Dissociated screw dislocation which can relieve strain energy in the epitaxial layer of GeSi on Si(001)

A dissociated screw dislocation parallel to the interface was found in the epitaxial layer of the Ge0.17Si0.83 Si(001) system. It is shown that this dissociated screw dislocation which consists of two 30 degrees partials can relieve misfit strain energy, and the relieved misfit energy is proportional to the width of the stacking fault between the two partials.

Aetiology of Hip dislocation

Written by the surgeons of the Exeter Hip Team and their colleagues from around the world, this book describes 40 years of innovation and development with cemented hip replacement. Topics covered include the basic science behind successful cemented hip replacement, modern surgical techniques and recent advances. There is also extensive coverage of the revision techniques developed at Exeter and elsewhere, focussing on femoral and acetabular impaction grafting. Each chapter is a self-contained article with an emphasis, where appropriate, on practical techniques and surgical tips, supported by line drawings and intra-operative photographs.

Going beyond ‘misfit’ as a reason for ERP package customisation

In an attempt to deal with the potential problems presented by existing information systems, a shift towards the implementation of ERP packages has been witnessed. The common view, particularly the one espoused by vendors, is that ERP packages are most successfully implemented when the standard model is adopted. Yet, despite this, customisation activity still occurs reportedly due to misalignment between the functionality of the package and the requirements of those in the implementing organisation. However, it is recognised that systems development and organisational decision-making are activities influenced by the perspectives of the various groups and individuals involved in the process. Thus, as customisation can be seen as part of systems development, and has to be decided upon, it should be thought about in the same way. In this study, two ERP projects are used to examine different reasons why customisation might take place. These reasons are then built upon through reference to the ERP and more general packaged software literature. The study suggests that whilst a common reason for customising ERP packages might be concerned with functionality misfits, it is important to look further into why these may occur, as there are clearly other reasons for customisation stemming from the multiplicity of social groups involved in the process.

Alternate destinies for survey items destined for the island of misfit toys: An analysis of teachers' perceptions of NAPLAN

This is a methodological paper describing when and how manifest items dropped from a latent construct measurement model (e.g., factor analysis) can be retained for additional analysis. Presented are protocols for assessment for retention in the measurement model, evaluation of dropped items as potential items separate from the latent construct, and post hoc analyses that can be conducted using all retained (manifest or latent) variables. The protocols are then applied to data relating to the impact of the NAPLAN test. The variables examined are teachers’ achievement goal orientations and teachers’ perceptions of the impact of the test on curriculum and pedagogy. It is suggested that five attributes be considered before retaining dropped manifest items for additional analyses. (1) Items can be retained when employed in service of an established or hypothesized theoretical model. (2) Items should only be retained if sufficient variance is present in the data set. (3) Items can be retained when they provide a rational segregation of the data set into subsamples (e.g., a consensus measure). (4) The value of retaining items can be assessed using latent class analysis or latent mean analysis. (5) Items should be retained only when post hoc analyses with these items produced significant and substantive results. These suggested exploratory strategies are presented so that other researchers using survey instruments might explore their data in similar and more innovative ways. Finally, suggestions for future use are provided.

Evolution of multivariant microstructures with anisotropic misfit: A phase field study

We study, in two dimensions, the effect of misfit anisotropy on microstructural evolution during precipitation of an ordered beta phase from a disordered alpha matrix; these phases have, respectively, 2- and 6-fold rotation symmetries. Thus, precipitation produces three orientational variants of beta phase particles, and they have an anisotropic (and crystallographically equivalent) misfit strain with the matrix. The anisotropy in misfit is characterized using a parameter t = epsilon(yy)/epsilon(xx), where epsilon(xx) and epsilon(yy) are the principal components of the misfit strain tensor. Our phase field, simulations show that the morphology of beta phase particles is significantly influenced by 1, the level of misfit anisotropy. Particles are circular in systems with dilatational misfit (t = 1), elongated along the direction of lower principal misfit when 0 < t < 1 and elongated along the invariant direction when - 1 <= t <= 0. In the special case of a pure shear misfit strain (t = - 1), the microstructure exhibits star, wedge and checkerboard patterns; these microstructural features are in agreement with those in Ti-Al-Nb alloys.

