a single stress-strain curve for all impact velocities. A family of stress-strain curves which differ slightly from each other and which depend upon the final strain is postulated in order to correlate both sets of data adequately.
The Rate of Growth of Vapor Bubbles in Superheated Water
Authors: Dergarabedian Paul
Published: June 2021

Calculations are presented for the dynamic stability of vapor and air bubbles in superheated water. These calculations indicate that the values of the bubble radii for which the equilibrium is unstable are restricted to a finite range of radii whose values are governed by the temperature of the water and the initial air content in the bubble. Two theoretical solutions for the rate of growth of these unstable bubbles are considered: (a) Solution of the equation of motion of the bubble radius with the assumption that there is no heat diffusion across the bubble wall; (b) solution which includes the effect of heat diffusion. The two solutions differ appreciably. These two solutions are then compared with the experimental data on the growth of the vapor bubbles in superheated water. This comparison shows agreement with the solution with the effect of heat diffusion included.
Stress Concentration Due to Elliptical Holes in Orthotropic Plates
Authors: Conway H. D.
Published: June 2021

Two plane stress problems of elliptical holes in infinite orthotropic sheets are treated: (a) Hole loaded by a pair of concentrated forces acting at the ends of the major or minor axis, and (b) hole in plate which is subjected to uniform tension. The solutions are obtained in a simple manner by transformation from corresponding problems in which the holes are circular. Closed-form expressions are obtained for the stress-concentration factors.
Analysis of Plastic Deformation in a Steel Cylinder Striking a Rigid Target
Authors: Lee E. H. , Tupper S. J.
Published: June 2021

The G. I. Taylor dynamic compression test consists of firing a cylinder of the material to be tested at a target of hardened armor plate, and deducing the dynamic yield stress from the resulting deformation. In the interpretation of the results, interest is concentrated on the wave front of initial plastic straining. The present paper attempts the theoretical determination of the entire strain distribution in such a test cylinder of nickel-chrome steel, this material being chosen since the dynamic influence on the stress-strain relation is likely to be small, thus permitting the static relation to be used in the theory. Strain distributions deduced by two theoretical approaches compare satisfactorily with the distribution of strain obtained in such a dynamic compression test, thus justifying the assumption for this material at the speed considered. The treatment of this problem requires a theory of the propagation of plastic waves, which is developed in this paper, for the particular type of stress-strain curve pertaining to the high-strength alloy steel tested.
The Elasticity of an Isotropic Aggregate of Anisotropic Cubic Crystals
Authors: Hershey A. V.
Published: June 2021

The elasticity of a polycrystalline aggregate is expressed in terms of the elasticity of the individual grains. The stress within each grain is estimated with the aid of an analysis of the stress distribution around a spherical cavity in an isotropic medium. The strain within each grain is expressed in terms of the average stress in the polycrystal as a whole by pseudoelastic constants which are related to the actual elastic constants. The calculated elasticities for physical tests and for x-ray diffraction measurements in polycrystals are given for a few cubic metals.
Vibration of Triangular Cantilever Plates by the Ritz Method
Authors: Andersen B. W.
Published: June 2021

Using the method published by Ritz in 1909, natural frequencies and corresponding node lines have been determined for two symmetric and two antisymmetric modes of vibration of isosceles triangular plates clamped at the base and having length-to-base ratios of 1, 2, 4, and 7 and for the two lowest modes of right triangular plates clamped along one leg and having ratios of the length of the free leg to that of the clamped one of 2, 4, and 7. A nonorthogonal co-ordinate system was used which gave constant limits of integration over the area of the triangle. The co-ordinate transformation made it necessary to modify the functions used by Ritz in approximating deflections and to consider cross products in the integration. The integration was done numerically, using tables compiled by Young and Felgar in 1949. To check the accuracy of results, a solution was obtained to the problem of a vibrating cantilever beam of uniform depth and triangular plan view. The results obtained were found to be consistent with those obtained for the plates by using an eight-term series to approximate the deflections of the symmetric plates (isosceles triangles) and a six-term series to approximate the deflections of the unsymmetric plates (right triangles).
Fretting Corrosion of Mild Steel in Air and in Nitrogen
Authors: Feng I-Ming , Uhlig Herbert H.
Published: June 2021

