bluuebunny/crossref_metadata_2025 huggingface dataset:
Occupation
Authors: DREYER L. , ANDERSEN A. , PUKKALA E.
Published: October 2011

A number of chemicals encountered predominantly in occupational settings have been causally linked with cancer in humans; furthermore, several industrial processes and occupations have been associated convincingly with increased rates of cancer, although the specific carcinogens remain to be identified. The tissues affected are mainly the epithelial lining of the respiratory organs (nasal cavity, paranasal sinuses, larynx and lung), and urinary tract (renal parenchyma, renal pelvis and urinary bladder), the mesothelial linings, the bone marrow and the liver. During the period 1970–84, almost 4 million people (3.7 million men and 0.2 million women) in the Nordic countries were potentially exposed to above‐average levels of one or more verified industrial carcinogens. It is expected that these exposures will result in a total of about 1,900 new cases of cancer every year in the Nordic countries around the year 2000, with 1,890 among men and fewer than 25 among women. The proportions that could be avoided if industrial carcinogens were eliminated would be 70% of mesotheliomas, 20% of cancers of the nasal cavity and sinuses, 12% of lung cancers, 5% of laryngeal cancers, 2% of urinary bladder cancers, 1% of the leukaemias, and 1% of renal cancers. Overall, it is estimated that verified industrial carcinogens will account for approximately 3% of all cancers in men and less than 0.1% of all cancers in women in the Nordic countries around the year 2000. No attempt was made to estimate the potential effects of suspected carcinogens in the workplace.
Summary of avoidable cancers in the Nordic countries
Authors: OLSEN J. H. , ANDERSEN A. , DREYER L. , PUKKALA E. , TRYGGVADOTTIR L. , DE VERDIER M. Gerhardsson , WINTHER J. F.
Published: October 2011

An overview is given of the most important known causes of cancer in the five Nordic countries and the resulting number of cancers that are potentially avoidable. The main causes include active and passive smoking, alcohol consumption, exposure to asbestos and other occupational carcinogens, solar and ionizing radiation, obesity, human papillomavirus infection in the female genital tract and infection with Helicobacter pylori. The organs most commonly affected are those of the respiratory system, the upper digestive tract and stomach, skin, the lower urinary tract and the uterine cervix. Annually, more than 18,000 cancers in men and 11,000 in women in the Nordic populations could be avoided by eliminating exposure to known carcinogens which is equivalent to 33% and 20% of all cancers arising in men and women, respectively, around the year 2000. Smoking habits account for a little more than half of these avoidable cases. Estimates of avoidable cancers are given for each Nordic country, separately.
Stimulation of pulmonary immune responses by the TLR2/6 agonist MALP‐2 and effect on melanoma metastasis to the lung
Authors: Schill Tillmann , Schön Michael P. , Pletz Nadin , Emmert Steffen , Schön Margarete
Published: October 2011

Abstract:  Given that metastasized melanoma is a fatal disease in most cases, it is tempting to develop strategies to a priori prevent metastasis. We have stimulated the pulmonary innate immune system by macrophage‐activating lipopeptide‐2 (MALP‐2), a specific agonist at Toll‐like receptor (TLR) 2/6, and investigated its impact on experimental melanoma metastasis. In C57BL/6 mice, intratracheal application of MALP‐2 induced a profound influx of neutrophils and macrophages into the lung, which peaked after 24 h (sixfold increase) and returned to baseline within 72 h. Further analysis revealed that MALP‐2 also markedly induced VCAM‐1 expression on pulmonary blood vessels. In vitro experiments demonstrated that this adhesion molecule mediates binding of B16F10 melanoma cells. Furthermore, in vivo or in vitro treatment with MALP‐2 did not significantly affect the ability of immune cells to lyse melanoma cells. As a consequence, notwithstanding the profound pulmonary immune response induction and in contrast to conclusions drawn from some previous publications, the net extent of experimental metastasis did not change significantly, regardless of the application regimen of MALP‐2 prior to, concomitant with or after tumor cell inoculation. Melanoma cells stably transfected with green fluorescent protein allowed tracking of early events after tumor cell dissemination and showed that MALP‐2‐mediated TLR2/6 activation did not interfere with pulmonary melanoma cell arrest. Likewise, boosting the immune induction after establishment of metastases did not change the clinical outcome. These unexpected results vividly counsel caution regarding predictions of immunomodulating therapies, as multiple intertwined effects may influence the net outcome.
Extended DNFB‐induced contact hypersensitivity models display characteristics of chronic inflammatory dermatoses
Authors: Röse Lars , Schneider Claudia , Stock Christine , Zollner Thomas M. , Döcke Wolf‐Dietrich
Published: October 2011