A large orthotropic plate with misfit pin under arbitrarily oriented biaxial loading

The problem of misfit (interference or clearance) pin in a large orthotropic plate was solved earlier by the authors for biaxial loading in the principal directions of orthotropy. Here, a more general case of arbitrarily oriented loading is considered. The most important aspect of the problem studied is the partial contact at the pin-hole interface. The solution is obtained by extending the use of ‘inverse technique’ which was successfully applied earlier by the authors to problems of pins in isotropic and orthotropic domains. The loss of symmetry because of the arbitrary orientation of loading makes the problem more complex. Additional parameters are then involved in the inversion of the problem for the solution. Numerical results are presented primarily for a smooth interference fit pin in a typical orthotropic plate.

Impression creep of zinc and the rate-controlling dislocation mechanism of plastic flow at high temperatures

The impression creep behaviour of zinc is studied in the range 300 to 500 K and the results are compared with the data from conventional creep tests. The steady-state impression velocity is found to exhibit the same stress and temperature dependence as in conventional tensile creep with the same power law stress exponent. Also studied is the effect of indenter size on the impression velocity. The thermal activation parameters for plastic flow at high temperatures derived from a number of testing techniques agree reasonably well. Grain boundary sliding is shown to be unimportant in controlling the rate of plastic flow at high temperatures. It is observed that the Cottrell-Stokes law is obeyed during high-temperature deformation of zinc. It is concluded that a mechanism such as forest intersection involving attractive trees controls the high-temperature flow rather than a diffusion mechanism.

Phase field study of precipitate growth: Effect of misfit strain and interface curvature

We have used phase field simulations to study the effect of misfit and interfacial curvature on diffusion-controlled growth of an isolated precipitate in a supersaturated matrix. Treating our simulations as computer experiments, we compare our simulation results with those based on the Zener–Frank and Laraia–Johnson–Voorhees theories for the growth of non-misfitting and misfitting precipitates, respectively. The agreement between simulations and the Zener–Frank theory is very good in one-dimensional systems. In two-dimensional systems with interfacial curvature (with and without misfit), we find good agreement between theory and simulations, but only at large supersaturations, where we find that the Gibbs–Thomson effect is less completely realized. At small supersaturations, the convergence of instantaneous growth coefficient in simulations towards its theoretical value could not be tracked to completion, because the diffusional field reached the system boundary. Also at small supersaturations, the elevation in precipitate composition matches well with the theoretically predicted Gibbs–Thomson effect in both misfitting and non-misfitting systems.

Dislocation after total hip replacement: there is no such thing as a safe zone for socket placement with the posterior approach

Introduction Malorientation of the socket contributes to instability after hip arthroplasty but the optimal orientation of the cup in relation to the pelvis has not been unequivocally described. Large radiological studies are few and problems occur with film standardisation, measurement methodology used and alternative definitions of describing acetabular orientation. Methods A cohort of 1,578 patients from a single institution is studied where all patient data was collected prospectively. Risk factors for patients undergoing surgery are analysed. Radiological data was compared between a series of non-dislocating hips and dislocating cases matched 2:1 by operation type, age and diagnosis. Results The overall dislocation rate for all 1,578 cases was 3.23% but the rate varied according to the type of surgery performed. The rate in uncomplicated primary cases was 2.4% which increased to 9.3% for second stage implantation for a two stage procedure for infection. There was no significant difference in the variability of the dislocating and non-dislocating groups for either inclination (p = 0.393) or anteversion (p = 0.661). Conclusions A “safe zone” for socket orientation to avoid dislocation could not be defined. The cause of dislocation is multifactorial, re-establishing the anatomic centre of rotation, balancing soft tissues and avoidance of impingement around the hip are important considerations.

