Automating abstraction functions

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 109-119).Data abstraction has been the dominant structuring paradigm for programs for decades. The essence of a data abstraction is the abstraction function, which relates the concrete program representation to its abstract meaning. However, abstraction functions are not generally considered to be a part of the executing program. We propose that making abstraction functions an executable part of the program can enable programmers to write clearer and more concise programs with fewer errors. In particular, we show that the object equality and hashing operations (which programmers are required to write), can often be expressed more clearly and more concisely in terms of the abstract state of the object. Getting these methods right has proven to be difficult for programmers at all skill levels, from novice through expert. In a case study of the standard Java libraries we show that rewriting the code with explicit declarative abstraction functions (and generating equality and hashing methods automatically) removed object-contract compliance faults previously found by Pacheco et al. To make abstraction functions part of the executing program we develop four techniques for the dynamic evaluation of abstraction functions written in a declarative first-order logic with relations and transitive closure. We observe that the abstraction functions programmers write in practice may often be viewed as navigation queries on the heap, and two of our techniques exploit this insight to synthesize executable code from declarative abstraction functions. The performance of our research prototype is within striking distance of hand-written code.by Derek F. Rayside.Ph.D

Jaw exercises in the treatment of masticatory myofascial pain : efficacy, patients’ views and dentists’ experiences

The main aim of this thesis was to gain better knowledge concerning different aspects of jaw exercises in the treatment of masticatory myofascial pain. Special emphasis was directed towards efficacy and cost-effectiveness of jaw exercises as well as patients’ views and dentists’ experiences. In study I the general practicing dentists (GPDs) self-perceived level of knowledge, attitudes and clinical experience in treatment of temporomandibular disorders (TMD) was investigated through a web-based questionnaire. The questionnaire was based on an earlier postal questionnaire study from 2001 and it was sent to all GPDs in the Public Dental Health service, Uppsala in 2010 and 2014. The cross-sectional follow-up study design and high response rate allows for comparison of data over time. In study II and III the patients’ experiences of jaw exercises in the treatment of masticatory myofascial pain were investigated both in a qualitative and a quantitative way. To gain a deeper understanding of the patients’ experiences, 10 patients were interviewed in a semi-structured manner according to an interview guide with 10 domains. Both open-ended and follow up questions were used to encourage the patient to reflect and freely comment on the different themes. The interviews were then transcribed, and the text material was arranged and analysed through systematic text condensation (STC). The data from the qualitative interviews were then used to construct a quantitative postal questionnaire that was sent to 150 consecutive patients with masticatory myofascial pain in order to check if the data could be generalized to a larger population. In study IV the opinions of an international group of 14 TMD experts concerning jaw exercises in the management of TMD were investigated. A Delphi method was used where the experts, anonymous to each other, were asked to respond to statements in a web-based questionnaire according to a five-item verbal Likert scale that ranged from “Strongly agree” to “Strongly disagree”. The questionnaire was answered in different rounds and the experts received a compilation of the other experts’ responses in relation to their own answer after each round. The process was repeated until consensus was reached or a stability in answers between rounds was seen. Finally, in study V the efficacy and cost-effectiveness of jaw exercises in the treatment of masticatory myofascial pain were studied in a randomized controlled trial (RCT) that included 97 patients. Jaw exercises were compared to occlusal appliance and no treatment (waiting-list patients). The primary outcome variable was reduction of pain intensity on a visual analogue scale (VAS 0-100 mm). The results from 2010 and 2014 showed that the GPDs (n=91 and n= 82, respectively) felt more insecure concerning TMD diagnostics, therapy decisions and treatment of TMD in children/adolescents compared to adults. The GPDs reported a high need for orofacial pain/TMD specialists and a majority of the respondents wanted the specialists to offer continuing education in TMD. The reported frequency of taking a case history of facial pain and headache increased between 2010 and 2014. In 2014, the GPDs were more secure and reported higher frequency of good clinical routines in treatment of children/adolescents with jaw exercises and pharmacological intervention compared to 2001. Interocclusal appliance was the treatment with which most dentists felt confidence and reported good clinical routines. In the process of analysing the qualitative data of the interview study (study II), four main themes were identified: Patient adherence, Symptoms, Treatment and Participation. Some informants suspected serious disease behind their symptoms. Jaw exercises were reported to reduce pain and physical impairment. To do the jaw exercises in conjunction with an already established routine was reported to be important to enhance adherence. Some of the patients also emphasized that they wanted to continue with the jaw exercises and that they felt safe and secure that they had tools to tackle the problems themselves if the symptoms should return. The follow-up postal questionnaire study (study III) showed that all these results could be generalized to a larger population of patients with masticatory myofascial pain. The international expert panel (study IV) came to consensus that jaw exercises are effective in the treatment of myalgia in the jaw muscles and in increasing mouth opening capacity due to hyperactivity in jaw-closing muscles and disc displacement without reduction. The patients should always be instructed in an individualized jaw exercise program and also receive both verbal advice and written information about the treatment modality. Even though jaw exercises might aggravate TMD-pain in some cases, the experts considered the treatment to be without any major adverse effects. The RCT (study V) showed that jaw exercises, compared to no treatment, significantly reduced pain intensity, headache and consumption of analgesics in patients with masticatory myofascial pain. Jaw exercises were also shown to be more cost-effective than occlusal appliance with lower over-head cost, fewer appointments and a lower mean treatment time. In conclusion, this thesis has shown that general practicing dentists seem to be more insecure concerning treatment with jaw exercises in children/adolescents compared to adults, but their confidence with the treatment increased over time. Patients with jaw myalgia experience that jaw exercises is an effective treatment for TMD and international orofacial pain/TMD experts recommend jaw exercises for treatment of jaw myalgia, reduced mouth opening and disc displacement without reduction. Finally, jaw exercises reduce jaw myalgia, headache and the need for analgesic medication (in the short term) and is a cost-effective treatment compared to occlusal appliance therapy