Abstract:  Despite recent developments, there is a high medical need for new treatment options for chronic inflammatory dermatoses like allergic contact dermatitis (ACD) and psoriasis. Particularly, more predictive skin inflammation models are required to facilitate the process of drug discovery. Murine contact hypersensitivity (CHS) models adequately reflect ACD and are also used to characterize therapeutic approaches for psoriasis. Using the hapten 2,4‐dinitrofluorobenzene (DNFB), we established new subacute and subchronic DNFB‐induced CHS models in C57BL/6 mice, which more closely reflect the characteristics of chronic T‐cell‐dependent inflammatory dermatoses as pronounced keratinocyte proliferation, strong hypervascularization, immune cell infiltration and overexpression of T cell and inflammatory cytokines. For the subacute DNFB model, we demonstrated anti‐inflammatory activity of the glucocorticoid, prednisolone, as well as of neutralization of TNFα, IL‐12/IL‐23 or IL‐18. In the subchronic DNFB‐induced CHS model, deficiency for MyD88 and IL‐12/IL‐35 p35 chain but not IL‐12/IL‐23 p40 chain led to decreased skin inflammation. Furthermore, as exemplified by the dose‐dependently effective therapeutic prednisolone treatment, the subchronic model allows the continuous therapy of a pre‐established stable contact dermatitis. Altogether, prolonged DNFB‐induced mouse CHS models closely reflect ACD sensitive to glucocorticoids as standard therapy, reveal a more chronic skin inflammation and are responsive to cytokine antagonization.
Periodontal healing following avulsion and replantation of teeth: a multi‐centre randomized controlled trial to compare two root canal medicaments
Authors: Day Peter F. , Gregg Terry A. , Ashley Paul , Welbury Richard R. , Cole Ben O. , High Alec S. , Duggal Monty S.
Published: October 2011

Abstract –  Background: Non‐setting calcium hydroxide (Ultracal XS®) is recommended by the International Association of Dental Traumatology as the initial medicament following avulsion and replantation for mature teeth. There is experimental evidence to suggest Ledermix®, placed as an alternative inter‐visit dressing may improve periodontal healing. Aim: This study investigated, using a multi‐centre randomized controlled trial, the effect of two root canal medicaments, Ledermix® and Ultracal XS®, on periodontal healing of avulsed and replanted teeth. Material and methods: Children were recruited if they fulfilled all inclusion criteria. Treatment followed a standardized protocol. Assessment of periodontal healing or ankylosis was made clinically and radiographically by an experienced, ‘blinded’, clinician at 12 months. Results: Over 200 patients were assessed for eligibility at five centres. Twenty‐nine patients were eligible for inclusion. Final analysis involved 22 patients with 27 teeth. Ankylosis was detected in four of the 12 teeth in the Ledermix® group and nine of 15 in the Ultracal XS® group. No significant difference between medicaments was found in the proportion of teeth or patients showing periodontal healing. Discussion: There was no significant difference in periodontal healing between the two medicaments at either a tooth or patient level. The numbers recruited fell short of an estimated power calculation. For patients meeting the inclusion criteria and completing the trial, periodontal healing was seen in 52% of teeth at the 12‐month assessment between both groups. The only factor found to significantly influence the periodontal outcome was dry time.
Recurrent pain, stress, tender points and fibromyalgia in childhood: an exploratory descriptive clinical study
Authors: Alfvén Gösta
Published: October 2011

Aims:  To study the occurrence of tender points associated with fibromyalgia and their relationship with the stress‐related pattern of tender points in children with psychosomatic recurrent abdominal pain.

Methods:  In an exploratory descriptive study, 47 children aged 6–17 years with psychosomatic recurrent abdominal pain were examined for tender points associated with fibromyalgia and those associated with stress. The individual scores for these two types of tender point were correlated at inclusion and at follow‐up after treatment.

Results:  At inclusion, all children had a score for stress tender points that was near the maximum. Eight satisfied the diagnostic criteria for fibromyalgia. The scores for stress and fibromyalgia tender points were correlated significantly at both inclusion (R = 0.42, p < 0.005) and follow‐up (R = 0.74, p < 0.00005). At follow‐up, the children who were free of pain had significantly lower scores for stress tender points (p < 0.001) and fibromyalgia tender points (p < 0.00001) than those who were not pain free.

Conclusions:  Children with psychosomatic pain can have an increased risk of developing fibromyalgia. A longer duration of pain and more locations in which pain is felt might increase this risk. In patients with a favourable outcome, the scores for stress tender points and fibromyalgia tender points decreased significantly.
Imaginative interaction with Internet games. For children and teachers
Authors: Hannaford Jeanette
Published: October 2011

This article explores children's imaginative interaction with Internet games in the belief that an understanding of children's life experiences is essential to effective teaching and learning within the classroom. It is underpinned by the idea that imaginative play is, at least in some part, the work of children undertaking identity practice. It focuses on a small group case study of 8‐ and 9‐year‐old children, from diverse cultural backgrounds, who were regular players on free‐access commercial Internet games. As children frequently perform imaginative narrative play both privately and in groups triggered from experiences with novels, films and television, the research initially focused on whether similar activities resulted from experiences with commercially sponsored free Internet game sites. If so, to what extent might these texts also influence children's creative output? To explore this, the children attended a weekly after‐school computer club during which they played on Internet games. During the course of the club sessions, each child was observed and interviewed about the experiences they had resulting from the gameplay. Through consideration of the children's play and opinions, the teacher researcher developed valuable insights into her students and their worlds to the benefit of her practice.
Exposure of Iranian emergency medical technicians to workplace violence: A cross‐sectional analysis
Authors: Rahmani Azad , Hassankhani Hadi , Mills Jane , Dadashzadeh Abbas
Published: October 2011

Objectives: Emergency medical technicians (EMTs) in Iran experience concerning levels of workplace violence, although until now there has been no investigation of this phenomenon. The objectives of the present study were to describe the exposure of Iranian EMTs to workplace violence and to identify the importance of related factors from their viewpoint.