Mies, talli ja moottoripyörä : Etnografinen tutkimus Misfit MC:stä ja bikerkulttuurin eetoksesta

Tutkimuksen punaisena lankana kulkee kysymys siitä, millainen on bikerkulttuurin eetos? Miten se on syntynyt, miten sitä ylläpidetään ja miten Misfit MC:n jäsenet sitä tulkitsevat ja toteuttavat omassa elämässään? Tarkastelen eetosta kahdenlaisen aineiston valossa. i) Kenttätyöllä (vuosina 1995-1998 ja 2000-2001) kerätyn aineiston valossa tarkastelen yhtä pääkaupunkiseudulla toimivaa HD-moottoripyöräkerhoa, vuonna 1989 toimintansa aloittanutta Misfit MC:tä. Jäsenet kutsuvat kerhoaan useimmiten talliksi, joskus pajaksi, kerhoksi tai klubiksi. Puhuessaan tallista, miehet voivat viitata kerhorakennukseen ("tuut sä tallille?") mutta myös ryhmään ("meidän talli") ja sen olemassaoloon ajallisesti ja paikallisesti. Aloittaessani kenttätyön vuonna 1995 Misfit MC:n kuului kymmenen 25-30-vuotiasta miestä. ii) Kenttätyöllä kerätyn aineiston lisäksi käytän materiaalia, joka koostuu Harley-Davidson-moottoripyörän ympärille rakentuneen bikerkulttuurin historiasta ja kulttuurituotteista, kuten kertomuksista, elokuvista, musiikista, kuvataiteesta ja moottoripyörälehdistä. Aineiston avulla valotan bikerkulttuurin eetoksen syntyä, alkuvaiheita, leviämistä ja keskeisiä elementtejä. Lähdeaineiston monimuotoisuus ja runsaus palautuu kenttätyöhöni jolloin vakuutuin siitä, että tutkimusmatka bikerkulttuurin historiaan, perinteisiin ja median välittämiin (mieli)kuviin on välttämätöntä, sillä menneisyys ja Harrikkaan ajan kuluessa varastoituneet merkitykset vaikuttavat ja ovat vahvasti läsnä Misfit MC:n toiminnassa ja talliin kuuluvien miesten elämäntyylissä. Tutkimus etenee seuraavanlaisesti. Luku I on Johdanto. Luvussa II Etnografia käsittelen etnografisen tiedon luonnetta niin tutkimusasenteena kuin kenttätyön valossa. Pohdin kenttätyötä ja sen suhdetta etnografian kirjoittamiseen eli miten kenttätyöllä kerätty aineisto muuntuu etnografiseksi monografiaksi. Käsittelen myös kenttätyöni reunaehtoja, kuten tyttöystävyyden ja sukupuolen merkitystä, ja tarkastelen tutussa kulttuurissa tehdyn kenttätyön ominaispiirteitä. Reunaehtojen kuvailu toimii myös johdatuksena bikerkulttuuriin sellaisena kuin se ilmenee Misfit MC:n tallielämässä ja käytänteissä. Lopuksi pohdin "tiheän kuvauksen" mahdollisuuksia ja vaateita aineistoni puitteissa. Luvussa III Bikerkulttuurin eetosta kartoittamassa, kuvailen Harley-Davidson-moottoripyörän ympärille rakentuneen elämäntavan syntyä, levittäytymistä ja keskeisiä elementtejä. Tarkastelen media- ja populaarikulttuurisia tekstejä (elokuvien kertomat tarinat, musiikkikappaleiden sanoitukset ja HD- ja bikerlehtien artikkelit) ja kuvia (elokuvien audiovisuaaliset aspektit, kuvataide ja HD- ja bikerlehtien kuvitus), jotka ovat vaikuttaneet bikerkulttuurin eetokseen. Luvun keskeisiä - aineistosta nousevia ja miessukupuoleen vahvasti sidoksissa olevia - käsitteitä ovat biker, outlaw ja chopper, jotka ovat bikerkulttuurissa säilyneet alkuperäisessä muodossa maantieteellisestä tai kielialueesta riippumatta. Luvussa IV Misfit MC ja bikerkulttuurin eetos temaattinen painopiste siirtyy Suomeen ja Misfit MC:hen. Aluksi käyn läpi suomalaisen bikerkulttuurin muotoutumista ja ominaispiirteitä. Alkukappaleiden jälkeen keskityn Misfit MC:n jäsenten elämäntyylin sävyihin ja heidän käsityksiinsä bikerkulttuurin eetoksesta. Analyysin kiintopisteitä ovat Misfit MC:n jäsenten näkemys bikeriydestä ja tallitoiminnasta, miesten elämäntyylin moraaliset ja esteettiset sävyt, tallirakennus miesyhteisöllisyyttä ja bikerkulttuurin eetosta luovana ja ylläpitävänä sosiaalisena tilana ja Misfit MC miesten yhteisönä. Luvussa V Eetoksen ytimessä: mies ja Harley-Davidson keskityn bikerkulttuurin ytimeen: miehen ja Harley-Davidson-moottoripyörän väliseen suhteeseen. Luvun alussa esittelen ruotsalaisen yhteiskuntatieteilijä Lars Lagergrenin moottoripyörään soveltamaa työkalu - leikkikalu - toteemi - välittäjä -typologiaa ja tarkastelen moottoripyörän olemusta sukupuolittavana ja sukupuolittuvana artefaktina. Johdanto-osion jälkeen siirryn kuvailemaan Misfit MC:n jäsenten suhdetta Harley-Davidson-moottoripyörään. Lähestyn miesten ja moottoripyörien suhdetta kahden toiminnan - moottoripyörän kunnostamisen ja rakentamisen sekä moottoripyörällä ajamisen - kautta. Avainsanat: aineellinen kulttuuri, arvot, biker, bikerkulttuuri, chopper, eetos, elämäntapa, etnografia, Harley-Davidson-moottoripyörä, Harley-Davidson-moottoripyöräkerho, kenttätyö, maskuliinisuus, mieskulttuuri, mieskuva, moottoripyöräily, osakulttuurit, outlaw, populaarikulttuuri, sukupuoliroolit, yhteisöt