Data are presented on fretting corrosion of mild steel using weight loss as a measure of damage. Relative slip was measured both by use of stroboscopic light and strain gages. Load was applied pneumatically. Humidity of ambient air was found to be a sensitive variable requiring control, a fact first discovered through discrepancies of weight-loss data obtained in winter compared with those obtained in summer. Fretting corrosion of mild steel in moist air is only 55 to 65 per cent of the weight loss in dry air, depending on duration of test. Because of this large difference, all tests were carried out in dry air. At the same time, it was observed that fretting corrosion is appreciably greater below room temperature than above room temperature (up to 150 C). Weight losses of specimens fretted at 50 C are approximately 50 per cent losses at 0 C. Rate of fretting corrosion in air is found to be constant with time after an initial run-in period during which the rate is temporarily higher. In moist or dry nitrogen, weight losses are much less, although not zero. The greater the relative slip, the greater is fretting damage, and in complete absence of slip the data indicate that no weight loss occurs. Increased pressure or load is found to increase fretting damage. Weight loss is greater the lower the frequency for the same number of test cycles. The frequency effect increases with relative slip, and in nitrogen the frequency effect disappears.
Gravitational Stresses in a Circular Ring Resting on Concentrated Support
Authors: Yu Yi-Yuan
Published: June 2021

Muschelišvili’s complex variable method in two-dimensional elasticity has been extended by the present author to solve a few gravitational stress problems. A further problem of a heavy circular ring resting on a concentrated support is solved by the same method in the present paper. The two analytic functions which constitute the solution of the problem are determined. A numerical example is given for a ring the radii of which are in the ratio of 1 to 2.
Remarks on Donnell’s Equations
Authors: Kempner Joseph
Published: June 2021

Flügge’s set of differential equations of equilibrium for circular cylindrical shells is expressed in a form analogous to the Donnell equations. The results of solutions of the two sets of equations for a simply supported cylinder under a centrally applied, uniformly distributed radial line load over a generator segment, as well as under sinusoidally applied line loads, are in very good agreement for the particular geometry investigated.
Prediction of Creep-Deflection and Stress Distribution in Beams From Creep in Tension
Authors: Findley W. N. , Poczatek J. J.
Published: June 2021

A method of predicting creep in bending from data on creep in tension has been derived and applied to creep of a canvas laminate. Both creep deflections and stress distribution were derived. The deflections compared favorably with test data. It was shown that the stress distribution remained constant during creep in bending when creep in tension and compression were equal and the coefficient of the time-dependent term was equal to the time-independent term. Methods of determining creep deflections of beams having nonuniform bending moments are described.
Thermal Shock on a Circular Surface of Exposure of an Elastic Half Space
Authors: Sadowsky M. A.
Published: June 2021

The paper presents an explicit determination of displacements and stresses in a uniform circular thermal shock. In a generalization to nonuniform shocks on surfaces of arbitrary shape, it is shown that the protrusion arising at any place is proportional to the intensity of the shock at that place.
Further Work on the General Three-Dimensional Photoelastic Problem
Authors: Frocht Max M. , Guernsey Roscoe
Published: June 2021

It is known that purely photoelastic procedures cannot solve the general three-dimensional stress problem. Photoelasticity furnishes data from which only the principal shears can be determined, but not the principal stresses. A new, general, and practical method of solution which has been described previously (1, 2) is reviewed briefly, and possible variations in procedure are discussed. This method combines the photoelastic data from frozen stress patterns with a numerical integration of one of the differential equations of equilibrium in Cartesian coordinates. The actual principal stresses at each point of a homogeneous and isotropic body of arbitrary shape subjected to a general system of loads are thereby determined. The method has been applied previously to a sphere subjected to diametral compressive loads of 172 lb. The present paper contains the results from a second sphere subjected to 79.6 lb which show that the degree of reproducibility of results is high. Very good agreement is also shown to exist with a theoretical solution of the same problem by Sternberg and Rosenthal (3) The paper also contains the solution of a short rectangular parallelepiped loaded through a small flat circular die. The investigation was conducted in the Photoelastic Laboratory of the Mechanics Department of Illinois Institute of Technology.
Frictional Vibrations
Authors: Sinclair David
Published: June 2021