Methods: In this descriptive, exploratory study, 160 EMTs agreed to participate in a survey that collected data regarding their exposure to the following forms of workplace violence: verbal abuse, physical assault, cultural harassment, sexual harassment and sexual assault.

Results: A total of 138 questionnaires were returned, representing a response rate of 86%. The majority of participants 75% (n= 103) experienced at least one form of workplace violence in the 12 months before completing the questionnaire. The most frequently reported form of workplace violence was verbal abuse (71%), followed by physical assault (38%) and cultural harassment (9%). Violence resulting in serious injuries was reported by only 4% of participants, with no more than 8% of participants experiencing workplace violence that included the use of weapons. The most reported response to workplace violence was to ‘invite the offender to calm down’. Participants took this approach because they believed that ‘follow up of workplace violence is ineffectual’ (34%), considered the workplace violence as a common in their job (30%), and did not know whom to report workplace violence to (13%).

Conclusion: Iranian EMTs experience a considerable amount of workplace violence. The present study highlights the recommendation for formal training programmes and clearer protocols about how to manage workplace violence, especially verbal abuse in the Iranian prehospital setting.
Conservation of Hipparchia autonoe (Esper) (Lepidoptera: Nymphalidae), Natural Monument in South Korea
Authors: CHO Youngho , CHOI Deuk‐Soo , HAN Yong‐Gu , NAM Sang‐Ho
Published: October 2011

Hipparchia autonoe, designated Natural Monument no. 458, is a species inhabiting Mt. Halla on Jeju Island, which is the only habitat of H. autonoe in South Korea. Recently, this species is in danger of extinction as the population has been remarkably reduced because its host plants and nectar plants are gradually disappearing due to plant succession in its habitat. On the climbing road of Jeju Island Eorimok, H. autonoe used to be observed at and above 1300 m a.s.l. However, since Sasa quelpaertensis has recently expanded its habitat up to 1400 m, H. autonoe is now observed at and above 1500 m. In Mongolia, the population of H. autonoe seems quite stable as there are dense populations of a host plant and nectar plants. Accordingly it is judged that we can maintain a stable community for support of H. autonoe if we successfully manage the host plant and nectar plant communities by controlling the density of S. quelpaertensis using biological and physical control methods. Comparative analysis of DNA barcode region of COI (658 bp) was done to check the homogeneity and the genetic diversity of H. autonoe collected in Korea and Mongolia. The DNA sequence difference among individuals collected in South Korea was 0.0–0.2%, and in Mongolia 0.0–1.4%. This confirmed a 0.06–1.2% barcoding gap. We believe that this result will provide basic information useful to guide conservation of H. autonoe in South Korea.
MNCs in Central, Southern and Central Europe and the former Soviet Union: investment decisions and the regulation of employment
Authors: Dibben Pauline , Wood Geoffrey , Le Hang , Williams Colin C.
Published: October 2011

This article explores the relationship between the regulation of employment and the decisions of multinational corporations (MNCs) to invest in Central, Southern and Central Europe and the former Soviet Union. Building on La Porta et al.'s work on legal origin, and its assumptions as to the incompatibility of owner and worker rights, the World Bank's Doing Business reports held that countries with stronger protection for worker rights represented poor destinations for investors. However, is it the case that investors are really deterred by employee rights? Our study investigates actual trends in foreign direct investment (FDI) through an analysis of UNCTAD World Investment Reports. We find that the level of individual and collective rights and social security legislation is not significantly associated with FDI.
Future HRM challenges for multinational firms in Eastern and Central Europe
Authors: Horwitz Frank M.
Published: October 2011

This article identifies and evaluates human resource challenges for multinational companies in transitional economies in Central and Eastern European countries. The nature of transitional economies and HRM in post‐socialist societies presents a range of issues. These pertain to the lingering effects of the previous institutional environment and state‐directed political economies that retain influence on the type of HRM practices adopted. Challenges of talent attraction and retention, remuneration systems, diversity and cross‐cultural management are considered.
Self and identity: a brief overview of what they are, what they do, and how they work
Authors: Baumeister Roy F.
Published: October 2011