Amorphization by dislocation accumulation in shear bands

Microcrystalline γ-Y2Si2O7 was indented at room temperature and the deformation microstructure was investigated by transmission electron microscopy in the vicinity of the indent. The volume directly beneath the indent comprises nanometer-sized grains delimited by an amorphous phase while dislocations dominate in the periphery either as dense slip bands in the border of the indent or, further away, as individual dislocations. The amorphous layers and the slip bands are a few nanometers thick. They lie along well-defined crystallographic planes. The microstructural organization is consistent with a stress-induced amorphization process whereby, under severe mechanical conditions, the crystal to amorphous transformation is mediated by slip bands containing a high density of dislocations. It is suggested that the damage tolerance of γ-Y2Si2O7, which is exceptional for a ceramic material, benefits from this transformation.

Grain boundary sliding during diffusion and dislocation creep in a Mg-0.7 pct Al alloy

Early studies on grain boundary sliding (GBS) in Mg alloys have suggested frequently that the contribution of GBS to creep is high even under conditions corresponding to dislocation creep. The role of creep strain and grain size in influencing the experimental measurements has not been clearly identified. Grain boundary sliding measurements were conducted in detail over experimental conditions corresponding to diffusion creep as well as dislocation creep in a single-phase Mg-0.7 wt pet Al alloy. The results indicated clearly that the GBS contribution to creep was Very high during,, diffusion creep at low stresses (similar to 75 pct) and substantially reduced during dislocation creep at high stresses (similar to 15 pct). These measurements were consistent with the observation of significant intragranular slip band activity observed in most grains at high stresses and very little slip band activity at low stresses. The experimental measurements and analysis indicated also that the GBS contribution to creep was high during the initial stages of creep and decreased to a steady-state value at large strains.