Frictional vibrations, such as stick-slip motion and automobile-brake squeal, which occur when two solid bodies are rubbed together, are analyzed mathematically and observed experimentally. The conditions studied are slow uniform motion and relatively rapid simple harmonic motion of brake lining over a cast-iron base. The equations of motion show and the observations confirm that frictional vibrations are caused primarily by an inverse variation of coefficient of friction with sliding velocity, but their form and occurrence are greatly dependent upon the dynamical constants of the mechanical system. With a constant coefficient of friction, the vibration initiated whenever sliding begins is rapidly damped out, not by the friction but by the “natural” damping of all mechanical systems. The coefficient of friction of most brake linings and other organic materials was essentially invariant with velocity, except that the static coefficient was usually greater than the sliding coefficient. Most such materials usually showed a small decrease in coefficient with increasing temperature. The persistent vibrations resulting from the excess static friction were reduced or eliminated by treating the rubbing surfaces with polar organic compounds which produced a rising friction characteristic.
The Elastic-Plastic Stress Distribution Within a Wide Curved Bar Subjected to Pure Bending
Authors: Shaffer Bernard W. , House Raymond N.
Published: June 2021

Analytical expressions are obtained for the radial and circumferential stress distributions within a wide curved bar made of a perfectly plastic material when it is subjected to a uniformly distributed bending moment. The elastic stress distributions are based on the use of the Airy stress function, whereas the plastic stress distributions in this problem of plane strain are based on the use of the Tresca yield condition. It is found that as the bending moment increases in the direction which tends to straighten the initially curved bar, an elastic-plastic boundary develops first around the concave surface. It meets a second boundary, which starts sometime later around the convex surface, when the bar is completely plastic. The elastic region within the bar decreases at a fairly uniform rate as the bending moment increases to within approximately 90 per cent of the fully plastic bending moment but then it degenerates very much more rapidly until it no longer exists when the bar is completely plastic. The position of the neutral surface is independent of the applied bending moment when the stress distribution is within the completely elastic and the completely plastic ranges. Within the elastic-plastic range, however, it moves away from and then toward the center of curvature as the bending moment increases.
Elastic-Stress Waves Produced by Pressure Loads on a Spherical Shell
Authors: Huth J. H. , Cole J. D.
Published: June 2021

The paper treats the problem of stresses in a spherical elastic shell subjected to a plane pressure wave traveling across it with constant speed, a case of technical interest when considering the effect of blast waves on the structure of a missile in flight.
Free Oscillations of Systems Having Quadratic Damping and Arbitrary Restoring Forces
Authors: Klotter Karl
Published: June 2021

In this paper, systems are treated which are subjected to quadratic damping forces (of any magnitude) and to restoring forces of any type. The differential equations of motion for such systems can be transformed into linear differential equations of first order for the velocity squared, whatever the restoring forces may be. A first integral can be obtained readily. From it the exact relationships between any two consecutive maximum displacements (“amplitudes”) are derived. These relationships are discussed in detail for various types of restoring forces. Examples are worked out numerically and illustrated by graphs.
On the Nonlinear Oscillations of Viscoelastic Plates
Authors: Eringen A. Cemal
Published: June 2021

Equations of motion of the three-dimensional finite oscillation theory are integrated across the plate thickness to obtain a second-order theory of oscillations for plates. For this purpose, components of the displacement vector are assumed to have power-series expansions in the transverse co-ordinate, and a systematic perturbation procedure in a nondimensional thickness parameter is used. Stress-strain relations include the hereditary damping.
Forced Vibration of a Clamped Rectangular Plate in Fluid Media
Authors: Yeh Gordon C. K. , Martinek Johann
Published: June 2021

Forced vibration of a thin rectangular plate clamped in a rigid infinite baffle is analyzed. The plate is assumed to separate two different fluid media and the vibration is excited by a simple plane wave of high frequency (as compared with c / 2 π ab ) normally incident from one side of the plate. Using the characteristic shape functions, the Lagrange equations of motion of the plate are set up in generalized co-ordinates. The solutions of the equations render series expressions for the plate deflection and an energy-transmission coefficient. Certain numerical results are given.