The human self exists at the interface between the animal body and the social system. Solitary beings would hardly need or have selves, but social and cultural systems define identities, and the human animal acquires selfhood in order to function in these systems. Self begins with the physical body, with acting and choosing as a unity, and as a point of reference distinct from others, and it acquires meaningful content by participating in the social system. The self is not contained in the brain, but rather the human brain learns to operate a self.
The Different Behavior of Rutile and Anatase Nanoparticles in Forming Oxy Radicals Upon Illumination with Visible Light: An EPR Study
Authors: Lipovsky Anat , levitski Luba , Tzitrinovich Zeev , Gedanken Aharon , Lubart Rachel
Published: October 2011

Photoexcited TiO2 has been found to generate reactive oxygen species, yet the precise mechanism and chemical nature of the generated oxy species especially regarding the different crystal phases remain to be elucidated. Visible light‐induced reactions of a suspension of titanium dioxide (TiO2) in water were investigated using electron paramagnetic resonance (EPR) coupled with the spin‐trapping technique. Increased levels of both hydroxyl (˙OH) and superoxide anion (˙O2−) radicals were detected in TiO2 rutile and anatase nanoparticles (50 nm). The intensity of signals assigned to the ˙OH and ˙O2− radicals was larger for the anatase phase than that originating from rutile. Moreover, illumination with visible (nonUV) light enhanced ˙O2− formation in the rutile phase. Singlet oxygen was not detected in water suspension of TiO2 neither in rutile nor in anatase nanoparticles, but irradiation of the rutile phase with visible light revealed a signal, which could be attributed to singlet oxygen formation. The blue part of visible spectrum (400–500 nm) was found to be responsible for the light‐induced ROS in TiO2 nanoparticles. The characterization of the mechanism of visible light‐induced oxy radicals formation by TiO2 nanoparticles could contribute to its use as a sterilization agent.
Riparian field margins: their potential to enhance biodiversity in intensively managed Grasslands
Authors: COLE LORNA J. , BROCKLEHURST SARAH , McCRACKEN DAVID I. , HARRISON WILLIAM , ROBERTSON DUNCAN
Published: October 2011

Abstract.  1. Riparian field margins (i.e. fenced off areas adjacent to watercourses) are becoming widespread in the UK as a means of mitigating diffuse pollution in intensive grasslands. By providing additional habitats for wildlife, they can potentially enhance farmland biodiversity. This study examined a range of riparian margins to determine their impact on invertebrates.

2. Over a 4‐year period, key invertebrates were monitored by pitfall traps at 69 riparian sites in south‐west Scotland. Riparian margins were classified as open margins (i.e. no fence between the field and watercourse), narrow margins (fences erected within 2.6 m of the watercourse) and wide margins (fences erected over 5 m from the watercourse). Pitfall transects were established at each site in the margin and field.

3. Generalised Linear Mixed Models (GLMMs) were used to model the influence of riparian management and vegetation height on invertebrate activity density. Riparian margins closed to livestock (i.e. wide and narrow margins) had the highest activity densities of Hemiptera, Opiliones, Symphyta larvae and Arionidae, and this could not solely be attributed to differences in vegetation height. For most invertebrate groups, activity density did not differ between wide and narrow margins. Only Linyphiidae, predatory coleopteran larvae and Lumbricidae had higher activity densities in the fields than adjacent riparian margins.

4. The erection of fences along watercourses creates habitat heterogeneity in intensively managed grasslands resulting in enhanced invertebrate populations and thus potentially more prey for foliage gleaning birds. Although margin width did not have a significant influence on invertebrate activity density, wider margins provide a greater area of semi‐natural habitat.
Why and How to Fill an Unfilled Proposition
Authors: RICKLESS SAMUEL C.
Published: October 2011

There are two major semantic theories of proper names: Semantic Descriptivism and Direct Reference. According to Semantic Descriptivism, the semantic content of a proper name N for a speaker S is identical to the semantic content of a definite description “the F” that the speaker associates with the name. According to Direct Reference, the semantic content of a proper name is identical to its referent. Semantic Descriptivism suffers from a number of drawbacks first pointed out by Donnellan (1970) and Kripke (1972). Direct Reference faces difficulties of its own, most importantly the problem of empty names. The most promising Directly Referential solution to this problem is the Unfilled Proposition view, according to which utterances of sentences containing empty names semantically express unfilled propositions. But this view faces the problem of accounting for the intuition that negative existentials involving empty names are true. The most promising way of dealing with this problem within Unfilled Proposition theory is to suppose (i) that utterances of sentences may be used to pragmatically convey propositions they do not semantically express, and (ii) that the proposition pragmatically conveyed by a speaker S's utterance of a sentence containing an empty name N (where “the F” is a definite description S associates with N) is identical to the proposition semantically expressed by an utterance of the sentence obtained by replacing N with “the F”. Call this view “Pragmatic Descriptivism”. With respect to the problem of negative existentials, Pragmatic Descriptivists can insist that, although an utterance of “Santa does not exist” is literally neither true nor false, our taking it to be true may be explained as the result of our having confused the unfilled proposition it semantically expresses with the clearly true descriptive proposition it pragmatically conveys. Despite its theoretical virtues, Pragmatic Descriptivism has recently come under fire. Everett (2003), in particular, has advanced four different lines of criticism, to which Adams and Dietrich (2004) have responded in some detail. In this article, I have two main aims. The first is to argue that Adams and Dietrich's replies to Everett's criticisms (with one exception) are ineffective. I conclude that there is no acceptable strategy for solving the problem of empty names within Direct Reference theory. The second is to argue that there is a promising alternative to Semantic Descriptivism and Direct Reference that requires us to fill unfilled propositions with names, thereby solving the problem of empty names.
How Albot0 Finds Its Way Home: A Novel Approach to Cognitive Mapping Using Robots
Authors: Yeap Wai K.
Published: October 2011