Primary Dislocation of the Patella : A Clinical Study

A total of 177 patients with primary dislocation of the patella (PDP) were admitted to two trauma centers in Helsinki, Finland during 1991 to 1992. The inclusion criteria were: 1. Acute (≤14 days old) first-time lateral dislocation of the patella. 2. No previous knee operations or major knee injuries. 3. No ligament injuries to be repaired. 4. No osteochondral fractures requiring fixation. 50 patients were excluded. 30 of these excluded patients would have met the inclusion criteria, 19 patients received treatment by consultants not involved in the study, 7 refused to participate and 4 had an erroneous randomization. 127 patients including, 82 females, were then randomized to have either tailor-made operative procedure (group O) or conservative treatment (group C). The aftercare was similar for both groups. The mean age of the patients was 20 (9-47) years. All patients were subjected to analysis of trauma history (starting position and knee movement during the dislocation), examination under anesthesia (EUA) and arthroscopy. 70 patients (52 females) were randomized by their odd year of birth to operative group O and 57 patients (30 females) by their even year of birth to conservative group C. The diagnosis of PDP was based on locked dislocation in 68 patients, on dislocatability in EUA in 47 patients, and on subluxation in EUA combined with typical intra-articular lesions in 12 patients. In group O, 63 patients had exploration of the injuries on the medial side of the knee and tailor made reconstruction added with lateral release in 54 cases. The medial injury was operated by suturing in 39 patients, by duplication in 18 patients and by additional augmentation of the medial patellofemoral ligament (MPFL) with adductor magnus tenodesis in 6 patients. 7 patients, without locking in trauma history and only subluxation in EUA had only lateral release for realignment. In adductor magnus tenodesis the proximal end of the distal tendinous part was rerouted to the upper medial border of the patella. In the conservative group C, the treatment was adjusted to the extent of patellar displacement in EUA. Patients with dislocation in EUA had 3 weeks’ immobilization with the knee in slight flexion. Mobilization was started with a soft patellar stabilizing orthosis (PSO) used for additional three weeks. The patients with subluxation in EUA wore an orthosis for six weeks. The aftercare was similar in group O. The outcome was similar in both groups. After an average of 25 (20-45) months´ follow-up, the subjective result was better in group C in respect of the mean Hughston VAS knee score (87 for group O and 90 for group C, p=0.04, visual analog scale), but similar in terms of the patient’s own overall opinion and the mean Lysholm II knee score. Recurrent instability episodes occurred in 18 patients in group O and in 20 patients in group C. After an average of 7 (6-9) years´ follow-up, the groups did not show statistical difference either in respect of the patient’s own overall opinion, or the mean Hughston VAS and Kujala knee scores. The proportions of stable patellae was 25/70 (36%) in group O and 17/57 (30%) in group O (p=0.5). In a multivariate risk analysis, there was a correlation between low Kujala score (<90) as dependent parameter and female gender (OR: 3.5; 95% CI: 1.4-9.0), and loose body on primary radiographs (OR: 4.1; 95% CI: 1.2-15). Recurrent instability correlated with young age at the time of PDP (OR: 0.9; 95% CI: 0.8-1.0/year). Girls with open tibial apophysis had the worst prognosis for instability (88%; 95% CI: 77-98). The most common mechanisms in trauma history of the patients were movement to flexion from a straight start (78%) and movement to extension from a well-bent start (8%). Spontaneous relocation of the patella had taken place in 13/39 of girls, in 11/21 of boys, in 26/42 of women and in 17/24 of men with skeletal maturity of the tibia. The dislocation in EUA was non-rotating in 96/126 patients followed by outward rotating dislocation in 14/126 patients. Operative treatment policy in PDP is not recommended. Locking tendency of the patella in PDP depended on the skeletal maturation. Recurrence rate after PDP was higher than expected.

Dislocation dynamics in alpha titanium Dynamique des dislocations dans le titane alphaVersetzungsdynamik in alpha-Titan

The activation area and activation enthalpy are determined as a function of stress and temperature for alpha titanium. The results indicated that plastic flow below about 700°K occurs by a single thermally activated mechanism. Activation area determined by differential-stress creep tests falls in the range 80−8b2 and does not systematically depend on the impurity content. The total activation enthalpy derived from the temperature and strain-rate dependence of flow stress is 1.15 eV. The experimental data support a lattice hardening mechanism as controlling the low-temperature deformation in alpha titanium.