Bone-to-bone and implant-to-bone impingement : a novel graphical representation for hip replacement planning

Bone-to-bone impingement (BTBI) and implant-to-bone impingement (ITBI) risk assessment is generally performed intra-operatively by surgeons, which is entirely subjective and qualitative, and therefore, lead to sub-optimal results and recurrent dislocation in some cases. Therefore, a method was developed for identifying subject-specific BTBI and ITBI, and subsequently, visualising the impingement area on native bone anatomy to highlight where prominent bone should be resected. Activity definitions and subject-specific bone geometries, with planned implants were used as inputs for the method. The ITBI and BTBI boundary and area were automatically identified using ray intersection and region growing algorithm respectively to retain the same ‘conical clearance angle’ obtained to avoid prosthetic impingement (PI). The ITBI and BTBI area was then presented with different colours to highlight the risk of impingement, and importance of resection. A clinical study with five patients after 2 years of THA was performed to validate the method. The results supported the study hypothesis, in that the predicted highest risk area (red coloured zone) was completely/majorly resected during the surgery. Therefore, this method could potentially be used to examine the effect of different pre-operative plans and hip motions on BTBI, ITBI, and PI, and to guide bony resection during THA surgery

A simple version and extension of Arrow’s Theorem in the Edgeworth Domain

This paper presents an Arrow-type result which can be simply demonstrated to hold within the standard domain of welfare economics: in the (m×n) Edgeworth Box, a best allocation must assign all goods to a single individual. Allowing the Social Welfare Function to take account of envy-freeness, or other related constructions, does not significantly resolve this problem.Arrow; Social Welfare Function; Edgeworth Box; Envy-Freeness.

Copyright

Copyright is the branch of Intellectual Property Law that governs works of expression such as books, paintings and songs, and the expressive aspects of computer programs. Intellectual products such as these have a partially public goods character: they are largely inexhaustible and nonexcludable. Intellectual Property Law responds to inexcludability by giving producers legal rights to exclude nonpayers from certain usages of their intellectual products. The goal is to provide incentives for new production at fairly low transaction costs. However, the copyright owner will charge a price above marginal cost and this, coupled with the inexhaustibility of most copyrighted products, creates deadweight loss. Various copyright doctrines (such as the idea/expression dichotomy, the limited duration of the copyright ownership term and the doctrine of ‘fair use’) work to reduce deadweight loss and other costs within a larger structure that creates incentives. Copyright Law, unlike Patent Law, gives owners rights only against those who actually copy the work. This limitation, too, may serve to reduce both transaction costs and deadweight loss. Empirically it is unclear how successful copyright has been in creating incentives for production, reducing transaction costs and keeping deadweight costs low

Stability and equilibrium in decision rules: an application to duopoly

This paper analyses an indefinitely-repeated Cournot duopoly. Firms select simple dynamic decision rules which, taken together, comprise a first-order linear difference equation system. A boundedly-rational objective function is assumed, by which the firm’s payoff is its profit at the point of convergence, if any. Stable Nash equilibria are characterised and located in output space, stability in this context being equivalent to subgame-perfection. Comparable results are derived for a conventional discounted-profit objective function, where this equivalence does not hold, but where stability may nevertheless be of intrinsic interest. In either context, stability is incompatible with joint profit maximisation.

Nonpathogenic Free-Living Amoebae in Arkansas Recreational Waters

Selected recreational waters of Arkansas were sampled for pathogenic free-living limax amoebae. Water quality parameters were determined for correlation with amoebic population densities and species diversity. Cultural criteria and animal inoculation revealed no pathogenic strains. The possibility of introduction and/or induction of pathogenic amoebic strains by environmental factors requires further ecological investigations

Class Certification and the Substantive Merits

The United States Supreme Court, in its 1974 decision, Eisen v. Carlisle & Jacquelin, held that judges should not conduct a preliminary inquiry into the merits of a suit as part of the decision whether to certify a class. The federal courts have struggled ever since to honor Eisen\u27s bar while still conducting a credible certification analysis-a task complicated by the fact that merits-related factors are often relevant to Rule 23 requirements. The result is a muddled body of case law in which courts tend to certify generously and avoid inquiring into the merits of substantive issues even when those issues are crucial to the certification analysis. This approach creates high social costs by inviting frivolous and weak class action suits. This Article argues that the Eisen rule should be abolished. Trial judges should assess competing evidence, not just allegations, and should evaluate case strength whenever the specific requirements of Rule 23 call for an inquiry into merits-related factors. For example, a party relying on a substantive issue to show commonality or predominance should have to demonstrate a likelihood of success on the issue. The Article also goes further and recommends that judges always conduct a preliminary inquiry into the merits before certifying a class, regardless of whether merits-related factors are directly relevant to a specific requirement of Rule 23. The Article first reviews the history of the Eisen rule and surveys the current state of the law, before turning to a policy analysis of the rule\u27s effects. The policy discussion criticizes the traditional arguments and then offers a systematic evaluation of error and process costs. Error costs must be evaluated in light of the extremely high probability of postcertification settlement. Eisen\u27s liberal approach creates a substantial risk of erroneous certification grants that cannot be corrected later when a case settles. This risk coupled with the high likelihood of settlement invites frivolous and weak class action suits. The result is a serious error-cost problem with regard to certification. At the same time, requiring a merits review at the certification stage increases the risk of erroneous certification denials. But for several reasons this risk is not likely to increase dramatically, and the associated costs are not likely to be large. The net result therefore supports a merits inquiry, and this conclusion remains valid even after process costs are added to the policy mix

Understanding Ohio Soils

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Factors relating to boundaries and self-disclosure within mental health contexts

Section A: Presents a systematic literature review synthesising and critiquing the evidence-base surrounding the use, and impact of therapist self-disclosure in cross-cultural therapy contexts with clients from ethnic minority groups. The review found that as well as mirroring the use and impact of therapist self-disclosure in more generalised therapy contexts, therapist self-disclosure was used to invite conversations about therapists’ and clients’ cultural or ethnic differences and identities. This included therapists using self-disclosure to validate clients’ experiences of racism or oppression and assert their commitment to an anti-racist stance. Risks to therapist self-disclosure within cross-cultural contexts are discussed, and findings and clinical implications are considered in the context of developing therapist cultural competency. The review found that studies had some methodological limitations (such as relying predominantly on self-report methods), and future research should further explore self-disclosure as the mechanism of change, and other possible therapist and client intersecting, or mediating factors. Section B: Presents a grounded theory study exploring how case-managers in Early Intervention in Psychosis Services (EIPS) develop their understanding and practice around navigating boundaries. EIPS are a unique service model, in which an assertive outreach approach is adopted. Case-managers employ flexible boundaries to meet clients in the community and support them towards recovery and holistic goals. Current boundary theory is therefore not easily applied to this clinical context. Participants were 13 EIPS case-managers. Semi-structured interviews with participants were analysed using grounded theory. A concentric model emerged, defining different layers of influence impacting case-managers navigation of boundaries. The model also depicted how case-managers navigated boundaries with clients over time. This model adds to current boundary theory outside of therapy contexts, and can be used as a tool in clinical practice to guide clinicians’ thinking and reflection around boundaries within EIPS. Other relevant clinical and research implications are discussed