Much of what we know about cognitive mapping comes from observing how biological agents behave in their physical environments, and several of these ideas were implemented on robots, imitating such a process. In this paper a novel approach to cognitive mapping is presented whereby robots are treated as a species of their own and their cognitive mapping is being investigated. Such robots are referred to as Albots. The design of the first Albot, Albot0, is presented. Albot0 computes an imprecise map and employs a novel method to find its way home. Both the map and the return‐home algorithm exhibited characteristics commonly found in biological agents. What we have learned from Albot0’s cognitive mapping are discussed. One major lesson is that the spatiality in a cognitive map affords us rich and useful information and this argues against recent suggestions that the notion of a cognitive map is not a useful one.
Introduction to the Topic on Modeling Spatial Cognition
Authors: Gunzelmann Glenn
Published: October 2011

Our ability to process spatial information is fundamental for understanding and interacting with the environment, and it pervades other components of cognitive functioning from language to mathematics. Moreover, technological advances have produced new capabilities that have created research opportunities and astonishing applications. In this Topic on Modeling Spatial Cognition, research crossing a variety of disciplines and methodologies is described, all focused on developing models to represent the capacities and limitations of human spatial cognition.
Experimental investigation of shock metamorphic effects in a metapelitic granulite: The importance of shock impedance contrast between components
Authors: OGILVIE Paula , GIBSON Roger L. , REIMOLD W. Uwe , DEUTSCH Alexander , HORNEMANN Ulrich
Published: October 2011

Abstract–

Shock recovery experiments were performed at 12.5, 25, 34, 40, and 56 GPa at 25 °C, and at 18 and 25 GPa at 400 °C, on a high‐grade, migmatitic, garnet‐cordierite metapelite from the Etivé aureole, Scotland. Objectives for this study were to (1) characterize shock effects in a complex polymineralic rock with a significant proportion of hydrous ferromagnesian minerals, both as a function of variable shock pressure and preshock temperature, and (2) to explore the effects of shock impedance contrast between component minerals on the respective abundances and distribution of these features. At any shock pressure, the order of decreasing intensity of shock metamorphic effects in component phases is: cordierite (Crd)→biotite (Bt)→plagioclase (Pl)→K‐feldspar (Kfs)→quartz (Qtz)→garnet (Grt)→orthopyroxene (Opx). Samples shocked to pressures below 40 GPa (25 °C) were typically characterized by marked heterogeneous distribution of shock effects on both intragranular and intergranular scales. Shock heterogeneity is mainly attributed to shock impedance contrast between contiguous phases, and manifests as shock amplification locally where shock impedance contrast is greatest, and shock suppression where impedance contrast is least. The heterogeneous distribution of shock metamorphic effects in both experiments and natural rocks is a signature of extreme disequilibrium at the submillimeter scale. The heterogeneous distribution of shock metamorphic effects mitigates against the use of shock effects in minerals exclusively as regional shock pressure barometers, and ought to be augmented by additional constraints on shock pressure from numerical models.
Testing an empathy model of guest‐directed citizenship and counterproductive behaviours in the hospitality industry: Findings from three hotels
Authors: Ho Violet T. , Gupta Naina
Published: October 2011

This research proposes and tests an empathy model of guest‐directed discretionary behaviours (i.e., citizenship and counterproductive behaviours) using two studies conducted in three hotels. Building on the two‐stage model of empathic mediation, we examined the mediating role of empathic concern in the relationship between perspective taking and both forms of discretionary behaviours in Study 1. Support for this mediated model was found in relation to citizenship behaviours but not for counterproductive behaviours. Study 2 was conducted to extend these findings using peer reports of discretionary behaviours, and to apply an interactional psychology perspective to predict guest‐directed counterproductive behaviours. We drew upon trait activation theory to highlight the importance of situational triggers, in the form of interpersonal injustice from guests, in moderating the relationship between perspective taking and counterproductive behaviours, mediated through empathic concern. We found support for the hypothesized moderated mediation effect, such that perspective taking inhibited counterproductive behaviours through empathic concern only when interpersonal injustice was high, but not when injustice was low. Replicating the results in Study 1, perspective taking also positively predicted peer‐reported citizenship behaviours, but this was not mediated by empathic concern. Research and practical implications from these findings are discussed.

Practitioner Points

Highlights to organizations in the hospitality industry the importance of perspective taking in generating customer goodwill, through promoting employees' citizenship behaviours towards guests, and in reducing their counterproductive behaviours in instances of guest injustice.

Suggests ways in which organizations can develop employees' perspective taking, such as appointing mentors or role models, providing training programmes to help employees improve their interpersonal skills, and assessing job applicants' trait empathy as part of the selection process.
Spinal inhibition of descending command to soleus motoneurons is removed prior to dorsiflexion
Authors: Geertsen Svend S. , van de Ruit Mark , Grey Michael J. , Nielsen Jens B.
Published: October 2011

Non‐technical summary  The coordination of antagonistic muscle activity starts well in advance of the onset of voluntary movement. We recently demonstrated that antagonist muscle responses evoked by stimulation of the brain were increased prior to voluntary contraction at the ankle. Although our data indicated that this was explained by activation of a subcortical motor program, the neural pathways involved are unknown. Here we probe the transmission in the underlying neuronal networks by peripheral nerve stimulation in order to investigate the neural pathways responsible for this facilitation of antagonist muscle responses. We demonstrate that this stimulation produces a spinal inhibition of the antagonist muscle responses, which is removed prior to voluntary contraction. We propose that the removal of this inhibition might explain the increased antagonist muscle responses prior to voluntary contraction at the ankle. This mechanism might enable the direction of movement to be changed quickly during functional motor tasks such as dribbling.
The Flexural Vibration of Rectangular Orthotropic Plates
Authors: Dickinson S. M.
Published: October 2011

A sine series solution previously used for the study of the flexural vibration of rectangular isotropic plates is extended to apply to the free vibration of orthotropic plates. Application to three particular plates with different support conditions is given and numerical results are presented for two of these examples. Where possible, the numerical results presented are compared with values given by other writers.
Uniaxial Loading in an Elastic Continuum With a Doubly Periodic Array of Material Discontinuities
Authors: Gaonkar G. H.
Published: October 2011

Stress and displacement fields are presented for uniaxially loaded infinite elastic continua with a doubly periodic array of holes, elastic or rigid inclusions with or without overlapping. The results are obtained by using an appropriate form of the finite-element method. When possible, a numerical comparison has been made with known solutions. In the treatment of not previously studied configurations, the convergence is ascertained by observing the trend with finer discretizations.
Response of an Infinite Elastic Medium to Traveling Loads in a Cylindrical Bore
Authors: Parnes Raymond
Published: October 2011

A line load applied along a transverse circle travels in the axial direction along the interior of a circular bore in an infinite elastic medium. The line load has an arbitrary distribution in the angular coordinate along the circumference of the circle and moves with a constant velocity V which is greater than the propagation velocities of the dilatational and equivoluminal waves in the elastic medium. Disregarding initial conditions at far distances, steady-state solutions which do not change in a coordinate system which moves with the velocity V of the moving load are obtained for the stresses and displacements at points in the medium. The components of the applied line loads are expanded into a Fourier series in terms of the angular coordinate. Expressions for the stress and displacement components at points in the medium are derived for each term of the series as a function of the radial distance from the cavity axis and the longitudinal distance behind the wave front. Numerical results are presented for the axisymmetric case for both the stress and displacement components on the cavity boundary. Corresponding results are also given for the case in which the applied boundary tractions have step distributions in the longitudinal direction behind the wave front.
Harmonic Dispersion Analysis of Incremental Waves in Uniaxially Prestressed Plastic and Viscoplastic Bars, Plates, and Unbounded Media
Authors: Williams R. A. , Malvern L. E.
Published: October 2011

The equations governing the propagation of infinitesimal incremental loading stress waves in a medium prestressed uniaxially into the plastic region are derived for a strain-rate-independent and a strain-rate-dependent constitutive equation. These equations, applied to a circular rod, a flat plate, and an unbounded medium, are solved using harmonic analysis to give the phase-velocity dispersion curves for component waves as a function of frequency. The results of this analysis are compared to the corresponding elastic dispersion curves.
On Foulkes Mechanism in Portal Frame Design for Alternative Loads
Authors: Chan H. S. Y.
Published: October 2011

Minimum-weight design of a portal frame for alternative loadings is discussed. A linear programming formulation is used. The concept of Foulkes mechanism as the necessary and sufficient condition for optimum is generalized for this class of problems.
On Stability of a Circulatory System With Bilinear Hysteresis Damping
Authors: Jong I. C.
Published: October 2011

Dynamic stability problems of a two-degree-of-freedom system with bilinear hysteresis damping and subjected to a circulatory force are considered. Steady-state oscillations and critical loads for flutter of the system are investigated using energy considerations and the method of slowly varying parameters. Problems concerning stability limits (limiting values of the critical load) for vanishing hysteresis damping are examined and compared with those found by earlier investigators for vanishing viscous damping. It is shown that, in a circulatory system, small hysteresis damping may have a destabilizing effect similar to linear viscous damping, but the hysteretic model generally yields a satisfactory stability limit as the hysteresis damping effect approaches zero. The viscoelastic model generally leads to unsatisfactory stability limits as the viscous damping effect varies from small values to zero. Thus, the hysteretic model is shown to be more adequate than the viscoelastic model. The study also shows that for some different sets of initial perturbation there may exist two disparate states of steady-state oscillations of the system under the same loading.
Approximate Correction for Unsteady Pressure Differential in a Capillary-Tube Gas Viscosimeter
Authors: van Doren K. R. , Guereca R. A. , Richardson H. P. , Cummins D.
Published: October 2011

Equations are developed which satisfactorily describe the change in the pressure differential with time for a closed, constant-volume system which utilizes a coiled-capillary tube and a constant-rate pump to determine gas viscosities. Viscosities are computed at transient, unsteady, and apparent-steady-state conditions. As long as the flow rates are not too high and the pressure level is not too low, the computed viscosities appear to be reliable.
Mean-Square Response of Simple Mechanical Systems to Nonstationary Random Excitation
Authors: Barnoski R. L. , Maurer J. R.
Published: October 2011

This paper concerns the mean-square response of a single-degree-of-freedom system to amplitude modulated random noise. The formulation is developed in terms of the frequency-response function of the system and generalized spectra of the nonstationary random excitation. Both the unit step and rectangular step functions are used for the amplitude modulation, and both white noise and noise with an exponentially decaying harmonic correlation function are considered. The time-varying mean-square response is shown not to exceed its stationary value for white noise. For correlated noise, however, it is shown that the system mean-square response may exceed its stationary value.
The Buckling of a Column With Random Initial Deflections
Authors: Fraser W. B. , Budiansky Bernard
Published: October 2011

We consider the buckling of an ensemble of infinitely long columns, with initial deflections, resting on nonlinear elastic foundations. The initial deflections are assumed to be Gaussian stationary random functions of known autocorrelation, and the problem is solved by the method of equivalent linearization. We find that each column in the ensemble has the same buckling load that depends only on the autocorrelation of the initial deflection functions. Results are presented for columns whose initial deflection functions have an exponential-cosine autocorrelation.
Influences of Large Amplitudes, Transverse Shear Deformation, and Rotatory Inertia on Lateral Vibrations of Transversely Isotropic Plates
Authors: Wu Cheng-Ih , Vinson J. R.
Published: October 2011

In the present paper, using an improved Reissner’s variational theorem along with Berger’s hypothesis, a set of governing equations which include the effects of transverse shear deformation and rotatory inertia is derived for the large amplitude free vibrations of plates composed of a transversely isotropic material. Applying the possibility of neglecting the rotatory inertia in primarily flexural vibration (discussed in the previous work [1]2), the lateral free vibrations of simply supported plates are treated in detail and the solution is compared with those of previous investigators. The free vibration of beams is studied as a special case of plates, while the small amplitude vibrations are treated as a special case of large amplitude vibrations. The numerical results show that the effect of transverse shear deformation is significant when applying to the plate constructions made of pyrolytic graphite-type materials.
The Physical Meaning of Astatic Equilibrium in Saint-Venant’s Principle for Linear Elasticity
Authors: Berg C. A.
Published: October 2011

When a boundary loading which is not only self-equilibrated but has the additional property that the loading system remains self-equilibrated when all the forces are rotated through an arbitrary angle about their points of application (astatic equilibrium), is applied to a small region of the surface of a linear elastic body, the long range stress field produced by the loading is in general of smaller order (with respect to the radius of the loaded segment of the boundary) than would be the long range stress field produced by a loading system which was merely self-equilibrating but which would not continue to be self-equilibrating if each force were rotated (von Mises [3], Sternberg [6]). The physical distinctions between astatic equilibrium loadings and merely self-equilibrated loadings, and the physical reasons why astatic equilibrium loadings produce smaller long range stresses, are examined. It is pointed out that astatic equilibrium loadings always produce zero mean deformation in a linear elastic body and that, therefore, if a small volume element, in the neighborhood of a small patch of the boundary surface subject to astatic equilibrium loading were considered as an isolated body, this small volume would undergo no mean deformation and would be easier to fit back into the main body than if it had been subject to merely self-equilibrated loading which would have caused mean deformation.
General Instability of Inclined-Stiffened Cylinders Under Bending
Authors: Lee R.-L. , Lu S. Y.
Published: October 2011

The effects of inclination of stiffeners on the instability of pressurized cylinder under pure bending is studied. The stiffeners are mounted at various angles from 0–90 deg with the longitudinal direction. Finite deflection and initial imperfections in the strain-displacement relations are considered. The Ritz method is used for the solution. Tests have been made applying pure bending at the ends of shells with stiffeners inclined at 30, 45, and 60 deg. Empirical data are plotted to compare with the numerical results.
Exact Transient Response of an Elastic Half Space Loaded Over a Rectangular Region of Its Surface
Authors: Norwood F. R.
Published: October 2011

The response of an elastic half space to a normal impulsive loading over one half and also over one quarter of its bounding surface is considered. By a simple superposition the solution is obtained for a half space loaded on a finite rectangular region. In each case the solution was found to be a superposition of plane waves directly under the load, plus waves emanating from bounding straight lines and the corners of the loaded region. The solution was found by Cagniard’s technique and by extending the real transformation of de Hoop to double Fourier integrals with singularities on the real axis of the transform variables. Velocities in the interior of the half space are given for arbitrary values of Poisson’s ratio in terms of single integrals and algebraic expressions.
Multiple Scattering of Elastic Waves by Parallel Cylinders
Authors: Cheng S. L.
Published: October 2011

The formal solution resulting from the scattering of a plane, time-harmonic, compressional elastic wave impinged on a group of parallel circular cylindrical inclusions in a finite domain is obtained. The inclusions are rigid as well as immovable and the geometry of their configuration is arbitrary. The technique of “multiple scattering” which was developed in acoustic and electromagnetic wave propagation is applied. The stress field around two identical circular cylindrical inclusions at a finite separation is studied in detail.
On the Axisymmetric Vortex Flow Over a Flat Surface
Authors: Schwiderski E. W.
Published: October 2011

The numerical study of the interaction of a potential vortex with a stationary surface recently published by Kidd and Farris [1] is extended through a transformation of the boundary-value problem to Volterra integral equations. The new calculations verified the results by Kidd and Farris and improved the bounds of the critical Reynolds number Nc, beyond which no self-similar vortex flows exist, to 5.5 < Nc < 5.6 The breakdown of the self-similar motions develops through an instability in the lower boundary layer, which is indicated by two inflection points in the tangential velocity profile. At the critical Reynolds number the lower inflection point reaches the surface and indicates the beginning of boundary-layer separation in the wake-type flow. If the Stokes linearization is applied, one arrives at a new Stokes paradox. However, this “paradox” can be resolved by correcting the free-stream pressure distortion of the Stokes approximation. The new slow-motion approximation is nonlinear and yields an integral which is also free of the Whitehead paradox. The properties of the new exact solution confirm the novel flow features previously detected in almost self-similar motions, which were constructed by adjustable local boundary-layer approximations.
Lower Bound to the nth Eigenvalue of the Helmholtz Equation Over Two-Dimensional Regions of Arbitrary Shape
Authors: Pnueli David
Published: October 2011

A method is presented to compute a lower bound to the nth eigenvalue of the Helmholtz equation over two-dimensional regions. The shape of the regions is arbitrary and only their area need be known.
Non-Darcy Flow Through Fibrous Porous Media
Authors: Beavers G. S. , Sparrow E. M.
Published: October 2011

Experiments are performed to explore the flow characteristics of porous media having the form of a latticework of metallic fibers. Five such media are investigated, four among which share the characteristic that there are no free fiber ends within the medium. The operating conditions of the experiments extend over a wide range of velocities greater than those for Darcy flow, but permeabilities deduced from the data are applicable to the Darcy regime. It is shown that for all the investigated media, the axial pressure gradient is representable as the sum of two terms, one linear in the velocity (viscous contribution) and the second quadratic in the velocity (inertia contribution). The flow-pressure characteristics for the structurally similar porous media are representable by a single dimensionless expression wherein the square root of the permeability is used as the characteristic dimension. Significant departures from Darcy’s law first occur at Reynolds numbers on the order of one; similar values of the Reynolds number are known to mark the termination of the regime of viscous unseparated flow about spheres and cylinders. This accord lends further support to the use of the square root of the permeability as the characteristic dimension.
Discrete Dislocation Model of a Fatigue Crack Under Shear Loading—Part 1
Authors: Swenson D. O.
Published: October 2011

Fatigue crack propagation in most engineering materials has an initial stage of crack propagation, commonly designated Stage 1. Stage 1 cracks initiate and propagate from slip lines on the crystallographic planes of both polycrystal and single crystal alloys. A Stage 1 crack is usually thought to propagate solely by local shear stresses. A computer model of a crack and its plastic zones is developed. The positions of a series of dislocations are calculated in order that their combined stresses satisfy equilibrium equations and crack boundary conditions. The range of the crack tip displacement per loading cycle, which appears to be the best model for incremental crack growth, is independent of the mean stress value for mean stress greater than one-half the maximum stress and the stress range small. For all mean stress levels a minimum stress range is predicted by this program below which the cyclic tip displacement is zero.
Higher-Order Theories for Structural Analysis Using Legendre Polynomial Expansions
Authors: Soler A. I.
Published: October 2011

Governing equations of plane elasticity are examined to define suitable approximate theories. Each dependent variable in the problem is considered as a series expansion in Legendre polynomials; attention is focused on establishment of a logical approach to truncation of the series. Important variables for approximate theories of any order are established from energy considerations, and the desired approximate theories are established by direct reduction of the field equations and also from an energy viewpoint. A new “classical” beam theory is developed capable of treating displacement boundary conditions on lateral surfaces. Higher-order approximate theories are studied to make certain comparisons with exact solutions; the results of these comparisons indicate that the new method yields approximate theories which may be more accurate than previous theories with similar levels of approximation.